How Adjustable are common chargers?

I have some 6A and 4A 72V chargers with an 83V cutoff. They're the common kind with the 3 pots for adjustment. I'm interested in going to 22s instead of 20s, and I'm wondering if it's perfectly safe to bring them up to the new 91V cutoff, or should I buy a set of new chargers?

Chargers is about the only thing I don't have good excess right now, unlike controllers, batteries, and motors, so a couple of blown chargers will put me in a pinch. If the risk is low, then I can put a fan blowing on them for extra cooling just to baby them a bit.

John in CR said:

I have some 6A and 4A 72V chargers with an 83V cutoff. They're the common kind with the 3 pots for adjustment. I'm interested in going to 22s instead of 20s, and I'm wondering if it's perfectly safe to bring them up to the new 91V cutoff, or should I buy a set of new chargers?

Chargers is about the only thing I don't have good excess right now, unlike controllers, batteries, and motors, so a couple of blown chargers will put me in a pinch. If the risk is low, then I can put a fan blowing on them for extra cooling just to baby them a bit.

Click to expand...

If they are the standard EMC type bulk chargers, I don't see 91V being a problem. Turning up voltage, you might have to reduce the current to stay within the charger's power ratings. I hookup a watt meter in line (usually a CA) and attach a battery until it starts to charge. Then I unplug the battery and adjust that limit pot until the desired voltage is displayed.

If the fans run of the IGBTs, there's no need to put in an auxiliary as they will turn on when needed.

Thanks for the reminder that it may be a good idea to turn the current down to 5A from the 6A they're set at. I've only adjusted the cutoff voltage by less than 1V before, so this is new territory for me.

Might be necessary to test with load or battery attached?
If necessary, try adjusting voltage with voltage out through 100w+ light bulb.
Test amp adjustment through 500w(?) halogen?, adjustable output heater 500-1000w?

Might have coarse and fine adjustment voltage pots.
Test adjustment range with multimeter attached.

Based on my experience with modding MeanWells ...
Typically, the trim pots allow a limited degree of adjustment.
However,... usually, the trim pot is in series with an additional resistor, often replaced to produce different voltage chargers from same production device.

1. Trace back from the voltage trim pot to a resistor
2. Test value of resistor and acquire resistor of slightly lower numeric value
3. Attach voltage meter to output and monitor while you touch lesser value resistor in parallel with designated resistor
You should be able to estimate necessary value resistor to attain desired voltage or just replace with a multi-turn pot

Repeat same procedure for current adjustment pot (most multimeters have a ≤10A Amp meter function)

Might be an additional voltage regulation using a zener diode, but only consider that if necessary ...

Thanks Drk Angel,

The possibility of only fine adjustment capability makes sense. I should have some backup chargers anyway, so I'll get more on the way first, before I go sticking my caveman fingers inside a box of electronics. That way I'll be sure to get the higher voltage I need, and I think Leo at Greentime will find out the range of adjustment for me.

I wonder if any of the guys doing 100V top of charge with 24s packs use common 72V battery chargers, or do they all use meanwells or even multiple chargers like I do with my 30s pack.

John

On a king-pan ? charger from bms batt pn# emc 600 factory set for 48 volt lifepo4 i just twisted the volt adj until it put out 75 volts. It has been working great for a couple years now.
I do not play up near 100 volts so good luck with that.

Bms battery has a 1200watt @ 288v 3a charger. Don't know how easily it's adjusted.

999zip999 said:

Bms battery has a 1200watt @ 288v 3a charger. Don't know how easily it's adjusted.

Click to expand...

If I needed a 288V charger, it would need to put out more than 3A. I wish I had a pair of controllers each capable of 150A battery side that could handle that voltage. That would put my HubMonster at 86kw peak input without stressing the motor. I might not be able to spin it up to full rpm at that voltage, but in a mid-drive I'm sure it would be fine well past the peak power point. HubMonster can handle so much more than I feed it, so my dreams are full of cheap high voltage controllers.

I was thinking about your 39s pack and having a adjustable charger. Like for your 22s and ? Adjustable with a noob and a meter. How different do bms battery chang there 1200w model ?