Lifepo4 Batteries

[Midnightsun]

Well I decided to take the leap to lifepo4 batteries. Probably going to need a bunch of advice so please jump in.

Lithium has come down to a some what reasonable price and the tech is now much more feasible in all respects.

Why Lifepo4? longevity is supposed to be 10 years plus. They can be drained to zero with no ill affects or voltage drop which means a 100ah battery actually has 100ah. They charge at full rate from zero to 100% basically on a bulk charge with no absorption phase which usually takes forever to get our standard wet cells to 100%. Discharge cycles are quoted as 2000 plus.

Enough of my babbling, read this. https://www.power-sonic.com/blog/lithiu ... batteries/

Will be using dual 300ah lithiums for a total of 600 usable AH which huge yet will only weigh in at about 68lbs each.
https://www.amazon.com/gp/product/B08N53GF81/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1


Unfortunately lithium is not all that good for use as stating batteries so those will remain the same. My 3 bank charger will service the 2 engines and my generator however the dedicated generator charger will be removed and replaced with a true dedicated lithium charger.
https://www.amazon.ca/gp/product/B07DP3X16F/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1


Still need to figure out how to handle the alternator Lithium issue but a call to Sterling should get me on the right track.
https://www.sterling-power-usa.com/Ster ... arger.aspx

[denders]

Please keep the forum posted , I am planning a battery / charger upgrade come spring..... From what I can see Lithium is only ( yeah ..... only ) about 300.00 more per 200AH battery. Bite the bullet now and I should be good for the remainder of my boating time !

[Midnightsun]

May not happen until end of season as I am still studying every I need to know. Have ordered the batteries and charger though.

[Helmsman]

May not happen until end of season as I am still studying every I need to know. Have ordered the batteries and charger though.

Some things to consider:

The alternator issues are partially served if you use conventional lead acid batteries for your start/gennie. That will prevent the alternator from frying itself if the BMSturns the lithium’s off while they are charging.

The other issue is that your alternators can toast themselves running full tilt while trying to match the charge acceptance rate of the lithium’s. Alternators with an external regulator which has temp sensing and the ability to set the highest charge rate of the alternators will help.

The other issue you will face is keeping the cells in balance, and also protecting against a spike charge when originally connecting the lithium to the lead acid systems. If the cells are out of balance to the point that one goes past the low or high set point, the BMS will shut the battery off. While your alternators would be protected with a properly set up ACR or battery combiner continuing to charge the lead acids, you still might experience a dark ship event, which might not be pretty, depending upon where you are located.

[Helmsman]

Jim Healey is an electrical engineer who I have spent time learning from. He is the engineering director for MTOA, a former computer engineer, a contributor to the ABYC electrical standards group, and he puts his articles on his web site. You can find two articles on lithium there.

https://gilwellbear.wordpress.com/

Hope that helps.

[denders]

Thanks for the link - A lot to consider in there

[bud37]

He is someone I have used as a resource for years now, well written good accurate info.

Should be a sticky.

[Viper]

Good article, pretty much validates my thoughts on using lithium batteries in boats at this time, and their too dangerous IMO.

[Helmsman]

One change to the below post, is that it would be better to use a DC to DC as opposed to an ACR due to being able to set the differing charge rates between the two battery types.

Source of the post

May not happen until end of season as I am still studying every I need to know. Have ordered the batteries and charger though.

Some things to consider:

The alternator issues are partially served if you use conventional lead acid batteries for your start/gennie. That will prevent the alternator from frying itself if the BMSturns the lithium’s off while they are charging.

The other issue is that your alternators can toast themselves running full tilt while trying to match the charge acceptance rate of the lithium’s. Alternators with an external regulator which has temp sensing and the ability to set the highest charge rate of the alternators will help.

The other issue you will face is keeping the cells in balance, and also protecting against a spike charge when originally connecting the lithium to the lead acid systems. If the cells are out of balance to the point that one goes past the low or high set point, the BMS will shut the battery off. While your alternators would be protected with a properly set up ACR or battery combiner continuing to charge the lead acids, you still might experience a dark ship event, which might not be pretty, depending upon where you are located.

[Midnightsun]

Pretty much convinced dc to dc charger is the way to go. Great articles and lots of info to digest. Thanks for everything and keep the comments coming.