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BMS & safety advice for 24v 280ah lifepo4

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Lorenzo90

New Member
Joined
Nov 27, 2020
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47
Hi,
I've just ordered 8x 3.2v 280ah cells to make up a 24v battery for my camper conversion.

Do you have any advice for a bms with low temp protection?

I'm thinking about coupling the battery with an all in one mmpt/inverter of 2500/3000v to power an induction top.

I already have a sterling 70a dc-dc charger..

So I guess that that 150a/200a bms should be sufficient..

Do you have any advice on what BMS I should use? (Low temp control is a must)

In the end, with potentially 200a current going through the system, any must regarding safety/protection for me and the sistem?

Thanks
 
OverkillSolar has low temp control, but is limited to 100A. I don't know of any higher current ones that have low temp protection.
 
You should be able to parallel BMS to up the current if needed. The one Overkill sells has a Bluetooth interface. I have one of them installed and a couple more ready for some upcoming projects.
 
I was thinking the same, I can make 2 12v batteries with 100a bms.. putting them in series will it give me 24v with 200a current?
 
To my knowledge you can't parallel a BMS on the same battery.

2X 12V in series would be 24V, but would still be subject to the same 100A current limit.
 
As much as I LOVE the all in one solutions available (MPP LV2424 is my current favorite- yes, beginner electrical joke), I would be really worried about using it in a conversion camper? Just driving around could scramble the innards of that sensitive piece of electrical equipment, and- I THINK they are limited to small cabins/ sheds/garages for 'off grid' use??? Just saying, because, HONESTLY- I would love to have all of that yummy goodness in a single unit for my 8x 280AH prismatic cell build as well.
 
snoobler said:
To my knowledge you can't parallel a BMS on the same battery.

2X 12V in series would be 24V, but would still be subject to the same 100A current limit
Click to expand...
@snoobler I'm not having luck with parallel use of the Overkill bms on 4s 12 volt... HOWEVER, @Will Prowse did a video using 60 amp Daly BMS. I'm having a separate issue with one of the Overkill, so I have an email in to them this morning in regard to the faulty protect for low temp cutoff. But I'm also asking about the Parallel use as well!
 
snoobler said:
OverkillSolar has low temp control, but is limited to 100A. I don't know of any higher current ones that have low temp protection.
Click to expand...
I have a Daly rated at 250 amps with Bluetooth and low temperature disconnect (and have both the 12 volt and 24 volt versions). I have yet to test them, but will be testing the 12 volt version sometime in the next week. I will let you know if they are adequate (since Daly defaults to strange settings that I won't use). I had to specify the low temperature disconnect and being able to change settings via Bluetooth when ordering, as well as the 250 amp rating (my anticipated max is 125 amps at 24 volts). Daly is a pain to deal with when ordering.
 
Just John said:
I have a Daly rated at 250 amps with Bluetooth and low temperature disconnect (and have both the 12 volt and 24 volt versions). I have yet to test them, but will be testing the 12 volt version sometime in the next week. I will let you know if they are adequate (since Daly defaults to strange settings that I won't use). I had to specify the low temperature disconnect and being able to change settings via Bluetooth when ordering, as well as the 250 amp rating (my anticipated max is 125 amps at 24 volts). Daly is a pain to deal with when ordering.
Click to expand...
Nice! All this is moot when I get four more cells... I am sticking with 12 volt I think... though I am tempted...REALLY tempted to go 24 volt. Only nice thing about 12 volt is redundancy. Having two "batteries" is better than one if one fails. My application is primarily for RV Trailer use for weeklong and weekend trips. Though, I realized the trailer is a great solar generator for Power Grid down situations. Just plug the trailer into the house to feed the house! Lol... Backwards than most plug in situations! Haha....
 
Just John said:
I have a Daly rated at 250 amps with Bluetooth and low temperature disconnect (and have both the 12 volt and 24 volt versions). I have yet to test them, but will be testing the 12 volt version sometime in the next week. I will let you know if they are adequate (since Daly defaults to strange settings that I won't use). I had to specify the low temperature disconnect and being able to change settings via Bluetooth when ordering, as well as the 250 amp rating (my anticipated max is 125 amps at 24 volts). Daly is a pain to deal with when ordering.
Click to expand...
How's the charging rate, and does it have a common port or separate port?
Where do you live? Imports are a mess now in UK, so I'm wondering if they are still shipping here..
 
Lorenzo90 said:
How's the charging rate, and does it have a common port or separate port?
Where do you live? Imports are a mess now in UK, so I'm wondering if they are still shipping here..
Click to expand...
It's a common port, 125 amp charge rate. I live in the Phoenix area, they ship out of Singapore via DHL. But I ordered them in November, just haven't tested them yet. I think that was the only shipping option they gave, but didn't ask. Shipping is not cheap.
IMG_20210123_171040575_HDR.jpg
IMG_20210123_171019077_HDR.jpg
 
Last edited:
I would prefer to have a separate charge port, since I'm going to use it in my camper, I want to be able to start my heater in -0c ersther6, instead of having a dead battery..
 
Lorenzo90 said:
I would prefer to have a separate charge port, since I'm going to use it in my camper, I want to be able to start my heater in -0c ersther6, instead of having a dead battery..
Click to expand...

The overkill is technically separate port internally. Low temp cut-off still permits discharge down to -10°C, and I believe that can be adjusted downwards.
 
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