First Charging and top balancing Lifepo4

[senormechanico]

Originally Posted by Q Xopa

.

But again if you could please share with us how you are such an 'expert' on LFPs to be offering such specific advice so authouritvely please?

Even with the best of intentions you have no 'skin in the game' and it will cost you nothing if you inadvertantly offer incorrect advice, or even if your advice is misunderstood.

I think you agree this should be a two way street to make this as open, transparent and thus credible as possible.

Thanks.

Good luck with that !

Several posters, including me have politely asked that very question and have been ignored. We know he reads them, but refuses to let his (to him) "expert" bubble be popped. lol

[Delfin]

Originally Posted by Montanan

Any comments?


It appears that you are using an inappropriate charging circuitry by applying the positive and negative lead to the terminals of the same battery of your parallel bank. This is the worst possible method of circuitry and will lead to imbalances and inefficiencies and comparatively poor amperage capacity and battery life expectancy. It is a very common error of circuitry for both connecting the charging circuitry and as to connections for discharge circuitry to loads.

Reference: https://www.impactbattery.com/blog/t...s-in-parallel/

See a close up of your photo attached. Both of your charger leads are to the same battery!

You should rewire your charging circuitry as described in the referenced article.

Ditto as to connecting your output power leads when you install the bank and connect to your loads.

I also wonder whether using a 5 amp charger on an 800 Ah bank isn't exploring new territory in how the bank will respond.

[john61ct]

I was directing you to resources addressing your denial of the whole endAmps concept. None of which authored by me, and pretty sure none were blog posts.

Apologies if I misunderstood, and you in fact do accept the concept of endAmps being the canonical measure of SoC at the top end.

Of **course** LFP should never get that Full! I've often posted that 0.03-.05C is my reco, but then only when precision is (very rarely) reqiired.

The lower endAmps specs are for lead only.

[john61ct]

And if you want to focus on LFP alone, look at the datasheet of **any** reputable manufacturer for their (IMO too stressful) endAmps spec..

You should be able to identify whatever term they use for it.

CAR is simply amps acceptance when depleted.

[Delfin]

Originally Posted by john61ct

I was directing you to resources addressing your denial of the whole endAmps concept. None of which authored by me.

Apologies if I misunderstood, and you in fact do accept the concept of endAmps being the canonical measure of SoC at the top end.

Of course LFP should never get that Full! I've often posted that 0.03-.05C is my reco, but then only when precision is (very rarely) reqiired.

The lower endAmps specs are for lead only.

I didn't deny the concept of observing a termination point for CC charging related to a percentage of C. I charging right now, 180 amps in, and I'll terminate at 28.4 volts which will be around 30 amps CAR, so I fully understand the concept, what with my having to use it on a daily basis right now in a real world application.

I objected to your typical assertion of a non fact of .005C as sacred knowledge coupled with another non fact that CAR, end amps, etc. is commonly espoused by battery manufacturers. But please correct me if I am wrong and link to a battery spec that discusses endpoint amp acceptance rate. If you can't, perhaps this would be a good time to a. correct your statement, b. stop posting as authoritative what you have no clue about, or c. all of the above.

[john61ct]

If you honestly try to find it from this list

Winston/Thundersky/Voltronix, CALB, GBS, Sinopoly and A123

and can't, then I will.

Not going to do the work for you if you're just being lazy.

[Delfin]

Originally Posted by john61ct

If you honestly try to find it from this list

Winston/Thundersky/Voltronix, CALB, GBS, Sinopoly and A123

and can't, then I will.

Not going to do the work for you if you're just being lazy.

Please do so, as I would welcome the opportunity to apologize for accusing you of making things up. You could start by linking to the datasheet or user's guide for your own LFP bank.

While you're at it, perhaps direct me to the concept of end amps as a sacred value for Trojan flooded batteries, since I believe you indicated that it was a common concept used by battery manufacturers of that chemistry. Here's a link you can explore: https://www.trojanbattery.com/product/scs150/

[Delfin]

John, not wanting to be lazy, I looked at Deka's datasheet for their deep cycle flooded battery as you suggested, but am having terrible locating the reference to end amps related to charging ( or anything). Do you have any other data sheet for Deka that does, since you asserted they were one of the mfg that commonly use this concept. Or is it here, but I am just missing it? https://documentcloud.adobe.com/link...2-bfbd01672507

And if it is not here or anywhere, would you want to withdraw your comment?

[john61ct]

No, I originally got the spec from Deka support via fax, but MS has posted it verbatim many times.

I think EPM / East Penn may be more useful than Deka.

It isn't an absolute number, but a relative one over time, and indeed more useful as a general default, especially as aging / declining SoH makes achieving .005C less practical.

It actually results in a much higher SoC / longer AHT than Lifeline's .005C, especially for a large FLA bank, or a relatively new / high SoH one.

Absorption End Point = Current change over 1 hour period of less than 0.1A

Since I retrieved that for you, will you at least try to find an LFP datasheet, they really are all over the intertubes, unlike this one.

[john61ct]

Found one direct from MS

http://www.cruisersforum.com/forums/...ml#post2092450

[john61ct]

Originally Posted by Delfin

value for Trojan flooded batteries

From their manual

[john61ct]

CALB is a good example, a favourite of mine, but yes not easy to find:

Note I am not "advocating" the use of using CV (much less endAmps) as the normal-cycling stop-charge setpoint.

I think it's pretty funny - once I understood the basis for your dispute - your reminding me that .005C is a stressfully high definition of 100% SoC. I had you pegged as in the "going high does no harm" camp.

As stated many times, I reco .05C, or maybe 0.03 - 0.02C but rarely, only when precision is needed.

________
From CALB directly:

During battery use, we recommend charging and discharging range between 10-90% DOD

https://static1.squarespace.com/stat...r%2BManual.pdf

Also

During CV charging period, charging process shall be regarded as over when charging current fall down to 0.05C

http://full-electric-drive.de/oneweb...e%2520CALB.pdf

_______
From MS, benchmarking a 400Ah CALB bank, using **under 0.02C** https://marinehowto.com/lifepo4-batteries-on-boats

Capacity Testing Process:
#1*Charging = 13.8V and current allowed to taper to <10A
#2*Cell Temps = 76F – 77F
#3*DC Load = 30A constant
#4*Voltage Cut Off = 11.2V / 2.8VPC
#5*Capacity Measurements = Ampere Hours & Time At Load

-------
For top balancing:

For these cells, based on the data available at the time, late 2010, I held the voltage at 3.75V and allowed the current to tail off to 20A then stopped charging and moved onto the next cell.

[john61ct]

From Morningstar
https://2n1s7w3qw84d2ysnx3ia2bct-wpe...e-Settings.pdf

[john61ct]

Back to Trojan

@nebster also often goes out of his way to dispute my guidelines, so take this instance of his agreement with me as extra special 8-)

http://www.cruisersforum.com/forums/...ml#post2493514

[Flod]

Originally Posted by Montanan

Any comments?





It appears that you are using an inappropriate charging circuitry by applying the positive and negative lead to the terminals of the same battery of your parallel bank. This is the worst possible method of circuitry and will lead to imbalances and inefficiencies and comparatively poor amperage capacity and battery life expectancy. It is a very common error of circuitry for both connecting the charging circuitry and as to connections for discharge circuitry to loads.



Reference: https://www.impactbattery.com/blog/t...s-in-parallel/



See a close up of your photo attached. Both of your charger leads are to the same battery!



You should rewire your charging circuitry as described in the referenced article.



Ditto as to connecting your output power leads when you install the bank and connect to your loads.

Yes i realized that myself as well and changed the setup after a few hours. Then I stopped completely after the responses in this thread. I now understand that it was a bad idea to only have the small 5A charger. I was thinking that this is a onetime job and I’ll never do it again so let’s go with the cheapest possible charger.