Id be stoked to use the same variable charger for both. Can you post a link please
Who's in the UK and Ireland?
- Thread starter squowse
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I’m going 2p4s as I only have 1 12v bms. I may add another bms at a later date and go 4s2p as I will eventually be running a bigger inverter to power a dishwasher as well as the rest of the truck.
having to buy the variable power supply was a pain but mine “broke” after I was finished with it and I sent it back to amazon for a refund
in the process of capacity testing them. So far all good. Weakest one tested at 281ah @2.75v. Not bad for 272ah cells.
I’m going 2p4s as I only have 1 12v bms. I may add another bms at a later date and go 4s2p as I will eventually be running a bigger inverter to power a dishwasher as well as the rest of the truck.
having to buy the variable power supply was a pain but mine “broke” after I was finished with it and I sent it back to amazon for a refund
It’s one of them things, pay and get the cells, don’t pay and don’t get them.
I paid £575 in total for 8 272ah lishen cells delivers to my door. That’s just under £72 each including delivery and import I can’t buy lead acid or agm for that price if you cost it at usable amp hours.
I bought a 10a power supply, I charged two sets of 4 cells with bms to 14.4v disconnected and left to sit overnight. It took nearly 14hrs to top balance them from that point. It’s a long slow process but if done right it shouldn’t need done again.
once they hit zero amps I left sitting for 2 hours still connected and let the voltage settle. Then I switched the power supply back on and let them top balance again, that took about an hour.
I would rather spend the time doing it now than spend the time wondering why my cells keep coming out of balance at a later date.
*disclaimer* I am no expert, I have only done this once and am making it up as I go along. This is not advice it is only a description of what I’ve done and how it went for me
once they hit zero amps I left sitting for 2 hours still connected and let the voltage settle. Then I switched the power supply back on and let them top balance again, that took about an hour.
I would rather spend the time doing it now than spend the time wondering why my cells keep coming out of balance at a later date.
*disclaimer* I am no expert, I have only done this once and am making it up as I go along. This is not advice it is only a description of what I’ve done and how it went for me
I've been looking since my last post for a bench power supply and the max I can find is 30V 10A but considering my capacity is only 5760 watts it'd be roughly 19 hours from 0 to full which it'll never be and I'll probably have a lower charge voltage maximise the lifespan. I haven't got to capacity test yet. I'll be scrolling through Wills videos when I get top balanced. I'd be happy with those results you got.
I connected the bms and charged with a normal 12v charger in packs of 4. Let the bms cut off when one cell hit 3.65v. Did both packs of 4 like that. I didn’t have enough busbars to connect them all up in parallel for top balancing, I ended up stripping 3 core mains cable. It’s about 1.5mm diameter solid copper core, wrapped it round each stud and tightened them down. I made up my own leads from the psu to the cells. It took a good few hours but at 10a it never really went much above 8a. Would take a lot longer with a 5a charger
I bought one of these for capacity testing
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Yeah I've just watched his video with it. If you fancy selling it on when you're done I'd be happy to buy it, save me waiting for it coming from ChinaI bought one of these for capacity testing
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I cant do it that way because I only have a 8s BMS. I ended making the missing busbars with copper pipe. I've ordered the 30v 10A power supply so at least I can get on with top balancing them
squowse
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Sorry I don't know what I was thinking - the 24V power supply won't be able to do your top balancing. You'd need one about 3.5V of course. I've got a 5V one here I'm going to see about extending the adjustment to 3-3.5v by replacing the variable resistor used to control the voltage. I've seen it done on a smaller one on YouTube. I'll find out I suppose.
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squowse
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Maybe the 24v one can be adjusted all the way down to 3.5V but it seems a bit of a stretch.
squowse
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I'd say they bypassed customs! Unless you've any paperwork for them? Happy days anyway, they obviously know what they're doing.
Yeah that's the plan. Because it's 0-30v I should be able to reduce it to 3.6v for the top balance and then upto 28.2 for the hookup charge.
squowse
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I could only get the voltage down to about 4.5 before it went all the way down to 2.9 and stayed there until switched off and on again. I assume it;s a feedback loop or something. The video I saw he took it down to 4.2 but his started lower than mine.
Annoyingly it did seem to work at first but I think I didn't notice it was stuck at 2.9.
Does it have course and fine adjustment on it or just the one?
squowse
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This is the kind of thing you could use for 24V charging - 60A (1500w) so a decent current. You don't want to messing about waiting days for them to charge. They do have smaller ones.
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squowse
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it's just a little screwdriver adjustment. I desoldered it and connected a bigger resistor to lower the voltage. Didn't work. I'll get a 3.3V volt one. I didn't see them originally. Thought I could adjust a 5V one.
Your probably right.
I think these are just fixed power supplies though so couldn't draw more than the 24v and thought the voltage needed to be higher than that to be able to charge fully (28v)This is the kind of thing you could use for 24V charging - 60A (1500w) so a decent current. You don't want to messing about waiting days for them to charge. They do have smaller ones.
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squowse
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They can be adjusted a bit plus and minus. I'll get a 12V one out tomorrow and see the max voltage it will do.
Actually you're probably right - these are easier to adjust downwards than upwards in voltage. A 30V would be ideal if you could find one.
squowse
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There are 27V ones. Biggest I could find it 1500W. They will adjust up in voltage about 10% typically.
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as you say 30v would be ideal but they jump to 36vThere are 27V ones. Biggest I could find it 1500W. They will adjust up in voltage about 10% typically.
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