Lithium Ion battery upgrade

[Rick Roberts]

Hi guys, the more I read and learned about lead acid and agm batteries. The more I keep asking myself, there must be a better solution. I kept thinking about hybrids and electric cars --- > *Lithium Ion*. There is multiple different chemical combinations but the one I was considering was the LiFePO4 (Lithium Iron Phosphate) for multiple reasons;

Lithium Iron Phosphate battery VS Lead Acid battery:
- Charging cycle: 2000 cycles (still gives you over 80% of the original capacity) vs 300 charging cycles
- 70% lighter than lead ( save a few hundreds pound and allow you to store more beers )
- Flatter voltage curve
- Zero Maintenance
- Fast charging: 3 to 5 hours vs 8 to 16 hours
- Discharge rate is <3% per months
- 99% efficient VS ~ 35-50% (don't really want to go under 50% charge and after %80, it doesn't charge efficiently)
- Warranty 3-5 years vs 12 months

Starting seriously about doing the switch. I could cut down my batteries weight from 400 to 60lbs (450Ah golf cart batteries to 240ah LiFePO4 batteries). Solar panels would charge more efficiently, less issues with voltage fluctuation for sensitive electronics, don't have to maintain them, last longer.

Let me know what you guys think, I haven't seen much downside beside the initial cost which seems to be well worth the upsides.

Eric

[Rick Roberts]

Also found an interesting article on the subject:
https://www.victronenergy.com/blog/2015/03/30/batteries-lithium-ion-vs-agm/

[Braxton]

I have a decent level of fear of them because of their volatility during charging.

I tried a quick web search to see if I was being paranoid or if my fear is justified and I didn't find anything new enough that I thought it was relevant to the fast moving world of battery technology.

At the very least I would have someone who has extensive experience with them give your charging systems the once over and make sure that you won't be running them to hot during the charging cycle.

[mainesail]

Rick,

#1 Consider the Firefly Carbon Foam AGM batteries. So far they are the only lead acid battery I have seen that can be regularly discharged to 80% DOD and fend off sulfation for long periods of time while doing so. I just recently capacity tested the first bank I installed, in a vessel that is 100% PSOC use (no solar on a mooring) and after 2.5 seasons of 80% DOD use they still delivered 100% of their Ah capacity. There is no other lead acid battery I know of that can do this, not even GEL. The battery is patented so you won't find this technology in any other lead acid battery. The Firefly is much easier to install and can be charged using regular lead acid technology.

#2 If you still feel the need to go LFP then the LiFePO4 system Bruce Schwab has developed, in conjunction with Lithionics, is really the way to go. Genasun recently got out of the LFP business leaving only Victron, Mastervolt and the OPE-Li3 system (purpose built marine systems) of which the  OPE-Li3 LiFePO4 system I find to be the best engineered. Avoid ALL OTHER snake-oil other than the 3 above and even then I would strongly urge the OPE-Li3 system over Victron and Mastervolt.

You need to look at LFP from all sides not just the positive.

[mainesail]

Don't get me wrong LFP is great but it is not for everyone and it is NOT lead acid and can't be treated as such. LFP must be installed as a "system" not just drop in batteries.

Here is a 100% discharge test at cycle #772. The bank is 400Ah rated and I used an intervalometer to capture the voltage, current, time and Ah's removed every 2 minutes. You will notice that at 80% DOD, under a constant 30A load for 10:42, the loaded voltage is still above 12.75V or the 100% SOC voltage of a lead acid bank...
https://youtu.be/fGBmEh72UlY