We could have an issue. The charger mA shows as if the charger is turning on/off ~20% of the time now and this is 2 hours in. Voltage is 286, it is cold out now. 0*c but should be 10*c tomorrow.

I'm wondering if I should put a third 90 supply in series? Would that be OK for the pack?

 

Yes, you can discharge using the car, but it's tricky... ensure you disable regen by putting it in Neutral when possible and you can also discharge using as much electric accessories as possible while in auto-stop.

I'm going to revert to my original recommendation... 2X APC-35-350. The no-name Chinese supplies are usually worthless.

I assume 286 = 186?

Charging in extremely low temperatures is horribly inefficient, and you'll see higher peak voltages if the pack fills. You may want to run the fan at a very low speed to give the cells an opportunity to heat from charging as they fill. You'll want the cells > 35°C when you're done charging.

The pack won't care what voltage you apply to it. It raises only so much as the applied current demands (V = I * R) and will pull the input voltage down to that level. If you put a 3rd in series, you'll likely break the charger as the 3 in series will likely not be able to regulate all 3 near their minimum 54V. Essentially, when energized, they go to max voltage, max current and regulate the voltage to maintain the current. You'll have all three of them trying to push 90V, but the current won't flow, and they'll pull down, but they won't do it in harmony with each other. They'll just trip on and off and keep trying again and again sending tiny pulses of current to the battery with no meaningful outcome.

As an example, I had 2X LPC-100-700 supplies (700mA, 72-143V). Two in series wouldn't start working until the pack was over 200V even though math says it should be able to start working at 72*2=144V.

 

Good info Steve, I've been looking to source the meanwell supplies locally and think I found something similar to what you recommend but in 1 supply.(actually I think the constant current range might be a problem 100-200v)

Meanwhile the car was charging overnight, my brother checked it after night shift 4am and it showed 188v and the current was still switching on/off but surprisingly this morning it's at 191.5v and the current is constant 290ma.
The temperature dropped below freezing last night, I know that's not great for charging in but I expect the car will heat up shortly in the sun and give good charging conditions for the rest of the day. If I see an increase in the voltage I'll keep it going till 5pm when it will get cold again.

Might just be OK with these chineseum supplies for this cycle.

 

The on/off switching may be the issue I describe. The pack's voltage may have risen high enough that they've stopped fighting with each other.

Want to stay away from the steel cased meanwells that are grounded. LPC-100-500 better. Neither will fit inside your PSU case.

 

So after 20 hours charging I cut it off. I'm trying a discharge cycle now but wonder what's a safe minimum voltage considering the sketchy charge?
See my measurements below. Outside temp(o temp) inside car temp(I temp)

 

158V. However, the time you spend discharging will likely be better spent charging. 186V is way too low for a peak voltage at 10°C. Period. The only exception is if you can locate the exit duct in the trunk and measure the battery outlet temperature as > 35°C.

The battery is not fully charged.

I recommend a space heater in the cabin to increase the interior temperature to 10-20°C.

 

It's certainly not that hot at the exhaust duct. Maybe 20*c
I don't think any further charging today will do good as the temperature is going below freezing again tonight.

For a test I'll just go to 158 and then charge back up again, let's see if it makes any difference to the current recals. Meanwhile I'll get some proper mean wells on order and fix it all up in a larger enclosure. Thankfully I got those Chinese supplies for free as the shipping was well delayed.

 

Given your mild climate, the recalibrations are likely more from imbalance than capacity loss. Discharging only restores lost capacity. Charging the pack to where all 132 cells are at true 100% restores balance.

 

Discharge complete, done 2x reset charge, each took 10mins and stopped at 3 bars.
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Doing final reset charge now and will do an overnight charge with space heater keeping it 20*c in the cabin



First charge/discharge results

 

Stopping at 3 bars is a very good sign that the battery is balanced, and the car is simply concluding that additional forced charging isn't needed now that the tap voltages are in range.

4 hours at an average of 770mA = 3080mAh from full to nominal... that's pretty good.