LiFePO4 Install

[john61ct]

I think you're right, not looking good at all.

3.6V/14.4V should be above the start-balance setpoint "SBV"

However the balancing (likely resistance bleed style) current rate could be something stupid-slow like a third of an amp.

So possibly, the amount of **time** spent above SBV was not sufficient to allow balancing to **complete** each cycle?

This problem would compound over time, until the per-cell LVC and HVC would make it look like capacity is way down.

But seems unlikely to explain **that** low a SoH.

More likely a bad cell. . .

 

[john61ct]

Would the BMS even **allow** 14.5 or 14.6V?

What are BB's published specs, recommendations for precise charging?

 

[dreadlocks]

I thought it was higher but the BB tech told me to hold it at 14.4v to do a balancing, which means my solar shoulda been balancing it daily pretty much.. My SmartSolar is set to hold max of 30mins absorb before it goes into float, was that not long enough? Its what BB had on their blog about configuring SmartSolar's: https://battlebornbatteries.com/programming-a-victron-smartsolar-charge-controller/

The battery says 14.4v on it and most charge params say 14.4, but it also says:

• Acceptable Voltages 14.4 – 14.6 for bulk charging
• For your Bulk/Absorption stage, the ideal voltage is between 14.2v-14.6v. For full charge and balance, the absorption mode should be set to last for at least 20 minutes per battery (for multiple batteries in parallel).

I charged it to 14.6 and 0.00A input twice this year just to get it full 100% and balanced.. since I got the solar online early this spring its been charging almost exclusively through the SmartSolar charger.. I kept it running fridge continuously even in storage all season because I keep it full of condiments and use it for extra beer storage, it'd go from about 70-90% every day with a quick drive up to 14.4 before backing down to a float of like 13.3v, which the fridge would draw it down to about 90% and then run off solar til sun went down.. when out in the field, I'd draw it no lower than ~35% SOC after making a few morning coffee's (~750W), and solar would do its thing usually by noon and everything would be full again and all evening it'd be running mostly off solar w/battery @ ~90%

Charge rates never really been higher than 30A, tho I had intended to take it up to 40A w/next round of improvements (new sterling charger, second solar controller for portable panel), max discharge rate was about 80-90A running microwave mebe a dozen times total for 3-5mins.. Coffee Maker is 60-70A, those are my biggest loads.. under the 1C/100A continuous discharge rate in specs.

 

[dreadlocks]

ok I did as @john61ct instructed, charged it fully.. let it sit for an hour:


I put 3.6A on for 1H, here is the first 20mins I watched it:


After 1h w/load:


then I let it sit for an hour, here was its final resting voltage:


its charging back up again now for another test w/more amps.

 

[shade]

Maybe I missed it, but I haven't seen any procedures for recovering from an internal BMS shutdown on Battle Born's site. Their manual doesn't offer much help.

Even if they keep their BMS locked down, publishing a basic recovery/reset procedure seems like a good idea.

 

[dreadlocks]

it seems to come out of protection mode on its own, over time.. I havent kept that close an eye to it but every time I bring it back inside in protection mode (0.00V across terminals) and leave it overnight its powered again the next morning..

this is the quote I got from BB:

If the voltage on the battery gets too low, down under 11 volts, the BMS will kick in and shut the battery down so it reads 0 volts. In order for it to begin charging again, a charger has to recognize there is a battery there for it to charge, in order for the charger to do that it has to read a voltage of 10 volts or higher. To get the battery back up over 10 volts you will have to wake it back up by "jump starting" it. Just like you would a car vehicle, you will want to apply another 12 volt source to the battery (some people even use their car to do this) and jump start it just like you would your car. This will spike the voltage on your battery back up to over 10 volts, it will then properly begin charging again.

Jodi

However, Ive got it hooked to a house charger that has no stages, just a dumb CCV charger from Progressive Dynamics that outputs 14.6V constantly.. it does not need to detect any battery voltage to start cranking out amps, its powering the trailer right now w/no battery all on its own.. that did not seem to bring it back out of protection mode, but mebe I didnt wait long enough? was hesitant to leave it unsupervised hooked to a charge source, especially this dumb one w/no float.

 

[shade]

If BB didn't see a problem with your usage data, come Monday I'd be looking for a warranty exchange. Without knowing exactly what happened, and that it was completely resolved, I'm not sure I'd have a lot of confidence in that battery.

It'd really suck if they decided that anything you've done over the weekend to remedy the situation voided the warranty. I'm not saying you have, but I'd keep that in mind.

 

[john61ct]

I thought it was higher but the BB tech told me to hold it at 14.4v to do a balancing

OK, good to know.

So let's call this "BB Full": hold 14.4V until amps accepted tapers to between 3 and 1A.

If more balancing time is needed, just cut current input to say 2A, those low-rate balancing circuits can literally take days and days to get back to balanced if the cells were far apart.


> My SmartSolar is set to hold max of 30mins absorb before it goes into float, was that not long enough?

Two criteria for "long enough".
A. balancing has time to finish
B. you want to get to your BB Full benchmark for calibrating the SoC meter at 100% (required frequently if you want it to be reasonably accurate), or for doing CC-load capacity discharge testing

Again, do you have any way to measure cell voltages?

> For your Bulk/Absorption stage, the ideal voltage is between 14.2v-14.6v

If indeed 14.2V is high enough to start balancing, that would be great. As an experiment with say 5A current:

14.2 Absorb until 1A, then
14.3 Absorb until 1A, then
14.4 Absorb until 1A
keep going to 14.6

Log the time taken, if possible Ah accepted, at each increment.

Three potential benefits - 1. over-riding temporary capacity loss from a potential "memory effect" 2. hopefully just getting fuller and fuller. 3. longer time for balancing

Higher current rate is not actual healthier for LFP in normal cycling, but in a temporary troubleshooting mode like this is something else to try for 1&2 above, for relatively short times.

For #3 holding maybe for days, definitely want a low rate, not much over the balancing current spec.


Your usual usage cycling sounds great, BB should not have any claim of improper care.

 

[john61ct]

However, Ive got it hooked to a house charger that has no stages, just a dumb CCV charger from Progressive Dynamics that outputs 14.6V constantly
...
was hesitant to leave it unsupervised hooked to a charge source, especially this dumb one w/no float.

See if you can keep pushing,

as long as the charger **is** holding 14.6V or less, which is within spec, independently verify it at the posts

**and** amps accepted is over the 2-3A range, you are not yet at true 100% Full.

Don't worry about no Float, just stop once you hit your end charge spec for the session.

Which in this case is stopping at 0.01C, call it 1A, that is Full.

Goal being to get it to 3.34-3.35V OCV isolated at rest, at least an hour.

None of this is stressing the battery in the usual definition, vendor specs

(getting max longevity is different, personally I would not go this high for regular usage daily cycling, but industry says NP)

 

[dreadlocks]

Again, do you have any way to measure cell voltages?

Unfortunately no, its a sealed black box for all intensive purposes..

 

[dreadlocks]

ive been charging it until its 0A input @ 14.6v, I figured if the shunt detects 0.00 going into battery its done with its cell balancing routine.. usually dont take very long.. no idea if BMS is just no longer accepting a charge or what.. its always seemed to me that the BMS cut off charge when it thought it was full, but I dunno if anyone has verified that w/BattleBorn Staff.. they said contridicatary things so I never left it on unsupervised for more than a few hours.

Ive verified the BMV is accurate w/Fluke, been verifying all readings w/it just incase, both at the battery terminals.. the supply outputs 14.6V solid, I unfortunately do not have an adjustable lab power supply, I been wanting one for like eons but keep making due with others.. I cracked this CCV PSU open to see if there was a pot I could adjust but unfortunately didnt find one.

The wiring between charge supplies, and battery is all insanely oversized.. I've got less than two feet of 00 running through the master disconnect and battery protect, then like 1ft 4awg going from charger to the battery side of the battery protect LVD.. there's a 200A master fuse on battery post and a 50A fuse on charge sources, neither have ever tripped.. and despite all that the SmartSolar is getting battery terminal voltage from BMV over their lil bluetooth network, everything's been cooking along fantastically until Labor Day weekend.. got the battery last year for 4th of July weekend.

 

[john61ct]

I charged it to 14.6 and 0.00A input twice this year just to get it full 100% and balanced

Some people and vendors have no problem with holding all the way to Zero amps acceptance.

Personally I think that's too stressful for good longevity, especially at 14.6 but IMO even at 13.8 (3.45Vpc)

and most especially at low charge currents available.

The 0.01C endAmps point is a good "highest SoC" stopping point for "vendor Full" benchmarking, and 0.03C for daily usage cycling, resetting the SoC meter frequently etc.

But other than those reasons, the battery health ideal is staying at **lower** SoC, as in 30-50%

Certainly for storage, no cycling for days

But even if you just aren't drawing much at the time.

Sitting anywhere near Full for long percentages of the bank lifetime, shortens it significantly.

Opposite of caring for lead, so hard to break that mindset.

The BMS-balancing requiring sitting at Full for long periods of time is IMO stupid, but very common and in this case nothing to be done.

 

[john61ct]

Unfortunately no, its a sealed black box for all intensive purposes..

For me personally, dealbreaker right there.

For one thing, no way to tell if the balancing is finished or not.

Or to see a "bad cell" problem developing.

 

[dreadlocks]

For me personally, dealbreaker right there.

I would tend to agree now with hindsight, but at the time I knew about 20% of what I know today about LFP.. and was attracted to the KISS approach.. this will be my last BattleBorn battery, even if they make this right my comfort w/the technology is high enough now that something like what Victron offers in LFP is far more appealing.

Some people and vendors have no problem with holding all the way to Zero amps acceptance.

Yeah I've never felt all that comfortable about it although all Battleborn literature suggests they dont care, so I had only been doing it rarely.. like only twice this year, until this issue developed.. mebe 4 times last year? since I have no access to the cells, it was the only way I comforted myself in knowing a full balance had been achieved.

 

[john61ct]

I would tend to agree now with hindsight, but at the time I knew about 20% of what I know today about LFP.. and was attracted to the KISS approach.

Yes that's the drop-in pitch, IMO deceptive.

Fine until it isn't.

That "10-year warranty" is a heck of a long-shot bet, in both directions, if they honor it, and the BMSs or chemistry quality can't deliver, they'll go under.

But then the knowledge required to DIY is too high for the mass market.

And the more open + sophisticated high quality vendors like Victron, just too pricey.

The fact that the US market offers quality lead deep cycling banks at $1/Ah, that makes LFP very hard to justify, such a ling payback ROI is just inherently too risky for most.