GoldenMotor.com Forum
General Category => General Discussions => Topic started by: Bedmountain on June 21, 2016, 08:48:09 PM
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Hi Guys
I just received a new battery from China. This one:
http://www.aliexpress.com/item/Great-Triangle-electric-bike-battery-48v-20ah-Samsung-cell-lithium-ion-for-1000w-1500w-2000w-motor/32401868802.html?spm=2114.01010208.3.203.lhDhZT&ws_ab_test=searchweb201556_8,searchweb201602_1_10037_10017_507_10032,searchweb201603_1&btsid=53664fc5-8fa4-46f1-be16-e6ccdf781989
The specs on the listing are:
1. Rated continual discharge current : 43A
2. Max continual discharge current : 50A
3. Pulse discharge current : 70A
4. Capacity : 20Ah
The battery came with this label attached:
(http://i328.photobucket.com/albums/l347/bedmountain/IMAG0220_zps3thbhn0v.jpg)
I've Googled it to death but I still don't understand the values on this label...
Is there anything on there that I should be concerned about? Is there anything that contradicts the specifications listed in the advert?
Cheers All
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Ben, that label is from a 400W 18V solar panel, not your battery!
It may simply be recycled packaging or it may have been deliberately used to get around the capacity restriction on shipping lithium batteries in case of a customs inspection.
I have seen batteries with incorrect voltages and capacities printed on their labels for this very purpose. ::)
Alan
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lol - thanks Alan :)
It was certainly deliberate - it was fixed to the outer packaging and the battery itself.
I suppose I better go get it off the roof then as it doesn't seem to have collected any magic juice in the last 2 days....
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The specs on the listing are:
1. Rated continual discharge current : 43A
2. Max continual discharge current : 50A
3. Pulse discharge current : 70A
4. Capacity : 20Ah
Hi Ben,
I've been doing some research on that particular battery and I think it is highly unlikely to match the above specifications stated by the supplier. :(
If you check out this post on Endless-Sphere (https://endless-sphere.com/forums/viewtopic.php?f=14&t=80860&p=1191159) you can find more information about it.
Even if it has the stated cells, it will not have the stated capacity, as there is physically not enough room within those dimensions to accomodate the required number of cells, even without the BMS unit!
I tried various layouts using my CAD package but could only manage to fit around 108 cells maximum in the same sized space, and ~13 of those would have to be left out to allow room the BMS to fit inside:
(https://i.imgur.com/xcQV5hO.png)
(http://www.arhservices.co.uk/GoldenMotor/LiPo/Triangle%20battery_zpswwrqw6xo.JPG)
Unless the physical dimensions are larger than the ones quoted, I reckon they will have used 91 cells (13 series sets of 7 paralleled cells).
If the cells are the stated 2.2Ah cells, this would only produce a maximum capacity of 15.4Ah instead of the stated 20Ah.
You can't have a capacity of 20Ah using 2.2Ah cells, it would either be 19.8Ah for 13S9P or 22Ah for 13S10P, but there definitely isn't room for 117 or 130 cells in that size package. ???
If your charger's voltage is marked as 54.6V, it will definitely be a 13S pack, but if it is marked as 58.8V it will be a 14S pack.
If it's a 14S pack, it will probably only have 6 cells in parallel blocks and the total capacity would then be just 13.2Ah, unless they have somehow managed to squeeze 98 cells and the BMS unit inside the stated dimensions, but I don't think that is very likely.
My biggest concern would be if they had used cheaper low power output cells instead of the stated "Samsung inr18650-22P 5C 10A high drain cells or LG 5C 10A high drain cells". If this was the case, the voltage would sag noticeably under heavy load and the pack could get very warm as a result.
Weaker cells do not appreciate having to work too hard and would be more prone to early failure, resulting in a greatly reduced battery lifespan.
I'd like to be able to say that the battery you received will meet all of the specifications stated by the seller, but I feel this is highly unlikely.
Alan
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Thanks Alan
That makes for depressing reading :'(...
I'm looking forward to it melting through the bag on my first climb...
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Hi Alan
I just took some dimensions from the pack and they are quite different to the image posted in the listing.
listing/actual:
26cm/33cm
7.2cm/5cm
24cm/30cm
5cm/7cm
18cm/20cm
Does that fit me in a few more sub-standard cells :D
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I drew the battery with the actual dimensions and was able to fit 128 cells and a bms in :)
(http://i328.photobucket.com/albums/l347/bedmountain/battery_zpsyrjkltwt.png)
that would make it feasibly a 117 cell 13S9P pack at 19.8Ah (it charges to 54.6V so it's a '13')
I guess there is no way of knowing what brand the cells are without unwrapping the pack...
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OK - so I had to see what the cells are....
(http://i328.photobucket.com/albums/l347/bedmountain/IMAG0221_zps0ubfa8sf.jpg)
I'm guessing a Samsung or LG cell would have their name on?
also 2000mAh and not 2200....
Any ideas what these are?
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That's a big difference in the dimensions, and with a slightly smaller BMS it looks like there's enough room to squeeze in 130 cells:
(http://www.arhservices.co.uk/GoldenMotor/LiPo/Triangle%20battery%202_zpszlfy96vg.JPG)
So it could actually be 13S10P 20Ah.
I can't find any information on those "YG" cells, but let's hope they are still high discharge cells even though they are not Samsung or LG. ;)
(http://lygte-info.dk/pic/Batteries2012/Samsung%20INR18650-20Q%202000mAh%20(green)/DSC_3563.jpg)
(http://lg18650.com/26-thickbox_default/lg-18650he2-2500mah-20a-.jpg)
(http://www.arhservices.co.uk/GoldenMotor/emoticons/fingerscrossed.gif)
Please let us know how it behaves during use.
Alan
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I'll take the side off the pack later to check if there is 130 cells in there.
I have 5 days left of aliexpress 'buyer protection' so I will be testing out their refund process once I've given the seller a chance to explain why he's lied about the brand of cells used...
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117 cells - so I have a 13S9P 18aH pack made from cells of unknown origin :)...
(http://i328.photobucket.com/albums/l347/bedmountain/IMAG0222_zpsvn5hwlb8.jpg)
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That's very sneaky and dishonest using packing pieces instead of the other 13 cells which would have made it a 20Ah pack.
(Assuming the cells have the stated 2000mAh capacity).
(http://www.arhservices.co.uk/GoldenMotor/emoticons/thinking.GIF)
They probably get away with this scam most of the time as not many customers are going to rip a new battery apart just to check what's inside.
It would not be easy to fit another 13 cells now (if you wanted to) as each cell has to be wired in parallel with each of the 9 parallel groups of cells spread throughout the pack.
It would have been so much easier to build a 13S10P pack correctly in the first place.
After causing you all this trouble, I hope you manage to obtain a decent refund from the scammer seller you bought it from.
(http://www.arhservices.co.uk/GoldenMotor/emoticons/fingerscrossed.GIF)
Alan
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Having an amusing dialogue with my Chinese seller at the moment....
The excuse for the non-brand cell 18aH 'mistake' is that the first battery they sent was held at customs and this 2nd battery was sent with wrong cells by accident :)
So far I've been offered the following options:
I can send them another $300 and they will send a Samsung branded 20aH battery this time - hmmm so I would have paid $734 for 2 batteries - the 2nd of which I can pretty much guarantee would be made the same as the first...
This is my favourite so far: - They will send me some PVC shrink so that I can make the battery look new again and then they want me to ship it to a UK customer for them - at which point they will send me a 20aH Samsung battery (at no extra cost to me!) - now that's a tempting deal - spending my time and money to scam another customer so that I can receive the item I paid for in the first place - lol
I'm not sure what happens when the Aliexpress dispute countdown ends in 4 days...
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Presumably the first battery was held up at Customs because (for some unknown reason) it didn't resemble a solar panel. ::)
Anyway, it's good to know they are at least replying to you and trying to come up with excuses and solutions, it's just a shame they can't come up with honest and acceptable ones!
It will be very interesting to see what the final outcome will be. ;)
Alan
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We finally agreed on a full refund (which has now come through) and I keep the battery...
Seems fair to me :)
Would have still rather had the battery pack I was expecting though...
I did take it for a test drive last week but the 100% regen snapped my rear dropout hanger before I could tell how it was performing - that was a fun 3 mile walk home carrying a 60kg bike.
What I have noticed is that it will only charge to 52V rather then the full 54.6V
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A full refund sounds like a very good result to me, and you don't have to break any laws by posting it back either. ;)
If your dropouts have broken, I presume you must have an alloy frame and didn't have any torque arms fitted.
Did it damage the wiring from the motor when the axle spun, and can the frame be repaired easily?
Perhaps you can post some pictures of the damage as a warning to others.
I am surprised that it is only charging to 4.0V per cell, I would have expected at least 4.1V, if not the maximum 4.2V.
Have you measured the voltage output from the charger while it is charging?
It might be worth checking the 13 cell group voltages to see how well balanced they are.
Alan
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Hi Alan
I have an alloy frame. I had torque arms fitted to both sides...
The gear hanger snapped and the axle came out of the other side dropout as well.
(http://i328.photobucket.com/albums/l347/bedmountain/IMAG0226_zpsutcmu6kd.jpg)
I guess the gear hanger is designed to be the weakest point to save damage to the frame which seems to have only suffered cosmetic damage.
There were 4 separate areas where the wires were stripped bare. I've repaired all these and the motor seems to be turning under throttle ok.
As always - I'm going to ask a daft question but how do I measure the voltage output from the charger? - Thanks Alan
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Hi Ben,
I'm surprised the axle has spun with two torque arms fitted. I suspect something may not have been tightened up quite as tight as it possibly should have been.
Do you have any pictures showing how the torque arms were attached to the frame before the axle spun loose?
You can usually check the open circuit output voltage of the charger by measuring across the two output terminals on the charger's connector plug, but be very careful not to short the two terminals together! :o
If your charging plug has a central pin and an outer cylindrical collar similar to this:
(http://www.electricscooterparts.com/images2/CNX-700b2.jpg)
Then I recommend using a short piece of drinking straw over the centre pin to ensure the meter probes cannot touch each other or accidentally short circuit the two contacts together. One probe goes inside the straw (usually the positive probe) and the other goes outside of it.
To check the charging voltage with the battery connected, simply insert your meter probes into the two contacts on the battery's power output connector while the battery is charging, and the reading taken from there should be approximately the same voltage as the battery itself.
At the very end of the charge, the voltage on your battery should be 53.3~54.6V dependant upon the charger voltage and/or the BMS maximum voltage settings (whichever is the lower).
There will be a very slight voltage drop across the battery's BMS as the output voltage is being switched via MOSFETs, but if good quality MOSFETs have been used, then the difference should be minimal (but definitely nowhere near as much as 2.6V even with poor quality MOSFETs ;)).
Alan
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Hi Alan
Unfortunately I don't have any pictures of the torque arms fitted. They were probably on upside down, wrong way round and inside out.
I checked the output of the charger and got a reading of 54.3V
The battery output voltage when on the charger is 52.8V
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One thing I learned was that the big nuts loosen up after an initial installation. Seems the high torque on start up and regen works them back and forth. I had to tighten mine several times before they would remain tight. I still check them regularly, but they seem OK now.
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I checked the output of the charger and got a reading of 54.3V
The battery output voltage when on the charger is 52.8V
Ben, the voltage reading for the charger output appears to be within 0.5% of the expected voltage, but this lower than expected reading may be due to the accuracy of your multimeter (cheap multimeters are usually accurate within ±1.0%).
If the charger output was calibrated absolutely spot on @ 54.60V, you could still have a voltage reading (on a cheap multimeter) anywhere between 54.05V and 55.15V and still be within the meter's specified tolerance. ::)
The 1.5V difference between the charger output and the battery output will be partially due to the slight voltage drop across two different sets of MOSFETs, one set on the charger input and the other on the battery output.
The main voltage difference is most likely due to the accuracy (tolerance) of the individual cell maximum voltage settings for each of the 13 balancing modules within the BMS, but it could also be slightly lower if some of the cells were not quite 100% fully charged. ;)
If you were to leave your battery on charge for at least 24 hours to ensure precise cell balancing and a full charge has been achieved, it's possible that the battery output voltage reading (measured while still on charge) might even increase slightly.
It is very unlikely that an expensive and highly accurate BMS has been used with that battery, so you may have to simply accept that the output voltage of 52.8V is all that you are going to get. ;)
52.8V is ~4.06V per cell, which should make the cells in your free battery last quite a bit longer. ;)
One thing I learned was that the big nuts loosen up after an initial installation. Seems the high torque on start up and regen works them back and forth. I had to tighten mine several times before they would remain tight. I still check them regularly, but they seem OK now.
Walter, most people don't understand quite how much torque is actually being transmitted through the two 10mm flats on the axle. If the axle nuts are not properly tightened they can work loose very quickly.
I measured the stall torque on my modified Magic Pie (http://goldenmotor.com/SMF/index.php?topic=4283.msg24990#msg24990) and calculated it to be around 93Nm. If this force is exerted on a 10mm deep dropout the lateral force acting upon the end of the dropouts by the edges of the flats is probably around 950kg (475 kg on each end of the axle).
To visualise this amount of torque, if you were to place a 130mm long 10mm spanner onto the flats of the axle, you would have to apply a force of 73kg (160lbs or 11.5 stone) on the opposite end of the spanner to produce 93Nm of torque!
(http://www.arhservices.co.uk/GoldenMotor/Spanner%20force_zpsbwpel2jr.JPG)
So Ben was lucky that it was only the hanger for the derailleur that broke and not his frame dropouts. If the dropouts in the frame had been deeper, then it might have been a different outcome.
I was never able to measure how much torque was produced with this much power:
(http://www.arhservices.co.uk/GoldenMotor/MaxPower.GIF)
But the torque was enough to easily flip the bike over backwards when trying to pull away from a standstill on the level.
Fortunately, I had steel dropouts on my bike and the axle nuts were tightened very tightly indeed, and the dropouts survived the huge amount of torque even without any torque arms fitted. ::)
The torque developed by your Smart Pie will obviously be a lot less than my modified Magic Pie (and a bit less than a standard Magic Pie) but it still has to be transmitted safely to the frame (or forks) through the dropouts.
Alan
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Hi guys - quick update on the dodgy (but free) triangle battery pack...
For the first 50 miles or so it was just about behaving ok - although I was experiencing the occasional cut out near the end of my 16 mile commute.
I went on holiday for a couple of weeks and when I used the bike for the first time back I didn't get more than a couple of miles before the cut outs started.
Just went for a test run today and within a mile I'm getting cut outs and my cycle analyst is showing minimum voltages of around 11-17v.
Not sure if it's the BMS or the controller cutting the power. Any ideas as to what is causing such an extreme voltage sag? Could it be simply the poor quality of these cells?
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Hi Ben,
If you are using this battery with your MP5 motor, then it will probably be the battery's BMS that is cutting the power completely, as the MP5's controller does not cut off the battery power under load, it simply reduces the motor power when the battery voltage reaches the minimum set voltage to prevent the battery voltage from falling any further.
The 11-17V figures on the CA are probably just the generated output voltages from the motor when the battery's BMS has isolated the battery from the controller and the Cycle Analyst.
If you increase the Undervoltage protection value (V) setting in the controller to 46~48V (which should hopefully be higher than the battery's BMS Low voltage cut off) it should prevent the BMS from cutting off the power completely when the cells are struggling under heavy load.
You should find that the motor power will noticeably reduce after a long trip instead of the battery cutting out, and the lowest recorded voltages on the CA should never be any lower than the controller set minimum voltage.
(http://www.arhservices.co.uk/GoldenMotor/emoticons/fingerscrossed.GIF)
If you find that it still cuts out completely at the end of your 16+ mile commute, it will probably be the BMS cutting out because the voltage of one or more groups of paralleled cells is being pulled down too far under load. :(
Reducing the Battery drawn current (A) setting on the MP5 should also help to increase the range of this poor quality battery pack.
Quality
We are professional Electric bike battery supplier on aliexpress, We have perfect production process and all kinds of scientific management tools to control the quality,such as Six Sigma,PFMEA,CP,SPC and so on.The battery is brand new and every single item you buy from our company has been completely tested before shipping , after several times of testing , so we can guarantee the quality.
I notice that they don't guarantee the quality as being; good, as specified or even acceptable, so perhaps the "perfect production process and all kinds of scientific management tools to control the quality" are simply needed to ensure that "after several times of testing" the quality is consistently poor and unable to match the stated specifications.
(http://www.arhservices.co.uk/GoldenMotor/emoticons/thinking.GIF)
Alan
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Hi Alan
Thanks, as always, for your advice. I'll have a try with amended settings.
I'm considering attempting to build my own triangle pack. I have read a lot around it but I'm still worried any cells I buy will not be as specified so I could end up with a poor end product anyway.
Anyway - thanks - for the time being I just need it to cover 16 miles without me having to push/carry it. I'll let you know how I get on....
Cheers
Ben