LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[sparrowhawk1]

I don't have any dogs in this fight just figured I'd pass this YouTube video on.https://youtu.be/QrAwI7SxLh4

[john61ct]

My eBay seller of adjustable LVD/OVD bank protectors from Latvia has informed me of new high-current models, 160 & 220A

http://www.ebay.com/itm/192238893988


http://www.ebay.com/itm/192250621117

If anyone checks these out before me, please post a comment.

[exMaggieDrum]

Originally Posted by evm1024

A quick answer for you while we wait for MainSail to come back online.

You just un-solder the shunt resistors (there are 2 on my cell boards). The shunts are the 2 large black rectangles by the "red wire".

Regards

Just now getting back to this. My BMS does not look like what you describe. I can't speak to SenorMechanico's but he may have one like mine.

See attached pdf for pic and info. So the question is, with this board, how to defeat the balancing?

[mbartosch]

Look at the four cell boards. On the top end of the boards you can see two black components near the red wire. Unsolder them
and you are good.

[exMaggieDrum]

Originally Posted by mbartosch

Look at the four cell boards. On the top end of the boards you can see two black components near the red wire. Unsolder them
and you are good.

Vielen Danke, Martin.

[Delfin]

Originally Posted by exMaggieDrum

Just now getting back to this. My BMS does not look like what you describe. I can't speak to SenorMechanico's but he may have one like mine.

See attached pdf for pic and info. So the question is, with this board, how to defeat the balancing?

Different suppliers no doubt have different approaches, but avoiding balancing on my LiFe Lithionics bank is accomplishing by setting charge voltages below the voltage where top balancing occurs. In Lithionics case, that is 29 v, so setting max charging to 28 volts means they won't balance unless you want them to by changing maximum CC voltage.

[ErikFinn]

Hi folks and pardon me for not reading all of the almost 400 pages on this thread in case this has been already discussed before.
This video from AltE store came out today and I couldn't help to notice the 899 USD price tag for the 100AmpH 12V LiFePO4 batteries, which I understand is much less than a few years back for LiFePO4, am I correct? So I wanted to ask, what do you guys think about these "Battle Born" batteries? Are they any good?

https://www.youtube.com/watch?v=-0QMKAXZo6k

[Maine Sail]

Any LFP battery with an internal BMS & internal contactor, that lack external communication to the DC system for proper shut down, and that does not have the proper contactor rating I would not consider for use on a boat.

Simple questions:

Let's say your alt regulator or inverter/charger have a hiccup or glitch or a failed program save and push the LFP battery to a disconnect/open circuit while charging.

• What happens to everything on your DC bus when the voltage transient, caused by an open circuit load dump, shoots your DC bus through the roof? Can your equipment handle 75V +? Can your alternator handle being open circuited at full bore?

I know of no regulation circuitry that can react fast enough, with a charge source at full bore, to eliminate the possibility of a voltage transient causing damage to your gear when the battery is removed from it.. This includes alt regulators, inverters and other charge sources.

• What happens if the internal temp sensor shuts the battery down without previous warning to you or the system bus?

• What happens to the little FET based switch inside the battery when you hit a bow thruster, electric winch, large inverter or windlass for more than just a few seconds?

• What happens when the ABYC standard is finalized and the "drop in" does not meet the minimum safe design and installation requirements? What will your insurer say?

• How well designed is the internal soldered end board connection to the small 18650 cylindrical cells inside the battery?

There is a reason the ABYC is working on a standard to address high capacity lithium ion batteries.

"Drop in" LI batteries that lack external communication, which can properly shut down charge sources before a disconnect occurs, is just one of the issues with "drop-in" batteries used on boats.

Look into how Victron, Mastervolt & Ocean Planet Energy/Li3 all do their house bank BMS systems... Look into the ratings of their contactors too.


I built our 400Ah battery and BMS for less than I can buy drop-in's. It also communicates with the rest of the system and uses 500A rated contactors. I don't think $900.00 for 100Ah is all that great a price for a bunch of soldered 18650's with a low rated contactor and no communication capability.

A sealed Li battery that can't externally communicate to anything or anyone of an impending shut down or opening of the internal switch .....

Give me a com port and a real contactor and I'd give one a try.....

[SailRedemption]

Hey friends,

Just wanted to get a idea of how my batteries are doing. I have 12 180ah CALB cells in 3P4S for a total of roughly 540ah. I'm charging to 13.8v currently with a 30a Victron Phoenix charger until it hits roughly 3a at 13.8 for a little bit. I recharge when the batteries hit 12.8. I get about 360-370ah out of a single charge from what my Victron BMV-702 is telling me. Thats roughly 65-70%. Is that sound good to you guys? I'm not getting the 80% but these were used batteries from a EV so they may have some capacity loss.

Should I let my charger taper down further than 3a or raise the charge voltage to 13.9v and leave the taper at 3a?

I don't have an inverter yet to do a decent battery capacity test. Hopefully by the end of the year I'll have that but I figured I'd ask this thinktank.

Ronnie

[Maine Sail]

Originally Posted by SailRedemption

Hey friends,

Just wanted to get a idea of how my batteries are doing. I have 12 180ah CALB cells in 3P4S for a total of roughly 540ah. I'm charging to 13.8v currently with a 30a Victron Phoenix charger until it hits roughly 3a at 13.8 for a little bit. I recharge when the batteries hit 12.8. I get about 360-370ah out of a single charge from what my Victron BMV-702 is telling me. Thats roughly 65-70%. Is that sound good to you guys? I'm not getting the 80% but these were used batteries from a EV so they may have some capacity loss.

Should I let my charger taper down further than 3a or raise the charge voltage to 13.9v and leave the taper at 3a?

I don't have an inverter yet to do a decent battery capacity test. Hopefully by the end of the year I'll have that but I figured I'd ask this thinktank.

Ronnie

I'd stop charging at 10A+ and discharge the cells below 3.2VPC if you need more capacity...

A 12.8V cut off is 3.2VPC.... These can easily go to 12.5V/3.125VPC or 12.6V/3.15VPC without issue. Don't try to make up your capacity by holding voltage at the top end any longer than you need to.

[TheThunderbird]

LiFePO4 charging. What to use?

I have solar panels (humm...), a Victron Phoenix 40A and a QUICK SBC NRG 60A.

BOTH have no plain setting for Lithium... But I see people using them alike... What's best to charge Lithium batteries? Power alternator?

Also,please consider this package from GWL, a Czech based provider to industrial installators, with an eye to off grid and RV solutions

200Ah for 1250eur, with BMS and control boards, with 4X modules
"
GWL/Power 12V, 2.4kW LiFePO4 yacht set with 200Ah cells, BMS mobile monitoring"

https://www.ev-power.eu/en/By-Brand-...hparam=winston

[Jd1]

I am currently doing a battery test. My low cutoff will be 12V (3V per cell). Recharging will be done to 14.2V or 3.55V per cell which is what I would call 100%. I will then drop back to below 80% to keep the batteries happy.
Part of this exercise is to test the batteries, part is to set my SOC meter to true 100% capacity.
I am standing by to get told that I am crazy for pushing the limits .......

[SailRedemption]

Originally Posted by Maine Sail

I'd stop charging at 10A+ and discharge the cells below 3.2VPC if you need more capacity...

A 12.8V cut off is 3.2VPC.... These can easily go to 12.5V/3.125VPC or 12.6V/3.15VPC without issue. Don't try to make up your capacity by holding voltage at the top end any longer than you need to.

Thanks, I will drop it to 12.6v and see what I get. I am trying to stay conservative with these. Not sure if you remember, Mainsail, these batteries were out of Dimitris EV car so they probably haven't been abused, knowing who he is.

Regards to the 10a charge cutoff, what is the general rule of thumb here? I was under the impression that it was a percentage of charger capacity. Do I have that confused, is it percentage of battery capacity?

[john61ct]

Yes, 2.5% (.025C) of bank AH capacity is nicely conservative, 2% is fine IMO, but shouldn't be grasping for capacity at the high shoulder.

Not charger capacity, that can be all over the map, think big truck alt vs solar-only.

[john61ct]

Originally Posted by Jd1

I am currently doing a battery test. My low cutoff will be 12V (3V per cell). Recharging will be done to 14.2V or 3.55V per cell which is what I would call 100%. I will then drop back to below 80% to keep the batteries happy.
Part of this exercise is to test the batteries, part is to set my SOC meter to true 100% capacity.
I am standing by to get told that I am crazy for pushing the limits .......

Not crazy, but sacrificing longevity, likely hundreds of charge cycles, in exchange for a tiny % increase in bank capacity.

3.45Vpc - 13.8V is highest I'd go in day to day usage.

Even hit it and stop.

If using tailing current, then stopping when current declines to .025C, no lower than 2%.

Whatever you define as "full" for daily ops, that's what to use calibrating the BM.

Your bank your call, but gentler is better for lifespan.