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 > LIFePO4 batteries - interesting challenges

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Itinerant1

Itinerant

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Posted: 07/23/19 03:37pm Link  |  Quote  |  Print  |  Notify Moderator

My gear is all Magnum (inverter/ charger & PT100 controller. The controller follows the same settings as the IC.

This is how I have mine set..
The following parameters are for programming the ME-ARC Version 4 advanced control.

LBCO Setting: Volts = 12.0
Battery Type: = Custom
Absorb Volts: = 14.2
Float Volts: = 13.6
EQ Volts: = 14.2
EQ Done Time: = 0.1 (I don't use EQ)
Absorb Done Time: = 0.1(I can't turn this off)
Max Charge Rate: = 100%
Final Charge Stage: = Float

I have not gone over 14.2 on my setup the % capacity resets/ balances the cells at that voltage.

Most drop ins require 14.4-14.6 occasionally to reset the % capacity/ balances the cells.

For your summer style with the camper I would use these but you can go with a bit less but you will have use 14.4 occasionally.

LittleBill

Scranton, PA USA

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Posted: 07/23/19 07:17pm Link  |  Quote  |  Print  |  Notify Moderator

i am going to back peddle on my comments.

my comments were mostly around li-ion which is what i use. looking at how life are composed the final voltage does matter, there is no charge controller inside most of these battery types simply a balancer lvc etc..

14.4 puts u at about 3.6v per cell which is max.

13.6 puts you at 3.4.

if you didn't want to run max somewhere around 14.0-14.2 i would go( really depends on if you need the higher capacity)

SOC is practically impossible from what i am reading, the voltage drop curve is practically straight

you would be better off basing it on AH removed and using that for SOC, instead of voltage. this is done by running down to LVDC.

sorry the misdirection earlier, we all learn something new every day.

link on DOD cycle life





phemens

Montreal, Canada

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Posted: 07/23/19 08:30pm Link  |  Quote  |  Print  |  Notify Moderator

Sorry, DODC?
Support from the various sources has been good (Samlex, Victron, Battery mfg), but I am assembling the overall system myself, I like to build things and figure it out. Not disappointed at all, I knew what I was getting into.
In this case I guess the complexity is in the various systems together and the specific use. It’s funny how little literature there is out there on subjects like dry camping with LIFePO4 and solar and parasitic charges and optimizing battery cycles and... [emoticon]
What can I say, I find this stuff interesting, I’d almost swear I like it better than actual camping!


2012 Dutchman Denali 324LBS behind a 2006 Ford F-250 V10 out of Montreal
1 DW, 1 DD, 1 DS, 2 HD (Hyper Dogs)
1Kw solar, 500 AH LIFePO4, Yamaha EF2000 gen, Samlex 3000w Inverter

steveh27

Grosse Pointe Woods, MI

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Joined: 08/21/2004

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Posted: 07/24/19 05:18am Link  |  Quote  |  Print  |  Notify Moderator

SOC seems to work OK with the Trimetric and my lifepo4.

phemens

Montreal, Canada

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Posted: 07/24/19 06:11am Link  |  Quote  |  Print  |  Notify Moderator

steveh27, the SOC on the Victron works fine. Initially I was trying to reconcile it with what the BMS was showing me, but the battery mfg said the SOC measurement on the BMS should not be considered accurate.

The battery guy got back to me and said that floating the batteries at 13.6 during the day on solar was fine, since they would draw down at night. This will let me leverage solar all day to run the fridge on electric with the excess.
His only concern was extended periods of floating voltage on shore power, but my Samlex is set not to do that, so we're good there.

phemens

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Posted: 07/24/19 06:14am Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

My gear is all Magnum (inverter/ charger & PT100 controller. The controller follows the same settings as the IC.

This is how I have mine set..
The following parameters are for programming the ME-ARC Version 4 advanced control.

LBCO Setting: Volts = 12.0
Battery Type: = Custom
Absorb Volts: = 14.2
Float Volts: = 13.6
EQ Volts: = 14.2
EQ Done Time: = 0.1 (I don't use EQ)
Absorb Done Time: = 0.1(I can't turn this off)
Max Charge Rate: = 100%
Final Charge Stage: = Float

I have not gone over 14.2 on my setup the % capacity resets/ balances the cells at that voltage.

Most drop ins require 14.4-14.6 occasionally to reset the % capacity/ balances the cells.

For your summer style with the camper I would use these but you can go with a bit less but you will have use 14.4 occasionally.


The battery guy said I was fine at 14.4, the cells reset at 14.6. Thanks for the info.

phemens

Montreal, Canada

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Posted: 07/24/19 06:22am Link  |  Quote  |  Print  |  Notify Moderator

LittleBill wrote:

i am going to back peddle on my comments.

my comments were mostly around li-ion which is what i use. looking at how life are composed the final voltage does matter, there is no charge controller inside most of these battery types simply a balancer lvc etc..

14.4 puts u at about 3.6v per cell which is max.

13.6 puts you at 3.4.

if you didn't want to run max somewhere around 14.0-14.2 i would go( really depends on if you need the higher capacity)

SOC is practically impossible from what i am reading, the voltage drop curve is practically straight

you would be better off basing it on AH removed and using that for SOC, instead of voltage. this is done by running down to LVDC.

sorry the misdirection earlier, we all learn something new every day.

link on DOD cycle life


Thanks for the info, I am definitely learning as I go! I am indeed basing off the amps out/in, as you say voltage is essentially useless. I have bulk set to 14.4 but may ease off to 14.2 as I don't need the extra oomph and I don't think it gives me much.
I got the discharge curve on my LIFePO4's, they run straight until you hit about 20% SOC remaining @ 12.8V, at which point it tails off pretty quickly (12V @ 10%, then precipitously steep decline from there).

LittleBill

Scranton, PA USA

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Posted: 07/24/19 06:50am Link  |  Quote  |  Print  |  Notify Moderator

what exactly do they mean by the cells reset?

Itinerant1

Itinerant

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Posted: 07/24/19 08:23am Link  |  Quote  |  Print  |  Notify Moderator

I believe he means balancing.

* This post was edited 07/24/19 08:32am by Itinerant1 *

LittleBill

Scranton, PA USA

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Posted: 07/24/19 01:43pm Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

I believe he means balancing.


do you have to reach a certain voltage for balancing to occur? i though the balancers worked continuously? not sure how the bms in them work

according to the battleborn faq need to be over 14v


"A passive balancing process is activated by the BMS at the top of each charge cycle, when the battery voltage exceeds around 14V. This ensures that all the cells remain at the same state of charge, which helps for pack longevity and performance"

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