BtrPower 140Ah LiFePo (updated)

[12VoltInstalls]

I have a couple 140Ah LiFePo batteries on their way. Ya, ya, ya, I know: cheap and maybe not dependable. I only see a few BMS failures- no other complaints and the price is right for ~3kWh of storage.
I bought these:



Now that that’s out of the way let’s not ramble into “should’ve bought …” but stick with selecting replacement BMSs.

Wanting to purchase one or two preemptively, I can’t seem to confirm exactly which to order. Going off of this thread excerpt:

As long as you can wait for shipping from China, the Overkill BMS is just a JBD BMS.
You of course get much better support from the USA, and a real warranty with the Overkill.
You want the "4S LFP 120A UART". This comes with a bluetooth dongle so you can use your phone and actually see what is going on.
Same BMS Overkill sells, Overkill just does testing and support better (and will make custom cables, I prefer the threaded connectors to cables soldered on).

Would I not want the 100A version as the oem rates their bms at 100?
Or was it meant to say buy the 120 and set it for the 100A?

 

[Just John]

I have a couple 140Ah LiFePo batteries on their way. Ya, ya, ya, I know: cheap and maybe not dependable. I only see a few BMS failures- no other complaints and the price is right for ~3kWh of storage.
I bought these:

View attachment 113288

Now that that’s out of the way let’s not ramble into “should’ve bought …” but stick with selecting replacement BMSs.

Wanting to purchase one or two preemptively, I can’t seem to confirm exactly which to order. Going off of this thread excerpt:



Would I not want the 100A version as the oem rates their bms at 100?
Or was it meant to say buy the 120 and set it for the 100A?

It's never a bad idea to use a BMS that is rated higher than your needs. In particular, Chinese BMS tend to exaggerate their capacity.
For myself, I tend to use things that are 25 to 50 % over the expected use capacity. No need to set it down to 100 amps rather than 120 amps, just don't draw more than 100 amps. JBD tends to be one of the more accurate BMS vendors for rating their products.

When you use them below their top rating, fewer failures, less heat, and longer lifespan. Speaking from personal experience, avoid Daly. Very poor quality control and testing, along with seemingly random changes to design that (to say the least) are not well documented.

 

[12VoltInstalls]

For myself, I tend to use things that are 25 to 50 % over the expected use capacity.

I get that completely. But for some reason I didn’t encapsulate the BMS rating with capacity but merely an output expectation.
Thank you for the correction.

 

[Vigo]

I bought two of those batts and have had no issues yet. Only been a couple months, though.

 

[Just John]

I bought two of those batts and have had no issues yet. Only been a couple months, though.

Why Has My 6-Month-Old "Once Perfect" Solar System Failed?

HELP, please! I am a newbie. And, I am near to conceding defeat. My 6-month-old DIY solar system in my RV has failed. It worked perfectly for 4 months. On heavy 120-volt appliance use days, I would consume 10% to 15% of the total battery amp hours. Then, even on cloudy days, the system would...

diysolarforum.com

Update. Replacement BMS? What's next?

Good evening, About a month ago, I posted: Why Has My 6-Month Old "Once Perfect" Solar system Failed? It became a long thread over several weeks. I learned a great deal and I will be forever grateful for everyone who helped this struggling beginner. At that time, the consensus was that it...

diysolarforum.com

 

[Vigo]

I'll have to read up. I've cycled mine pretty deeply on a nightly basis for part of the months i've owned them, and actually ran an ac for 7 hours overnight on Saturday night on them (they're in a small RV) but who's to say what will happen in the future. I do kind of acknowledge that by buying cheapy pre-builts im taking a discount upfront in exchange for the fact that i might have to pry them open one day and fix whatever crap is in there. But my understanding so far.. is that the cells themselves, even if they ARE old/used cells with a high cycle count already on them, will mostly still be pretty good if the bms can keep them in balance. It seems that degradation even after the 80% mark is gradual, and sudden/instant cell deaths are rare. So hopefully the bms and some crappy connections are the extent of what would ever need to be fixed, making it not a total waste of money even if it does need it down the road.. just not as good a value as originally assumed.

But i haven't read those threads yet so we'll see how far i just stuck my foot into my mouth after i do so.. lol

 

[12VoltInstalls]

I do kind of acknowledge that by buying cheapy pre-builts im taking a discount upfront in exchange for the fact that i might have to pry them open one day and fix whatever crap is in there

I bought a pair of BTR batteries with knowledge.

I haven’t ordered yet (deciding on china post VS usa stocking vender) but I’ll have two quality BMSs on hand to remediate the inevitable. Probably I’ll be china-posting them.

The fact is at $397/ea plus the spare BMS that makes them roughly the same cost/kWh as some available server rack batteries are BUT I need to support 12V, and I can scale in other batteries later if need be. I probably won’t be depleted daily except on cloudy days, but I have about 3kW of solar that I’ll be finding out if it is enough.

But you are right: when buying cheap you need your eyes open.

 

[Just John]

I'll have to read up. I've cycled mine pretty deeply on a nightly basis for part of the months i've owned them, and actually ran an ac for 7 hours overnight on Saturday night on them (they're in a small RV) but who's to say what will happen in the future. I do kind of acknowledge that by buying cheapy pre-builts im taking a discount upfront in exchange for the fact that i might have to pry them open one day and fix whatever crap is in there. But my understanding so far.. is that the cells themselves, even if they ARE old/used cells with a high cycle count already on them, will mostly still be pretty good if the bms can keep them in balance. It seems that degradation even after the 80% mark is gradual, and sudden/instant cell deaths are rare. So hopefully the bms and some crappy connections are the extent of what would ever need to be fixed, making it not a total waste of money even if it does need it down the road.. just not as good a value as originally assumed.

But i haven't read those threads yet so we'll see how far i just stuck my foot into my mouth after i do so.. lol

The biggest problem (in my mind) with buying used cells (especially those that now only supply 70 to 80% of their original rated capacity) is that dendrites formation gets more likely the older and more used the cells are.

Battery Power Online | A Look Inside Your Battery: Watching the Dendrites Grow

www.batterypoweronline.com

"Capacity fade is another potential hazard of lithium dendrite growth. The lithium dendrite reacts with the electrolyte, causing it to decompose and triggering the loss of active lithium inside the battery. The capacity loss is an accumulating effect along with the gradual lithium dendrite growth."

Now, how true this is for LFP chemistry, I don't know. I personally avoid used cells, since you never know how they were treated, and there is a reason why cell manufacturers recommend replacing them at 70% of their original capacity. It could be the chance is low and they recommend that so you will buy new cells, but I don't know.

 

[Alkaline]

Now that that’s out of the way let’s not ramble into “should’ve bought …”

haha... you aint' getting off that easy.

I would say a 60 Amd Daly would be good and easy, its about $25.00 on amazon.

 

[12VoltInstalls]

haha... you aint' getting off that easy

???

I’ll look that Daly up. I’d have to guess the 60 doesn’t denote amps ?‍

Most likely going to order the wonky-branded jbd

 

[Just John]

???

I’ll look that Daly up. I’d have to guess the 60 doesn’t denote amps ?‍

Most likely going to order the wonky-branded jbd

I own multiple models of JBD and Daly.

All of the Daly's are currently sitting in their boxes. I don't recommend them at all.
JBD just works.

 

[12VoltInstalls]

Update question: I’ve been waiting two weeks for 3 Class T 125A fuses, planning to fuse each battery at the + post before paralleling. The idea is to protect against a catastrophic failure, and use a busman 150A DC breaker between the parallel connection and busbar.

At this point I want to get the LiFePo on line and may just order a 200A Class T to install after the parallel and before the busbar as it ships UPS not friedEx.

Is that acceptable? Battery cables are 2/0. So 3’ each unprotected.

 

[12VoltInstalls]

So I can’t get a manual from btrpower on the batteries. When I inquired they sent:
So I’m going to set the SCC lithium parameters to 14.6 bulk and 13.2V ‘float’ with low voltage disconnect at 12V unless someone has a better idea and why. My idea seems to be ok according to another thread.

 

[12VoltInstalls]

Finally got around to charging these batteries. I used the little dubious chinese PZ.P knob adjustable 10A charger. What a pleasant surprise that has been.

I set it at 13.8 on the first battery and checking periodically moved it up 0.1V at a time. I was standing there after moving it to 14.2 and amps steadily dropped 0.1A at a time from 3.2A and within seconds went to zero.
Apparently the BMS cuts off at 14.2V which surprises me. I have half a mind to hook up the 1200W Giandel and plug an 800W heater in and do a rudimentary capacity test. With the 140Ah rating I should see ~2.5hrs of runtime to the bms cutout.

Really curious now. If I’m understanding LiFePo correctly 14.2 is nowhere near fully charged? Please correct me if I’m wrong.

 

[Just John]

Finally got around to charging these batteries. I used the little dubious chinese PZ.P knob adjustable 10A charger. What a pleasant surprise that has been.

I set it at 13.8 on the first battery and checking periodically moved it up 0.1V at a time. I was standing there after moving it to 14.2 and amps steadily dropped 0.1A at a time from 3.2A and within seconds went to zero.
Apparently the BMS cuts off at 14.2V which surprises me. I have half a mind to hook up the 1200W Giandel and plug an 800W heater in and do a rudimentary capacity test. With the 140Ah rating I should see ~2.5hrs of runtime to the bms cutout.

Really curious now. If I’m understanding LiFePo correctly 14.2 is nowhere near fully charged? Please correct me if I’m wrong.

That's 3.55v per cell. Good enough.

 

[12VoltInstalls]

UPDATE

I have not done my full install yet- my available time reality is different than my desired free time.

I have installed the two 140Ah BtrPower LIFEPO batteries in front of individual 125A Class T fuses to my existing system running under a MPPSolar 1012LV-MK currently. Other equipment installations will happen later.

The context is that after nearly two months of low-sun hours and typically endless cloudy days we have locally (Late Oct21-Jan1,2022) my FLA battery bank was weakened.​

I began supplementing with 'grid' to resolve this Dec2021(ish). I was fine over spring/summer/early fall 2022, but it was clear once that the Dark Season began that the batteries had been used up and wouldn't last overnight with supplemeting even with good sun anymore. I regret not paying attention to the FLA batteries better ~Nov21 because now I can't see how long they would have lasted with proper TLC and charging- got covid Nov2021 I just didn't pay attention or do much of anything for like six weeks... yet still lasted long enough to be less than LiFePo cost/year at the time....​

So I installed the 140Ah LIFEPOs late last week.​

​

I don't have the monitoring cables hooked up to the 1012LV so I cannot speak to the 120V usage (fridge, coffeemaker, cell signal booster, powertool charging, vacuum briefly), but the 12V side has been about 0.7kWh/day usage.

Charging settings are boost/bulk 14.4V with solar, and 13.7V float.

This morning and others at sunup I have been at 12.9V battery voltage. Overcast 80% this AM I am at 13.1V 8AM, 13.1V currently. Basically using what I am making 1:1
I observed yesterday that with a potential 300-400W mid afternoon of solar input, the BMS's had curtailed charging to ~3.3A/13.7V with a steady 2.7A 12VDC load displaying- so 0.5A charging- with batteries at 13.7V. So the BMS's appeared to have been happy. 0.0kWh on the grid input kWh meter for three days(nights?!) running.

With just a few days to observe, I have to say I am relieved at my purchase LOL - these cheap batteries are working properly. I have not and likely will not do a proper load test but once the other couple of minor things get delivered in the next 400 years I will have installed the meters to monitor Watts charging into batteries, 120V watts drawn, and 12V watts drawn.

I will also update down the road on battery performance. I am expecting a BMS failure or two which is what started this thread to begin with. If these two batteries perform acceptably over the next 2-4 weeks I will probably add a third. The 1012LV-MK will stay on the wall, but I will begin using a 6420AN SCC with an unused 4215AN option next to it, and the 1012LV-MK as an option for backup and its charger- Or I may see which/what of my FLA's show after a day of manual charging and 24hrs or rest and use them in the office trailer for lights. I have extra panels...LOL

At this point I am somewhat optimistic that this will work out well for the BtrPower 140Ah LiFePo battery options.


*Post Script; PS for the young folks:
With the price of commodity panels appearing to be poised to fall precipitously (saw a pair of commodity-shelf 100W panels new w/ warranty the other day on Amazoney for $136. A pair. And another more dubious brand at $72- which is cheap under inflationary times. Not only that- and I haven't been able to verify myself but a person I know mentioned it- there are apparently some 'rack' lifepo batteries 300Ah out there for $650? It was assumed to be 12V but I dunno; I can't find them with searches unless one is alleybarbershopping.

I don't need 12V in the shop for anything besides a diesel heater.

It would be interesting if Will has come across them because those are "ish" expensive cheap batteries but fairly inexpensive lifepo batteries nonetheless.

 

[Vigo]

Cool. My 2 btr 140ah batteries have not given me any issues so far, but i have not done a real capacity test either. I remember paying $400/ea for them, but the last lifepo4 i bought was a 100ah which was $200 w/coupon on Amazon and that one hasnt given me any problems either. Once they hit that price point per-Wh consistently i cant see anyone choosing lead acid outside of extreme cold, or in applications that are relying on lead for its weight, like old forklifts. ?

 

[12VoltInstalls]

Once they hit that price point per-Wh consistently i cant see anyone choosing lead acid outside of extreme cold, or in applications that are relying on lead for its weight, like old forklifts.

Don’t forget that these are likely bottom shelf with perhaps capacity-tested ‘used’ cells inside, and BMS’s that have a number of failure reports.

With an origin-to-user 80%+ margin history for cheapo-nise electronics there’s not a whole lot of value or support to support warranty or even quality control at origin price.

So do the cartwheels with a grain of salt.

We are absorbing ‘fitness for a particular purpose” risks entirely to ourselves other than the initial 30 days of Bezos Buyback and the 90-day exchange the ‘brand’ offers. Vpauexii 100Ah is $250, weize and eco-worthy are 100Ah at the <=$300 price point.

 

[Rednecktek]

So you've finally gone to the Light Side there? I feel so betrayed by my FLA brother...

Next question is what happens when they get cold...

FLA FOREVAR!!!

 

[12VoltInstalls]

So you've finally gone to the Light Side there? I feel so betrayed by my FLA brother...

Next question is what happens when they get cold...

FLA FOREVAR!!!

No. I have the batteries inside.
FLA is great for a lot of applications including a low-budget necessity start with solar, or cold winter environments without warming logistics to be concerned with.

LiFePo made sense at <$800 for 280Ah usable as that is virtually the same as $110/each walmartha is getting for the deep cycle batteries. When factored for the LiFePo advertised cycles for the lithium batteries and fla cost for 3-5 years lifespan I took a long view and bought the cheapest lithium iron chemistry I could find for the most amp hours with the least publicly available complaints volume. That last part was the actual deciding factor.

Three months later at $900/300Ah present offerings it is still a good choice on price.

Time will determine whether it was a great inexpensive choice or an “OK” value if I have to buy any BMS’s. Or if they don’t last 8-10 years.

FWIW I’ve got a mind to order and DIY a huge battery July/August that might be enough with the right inverter to run my tig intermittently. If I can come up with another 2kW of new panels cheaply and only use equipment in daylight hours, I could potentially “use” the solar production of 4000W of panels ’real time’ but in truth just grid power makes the most economical sense. The hobby element, however, lurks in waiting