CALB SE LiFePO4 BMS

[bdosborn]

I've been doing a lot of testing on the new CALB SE 200a-h LiFePo4 cells, I did a discharge test to make sure the batteries were in acceptable condition. While the batteries were listed as "new" they were clearly used. I got them for a great price and luckily they still have enough capacity that I don't feel cheated (much). They were listed as 400 a-h and they tested to around 92% of that. I did my testing using a 1000W load via a modified sine wave inverter (90A @ 12V ~ 0.5C). I didn't take them much below 11V so I interpolated the capacity at 10V (completely discharged voltage). :



I complained to the vendor and they were happy to refund my money, I would just have to ship the batteries back on my nickel. That's Aliexpress; you rolls the dice, you takes a chance. Anyways, here's the Frankenstein setup for testing:


I'm using the iCharger to cylcle the battery back up, it does a great job of balancing the cells and charges at 30A. Right now my cell imbalance is only 2mV, which is awesomely low. You can calibrate the iCharger voltage sensing, which I did with my FLuke 115 so I trust the voltage reading.


I finally found a BMS that doesn't cost an arm and a leg (~$130)and does what I want. I hate BMS that don't annunciate anything, which is typical of most of the cheap chinese BMS. You have to get a multimeter out to see if they are working. The Electrodacus SBMS0 does everything I want, displays cell voltages, state of charge, tracks a-hrs in and out, and you can tweak the settings for about everything.

It also has contacts to control Victron battery disconnects so I can disconnect the load at low voltage, disconnect the charger at high voltage, low temperature charging disconnect, and control relays to do things like divert solar power for heating water when the battery is charged . It's got a few warts; it was designed by a microelectronics guy who doesn't know how to terminate power wires and the software is a little "kickstartery". But so far it is leaps and bounds better than anything else I've tried. The developer has a forum that he's very active on, he actually answers peoples questions. Try that with a chinese BMS!

He has optional modules that control solar panels, so you don't need an expensive charge controller. You have to use 36 cell 12V panels but it's so much cheaper (~$40/20A module) than a good controller so I'm going to try them out.

It has a WiFi connection and a web page so I can monitor the battery from anywhere on my cell phone. I just charged the battery so the cell voltages are out of wack. They settle back into balance after charging stops, which is a new realization for me. Don't do any cell balancing until about 12 hours after charging.


Helps me to get my geek on.

Bruce

[Tom&Shelly]

Helps me to get my geek on.

Bruce

Cool stuff!

Tom

[John61CT]

Yes CALBs are rock solid, but just as important is a trusted seller that accepts credit cards directly, and handling warranty returns on the same continent as you.

http://www.calbusainc.com/calb-buy

Other prismatic makers in the same league include Winston, GBS, Sinopoly and CAT

And yes Electrodacus has a fantastic rep, not unlimited flexibility in design of your system, but very reasonably priced for that level of QC, accuracy and reliability.

[tony.latham]

Helps me to get my geek on.

Amazing. If something cracks, some piece of steel --you can always weld it up with a coathanger.

Tony

[bdosborn]

I noticed that 2P cells 3 and 4 had a relatively high voltage difference after charging. I waited overnight for the battery voltage to stabilize and there was still a 24mV difference between the two paralleled cells 3 and 4. So I swapped two of the cells to try and minimize the impedance differences between cells. The voltage difference went down to 10mV afterwards. I haven't read about doing this kind of tweaking to a 2P4S configuration so I wanted to share it.


I'll run a couple of discharge cycles and see if it helps the final voltages after charging.

Bruce

[bdosborn]

Amazing. If something cracks, some piece of steel --you can always weld it up with a coathanger.

Tony

Hey,, that's a good idea. I bet jumper cables and a coathanger would work.

Bruce

[lfhoward]

Really neat setup! I will be following this thread to see how it works out in the long run. I would eventually love to run LiFePO4 as well, and the only way I will be able to (eventually) afford it is to DIY like you.

[bdosborn]

There's definitely a learning curve with the DIY approach but its worth it. Lithium batteries are so much better than lead acid!

Bruce

[featherliteCT1]

Great info … thanks for posting!

[saltydawg]

Really neat setup! I will be following this thread to see how it works out in the long run. I would eventually love to run LiFePO4 as well, and the only way I will be able to (eventually) afford it is to DIY like you.

There is a 280 ah lifepo4 cell you can get for right around 430 bucks delivered for 4. Yes they are grade B, but every review I have read they have given full capacity. Pair that with a decent smart bms and your just over 500 bucks for 280 ah of battery.
https://www.youtube.com/watch?v=3U4ZfQ_IToI&t=17s

[featherliteCT1]

bdosborn,

I cannot tell from the photos, but are the bolts on each terminal the original bolts that came with the cells, or did you install your own studs or use longer bolts?

Thanks!

[bdosborn]

I was supposed to get bolts and busbars with the cells but the vendor cheated my out of both. I ordered M8-1.25 x 16mm bolts from Amazon and made my own busbars from copper bar I got on eBay. Buying on Aliexpress is such a roll of the dice, you don't have any recourse if anything goes wrong.

Bruce