GoldenMotor.com Forum
General Category => General Discussions => Topic started by: DirtyGinge on May 25, 2011, 07:16:51 AM
-
Mark, did you mention lipo ?
Biggest problem I find with lipo is its eagerness to catch fire !!.......really easy to puncture/damage etc...should be alright thought in a metal case :D
When I get paid ;)
-
Ginge - here's a useful n00b lipo thread http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=19956
how to set it up, avoid fire (caused by overcharging)and bricking cells (caused by over using) - some useful info in there if you go down that route let us know how you get on (and take pics !)
seeing like these lipo batteries are cheap and lighter than Lifepo4 they pack a mean punch but at a cost of fire risk, setting up, maintaining and all the other overheads. It's only for experts it would seem...
-
Mark, did you mention lipo ?
Biggest problem I find with lipo is its eagerness to catch fire !!.......really easy to puncture/damage etc...should be alright thought in a metal case :D
When I get paid ;)
Lol Yes I did happen to mention Lipo once or twice! ;D
A lot of the guys on ES seem to have great faith in it these days, and it's even starting to appear in laptops, I think one oif the thinkpads can charge to 80% in 30 mins, I'm sure it could be done in 5 but I bet they are playing it safe!
I think they are safe enough and most problems were from over charge or discharge! But yeah, don't puncture it lol ;D
Mark
-
Ginge - here's a useful n00b lipo thread http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=19956
how to set it up, avoid fire (caused by overcharging)and bricking cells (caused by over using) - some useful info in there if you go down that route let us know how you get on (and take pics !)
seeing like these lipo batteries are cheap and lighter than Lifepo4 they pack a mean punch but at a cost of fire risk, setting up, maintaining and all the other overheads. It's only for experts it would seem...
I'm still waiting for Hobby King to get the batteries!
I'll take pics when I get it all up and running which could be a few weeks yet!
Mark
-
Yup, been working with it a lot at work recently......fully charged lipo with a small tear, and its run for the door with battery in hand.......
Regarding your old pie, whats the max continuous you used to run at with your infineon ?
-
HAHA stop trying to scare me! ;D
Max continuous was about 40 amps, I can't remember what the peak was!
But as I said many times before, the current drops of quickly once up to speed, though of course very long steep hill climbs saw 40 amps being sucked from the battery, poor ping! ;D lord knows what the phase currents were, but I think it's usually 2-2.5 times the battery current!
Mark
-
Not trying to scare you buddy, I know you know what youre at ;)...btu no, actually happened a lot....we had a fault with faulty batch of batteries failing at 14C, but fine at room temp...had to do a lot of dissasembly of casings etc for batch codes, then began a fight with the manufacturer
Nothing at all to do with ebikes though :)
-
Haha you mean, you hope I know what I'm at ;D
They weren't hobby king batteries were they? What batteries were they?
-
Some how the Hobby King LiFePo4 batteries are lighter and smaller them from other manufacturers... I dont' know why...
As for the performance, they put 30C limit on the continuous current - pretty good! And price is very cheap...
So, there is the catch?
P.S. the come without BMS, just with wires from the cells for proper balancing...
-
yep, the idea is that your charger does the balancing
Nope, not hobbyking, polaroid as it goes.....
Truth is ( as the industry knows) , currenntly the only way to increase the watts per kilo is to decrease the insulation ( safety margin)
Ive dropped my li-ion before....scared me a little, but had it been lipo, would have dived out the window :)
-
"the idea is that your charger does the balancing" - but what's about the discharge control?
Do the regular BMS manage the cells while the discharge? I mean, do the BMS protect the cells from the voltage drops when they are over-discharged?
What's purpose of the BMS while the battery is discharging?
-
"the idea is that your charger does the balancing" - but what's about the discharge control?
Do the regular BMS manage the cells while the discharge? I mean, do the BMS protect the cells from the voltage drops when they are over-discharged?
What's purpose of the BMS while the battery is discharging?
If one cell's voltage drops too low the bms shuts off the battery to prevent that 1 cell from being destroyed!
There is not yet a good solution to LiPo bms afaik?
usually with LiPo you get cell monitors that sound an alarm to notify you that one cell has gone too low!
Mark
-
Recently I've got LiFePo4 batteries from HobbyKing - 4 batteries of 4S2P 4200mA each one, connected them in serial and got a single pack of 48V4.2Ah just to try it.
In fact, with continuous current of 15A (30A in peaks), I would able to run with my bike for just about 2-3km on the flat - that's all.
The pack was without BMS.
After I came home and checked the original battery packs, then I realized what the first cell (one, which is connected with its negative pole to the "battery ground") in each pack was over-discharged to about 1.5V-1.9V. Rest of the cells were discharged to just 3.1V. And this phenomena I met in each pack!
Is everybody know why this phenomena happened? Is it a common to happen?
In fact, just because the cells were not discharged identically and one cell was discharged deeply, the whole package shut down! frustration...
But, this pack was without BMS...
May the same thing happen with batteries with BMS.
As for me, BMS should manage discharging of the cells as well as charging.
-
If several equal cells were charged and balanced to the same voltage, why one of them should be discharged faster than others?
Why the BMS don't balance cells while the discharge process? If so, the battery might be more effective and don't shut down itself just because one over-discharged cells. If BMS manage discharge currents from the cell, then voltage drops on the all cells will be equal. This would allow to increase the battery life time (at least to increase an effective discharged capacity).
Am I wrong? If not, why nowadays BMS do not do so?
-
In other devices I also paid attention that the battery, which are connected in serial, do not discharged equivalently.
Does anybody know why?
-
If the cells are perfectly matched, they will normally discharge at approximately the same rate.
I use 5000mAh Turnigy LiPo packs and the cell voltages always seem to stay nice and even.
When I put them on charge after use, the cells are usually within ±0.01V of one another, both at the beginning of the charge and at the end of it.
I'm guessing that when the packs are assembled at the factory, the individual cells are matched up with similar cells.
One of my original packs was faulty, so I dismantled it and removed the faulty (Puffed up and low voltage) cell, converting it from a 3s to a 2s pack.
(http://www.arhservices.co.uk/GoldenMotor/Lipo1.JPG)
The individual cells each had a sticker with two numbers on, and the cell I removed was marked 5300 and 5338 (see attachment below).
I don't know whether they test each cell twice, or whether one is the discharge capacity and the other is the amount taken to fully recharge it, but presumably these figures are used to allow all the cells in each pack to be matched as closely as possible.
Alan
-
a lot of accidents happen after a deep discharge and then charge...same with li-ion ....
I know we are all heading that way in a couple of years.... Time to man up I guess :)
still, I don't use bms on my li-ion , no problems if you are careful
-
A bms is good for people who are not knowledgeable about cell voltages, or for people who couldn't car less, or for people who just want simple worry free plug in and forget!
However I've learned that you do not need a bms at all, while out on a ride get a few of these, one for each pack
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4654;image)
You have to set the low voltage alarm so you know it's time to back off on the throttle or even to shut off the controller altogether.
Some bms also add another 100-200 Euros to the price of the batteries and they don't have a very good reliability record, though I had no issues with my Ping bms!
LiPo is definitely the best in the business for E-Bikes as they pack some energy and can discharge very high C from a very small pack, LiFeP04 can't begin to touch it! Sure A123 make good cells but they can't offer the high discharge and charge rates of LiPo and they are very expensive! You can make a cheap 16ah 44 volt pack for around 330 U.S.D.
Then there is around 100 U.S.D for shipping to Europe, and maybe the same for other countries.
44 volts is plenty for my geared motor but not so for pie users who would need 60+ volts for decent speed! But the beauty of LiPo is I can change my pack from 16ah to 8ah for short trips or cycles that I want to exercise, I can dump the extra weight, you can't do that with a 20ah ping! And the 8ah pack will weigh only 2.5 kgs or the 16ah 5.5. 32ah 44V LiPo would weigh around the same as a 20ah Ping!
The cost of the charger and power supply can add another 150-200+ depending on how fast you want to charge. My Icharger setup will be capable of charging at around 20 amps, and should charge my 16ah pack in just under an hour, of course you can charge much faster than that but it get's damn expensive and besides 1 hour is plenty fast, much better than 4 hours for a 48V 20ah ping with a 5 amp charger!
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image)
And power supply
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4658;image)
Of course you could use a bulk charger and disconnect the ping bms and charge it much faster and use it's normal bms for discharge or to balance now and then, though I never had a balance issue with the ping and the lights always came on within 1-2 mins of each other!
Faster charging LiPo gets expensive, and it's the power supply that's the most expensive, you can pay up to 350 U.S.D for a meanwell 24V 1500watt P.S.U and I think many people in the U.S and Canada have problems after that on 120AC mains!
You can be lucky to find a power supply cheap on e-bay used, or new. SOme guys even bulk charge with just the meanwell, they seem to be the best out there!
Say my pack would be 49.44 volts charged, going by 4.15 ish seems to be the agreed maximum voltage to extend the life of LiPo to some say 800+ cycles! So you set your meanwell to 49.44 volts and it will limit the current when the desired voltage is reached!
That way of charging is usually done after a few cycles to make sure all the cells are closely matched because you will be charging without balancing and balancing is not necessary most of the time if you don't bring your pact to lvc all the time!
It's the easiest way to charge, because for my Icharger I'll have to break my pack's series packs into parallel to charge while it monitors the cells, no big deal really, but you could get a cheap 10 amp meanwell for charging while out on the road without the need to bring the Icharger along!
I know it may seem daunting for those used to plug in and forget ;D but once you do your research and pay attention to your wiring you will be fine. I'm still waiting for my batteries! :'(
-
ok so why didn't it put the pics where I wanted to??? ???
-
now they are where I want them to be, and there is 3 at the bottom. wtf? ;D
-
As for the CellLog, it's able to monitor up to 6 cells only (for LFP 3.3V*6=19.8V). So, for 48V battery you would need four LogCells (one for each pack of 13.2V=33.V*4). The price of one LogCell is about $13 + $2 for a proper connector with wires. Finally you will pay about $60 and lot of headache just for monitoring cells while riding... Isn't better to buy BMS for the same price from Chinese manufacturers + $40 for postage? Conclusion: if you value your headache less than $40 then stay with CellLogs. If not - switch to BMS!
P.S. sorry for the rude tone, if you find it so - it was not my intention...
-
ok so why didn't it put the pics where I wanted to??? ???
Mark, when you attach a picture from your computer, it just puts them at the bottom of your post as an attachment.
You can insert the image within your post by copying the URL of the attachment and pasting it inside the image tags, but this can only be done after you have posted and the attachments uploaded, which is what I have already done with your post. ;)
To insert an image within your post from another website or image hosting site like Photobucket etc., you simply copy the URL of the image and paste inside the image tags like this:
[img]https://cdn-global-hk.hobbyking.com/media/catalog/product/cache/1/image/660x415/17f82f742ffe127f42dca9de82fb58b1/1/8/189966.jpg[/img]
and the image will be displayed like this:
(https://cdn-global-hk.hobbyking.com/media/catalog/product/cache/1/image/660x415/17f82f742ffe127f42dca9de82fb58b1/1/8/189966.jpg)
You can also link to a full size image by putting the reduced image inside a hyperlink as shown in the first example below.
To reduce the size of large images you must specify either a height or width (in pixels), or you can even distort the picture by specifying both the required height and width measurements:
[url=http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image]
[acronym=Click to see full size image]
[img width=200]http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image[/img]
[/acronym]
[/url]
The above code would normally be a single line of code.
I have separated the lines to stop them from disappearing off the screen, and it should also make it easier to understand.
[img height=200]http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image[/img]
[img height=300 width=100]http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image[/img]
[img height=100 width=600]http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image[/img]
and this is the result:
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image) (http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image)
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image;image)
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image)
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=3302.0;attach=4656;image)
I hope this hasn't confused you too much. ;)
Alan
-
haha Thanks Alan, that is very helpful! ;D
-
As for the CellLog, it's able to monitor up to 6 cells only (for LFP 3.3V*6=19.8V). So, for 48V battery you would need four LogCells (one for each pack of 13.2V=33.V*4). The price of one LogCell is about $13 + $2 for a proper connector with wires. Finally you will pay about $60 and lot of headache just for monitoring cells while riding... Isn't better to buy BMS for the same price from Chinese manufacturers + $40 for postage? Conclusion: if you value your headache less than $40 then stay with CellLogs. If not - switch to BMS!
P.S. sorry for the rude tone, if you find it so - it was not my intention...
A bms doesn't mean that your cells won't get damaged if it fails, and you are paying 100-200 U.S.D for a good bms anyway!
A lot of people had big problems with bms for LiPo, and yes the initial investment is a lot, but for high power use, LiFeP04 will cost a lot more, and you probably won't be able to charge as fast, + it weighs a lot more also!
If you want a cheap LiFeP04 plug in and forget, for 1C or 2C max, then ping is your man, however his batteries are rated for 1C and so are most batteries available, now push a ping to 2C and you will get a lot less charge discharge cycles.
GM batteries are not cheap, and can't dish out more than 1C either without effecting their life.
If you want to draw more than 1C continuous then LiPo is is the best out there at the moment.
For instance, many people want a 10 ah battery because it's small and light, but you can't pull more than 10 amps, that's 1C, with LiPo you can pull 30 C+ that's 300 amps continuous and completely over rated for E-Bike use, but will be a lot easier on the battery. You can even get cheaper 15 C batteries, only disadvantage is the charge rates really!
With lipo you can buy more batteries as you get more money and add to the pack for higher voltage or capacity or both, with a ready made LiFeP04 you cant!
If you want to go on a short ride you can split the pack or add it again for longer rides. Charge LiPo to 4.1v and you will nearly double the cycle life, according to some experts in the RC community and on the ES forum!
-
As for the CellLog, it's able to monitor up to 6 cells only (for LFP 3.3V*6=19.8V). So, for 48V battery you would need four LogCells (one for each pack of 13.2V=33.V*4). The price of one LogCell is about $13 + $2 for a proper connector with wires. Finally you will pay about $60 and lot of headache just for monitoring cells while riding... Isn't better to buy BMS for the same price from Chinese manufacturers + $40 for postage? Conclusion: if you value your headache less than $40 then stay with CellLogs. If not - switch to BMS!
P.S. sorry for the rude tone, if you find it so - it was not my intention...
The CellLog actually handles up to 8 cells:
(http://www.hobbyking.com/hobbyking/store/catalog/CellLog-8M.jpg) (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10952)
so you would only require two of these to monitor every cell in a 16 cell pack.
The other alternative for LiPo packs is a simple battery monitor:
(http://www.hobbyking.com/hobbyking/store/catalog/batt-monitor-4S.jpg) (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7225)
but these can only monitor each LiPo pack voltage rather than individual cells (unless you use one per cell) but are much better than receiving no warning whatsoever and risk ruining a perfectly good LiPo pack.
I have both of the above devices, but I tend only to use the basic battery monitor most of the time as I don't tend to run my packs anywhere near empty, but it does have a very loud warning device which can be handy if you forget to disconnect the pack. ;)
It may be cheap and cheerful, but it certainly does the job for me.
Alan
-
For instance, many people want a 10 ah battery because it's small and light, but you can't pull more than 10 amps, that's 1C, with LiPo you can pull 30 C+ that's 300 amps continuous and completely over rated for E-Bike use, but will be a lot easier on the battery. You can even get cheaper 15 C batteries, only disadvantage is the charge rates really!
The Turnigy Nano-tech pictured in a prevoius post can supply 45C (225Amps) continuous with bursts of up to 90C (450Amps).
I'm currently using the cheap and cheerful 20C packs which can produce 100Amps continuous and bursts of 150 Amps., but as Mark has already mentioned, the charge rate is limited to 2C (10 Amps) which is fine for my 7Amp charger, but not really enough for high regen currents if you are using a small 5Ah pack.
This is not a problem with the Turnigy Nano-tech packs, as they have a much higher charge rate, this 6Ah pack can safely be charged at 30Amps, which is more current than I've ever managed to get from regen:
(http://www.hobbyking.com/hobbyking/store/catalog/N6000.4S.25.jpg) (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11940)
My Icharger setup will be capable of charging at around 20 amps, and should charge my 16ah pack in just under an hour, of course you can charge much faster than that but it get's damn expensive and besides 1 hour is plenty fast, much better than 4 hours for a 48V 20ah ping with a 5 amp charger!
Sorry to burst your bubble Mark, but your charger has a maximum charging output of 350Watts, so unless you're only charging 4 cells at a time, the current will be much lower (nearer 10.5 Amps for an 8 cell pack) so expect an hour and a half at least for a fully discharged pack.
My Imax B8 (7Amp charger) can only manage 5.4Amps on seven cells (150Watt) and I'm using a 14V 20Amp (280Watt) power supply.
Two chargers is one option for faster charging, provided you can split the pack in two, but you will definitely need a heavy duty power supply to power them. ;)
Alan
-
It's a 15V 23 amp charger Alan?
That was the charger recommended intheir specs?
And I thought it would charge all 8 cells @20 amps?
Though I'm only using 6S and I'll be parallel charging
Mark
-
o00scorpion00o wrote: "With lipo you can buy more batteries as you get more money and add to the pack for higher voltage or capacity or both, with a ready made LiFeP04 you cant!"
Really? Can you explain why? Or just go over the Ping's site and he will explain how to connect its LFP4 battery packs (with BMS) is serial as well as in parallel.
Any comments?
-
Alan, where can I buy this basic battery monitor, which you mentioned in your post above? What's its voltage range? Is it programmable?
you wrote: "very loud warning device which can be handy if you forget to disconnect the pack" - don't you disconnect it at all from the battery? What's its power consumption (my guess it's just a leakage...)?
-
Bikemad, you wrote: "but not really enough for high regen currents"
So, how high are the regen currents usually? Do they depend just on the motor or both the controller and motor? Please tell more...
-
Alan, you wrote: "Two chargers is one option for faster charging"
Do you connect the chargers in parallel? Do you put diodes between them?
-
o00scorpion00o wrote: "With lipo you can buy more batteries as you get more money and add to the pack for higher voltage or capacity or both, with a ready made LiFeP04 you cant!"
Really? Can you explain why? Or just go over the Ping's site and he will explain how to connect its LFP4 battery packs (with BMS) is serial as well as in parallel.
Any comments?
Okay let me rephrase!
You can parallel 2 ping batteries sure, however it will cost you more to do it that way initally, where as with LiPo or indeed even hobby king's LiFeP04 batteries you can buy the smaller 5 ah batteries and keep adding until you have the capacity that meets your demands!
But most of all you will be getting 30C instead of 1C rated batteries, which is much better if you want to use a smaller 10 ah pack but you pull or want to pull more than 10 amps from the battery!
I hope that makes sense?
Mark
-
Alan, where can I buy this basic battery monitor, which you mentioned in your post above? What's its voltage range? Is it programmable?
you wrote: "very loud warning device which can be handy if you forget to disconnect the pack" - don't you disconnect it at all from the battery? What's its power consumption (my guess it's just a leakage...)?
All the info for the cell log
http://epbuddy.com/index.php?main_page=product_info&cPath=30_8&products_id=27
You leave it connected to the battery while riding your bike and disconnect when not using it!
-
Bikemad, you wrote: "but not really enough for high regen currents"
So, how high are the regen currents usually? Do they depend just on the motor or both the controller and motor? Please tell more...
You can set the regen on some controllers, but you can get 20 amps or more regen current depending on your speed and the hill you are going down! That's why your batteries need to be able to take it!
And for connecting, for instance 2 Ichargers, you can use 2 separate power supplies to power 2 chargers or 1 power supply provided it's rated for 2 chargers!
And you simply parallel your packs, if you have 2 packs and 2 chargers that's fine, if you have 4 packs and 2 chargers you gust parallel 2 packs balance and power leads to 1 charger and the other 2 packs to the 2nd charger!
But really buying 1 decent charger is more than enough, and just parallel all your packs to the 1 charger!
-
"you gust parallel 2 packs balance and power leads to 1 charger" - how can you do so? the balance lines as well as power leads in separate packs have different voltages (at least 0.1V will have)! As for me, I use a special board to connect them in parallel while charging...
-
"you gust parallel 2 packs balance and power leads to 1 charger" - how can you do so? the balance lines as well as power leads in separate packs have different voltages (at least 0.1V will have)! As for me, I use a special board to connect them in parallel while charging...
You only parallel charge (afaik) I'm still learning about LiPo also, if the cells are not very out of balance. Parallel charging will still sense if a cell is over charged and adjust accordingly.
You can parallel charge as many packs as you want!
Mostly though if you keep within the specs of LiPo you should not need to balance charge very often, though I would still connect all the balance leads, just in cast 1 cell decides to go over!
I think 0.1 volts is acceptable between some cells, probably even a little more, though I stand to be corrected on that!
-
if so, you can just make the cells in different packs be in parallel by connection its balance wires... But way do you disconnect them while discharge? Why not to leave them connected forever?
-
As for the CellLog, it's voltage range is up to 44VDC, but I need up to 52VDC at least
-
if so, you can just make the cells in different packs be in parallel by connection its balance wires... But way do you disconnect them while discharge? Why not to leave them connected forever?
Afaik, voltage still travels through the balance wires and one battery may try charge another that way and it might not be good!
And you will need the balance wires connected to the cell monitor!
You need a cell monitor for 52 volts? Right, the cell monitor will monitor up to 8 cells for up to 44 volts each pack, for instance you want 52 volts? well the closest in LiPo is 12S for 49 volts charged!
So you connect 2 x 6S packs to give you 44 volts nominal or 49 volts charged!
In other words 2x 6S 8ah packs in series for 44 volts and another 2 in series then wired for parallel to give 16ah
That's 4 batteries that's 4 cell monitors? make sense?
I suggest you check out the endless sphere forum, there is endless information there on LiPo, oir any battery from much more experienced people than I.
But I hope I am of some help!
Mark
Mark
-
It's a 15V 23 amp charger Alan?
That was the charger recommended in their specs?
And I thought it would charge all 8 cells @20 amps?
Though I'm only using 6S and I'll be parallel charging
Mark, I presume it's the power supply that's 15V 23Amp (345Watt).
The icharger 208B pictured in your earlier post has the following printed on the case:
Charge: 0.05-20A(350W max)
Basically, the maximum current is limited to 20Amps, but as the maximum charger output is 350Watts, the current will be reduced if the pack voltage exceeds 17.5V
If a five cell pack has been discharged to 3.5V per cell, the pack voltage will be 17.5V.
So your charger would begin charging at ~20Amps and be producing the maximum Wattage (17.5V x 20Amp = 350Watts).
As the pack voltage increases during the charge, the current will automatically reduce to stay within the 350W max output.
At 4.0V per cell the current will have fallen to 17.5A, and at 4.2V per cell it would be down to 16.7Amps.
If a six cell pack has been discharged to 3.5V per cell, the pack voltage will be 21V, so it would commence charging at ~16.7Amps.
At 4.0V per cell the current will have fallen to 14.58A, and at 4.2V per cell it would be down to 13.88Amps.
When the charger reaches the maximum preset pack voltage, the current will slowly start to decrease as less current is required to keep the pack voltage at its maximum. This gradual wind down takes almost 20 minutes on my 7 cell 10Ah pack (see attached graph) and noticeably extends the charging time.
The attached graph shows a maximum current of 5.2Amps (my charger has a 150Watt limit) and 1.2Ah being put back into a partially used 10Ah pack. If the charger was able to put all of the 1.2Ah back in at a continuous rate of 5.2Amps it would only take 13 minutes 50 seconds, but this gradual current wind down extends the charge time to almost 25 minutes (and a balance charge extends it considerably more).
Hopefully you will be able to understand why a 350 Watt output cannot charge an 8 cell pack at 20 Amps.
In order to produce 33.6 Volts (8 x 4.2V) @ 20 Amps you would require 672 Watts, but your charger will only supply 10.42 Amps (33.6V x 10.42A = 350W).
Alan
-
I think what you are saying is that I should have got a 24 V power supply then?
The Charger itself has a 4-32 volt input range!
I think I understand, so I set my charger to charge each cell to 4.1 V to per long battery life. 4.1 x 6S =24.6 volts.
So the charger has a max of 350 watts charge, meaning 24V divide by 350 = 14.22 amps! Yeah I think I got that. I never thought about that!
Now I will set the balance to fast so that should speed things up a bit + by charging to 4.1 should help keep the cells in balance anyway. There is an option on the Icharger to stop charging when the total voltage reaches whatever you want so that would be 24.6 volts and not balance charge at all, provided the cells are closely matched to begin with.
To be honest I would probably leave the balance wires connected all the time on fast balance, as it will still probably charge plenty fast for me anyway!
Some guys don't balance at all if they are pretty closely balanced to begin with!
I can always find a meanwell charger on E-Bay when I get the cash together again. I intent to bulk charge so as not to have to break my pack down to parallel charge. So I would need a 48 V meanwell adjusted to 49.2 Volts and maybe 1500 watts, that's 30 amps charge! :o
For now though I would still be happy with 14 amps charge!
-
o00scorpion00o wrote: "With lipo you can buy more batteries as you get more money and add to the pack for higher voltage or capacity or both, with a ready made LiFeP04 you cant!"
Really? Can you explain why? Or just go over the Ping's site and he will explain how to connect its LFP4 battery packs (with BMS) is serial as well as in parallel.
Any comments?
Alan, where can I buy this basic battery monitor, which you mentioned in your post above? What's its voltage range? Is it programmable?
you wrote: "very loud warning device which can be handy if you forget to disconnect the pack" - don't you disconnect it at all from the battery? What's its power consumption (my guess it's just a leakage...)?
Bikemad, you wrote: "but not really enough for high regen currents"
So, how high are the regen currents usually? Do they depend just on the motor or both the controller and motor? Please tell more...
Alan, you wrote: "Two chargers is one option for faster charging"
Do you connect the chargers in parallel? Do you put diodes between them?
"you gust parallel 2 packs balance and power leads to 1 charger" - how can you do so? the balance lines as well as power leads in separate packs have different voltages (at least 0.1V will have)! As for me, I use a special board to connect them in parallel while charging...
if so, you can just make the cells in different packs be in parallel by connection its balance wires... But way do you disconnect them while discharge? Why not to leave them connected forever?
Dmitryl I think it's fair you start paying poor Alan $2 for his responses :D Have you bought a Magic Pie yet!!???
DID SOMEONE MENTION LIPOOOOOO!!!!!!!!!!!!!!!!!!@!@!@!!@??????????
lol
-
HAHAH
I might have mentioned LiPO once or twice!
LiPo! ;D
-
Alan, where can I buy this basic battery monitor, which you mentioned in your post above? What's its voltage range? Is it programmable?
you wrote: "very loud warning device which can be handy if you forget to disconnect the pack" - don't you disconnect it at all from the battery? What's its power consumption (my guess it's just a leakage...)?
Dmitryl, you can purchase these from HobbyKing (http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?idCategory=409), but they are not adjustable and are meant for LiPo packs (not LiFePO4).
They are available for 1-6s packs.
I use a 6s version to monitor my 7s pack by simply connecting it across 6 cells using the balance lead. As my cells are always closely matched, it is good enough for me. ;)
I always connect my battery monitor/warning device to my pack before I connect the pack to the bike, and I usually remove the pack with my Turnigy watt meter and the battery monitor still connected, and it stays like this until I have chance to enter the details from the watt meter into my spreadsheet.
As I don't always do this straight away, it's reassuring to know that the battery monitor will alert me before the pack discharges low enough to cause permanent damage, just in case I'm distracted and completely forget what I was doing.
Once everything has been disconnected from the packs power leads, I finally unplug the monitor from the balance lead.
Its current consumption is ~17mA.
Alan
-
Alan,
you can adjust cell monitors voltage alarm range can't you?
And they can monitor up to 8S.
Mark
-
you can adjust cell monitors voltage alarm range can't you?
I can't remember offhand what parameters are adjustable, but you can check out the PDF manual attached to this post (http://goldenmotor.com/SMF/index.php?topic=3057.msg18431#msg18431) for full details.
Alan
-
Cheers Alan! :)
-
if so, you can just make the cells in different packs be in parallel by connection its balance wires... But way do you disconnect them while discharge? Why not to leave them connected forever?
If the packs are identical and are going to be charged and discharged in parallel, there is no reason why the balance leads should need to be disconnected.
I mainly use a 25.9V 7S2P 10Ah pack made up of 2 x 3S 5Ah and 2 x 4S 5Ah, and this pack is permanently connected on both the power leads and the balance leads, apart from when I have to disconnect the balance leads to reconfigure it to a 51.8V 14S1P pack.
Failure to disconnect the balance leads usually causes big sparks and melted connectors when you attempt to connect the power leads in series while the balance leads are still paralleled! ;)
I made up a simple balance board connector unit using Veroboard that allows me to connect the balance leads of up to 8 LiPo packs (4 x 3S and 4 x 4S) for simultaneous balanced charging. This board has a separate balance lead (made from balance lead extentions (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9737)), which is needed for balanced charging and monitoring the cells, without having to disturb any of the balance leads from the individual packs.
Here are some photos of my setup showing how it all goes together:
(https://i.imgur.com/SDSEWvv.png)
The completed balance board:
(http://www.arhservices.co.uk/GoldenMotor/BB2.JPG)
Fitted and connected to four battery packs (with connectors for four more packs):
(http://www.arhservices.co.uk/GoldenMotor/BB3.JPG)
Power cable "Y" adapter to connect both 7S packs together in parallel:
(http://www.arhservices.co.uk/GoldenMotor/Adapter.JPG)
Here's the complete pack ready to use, but without any physical protection:
(http://www.arhservices.co.uk/GoldenMotor/connectors.JPG)
Home made gender changers are required to allow the watt meter to be reversed for monitoring the pack's charging capacity instead of just its discharge capacity.
(http://www.arhservices.co.uk/GoldenMotor/Deans-1.JPG)
Watt meter is fitted in normal direction to measure consumed current etc.
The Simple battery monitor device plugged into the balance lead at the top of the picture beeps very loudly if the pack voltage falls too low during use.
I unplug this when the battery is not being used to prevent it from slowly discharging the pack while it sits unused.
(http://www.arhservices.co.uk/GoldenMotor/Batterypack.JPG)
This adapter/extension lead converts 1 x 3S and 1 x 4S to 1 x7S plug to suit the charger:
(http://www.arhservices.co.uk/GoldenMotor/Chargelead.JPG)
My charging setup, shown without the usb lead that I use for monitoring on the PC using LogView (http://www.logview.info/cms/e_logview_info.phtml).
(http://www.arhservices.co.uk/GoldenMotor/Charging.JPG)
The pack is tucked inside a Jiffy bag, which is taped inside a cardboard box before being placed into the foam padded pannier for added shock absorption, and it seems to be protected well enough to cope with all the punishment I've subjected it to so far!
(http://www.arhservices.co.uk/GoldenMotor/PanierPack.JPG)
(http://www.arhservices.co.uk/GoldenMotor/PanierPack2.JPG)
And this is the ideal result for a properly balanced 7S LiPo pack pack after a full charge:
(http://www.arhservices.co.uk/GoldenMotor/chargedcells.JPG)
I must apologise to anyone who is trying to read this post using a dial up connection instead of broadband.
Alan
-
Nice set up Alan! (http://i1192.photobucket.com/albums/aa336/o00scorpion00o/sSig_goodjob2.gif)
I think if you wanted to monitor each cell, then you would need to disconnect from parallel because 1 cell could go bad and you wouldn't know it?
-
I think if you wanted to monitor each cell, then you would need to disconnect from parallel because 1 cell could go bad and you wouldn't know it?
When one cell fails (or starts to fail), it usually affects the cell/s paralleled to it, and this should show up as a noticeably lower reading on one group of cells.
If this happened, it would be easy to separate the packs to locate the faulty cell.
As long as my cell readings continue to be within ±0.01V of each other when the discharged pack is first put on charge, I'm pretty confident that the cells are all good. ;)
Alan
-
Hi Chaps
Great thread.....informative :)......
Whats the average weight on 20ah worth of 48V lipo ?
-
Hi Chaps
Great thread.....informative :)......
Whats the average weight on 20ah worth of 48V lipo ?
6.2 KG for 8x 5ah 6S Zippy 30C for 44 volts 20ah,
A ping 48V 20 ah would weigh 9.9 kgs!
Or 6 x 6S 8AH Zippy would give you 44 Volts and 24 ah, and weigh only 7.5 kg!
For some reason the zippy LiPo seems to be lighter than the turnigy?
Did I mention LiPo? (http://i1192.photobucket.com/albums/aa336/o00scorpion00o/sSig_lol3.gif)
-
What's the average weight on 20ah worth of 48V lipo ?
My 7S2P 10Ah 25.9V (14S1P 5Ah 51.8V) weighs 1.92kg, so a 14S4P 20Ah would weigh 7.68kg
As you're using an Infineon controller you could go for 16S4P 59.2V (67.2V fully charged) using 16 of these:
(http://www.hobbyking.com/hobbyking/store/catalog/T5000-4-20.jpg)
Click pic for more details (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9177)
Sixteen packs @ 536g each = 8.576kg (cost = $479.84 + delivery)
Or you could have a 12S4P 44.4V (50.4V fully charged) using 8 of these:
(http://www.hobbyking.com/hobbyking/store/catalog/T5000-6-20.jpg)
Click pic for more details (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9176)
Eight packs @ 793g each = 6.344kg (cost = $353.60 + delivery)
For some reason the zippy LiPo seems to be lighter than the turnigy?
That's how they justify the extra cost by paying more for less.
I wonder if it's enough weight saving to reduce the postage cost?
Alan
-
That's how they justify the extra cost by paying more for less.
I wonder if it's enough weight saving to reduce the postage cost?
Alan
I doubt it, it still weighs enough and cost me 97 Dollars, for 4x 8AH 6S
-
As we've wandered miles off topic, I have separated this portion of the original thread and moved it to the General Discussions section.
Alan
-
LiPo is definitely the best in the business for E-Bikes as they pack some energy and can discharge very high C from a very small pack, LiFeP04 can't begin to touch it!
I decided to do a comparison between two similar capacity packs to see what the differences actually are:
Zippy 4S1P 8000mAh LiPo pack Zippy 4S2P 8400mAh LiFePO4 pack
(http://www.hobbyking.com/hobbyking/store/catalog/Z80004S-30.jpg) (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16226) (http://www.hobbyking.com/hobbyking/store/catalog/Z84004S-30.jpg) (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14074)
Click either picture for more details.
Here are the specifications:
Capacity: 8000mAh 8400mAh
Voltage: 4S1P 4 Cell 14.8v 4S2P 8 cell 13.2V
Discharge: 30C Constant 40C Burst 30C Constant 40C Burst
Charge Rate: 40Amps (5C) 16.8Amps (2C)
Weight: 845g 1026g
Dimensions: 166mm x 69mm x 35mm 150mm x 52mm x 70mm
Balance Plug: JST-XH JST-XH
Discharge plug: 5.5mm Bullet-connector 5.5mm Bullet-connector
Volume: 400.89cc 546cc
Stored Energy: 118.4Wh 110.88Wh
Specific Energy: 140.12Wh/kg 108.07Wh/kg
Energy Density: 295.34Wh/litre 203.08Wh/litre
Price: $58.8 $119.78
Cost per Wh: $0.50 $1.08
Looking at those figures we can see that the LiFePO4 pack can actually deliver 5% more current than the LiPo, but only because its capacity is 5% greater! ;)
The LiFePO4 pack is heavier, larger, more expensive, holds less energy, has a much lower charge rate and its voltage is also 10.81% lower than the LiPo.
Unfortunately HobbyKing do not mention the expected number of cycles, so it's difficult to compare the expected lifespan of these packs, but I would expect the LiFePO4 to have the longest lifespan.
One thing that did surprise me was the discount offer that popped up on screen for both products, because I had both windows open for quite a while as I was gathering information:
One time only offer!
Hello shopper!
We noticed you've been looking at this product for a while and we would like to offer you a discount. If you click on the add to cart button below we can offer you this product for $55.63.
This offer will only show once.
If you leave this page or close this window you will not see this offer again.
$55.63
One time only offer!
Hello shopper!
We noticed you've been looking at this product for a while and we would like to offer you a discount. If you click on the add to cart button below we can offer you this product for $100.86.
This offer will only show once.
If you leave this page or close this window you will not see this offer again.
$100.86
The next time you buy anything from HobbyKing, open a separate window for each item and wait and see if they offer you discount. ;D
I hope you find this comparison as interesting as I did.
Alan
-
Yes I waited because the guys at E.S said that the discount window pops up after a while! ;)
You still can't compare LiFeP04 to 90C Lipo! (http://i1192.photobucket.com/albums/aa336/o00scorpion00o/sFun_nahnahna2.gif)
Then there is the extra weight!
And if charging to 4.1 and not 4.2 volts can considerably increase cycle life, or so I'm told anyway, but I trust the R.C guys as they have use LiPo for a long time!
-
Listen guys and girls... ;)
I think it's time for a cleanup of acronyms and expressions here... ;D
First, you all use 'BMS' for electronics that manages the battery in any way... There are at least 3 different battery management systems:
PCB/PCM - Protection Circuit Board/Module
These are the basic boards, preventing overcharge and overdischarge; some also have balancing function and max.discharge current protection. Price from $10 and up...
This is what GM batteries use!!!
CMB - Charge Management Board
These are a bit more advanced than a PCB/PCM, often with balancing function, fuel gauge and charge-while-discharge capabilities in addition to basic PCB/PCM functions. Price range from $40 and up.
BMS - Battery Management System
This is the most advanced system which monitors and controls everything, and then some; also the most expensive - usually $400-$500 and up...
And second... :)
You say LiPo... What chemistry?!?!
Are we talking about LiCoO2 specific, or any Li-Ion cells with Polymer casing?
There's a jungle of different chemistrys out there; all with advantages and disadvantages, so it's important to be precise when discussing and recommending cells... :)