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12V 4s Separate port smart BMS recommendations?

Luk3jay

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Joined
Jun 20, 2021
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Hi All, I know this has been asked a thousand times but I've had a look through previous posts and can't find what I'm looking for.

I'm planning to build a 200ah 4S pack. I already have 4x cells and am now looking for a BMS.

Daly seem popular but I've also seen/heard some bad things about them.
I've been looking at one on ebay which looks like it uses the 'overkill' app. It's 120a and £115 but seems to be Separate port which I like the idea of.

I'm just wondering if anyone has any other suggestions? or any reason to go for 'combined' port vs split? I like the idea of being able to discharge if the BMS cuts charging and vice versa. Also MOSFETS seem less likely to fail than the contactors used in other BMS's from what I've heard.

I'm based in the UK and would rather not wait months for delivery which I'm sure limits my options. I'd rather not spend more than around £120 but would if there's a good case for it.

I'd like discharge to be at least 100A and charge to be at least 70A or there abouts. I've got a 30A solar charger and I'll have a 40A b2b although they're unlikely to both be maxed out very often so if the BMS limits the charge to, say, 50A rather than shut off if it got to 51A, then that would be fine.

I'm also very interested to hear opinions of Daly as there's lots on ebay and it does look impressive. and I do like the price...

Thanks in advance as always! This is quickly becoming my new favourite forum :)
 
All JBD I've had so far are with common port, and that's no issue to work with.

If the charge is stopped for some reason (Eg low temp protection) discharge still works. It's not a hard cut of the 'wire' but you can disconnect in a single direction. So disabling discharge still allows charge, disable charge still allows discharge

If you want to discharge with 100A, I would go for a 150 or 200A BMS. I'd like to oversize any electronics for the long-time reliability.

I don't have any experience with the Daly smart ones, but the experiences seem to be not so consistent. some have issues, others not. For the JBD's basicly everyone is having no issues, so I opt for the JBD

I don't know for the UK, but my order from https://www.lithiumbatterypcb.com/ take usually about 2 weeks to arrive (in NL, things might be different for the UK)

200A BMS costs you around 100 USD (75 GBP) ( https://www.lithiumbatterypcb.com/p...on-selection=4S+Lifepo4+200A+with+Heating+pad )
The 120A is about 70 USD (52 GBP)

The Overkill ones are the same, only they are directly available in the US (no long shipping times), optional custom wiring, and local service. All at at a price. For non-US, buying at another JBD reseller might be a cheaper option, but at the cost of basicly no warranty (Well, that is going to be hard - as all warranty claims in China)
 
Thanks. I ended up going with the JBD 200A with heater. Ordered from China so it'll be a while before I can play with it.
 
Thanks. I ended up going with the JBD 200A with heater. Ordered from China so it'll be a while before I can play with it.
Did you get the JBD 200? What size holes are on the B- and C- connection bars?
 
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