Looking for a quality 30-50A BMS for a pack I just bought

[AlpineJoe]

Just bought one of these as the AH rating is good for the price. Considering diesel is $6+/gallon, I decided the $23 shipping was worth it also.

SLM12 LiFePO4 12v 50A 4s 600Wh Battery | Jehu Garcia JAG35.com DIY Powerwall Batteries EV eBikes eScooters eBoards

PLEASE READ THE DESCRIPTION CAREFULLY. Shipping to Lower 48 USA states only via Fedex Ground Shipping. No international shipping, including Hawaii, Guam, Puerto Rico. Non-USA customers click here. 12v LFP energy storage capable of 50A continuous discharge in 4s configuration. Safer, better...

jag35.com

This does not come with a BMS. My use case is for ham radio comms and my HF rig will only pull ~ 22amps so I'm thinking a 30A BMS would be fine but I read horror stories in the reviews of BMS's sold through Amazon and don't know what to get. This pack will be located in my house.

Anyone have a recommendation for a low amp BMS in the 30-50A range?

Thanks.

 

[meetyg]

I like the JBD BMSs. They have Bluetooth so you can configure and monitor them.
They are also reasonably priced and the forum has alot of experience and knowledge of them.

Among others, I have a 35a model and a 60a model, both for 4s Lifepo4. I haven't really stress tested them, but I do recommend to over-spec. So for your case I would get a 50-60a model.

If you don't mind waiting, you can get them from Aliexpress.

 

[mikefitz]

Smart BMS of Power Battery – LLT POWER ELECTRONIC

Fast delivery if you use the air freight option.

Mike

 

[AlpineJoe]

Thanks everyone! Ended up buying this one in the 40A version

12.69US $ 29% OFF|Jbd Bms 4s Lifepo4 60a 40a 30a With Common Port Balance Protection Board 3.2v Lithium Battery For Electric Energy Storage Tools - Battery Accessories & Charger Accessories - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

Hopefully the voltage cutoff for discharge and charge are accurate. That's what has me leery of the Amazon ones - seems all the LFP version use the same chips and their voltage trip points are not accurate at all (per the reviews).

 

[meetyg]

Just note that the model you ordered is not a "smart" BMS, meaning that you can't configure its settings.
For a few more bucks you could have gotten one with Bluetooth for monitoring and configuration to your needs.

 

[AlpineJoe]

Just note that the model you ordered is not a "smart" BMS, meaning that you can't configure its settings.
For a few more bucks you could have gotten one with Bluetooth for monitoring and configuration to your needs.

Do I need to configure it? The taps on the battery will be exposed so I can monitor the battery if I want to. What I need the BMS to do is to cut out the whole pack when one cell reaches cutoff voltage, or reaches max charge voltage. If it does that, I don't need anything else. Plus the smart version was $20 more.

Edit: $33 for the UART capable one, plus another $11.64 for the BT module. So $32 more to get a smart, BT version and only 35A.

 

[meetyg]

You don't have to configure it, but it's parameters are fixed. I personally prefer BMSs that are configurable, so that I can set the parameters to match my needs. For example setting low/high voltage disconnect values. This is helpful if you want to increase the lifespan of your battery and use it in a specific SOC "window" (for example 10% to 90%).
I also like monitoring so that I can check if cells are properly balanced and see current draw, capacity left etc...

 

[AlpineJoe]

Received the JBD 40A non-smart BMS. Construction is similar to the inexpensive Amazon units. It too is using the Hycon Tech HY2112 and HY2212 charge and balance chips. The ones they chose have the balance set to 3.6V and turns on a pair of 300 ohm resistors in parallel. The overcharge, overcurrent, undervoltage chip chosen, turns off the pack at 3.75V set, and at 2.0 V per cell.

So really not any better than other brands, and values chosen are in the realm of 'worst case' and not to be depended on for charging and discharging.

Bummer.

 

[meetyg]

That's why I recommended a smart BMS. You can set parameters as suitable for your needs.

 

[acdoctor]

3.7 and 2 volts isn’t good. But I disagree with changing settings to extend life.
CHARGER settings should be set to extend life. BMS is to prevent problems if charger doesn’t. Plus balance and individual cell’s reaching thresholds.
I do like setting my own parameters through.

 

[Daddy Tanuki]

folks are starting to realize not all of the "knowledge" of this site is necessarily the best.