Charging issue

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holmesjtg
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Joined: 09/01/2011
Points: 61

Hi all,

It's a chilly morning here in New England with temps in the 20s and I seem to have run into a charging problem. My C-124 was left to charge after work on Friday and when I went to start it up this morning, the gauge showed empty. I thought maybe the fuse that's gone on me before was the culprit but that seems fine. The strange thing is that when I plug it in, the regular charge indicator begins but then after a few seconds, it switches to "balance mode", as if it is fully charged. But if I try and run the motor a bit (after unplugging it), the dash indicator (in agreement with the gauge) shows 3 short flashes indicating low batteries.

Anyone else seen something like this before? Not sure if it is cold weather related or not.

Many thanks!
Jeff

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Jeff Holmes
Wheels: Current Motor Co C124
Work: Encyclopedia of Life www.eol.org

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MEroller
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Joined: 09/26/2011
Points: 847
Re: Charging issue

It IS cold-weather related! The GBs Batteries in your scooter should not be charged at below freezing temps in the battery, and the charger may know that too. See to it that you get your baby to a warm garage, let it warm up for a few hours and then try charging again.

That is why I put battery heating in my battery box, and the first thing I actually modified was to burry a temperature probe in the center of my battery and a solar-powered digital readout in one of the fairings so I can keep an eye on the temperature in the battery cellar. Below about 15°C my charger already starts to act up, just like you describe...

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QvR vR one: a Swiss package of pure understatement - innocent and to some eyes (from some angles) exceedingly ugly looks, but with raw and hardly containable electron power up to real 95 to 100km/h! And a literally rock-hard suspension due to a carrying capacity of twice it's unladen weight... Now converted to more controllable and efficient brushless motor and vector-contoller.

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holmesjtg
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Joined: 09/01/2011
Points: 61
Re: Charging issue

Hi MEroller,

Thanks for your advice. I think it was actually charged but just not showing it on the gauge, perhaps as you suggest, the controller was acting up because of the cold and not registering the full charge properly. I just checked it a few minutes ago and the charge (balance mode) had shut off. When I turned it on, low and behold, the gauge shows full.

I don't unfortunately, have a heated garage, but I might consider getting a small portable heater that I could switch on early in the morning to heat the bike up a bit on cold days.

Cheers,
Jeff

__________________

Jeff Holmes
Wheels: Current Motor Co C124
Work: Encyclopedia of Life www.eol.org

MEroller
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Joined: 09/26/2011
Points: 847
Re: Charging issue

holmesjtg wrote:

I don't unfortunately, have a heated garage, but I might consider getting a small portable heater that I could switch on early in the morning to heat the bike up a bit on cold days.

Been there, done that :-) Though in my case blowing into the battery compartment with a heater had a slightly different background at the time: While I still had a balancer board-based BMS on my battery (and no cover over the battery box) one or two of those boards whould at times gather too much moisture after riding in a heavy downpour and keep the charger from charging with a BMS fault. Then the heater would be my only means to dry those balancer boards enough so that they resumed responsibilty for their cell again and let the charger do it's job.

__________________

My rides:
QvR vR one: a Swiss package of pure understatement - innocent and to some eyes (from some angles) exceedingly ugly looks, but with raw and hardly containable electron power up to real 95 to 100km/h! And a literally rock-hard suspension due to a carrying capacity of twice it's unladen weight... Now converted to more controllable and efficient brushless motor and vector-contoller.

E-Sprit Fury (basis is the Erider Thunder 5000) since May 03, 2011. Highly moded - but now in active retirement

PJD
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Joined: 11/22/2006
Points: 1416
Re: Charging issue

Jeff,

Do you have the BCU access and configuration software and the USB cable needed to connect to it? I have experienced this problem in the past with an older version of the BCU. For some reason, the SOC would sometimes be erroneously set to zero after charging - and also sometimes, the balance charge time-out would get set to one minute instead of the proper 360 minutes. With the software you can manually reset the SOC it to 100% and reset the time-out to the correct value (after verifying this by checking cell voltages - see below). However, this problems was fixed when I upgraded the BCU software to the latest version. Of course, just running a charge cycle again like you did should work too.

Current's fairly crude charging protocol consists of charging at the full 8 to 10 amps until any cell reaches about 3.65 volts, then switches to 0.5 amp trickle charge until all cells come back up to their full shunt voltage at about 3.65 to 3.75 volts. Then, charging is switched off and the BCU sets the SOC to 100% (if it hadn't already reached 100% indication during charging). This works OK in warm weather unless there is bad cell with unusually high internal resistance. But at cold temperatures, the internal resistance (especially the charging internal resistance) goes way up - especially as the pack ages. This causes the voltage in some or all the cells to peak up to 3.65 volts prematurely under the full charging current, resulting in a very long time in balance mode - so long that it may hit the "time out" first. This will result in an error message too.

This has always been an annoying aspect of Current's charging protocol. On my other smaller scooter, I have an early version Goodrum-Fecher BMU which throttles the charge current proportional to the percent-on of the shunts. This results in a much faster balancing under the proper CC-CV protocol - where the the current is tapered just enough to hold the full 3.65-3.7 volts on the cells until completion.

Another critical thing that Current scooters really need is the ability to check individual cell voltages during charging. Almost all charging troubleshooting starts with doing this. I ended up rigging my own connector just under the charging door to do this.

And, as MERollier mentioned, all LiFePO4 cells and their variants don't charge very well below 0C - in fact, it isn't recommended. I keep my scooters in a basement-level garage that stays at least a few degrees above freezing throughout the winter.

holmesjtg
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Joined: 09/01/2011
Points: 61
Re: Charging issue

Just wanted to update my post to say that now that temps are back in the 40s, and with a fresh charge in a warmer garage, my batteries seem to be back at full strength. I'll follow the advice of you guys (and Terry, thanks!) and provide the bike with a heat source on cold days/nights. I'll try draping a tarp over top and just put a 40W work light underneath.

__________________

Jeff Holmes
Wheels: Current Motor Co C124
Work: Encyclopedia of Life www.eol.org

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