Lithium ion batteries

Batteries, Generators, Solar, Wind and Electronics
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jlodolce
Posts: 38
Joined: Sun Jan 06, 2013 12:30 pm
Location: Sackets Harbor, NY (Lake Ontario)

Lithium ion batteries

Post by jlodolce »

I have 1995 40/40 #16:

I have to replace my batteries this year due to their age and not holding charge. This will be my third replacement in 15 summers with the boat. I have three house 4D AGM's (200Ah each x 3 = 600Ah) and a group 31 AGM starter battery and monitor them with a Victron. We commonly anchor several days at a time. I understand I can safely let them go down to 50% charge, but generally don't let them drift down past 75%. I don't like starting a voyage with depleted batteries, since I do not have either solar or wind generators.

All my cabin lights are LED. About 10 years ago, I replaced my refrigeration to a Frigi-boat system, using a brass through hull fitting for heat exchange, one of the best improvements I ever made to the boat. I can stay at anchor for about 3 days before I get anxious to recharge, while in reality, I tend to recharge and replenish hot water using a portable Honda EU2200i generator for about 45 minutes once per day.

I have often considered changing from AGM to Lithium ion, because they are supposed to last 10 years, are about 50lb each compared to 120lb, can be discharged to 80% without damage, and they are supposed to recharge 6 times faster. The expense always held me back, but I see online that I can now buy 200Ah 4D size lithium ion batteries for about the same price as AGM's ($600-$800 each).

I have a 4 year old high capacity Electromax programmable alternator/regulator and a 5 year old Mastervolt 40 amp 12/40-3 44210200 dockside charger which I believe are both programmable for Lithium ion batteries.

My greatest fear is fire. I read that the new Li batteries have built in regulators to prevent them from being over charged, and that properly setting the alternator and dockside charger to Li specs should also prevent this. If I make the change, I will have my boatyard mechanic do the work, since they installed the alternator and dockside charger, and would be responsible for ensuring that they are programmed correctly.

Does anyone have any thoughts to offer me on this?
Jim Lo Dolce
Lo Dolce Vita VII
Freedom 40/40 #16 1995
Sackets Harbor, NY (Lake Ontario)

RonR
Posts: 23
Joined: Mon Jan 05, 2015 7:03 am

Re: Lithium ion batteries

Post by RonR »

The LiFePO4 batteries used in marine systems are not the chemistry that raises concerns about fire. They are very (very) safe, and aren't subject to the kind of thermal runaway that can happen with other lithium chemistries.

I'm not an expert on marine conversions, but just someone who as been looking at the same conversion for much the same reasons, and I have some experience with the other, less safe chemistries in other applications. From what I gather you do need to make sure your alternator/ regulator system will handle the load and provide an appropriate charging profile. Here are some links I found helpful.

Here is a link to a fairly informative thread:
https://forums.sailinganarchy.com/index ... nt-7682901

Stan honey has links & comment I found helpful:
http://honeynav.com/wp-content/uploads/ ... -notes.pdf

And Marine How To is great for so much, lots on Lithium batteries:
https://marinehowto.com/

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newt2u
Posts: 236
Joined: Wed Sep 11, 2019 11:24 am
Location: UK

Re: Lithium ion batteries

Post by newt2u »

I have switched to LifePo4 batteries. I charge mine via solar and very infrequently a regular multiphase car battery charger, both set to flooded. The chemistry is safe, there is no problem in damaging with over charging or discharging, as the batteries have inbuilt battery management electronics that isolate the cells if necessary. It also does the cell balancing. Different batteries have different parameters but the key issues are max charge and and discharge rate. I have no starter but do have with a 24v emergency electric outboard. I have 2 50Ahr 12v batteries in parallel for my electronics and cold box and switch them in series for the motor, which draws about 20A.

Prices have come down significantly since I got mine. But quite happy with them anyway.
Rockin - F21 twin drop keels - located Whitehaven, Cumbria, UK

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