Battery backup and BMS question

[TheMakerJake]

Hello,

I've read several posts on BMS's and battery options and this is where I think I'm going to start. Any constructive feedback would be appreciated. I’m going with a battery backup for now and plan to incorporate solar panels at some point in the future. My home is already wired with a manual transfer switch where I plug in my gas generator and the battery backup will offer another (quieter) option when the power goes out.

I’m going a 48V DIY approach because I like to know the ins and outs of how things work. You know, so when it breaks on a Saturday night you know how to fix it.

DIY purchase list:

Qty 1 - EG4 12000XP 48V Split Phase Off-Grid Inverter - Constant Current.com

Qty 32 - EVE LF280K V3 Grade A Cells - 3.2V LiFePO4 280Ah Battery $72 each 18650batterystore.com

Qty 2 - JBD Smart BMS 16S 100A 48V Lithium Battery PCB Can’t find in stock???

I decided to go with the JBD BMS based on several positive posts, but I’m not sure which model to go with for a 48V 280ah set up. Does the charging current matter other than charging faster? Like would a 60amp BMS work basically the same as a 200amp version? I don’t think that it would change anything other than the charge time and the size of the charger I can attach to it. But I thought I’d ask…

Also where’s the best place to buy hookup wire? Connectors and crimpers too? I’d like to build my own cables for something like this.

Any vendors to stay away from?

Thank You

 

[miran90]

Jbd bms 20s 100a I had is very bad at soc calculations.

 

[TheMakerJake]

Jbd bms 20s 100a I had is very bad at soc calculations.

Do you think that was a BMS problem or a software problem? Which application did you use to control that BMS? I've read that the JBD BMS can be controlled by various software applications.

 

[DIYrich]

I would go with 200a bms. If one pack goes down, the remaining pack can supply 10kW to the 12kW inverter.

The 12000xp has a 250a battery connection, so I would have a total of at least 300a of bms. The amp rating of the bms is how much power it will pass. You are concerned with draw rate, not charge rate.

 

[timselectric]

Also recommend 200a BMS.
For the reason above and for surges.

 

[mikefitz]

was a BMS problem or a software problem?

My experience with the JBD units is that some modification of the parameters improves the SOC calculations.
Using the 200A BMS would be prefered. You can charge or discharge at any current up to the 200 amp limit.
For example you can charge at 10A or 100A, it just takes10 times longer at 10A.
BMS from the company retail outlet, 500 in stock. Option for express delivery , takes 7 days to reach me in the UK. Company take PayPal.

6S 7S 8S 9S 10S 12S 13S 14S 15S 16S 17S 18S 20S smart Bluetooth BMS with 150A to 200A constant current for electric tricycle battery pack - LLT POWER ELECTRONIC

Features and Characteristics : Characteristics : This is a smart BMS with UART or RS485,CAN Communication which will be used to protect and monitor your battery status visible from the computer and your android APP phone .which can support parameters setting and adjustment .the charge and...

www.lithiumbatterypcb.com

Use the Overkill app

 

[TheMakerJake]

Super helpful information @mikefitz , @timselectric , & @DIYrich . Thanks!

 

[miran90]

Do you think that was a BMS problem or a software problem? Which application did you use to control that BMS? I've read that the JBD BMS can be controlled by various software applications.

I use solar overkill but the issue that it depends on battery voltage for soc estimation and it's always crap.