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Old 05-30-2021, 02:07 AM   #1
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Need a BMS fast

Apparently I was scammed by DALY. I ordered a 250amp bms from them and it's now way over a month overdue. All they say is "wait my friend" I am going to go ahead and do a chargeback. They can't give me a real answer.

Where can I get a BMS that is either a 200amp or 250amp quickly?

I need it for a 280AH lifepo4 12 volt battery I am building.

Help and thanks!

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Old 05-30-2021, 11:01 AM   #2
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I was going to look hard at electrodacus but I haven't ordered batteries yet. At least a lead. electrodacus.com. I think Canada, not sure how that effects shipping time but I think its a one man operation so you may get decent customer service.
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Old 05-30-2021, 02:03 PM   #3
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I was going to look hard at electrodacus but I haven't ordered batteries yet. At least a lead. electrodacus.com. I think Canada, not sure how that effects shipping time but I think its a one man operation so you may get decent customer service.
I was going to look at them but so far have not figured them out. Seems you need multiple parts to build a BMS. Still looking, they just confuse me.
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Old 05-30-2021, 02:07 PM   #4
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I agree, it's kind of a mess but from what I see you only need the bms if you have charge controllers already. The add-ons are just $27 charge controllers, I think. click into the forum and poke around there if you need more clarification, I think it's way easier to understand that way.
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Old 05-30-2021, 02:18 PM   #5
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this is very helpful: worth 16 min if you don't find a different bms
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Old 05-30-2021, 07:51 PM   #6
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Make two 100A strings each with their own BMS.

Overkillsolar.com and batteryhookup.com sell the same Xiaoxiang BMSes that I am very satisfied with.

I have three of them in parallel.

IMG_9526.jpg
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Old 05-30-2021, 09:29 PM   #7
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Make two 100A strings each with their own BMS.

Overkillsolar.com and batteryhookup.com sell the same Xiaoxiang BMSes that I am very satisfied with.

I have three of them in parallel.

Attachment 57978
The 4 cells I have are 280AH cells. Any way to do anything with those?
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Old 05-30-2021, 10:20 PM   #8
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The 4 cells I have are 280AH cells. Any way to do anything with those?

Sure, whatís the problem?

Wire them up 8S (22-28V) and you have a metric ton of power for cheap.

280AH doesnít mean you need to draw 280H. 100A at 25V is 2.5kW.
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Old 05-30-2021, 10:22 PM   #9
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Or you have ONLY 4 cells?

Then get another 4, or in the meantime buy a 4s xiaoxiang bms.
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Old 05-30-2021, 11:19 PM   #10
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Or you have ONLY 4 cells?

Then get another 4, or in the meantime buy a 4s xiaoxiang bms.
I'm totally confused now. That's the real problem.

I have 4 EVE 280Ah cells. I have them wired in series to give me 12 volts. I don't have space for another 4 cells and don't need the extra. This is going in the chase van. The van only has 600watts of solar.

What I am trying to do is get a good BMS for the battery I built. It will have a 2000watt / 4000watt surge inverter on it plus the normal 12 volt stuff like refrigerator, lights, charging ports, water pump etc.

I know I don't want anything DALY. But do need something simple.
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Old 05-31-2021, 12:01 AM   #11
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Your problem is that if you want to have 4000W out of your inverter you are just not going to have a good experience. Drawing 500A out of a 280Ah pack is too much.

But Iím guessing your needs arenít that crazy. Maybe you bought a 2000 W (4000 W SuRGE!) harbor freight modified sine wave inverter.

What are you trying to do? How much mower you really need?
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Old 05-31-2021, 02:04 PM   #12
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Your problem is that if you want to have 4000W out of your inverter you are just not going to have a good experience. Drawing 500A out of a 280Ah pack is too much.

But Iím guessing your needs arenít that crazy. Maybe you bought a 2000 W (4000 W SuRGE!) harbor freight modified sine wave inverter.

What are you trying to do? How much mower you really need?
I never said I wanted to draw that much. I just stated the inverter I have.

Yes that was what I said. I have a (2000 Watt / 4000 watt surge) inverter.
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Old 05-31-2021, 09:22 PM   #13
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this is very helpful: worth 16 min if you don't find a different bms
Thanks. That helped. I can see how you can have it turn off the inverter automatically.

What I still am confused with is how it prevents over charging of a cell.
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Old 05-31-2021, 09:26 PM   #14
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I was confused about that too... I think the best approach with that is to use the settings in the charge controller to turn off at a specific point and then to have a high voltage disconnect relay on the input of the wires from the panels to the charge controllers, but I am not 100% sure. I will look into it a bit.
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Old 05-31-2021, 09:39 PM   #15
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Thanks. That helped. I can see how you can have it turn off the inverter automatically.

What I still am confused with is how it prevents over charging of a cell.
so that's really it. you can use a relay, figure out how to interface to your charge controllers or use a victron battery protect, which seems like the easy way. you wire that to the extio4 port thats high voltage disconnect by default and it'll disconnect the solar panels from the charge controller. I'll probably use relays because I have multiple charging sources and the battery protects are a bit more expensive but they're easy and just about ready to go from what I understand... still more technical details to work out but thats the basic idea.
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Old 06-01-2021, 05:12 PM   #16
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so that's really it. you can use a relay, figure out how to interface to your charge controllers or use a victron battery protect, which seems like the easy way. you wire that to the extio4 port thats high voltage disconnect by default and it'll disconnect the solar panels from the charge controller. I'll probably use relays because I have multiple charging sources and the battery protects are a bit more expensive but they're easy and just about ready to go from what I understand... still more technical details to work out but thats the basic idea.
Do you know if it automatically discharges cells that get to high above the other cells?
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Old 06-01-2021, 05:20 PM   #17
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From my understanding it does balancing through the little wires that connect to each cell. Not high current but if one cell goes out of whack it does something to balance over time.
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Old 06-01-2021, 07:19 PM   #18
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Originally Posted by Bert06840 View Post
Make two 100A strings each with their own BMS.

Overkillsolar.com and batteryhookup.com sell the same Xiaoxiang BMSes that I am very satisfied with.

I have three of them in parallel.

Attachment 57978

I second the JBD/Xiaoxiang BMSes. They're excellent. I also made an Arduino-powered monitor for them (with code) here: https://diysolarforum.com/threads/fi...65#post-247858
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Old 06-01-2021, 09:08 PM   #19
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Oh, wow!! Fantastic. I'm going to rely on your code in a few months when I will start integrating all my nodes.

I had been reading the protocol spec in some documentation that Steve from overkillsolar.com had put out there, so I knew it wasn't too much of a stretch.

Thanks!
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Old 06-02-2021, 07:04 AM   #20
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Drawing 500A out of a 280Ah pack is too much.
Wut?

bulldust

True for other infrastructure maybe, things might warm up

and of course can't do for very long as the energy will run out, voltage start sagging, lifespan is lower

all that depends on cell quality

But no actual damage to the pack

That's under 2C

many cells can do 10C, some LiPo routinely even past 30C.

All depends on the use case.
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