GoldenMotor.com Forum
General Category => General Discussions => Topic started by: Onetom2 on July 30, 2010, 02:34:39 PM
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Last week I installed a 250w kit with the 36volt 16ah battery. after riding some time and experiencing what appeared to be a premature loss of battery power. Returning home I attempted to charge battery with supplied charger. The unit flashed a red indicator for a few seconds then stopped, with no further indication of what is happening. After approximately 6 hours the LEDs on the twist throttle only show red and yellow, no green. I somehow want to see some indication from the charger pack that it is functioning, considering the red led did flash for that few seconds. I read as much as I could find about the charging process and this suggests 4 hours should give a full charge? Could you please advise?
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I've had some charging problems myself and found out that my female connector wasn't that good connected, try somethings with that like using a bandage(elastic) to push it in harder. After that you could check your voltage, if it really is to low(don't excactly know what the lvc is for 36v) then you could try using regen breaking to fill the battery a bit for the bms to recognize it's almost empty and after that is all failed to give you what you paid for then I would suggest emailing tom explaining your problem. I would like to suggest a small amount of words to explain your problem as I think tom isn't that great in english. When he doens't replies withing 2 to 3 days contact the rest of goldenmotor, maybe before that you could also check with your.
In my experience it's probably a lose connection between the battery and charger as it is charging a bit but not in the time that would normally give you a full battery.
Hope this helps
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Does the battery have to be switched on to charge? I actually went back to the charger and having switched on the battery then plugged in and switched on the charger. Once again it began the clicking and the led flashing for about 30 seconds or so then stopped? No amount of cautious fiddling and pressuring would make any difference. I think connections are very weak all round actually. There were no connectors crimped onto the battery power lead. I ended up soldering those. Thanks for your input I will do more tomorrow. I am in Melbourne Australia at 01.40hrs I have some Chinese friends not far from the factory actually...I might try and get a chinese translation of my problem to post to Tom.
Thanks again ;D
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Are you able to check any voltage, the one out of the battery and/or the charger(be carefull with the charger as the pos and neg can't touch eachother while plugged in)
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Yes hmm, I looked at that coaxial style connector and pondered the question of safe testing. At the same time reconnecting the battery & charger the switch on had the same few seconds of what sounds like a relay switching accompanied by the flashing red led in the charger case. I just noticed on the charger case label some extremely small type with red and green dots. It seems they Indicate the chargers state. The red dot (I assume refers to the red led) indicates charging. The green dot indicates full....meaning fully charged I assume. So it would seem something isn't quite right with this charger if it keeps switching on and off, right? I have not seen any green indicator. I was just about to attempt using an insulated aligator clip on the charger connector pin but I suspect it wouldn't actually tell me much. Does anyone have answers to what must be a know state i.e., as previously described? I think I might need a new charger
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Does your charger have a voltage selection switch?
If you cannot see an obvious switch on the outside of your charger, it is probably an auto select type, so there's nothing to adjust.
If your charger has a voltage selection switch, make sure it is set to your correct mains voltage (230 Volts for Australia), if it was set to 115V it could well have been damaged.
Are you able to check any voltage, the one out of the battery and/or the charger(be carefull with the charger as the pos and neg can't touch eachother while plugged in)
Just to give you some idea of the expected voltage, a fully charged 36V lithium battery pack should be somewhere around 42 Volts (the charger output voltage should be a little bit higher than this).
I read as much as I could find about the charging process and this suggests 4 hours should give a full charge? Could you please advise?
If you have a 4 Amp charger it would require a minimum of 4 hours to charge a completely exhausted pack (a 2 Amp charger would need at least 8 hours) but it's better if it can be left on charge longer if possible, as it allows the voltages of the individual cells within the battery to become more evenly balanced.
Forget the earlier regen suggestion as regen doesn't work with minimotors. ;)
Regarding the battery gauge, did all three LEDs light up before you first used the battery?
Alan
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Please excuse me if I am making a mess of this posting and quoting but I am learning the ropes here.
Does your charger have a voltage selection switch?
If you cannot see an obvious switch on the outside of your charger, it is probably an auto select type, so there's nothing to adjust.
If your charger has a voltage selection switch, make sure it is set to your correct mains voltage (230 Volts for Australia), if it was set to 115V it could well have been damaged.
The charger model SSLC084V42 is variable input.
Are you able to check any voltage, the one out of the battery and/or the charger(be carefull with the charger as the pos and neg can't touch eachother while plugged in)
Just to give you some idea of the expected voltage, a fully charged 36V lithium battery pack should be somewhere around 42 Volts (the charger output voltage should be a little bit higher than this).
The battery voltage is presently 32.6V. The charger clicking & flashing ran for a full 3 minutes before stopping, with no leds lit.
I read as much as I could find about the charging process and this suggests 4 hours should give a full charge? Could you please advise?
If you have a 4 Amp charger it would require a minimum of 4 hours to charge a completely exhausted pack (a 2 Amp charger would need at least 8 hours) but it's better if it can be left on charge longer if possible, as it allows the voltages of the individual cells within the battery to become more evenly balanced.
I estimated the 8-10 hour charging would be appropriate using the 1.8amp charger.
Forget the earlier regen suggestion as regen doesn't work with minimotors. ;)
I seem to recall reading that somewhere.
Regarding the battery gauge, did all three LEDs light up before you first used the battery?
YES! All three LED's lit prior to use.
Presently only red and yellow leds are lit
Returning from the 'maiden voyage' a leisurely cruise along the banks of a creek (proper concrete paved pathway) I plugged in the charger. This was the first experience of about 30 seconds of clicking and red led flashing. The duration time varies from connect to connect.
Alan
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Tom, I suggest you email the other Tom (zhourenli@goldenmotor.com) and explain your problem as simply as possible and see what he recommends.
Your battery voltage is obviously very low and does not appear to be charging at all. This could be down to a faulty charger, bad wiring connection or even a problem with the battery's internal BMS.
Tom (from GM) will hopefully tell you where the fault lies and provide a solution for you.
(http://www.arhservices.co.uk/GoldenMotor/emoticons/fingerscrossed.GIF)
Alan
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Check the polarity of the charger output and the charger battery input.
I have one charger that this happens to if it's reversed polarity. This is a safety function in my charger for short circuits and or reverse polarity,
The drain goes to max over a resistor and this resistor sets the warning light off and attempts to switch the charger off at the output.
I can not be sure as my charger is different. But it behaves the same way with short circuits and reverse polarity.
A couple of years back here in GM forums testing polarity was kind of "the always to do thing" before we connect any charger up to a pack.
Make sure the voltmeter tester has the right color probes in the right color holes. This was one of my mistakes way back when.
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I have checked polarity of both battery and charger. Interestingly, having connected an insulated alligator clip to the positive on the male connector (Charger output plug) reducing the possibility of an accidental slip and short, then connecting my DMM probes, the charger green indicator came 'on' for the first time. I read 41.7Volts coming from the charger and having removed my clips plugged the charger back into the battery and switched on the power. Once again the red led began flashing accompanied by the audio clicking. This ceased after a approximately 3 minutes.
I have written to Tom with my briefest explanation of symptoms.
In my desperation to find answers I surveyed many forums and was dismayed at some of those basic errors you mention. I only have a very rudimentary understanding of electronics and love to dabble, but I am extremely cautious with a device such as this with advanced circuitry and expensive battery pack.
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I have checked polarity of both battery and charger. Interestingly, having connected an insulated alligator clip to the positive on the male connector (Charger output plug) reducing the possibility of an accidental slip and short, then connecting my DMM probes, the charger green indicator came 'on' for the first time. I read 41.7Volts coming from the charger and having removed my clips plugged the charger back into the battery and switched on the power. Once again the red led began flashing accompanied by the audio clicking. This ceased after a approximately 3 minutes.
I have written to Tom with my briefest explanation of symptoms.
In my desperation to find answers I surveyed many forums and was dismayed at some of those basic errors you mention. I only have a very rudimentary understanding of electronics and love to dabble, but I am extremely cautious with a device such as this with advanced circuitry and expensive battery pack.
What? It went into bulk charge mode testing the voltage?
It isnt a good idea to keep repeating the error for three minutes. If it doesnt work unplug immediately.
Another error mode is if you were to plug a the wrong voltage charger the into voltage wrong battery
41.7 (42v) volts is bulk mode charge rate for a 36v pack.
What is your pack voltage sitting at?
Do you have some 12v SLA's handy?
I would like to see your BMS and how many B wires connections it has, and if you dare take a look at the cell voltages.
The voltages on the pack are getting lower with the charger plugged in malfunctioning? You say the red led appeared on throttle after 6 hours of error charging?
Is this right^^^
You need to get it looked at or return it ASAP.
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41.7 (42v) volts is bulk mode charge rate for a 36v pack.
What is your pack voltage sitting at?
Do you have some 12v SLA's handy?
I would like to see your BMS and how many B wires connections it has, and if you dare take a look at the cell voltages.
41.7V will be the final float/trickle charge voltage which keeps the pack fully charged (Each of the cells should stabilise at ~4.2V).
These chargers usually works on a two stage principle:
Stage 1 Constant current
During this stage, current is supplied at a safe, continuous fixed level until the battery voltage rises to the required maximum setting.
When the maximum voltage setting is reached, the charger will automatically switch to the next stage.
Stage 2 Constant Voltage
During this stage, the current is automatically adjusted (slowly reduced) in order to keep the battery voltage at the pre-set level (usually the safe maximum voltage level).
When the charging current falls below a certain level, the green LED will light up indicating that the battery is fully charged, but it will continue to supply enough current to ensure the pack remains fully charged.
In theory it should be safe to leave the charger on continually when the battery is not being used, but I would prefer to use a plug in timer to limit this to an hour each week during storage just to play safe (and also extend the chargers life).
By doing this, the battery should always be at least 98% charged ready for immediate use, and should not deteriorate unnecessarily during the winter. ;)
My timer also has a countdown function, so I should be able to set it for a full 10 hour charge after a long run and leave it to automatically charge and then return to the pre-set weekly charge mode, but unfortunately it seems to switch off automatically at midnight. ???
Alan
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I believe this switching of the charger once it is presented with a load is clear indication of a faulty charger. I have written to Tom at GM and await an answer. But having already spent well over a thousand dollars (AU) on this project as a pensioner the cost of posting this charger unit back and then waiting for a replacement is going to be most vexing. But first there has to be an agreement in place. There are other accessories and products I wish to purchase from GM but not at this point in time. The 'solar charging' is of great interest to me. It has taken me a very long time to reach this point unable to enjoy smooth operation because of a faulty charger. I have a short video clip showing the red LED flashing but doubt its value as an attachment (too big).
To 217537...The battery voltage is presently 32.95V The battery pack is a 36v 16ah and I do not have any spare SLA's on hand. I decided in favour of the Li-ion battery pack for all the reasons you can imagine. I note you are local with a reference to Jaycar.
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I believe this switching of the charger once it is presented with a load is clear indication of a faulty charger. I have written to Tom at GM and await an answer. But having already spent well over a thousand dollars (AU) on this project as a pensioner the cost of posting this charger unit back and then waiting for a replacement is going to be most vexing. But first there has to be an agreement in place. There are other accessories and products I wish to purchase from GM but not at this point in time. The 'solar charging' is of great interest to me. It has taken me a very long time to reach this point unable to enjoy smooth operation because of a faulty charger. I have a short video clip showing the red LED flashing but doubt its value as an attachment (too big).
To 217537...The battery voltage is presently 32.95V The battery pack is a 36v 16ah and I do not have any spare SLA's on hand. I decided in favour of the Li-ion battery pack for all the reasons you can imagine. I note you are local with a reference to Jaycar.
I build my own charger if I need them. Buying is easier.
You can use a relay and resistor setup with the solar panels. Just hook 3X12v panels in series to the pack and run a resistor and variable resistor to the switch coil and when the pack reaches 42v turn the pot very slowly until it switches off. Reset the switch to charge and repeat and fine tune the voltage until it is perfect.
Decide your relay and post what it is and I can tell you the value resistors you need. It will be good enough to get you going in the mean time.
32v is pretty high for a 36v pack to giving LVC. The cells in the GM packs can be 2.4v~2.6v and there are 10 cells in the pack. So a flat GM 36v pack can read as low as 24v~26v. So who know what is happening. You could have a 48v pack.
I go to dick smith too and would go to Tandy if it was local.. I also buy from Ebay...
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Decide your relay and post what it is and I can tell you the value resistors you need.
Thank you for the information and offers. The solar panel rig is on my mental drawing board at the moment and the original plan had not taken into account GM's own solar set up. I will keep in mind your offer of assistance when I get around to financing that project. The Li-ion battery pack seems to require some specialised treatment and so I am treading carefully. cheers
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Decide your relay and post what it is and I can tell you the value resistors you need.
Thank you for the information and offers. The solar panel rig is on my mental drawing board at the moment and the original plan had not taken into account GM's own solar set up. I will keep in mind your offer of assistance when I get around to financing that project. The Li-ion battery pack seems to require some specialised treatment and so I am treading carefully. cheers
Yes there are some concerns about the charging type being used on Li-on batteries. The electrolyte isnt so aqueous as SLA's so I doubt to much problems can come from this. EG acid boiling off at lower current at 15v.
If you already have the panels the relay charger is cheap.
$5 relay
$2.50 resistor pot
25c resistor.
I do a few more tricks like use a regulator to give me a standby charge voltage on one of the relay switch points and a reset switch. Among other things I could make it vibration proof by using a fet or transistor threshold to the switch coil. So if the relay gets a bump close to switching voltages it doesnt shut off the full charge voltage.
Ive seen folks use a light bulb a diode an AC wall socket supply feeding 120v through a light bulb and using the constant current from the series feed into a small gel battery.
Like this
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=2346.0;attach=2926;image)
Disclaimer: If you do this to your GM battery and it dies LOL at you.
Cost you a few dollars at most.
It looks bloody shocking doesn't it :o. And it would be if you didnt turn it off. or you kill yourself. So don't do it at home kiddies. LOL But it proves that you can charge a battery off anything if you want.
But you just need the watts and volts here.
Say your wall socket is 220v and you bulb is 100watts. 100/220=454ma This will allow 454 ma into the battery. So use 5 bulbs and you have 2.2 amps. People with 110v AC outlet are more lucky. I would put in a cap at least to filter out the the ripples.
You just need a switch like my relay to turn it off at the right volts. The lights will go brighter as the battery charges up. LOL youre looking at 420 watts down the drain when the battery fill up. I think the Li-ion batts would use a little more watts in the beginning stages.
I could do some tricks to make it better.
It does work and I can show you if you want.
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Hi
I've a similar or perhaps equal problem with my charger. It is of the same type, all new. First time use --> OK. After , it will not start. My charger just 'blips' green and clicks when connected to the battery. My battery voltage is not as low as Onetom2, it is 37V. Output of charger is variating, 0V - abt 10V for every 'blip'.
I've also mailed Tom; No reply yet, I'll wait a little...
BR Stein
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(http://www.bombayharbor.com/productImage/0528433001254989543/12v_Halogen_Transformer.jpg)
(http://circuitzoo.com/wp-content/uploads/2010/06/12V-Halogen-Lamp-Electronics-Transformer-Circuit-Diagram..png)
These are pretty cool
You can use these in series to get 48v if they have an isolation transformer like above. Then use a LM338 for constant voltage and a shunt and resistor to regulate constant current and a relay switch to cut the bulk charge.
Until GM responds to your emails, I will keep posting other solutions. I wont post other brands in the GM forums but there are other alternatives we can make to keep us on the road..
I used a 15v 6 amp transformer and made an old school voltage multiplyer that could do 2.2 amps to a 48v SLA pack. The current drops out as the voltage rises to 60v to 1 amp.
The half wave seemed to fail with polarized caps but the full wave above worked well with big electrolytic caps and lasted for a year until I defunct it on a 36v pack. It drew too much current from the transformer.
The below is a full wave voltage multiplier.
(http://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Full_wave_Cockcroft_Walton_Voltage_multiplier.png/220px-Full_wave_Cockcroft_Walton_Voltage_multiplier.png)
This really charged my SLA's better than anything I have used to date. at 15v per SLA I would have the voltages at rest sitting at 13.6 comapered to 13.2v Strnage beahavior and I thought the batteries were not liking this. But the bike flew like a hawk every day, up to three times a day, for 6 mths until the SLA finally lost capacity.
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I think I will have to try to make me a charger... I've ordered a new one from GM. But since two already has failed, I am not shure if it will last.
As I understand, the principle is to be able to limit current and also be able to limit voltage? If I limit voltage to 42 volt, it will be safe?
BR
Stein
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I think I will have to try to make me a charger... I've ordered a new one from GM. But since two already has failed, I am not shure if it will last.
As I understand, the principle is to be able to limit current and also be able to limit voltage? If I limit voltage to 42 volt, it will be safe?
BR
Stein
What you need to understand is why your chargers are failing before you can pass go.
As I understand, the principle is to be able to limit current and also be able to limit voltage? If I limit voltage to 42 volt, it will be safe?
Yes. But it would be good to have a shut off and maybe, good to bypass that shut off if you want to gain manual charge absorption at 42v..
Current limiting is very easy. Either use a shunt
Or this for precision limitation.
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=2346.0;attach=2932;image)
The math is very easy. 1.25v/AMPS require = resistor needed.
If you want 2.5 amps
1.25/2.5 amps = .5ohms 5 watt resistor for anything up to 3 amps.
An easy calculator is handy.
http://www.reuk.co.uk/LM317-Current-Calculator.htm
This Lm338 chip is identical to the lm317t but it can handle 5 amps.
You cant have anymore than 50 watts appear over the package with no cooling. To be safe use a heat sink.
If you regulate the input voltage at 42v with a pack as low as 24v will produce 45watts at 2.5 amps.
As the battery charges the watts will dissipate.
here is the CV vesrion of this chip. It is adjustable.
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=2346.0;attach=2934;image)
Here I drew up what an CC CV linear reg auto switching bulk mode/standby mode charger circuit could look like. I believe it would work with some tweaking.
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=2346.0;attach=2935;image)
I could put a led light indicator in there. And maybe a switcher in the place of the linear regulator.
There is easier ways to do up a reliable charger that wont break your brains. Im just bored and wanted to practice some stuff.
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Hi! ;D
Charger failing: Agree , why they fail ? Mine is same type as onetom2's charger. Behave in the same way.
When the new charger arrive; How should the charger be connected?
I did use mine OK for one time only. Cannot recall (100% sure) how I connected it / diconnected it. But probably it died in this process...
Connect:
Alt 1. Charger to battery, then charger til 220V AC?
Alt.2 ehhh the other way, 220V first, then 42V to battey
Disconnect:
Alt 1. Charger to battery, then charger til 220V AC?
Alt.2 ehhh the other way, 220V first, then 42V to battey
Any recommendation? I will ask GM/tom these questions too...
Building: Great ;D. I have LM317t's at hand. I will search for a >42V dc - source. In the junk - bin I had lot of 24V DC trafo - supplies. I will continue charger-making also.
I'm currently back on SLA's , two 12V packs with a long work - history as UPS - batteries. Performance - wise it really ment back to 'pedal assist' compared to 36VLIION ;D
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Hi! ;D
Charger failing: Agree , why they fail ? Mine is same type as onetom2's charger. Behave in the same way.
When the new charger arrive; How should the charger be connected?
I did use mine OK for one time only. Cannot recall (100% sure) how I connected it / diconnected it. But probably it died in this process...
Connect:
Alt 1. Charger to battery, then charger til 220V AC?
Alt.2 ehhh the other way, 220V first, then 42V to battey
Disconnect:
Alt 1. Charger to battery, then charger til 220V AC?
Alt.2 ehhh the other way, 220V first, then 42V to battey
Any recommendation? I will ask GM/tom these questions too...
Building: Great ;D. I have LM317t's at hand. I will search for a >42V dc - source. In the junk - bin I had lot of 24V DC trafo - supplies. I will continue charger-making also.
I'm currently back on SLA's , two 12V packs with a long work - history as UPS - batteries. Performance - wise it really ment back to 'pedal assist' compared to 36VLIION ;D
The Lm317t wont do the thermal dissipation like the LM338.
Power transformers are good as the current is transferred through magnetism. They are not that good with heat. But you can parallel the primary windings and series the secondary.
Those old heavy auto chargers are good.
I can use an arc welder and rectifier set up to get 48v adjustable from 30~120 amps. :o LOL you need to shunt that one. But you can pick up welders second hand for real cheap these days.
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I bought two of these from Dick Smith for $3.99 each I think. Worth getting the bigger device IMO.
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=2346.0;attach=2939;image)
Some extra care with some diode protections, isolate the package output from the sink with thermal transfer matting, and use of thermal paste, and these current and voltage regultor things have been around me for quite some time now. They seem to be rock sold and never let me down.
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=2346.0;attach=2942;image)
I'll take a guess but that big sink with a fan could do 8 amps or 300+ watts or which ever comes first, good of discharging and current limiting. Id love to test it some day but I need them more than I care to admit.
Silly inefficient linear regulators ::). Hmm maybe not so silly in hind sight,
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Hmmm, I was sent some interesting information on the charging and life support for Lithium ion batteries, amazingly, from China. It explained how limited periods of charging with breaks of up to 2 hours improves the life expectancy of these batteries. I had no indication of what to expect when connecting a charger to a Lithium ion battery. I had no possible explanation for what transpired but was aware that @ 1.8 AH there wasn't likely to be any problems during a short top up charge, little did I realise how wrong I was. Armed with the new information I set up a timer which gave 30 minute bursts of the GM charger to the GM lithium 4 battery with a 2 hour break between each charge. Over night the charge cycle I had set on the timer had been in operation for 6 hours and only amounting to a total of about 2 hours normal charge time. Low and behold the usual one second pulsing continued at the beginning of each charge period as expected but this time when the pulsing stopped the red LED stayed on, which was reassuring, don't ask me why, its just was, ok? Occasionally the pulsing would start again and then stop with the LED remaining lit indicating it was doing its job. The voltage at the discharge end is now 38.2V So I think I have a little way more to go but will wait until I have run the bike again. There was quite a bit more information on the subject like not allowing the battery to discharge more than a few percent. There was other information especially in regard to electric cars in China. Has anyone come across a detailed instruction manual describing the rather irregular LED indicators or anything else on charging? I suppose like the rules about connecting any charger to any battery and mains is so widely known that assumptions are agreed and nobody bothers to write it down?
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Sounds very interesting, is this information in a format that you could upload so we can all see it?
Does it differentiate between the different types of lithium ion batteries?
(Lithium Polymer, Lithium Manganese and Lithium Iron Phosphate etc.)
There was quite a bit more information on the subject like not allowing the battery to discharge more than a few percent.
I hope that's just while the battery is not being used, as I can't see anyone sticking to that suggestion.
It would be ridiculous having a 16Ah battery and not being allowed to use more than ~0.5Ah.
Glad to hear your battery is charging again, it will be interesting to see if the problem eases after a few cycles of the battery.
Alan
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Actually, if you think about the voltage, then yes, discharging
more than a few percent is bad.
A 2.7 volt cell should not be discharged below 2.5 volts,
thats about 8%.
You can still discharge lower than that, but it shortens the
battery life.
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Actually, if you think about the voltage, then yes, discharging
more than a few percent is bad.
A 2.7 volt cell should not be discharged below 2.5 volts,
thats about 8%.
You can still discharge lower than that, but it shortens the
battery life.
I once set my SLA charger up on a timer to charge every 15mins and off every 15 mins for 8 hours. Four hours on and four at rest in total. When I woke up the next morning, All my batteries were fully charged, in balance and discharged in balance too.
I have some theory in the works.
I will post it when I can understand how to explain best, that the more voltage drop over each cell equates to less resistance due to charge storage/
With resistance, more resistance usually equals more voltage drop.
Inside the cell this is opposite. Like a mirror. Voltage drop from one cell to the other indicates charge state not internal resistances. This may allow me to understand why higher voltages to the pack don't charge batteries faster than current, yet I have observed that using a higher voltage seems to make cell voltages vary wider. This sounds like a bad thing, may be not. As we observe that the smaller V drop on any cell indicates the lower charge state so to the wider voltage differences between cells may indicate better charging of the lower charged cells. The actual charging voltage into the cell is higher the more variance you can achieve between cells with the nominal pack.
What I mean is that, if you put a 56v charger on a 48v pack it will charge fine if balanced, but if it isnt balanced, try putting 72v @ 1 amp on the pack and you will see larger voltage variances between low cells and high cells. This can let the BMS work better as it can sense the larger voltage differences between a low charged cell and a full charged cell.
It must be rated under 80 watts so this allows time for the energy and BMS to work its job.. The pack must be cut at HVC at the rated pack voltage regardless of the 72v input voltages so no damage is done to any cell and one must watch the cell voltages like a hawk.
Other wise try the timer at bulk mode voltages as you will notice at the beginning of the charge the same anomalies I described above larger variances of cells voltages every time the timer charge kicks in. The full cells will be higher and the low cells will be lower.
I am scared to tell people to put 80v on there packs as you know what could happen if it left on too long. And just as scared suggesting the timer method I have used with my SLA's.
I just tell people to leave it on for days and hope the trickle will balance things out.
Edit:
Surface charge can have no time to be absorbed when the variances are so little and trip the charger off earlier. Where as at higher voltages one will observe strange balance behavior not yet described or defined by anyone I have seen yet.
On the 48v SLA's I balanced with a zener shunt looked scary with a 72v input. The fuller capacity would rise sharp and then emptier battery responded by picking up the charge potential. As the lowest charged battery was the highest resistance it had more voltage potential over the terminals.
After not too long the voltages would rise up like a Mexican wave along the batteries finding any missing capacity in the lower cells.
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I'm sorry if this doesn't seem much I have left out the guys story about "electric bicycle lithium battery protection board"
and solar charge. These passages were translated by a friend in China and I have asked her for more. It was her input about the characteristics of smart chargers that influenced my idea. I asked Tom from GM for more information but have received nothing further regarding charger behaviour.
Based on the characteristics of lithium batteries, lithium batteries and maintenance techniques we summarized as follows:
1. Do not let the lithium battery power less than 3% (20% recommended start charging)
2. 1% lithium battery can become a "deep discharge" must avoid "deep discharge." As "deep discharge" directly affect the life of lithium batteries.
3. Long-term (more than 3 months) when not in use lithium batteries should be charged to 50% of the electricity saved
Battery electric vehicles are now almost 95% of the lithium battery, the principle is the same, the battery electric vehicles and mobile phones are the same nature, only voltage and current difference between the size of it. . This is currently one of the words should all know. . So I ask you that again with the photoelectric charge of, your use of light electric vehicle battery is fully depleted you go? The batteries have to charge you 12 hours? Strange if it does not charge explosion. The correct way is to post full of tips, about 1 to 2 hours a buffer can be, this is the most authoritative methods. Lithium batteries and other power must not be exhausted. Otherwise, will be in trouble soon.
My burden is ignorance of the subject in its entirety. Conventional LA & SLA I understand basically but I am at sea in a thick fog without a paddle when it comes to these babies. The information aired online in various papers by industry observers, suggests that most Lithium Ion Battery manufacture's design and develop their own individual charge management systems which means without any further offerings of data and problem solving I am stumped? Can't just go buy another battery charger off the shelf and I don't know anything about that 4amp charger someone mentioned? ???
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If your charger still fails to work.
You may have to purchase another GM charger or get one on warranty.
This is the closest thing I found on ebay. It is too high for the GM packs.
http://cgi.ebay.com.au/Electric-Scooter-Battery-Charger-48V-17-20AH-/360288483959?cmd=ViewItem&pt=UK_ConsumerElectronics_Batteries_SM&hash=item53e2ddfa77 (http://cgi.ebay.com.au/Electric-Scooter-Battery-Charger-48V-17-20AH-/360288483959?cmd=ViewItem&pt=UK_ConsumerElectronics_Batteries_SM&hash=item53e2ddfa77)
with 48V, 17 - 20AH batteries * Input power: AC 220V, 50Hz * Output power: DC 56.5, 48V * Max input wattage: ?85W * Output current: DC 2.5A *
Your pack requires 54.6v. The above charger has 56.5v. So you need to modify it. Easy done!
3 Schottkey diodes in series .62v drop =1.86v drop on the charge line will fix the voltage down for this charger.
The part no, for the schottky is MBRF30H60CTG
Can be purchased here or else where.
http://au.mouser.com/ProductDetail/ON-Semiconductor/MBRF30H60CTG/?qs=sGAEpiMZZMtvcUztdGSumOtO%252bDV5KVJy5xaTawNqY7A%3d (http://au.mouser.com/ProductDetail/ON-Semiconductor/MBRF30H60CTG/?qs=sGAEpiMZZMtvcUztdGSumOtO%252bDV5KVJy5xaTawNqY7A%3d)
Personally I would just get a handful of 3 amps diodes schottky and rectifiers and mix and match and test the drop cautiously until I got 54.6v on the mark