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Which 4s 250a+ bms?

Wooly

WoolyAdventure.com
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Oct 2, 2021
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After my 300a Daly non smart bms decided to die (See this post) I'm looking for a replacement.

Im loathed to go for Daly again as this one died after only a few months but I'm struggling to find anything 4s 250a+.

Ideally I'd like something "smart" (Bluetooth/app) this time around too.

I need 250a+ so I can run power tools (eg my table saw and shop vac/extraction pull nearly 3000w continuous).

Aliexpress is not coming up with anything that looks anygood.....

My system:
310ah 4s LifePo4 12v battery
Daly 300a BMS (Dead)
Abso 50a B2B/MPPT
480w bifacial mono PV
3000w puresine inverter
In a motorhome.
 
After my 300a Daly non smart bms decided to die (See this post) I'm looking for a replacement.

Im loathed to go for Daly again as this one died after only a few months but I'm struggling to find anything 4s 250a+.

Ideally I'd like something "smart" (Bluetooth/app) this time around too.

I need 250a+ so I can run power tools (eg my table saw and shop vac/extraction pull nearly 3000w continuous).

Aliexpress is not coming up with anything that looks anygood.....

My system:
310ah 4s LifePo4 12v battery
Daly 300a BMS (Dead)
Abso 50a B2B/MPPT
480w bifacial mono PV
3000w puresine inverter
In a motorhome.
What did you end up buying?
 
Daly is still the only manufacturer I can find that make a 4s BMS over 200a.

I have a feeling its something to do with cooling the mosfets ?‍♂️
 
I'm also curious as I'm starting my planning on a similar build.
Honestly if you were planning a build I feel like this is not the right way to go... If I was intent to stay with 12 volts I would probably run two smaller battery packs and a pair of 150 or even 200 amp BMSs

Not only does this give you likely more capacity for around the same price.. but it gives you a really simple option for continuing to be able to operate should one pack or one BMS fail.. it's called redundancy

All that being said if you were planning a build it would make sense to go 24 or even 48 volt with the money you save on wire you can spend that to buy converters down to 12 volt
 
Honestly if you were planning a build I feel like this is not the right way to go... If I was intent to stay with 12 volts I would probably run two smaller battery packs and a pair of 150 or even 200 amp BMSs

Not only does this give you likely more capacity for around the same price.. but it gives you a really simple option for continuing to be able to operate should one pack or one BMS fail.. it's called redundancy

All that being said if you were planning a build it would make sense to go 24 or even 48 volt with the money you save on wire you can spend that to buy converters down to 12 volt
It also give you twice the weight and takes up twice the space which are both of a premium in mobile builds.
Not disagreeing with the redundancy element though.
 
It also give you twice the weight and takes up twice the space which are both of a premium in mobile builds.
Not disagreeing with the redundancy element though.
It's their own that's the decision I ended up doing for my mobile build my thought was that I was cutting the size of my existing lead acid Bank in half or less and more than doubling my capacity
 
I went with Batrium for my 4s battery- It is 2p4s with 272a cells - so roughly a 500ah 12v battery. I use it on my MotorHome. I did this arrangement so I could keep the Boost ability of the MotorHome- boosting the chassis battery with the house battery if the chassis gets low. (Although to do that I need to change out a class T fuse).

At a 2C short discharge while starting that could be 1000amps. The engine asks for a 1000 CCA battery. Hopefully I never find out…

I use a Kilovac EV200AAANA contactor (relay) to in the system.

The large amps are way too much for a bms without a contactor.

Good luck
 
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