Smart BMS 4S 12V Lifepo4 Lithium Battery Management PCB Protection Board with Balance Leads and Wireless Bluetooth - Supports 4 Cells 12.8 Volts DIY Programmable (150A)

This is a very capable BMS. I built it up around 55ah batteries in a 2P4S configuration. Seems to do a good job of balancing during charge, maintaining about a 2-3mV max differential between cell pairs. Discharge is even until the lower end which probably indicates I have a weak cell in there. This thing is robust! I screwed up when initially connecting a switched the battery and load/charge sides. Honestly it worked just fine except indicating discharge on charge and vice versa. Corrected that mistake and everything is working well. Bluetooth connection is very handy for setup and monitoring, it even has a strong signal allowing better than 10m separation between spots on opposite sides of the house and on two different floors. The one down side for me is the three 10 AWG wires, I’d rather see a 6mm screw terminal like Overkill Solar offers, allowing for more flexible hookup options. I’m looking around for terminals to modify at some point, but for now I just crimped on a connector for 4 gauge with my hydraulic crimped. The three 10ga yield an equivalent of about 5ga, so they’re adequate.All in all a good buy.

So far I’m very happy with this BMS. It paired perfectly with the iPhone app. Config was easy and straightforward. Definitely a good alternative to the Overkill units which have been on back order for quite some time. The only downside is the length and gauge of the connection cables. They’re a little short and only 6 AWG. Definitely would have preferred some of the options offered by Overkill.

I bought two of these BMS’s. It’s my first experience with DIY LiFePo4 batteries and I’m quite pleased how they work. Over 30 years on my boat I’ve been through lead-acid, Gel, and AGM batteries, constantly worrying about keeping them charged on a daily basis. In the space where I had a couple of 100AH AGMs (so total 100AH useable power), I installed 530 AH of LiFePO4, with something like 400 AH of useable power. I am amazed at how I can now monitor the batteries (including three temperatures) with the Xiaoxiang BMS app on my iPad.My one complaint is the design of the input and output leads. There are three short 10 AWG(?) leads on each side. It is up to the user to couple them together and connect them to the battery negative and to ground. The package contains six crimp ring terminals but (get this!) they connectors won’t fit over the leads! I had to laboriously trim the wires to reduce them to fit the terminals. Since they have soldered ends, it made a complete mess of the wires. If anyone at RadioB Tech had tried to install their BMS, it would have become quite obvious that someone screwed up.Once the ring terminals were on the leads, it was easy to connect three of them to the battery negative post. But, how to connect the other three ring terminals to the ground bus bar that was less than a foot away??? I wound up making another ground cable with ring terminals and used a 1/4” nut and bolt to get them attached to ground.On a (not cheap) device like this, how hard would it have been to give the user a single lead on each side; either a larger wire gauge or some sort of 4-way connector that fits the leads!!!

I connected it to my battery and it just plain worked. Bluetooth and all. I have never connected a BMS before. It was easier than I expected. First time success. The Bluetooth module works great. I'm viewing the battery settings and stats on my tablet.Very happy with this purchase

Bought this BMS based on the mostly good reviews. Hooked it to my LiFe PO4 battery and it worked fine for a day. Then the bluetooth stopped working. Checked voltages. All was fine. Tried to call company. Their phone number goes to a senior center. Nice people there but they don't sell BMS. I emailed customer support; no response. For the heck of it I looked up their address on Google maps. They appear to be located between a Safeway and a CVS pharmacy in a shopping center. Further research with the California Sec of State shows their location is in Vallejo, CA. Too much phony looking stuff. I'm returning it after wasting a bunch of time on it.

Was given a broken one. The temperature sensor was broken. Had to set parameters to -40 and 40 degrees F or C one of the two. Told the seller. The seller set me a new one and a postage stamp to send the broken one.

The wires are so short that they are pretty much unusable. Just spend the extra 30 th get an overkill solar. They come with 12" wires with an option for 24". I'm going to have to ad longer wires.

This wouldn’t send full voltage through and wouldn’t support my inverter. It works fine as a voltage meter/monitor for each of 4 LiPO4 cells.