Lithium and older outboards

Asking the combined wisdom of the site if there is any concern of the alternator of my 2001 90hp mercury (4 stroke (not efi)) damaging a lithium battery if I were to replace my current starting and house battery with just one lithium? Not anything I’m looking to do asap but rolling around the ideas of ways to reduce weight on the boat in general and specifically the rear of the boat. Now that I’ve fixed/replaced a lot of the wiring that was causing issues I dont plan to go back with 2 batteries when it’s time to replace either way, lithium certainly not cheap but it would help take a solid 60 pounds out of that compartment.

It is not recommended to use a lithium battery as a cranking battery. The current spike needed to start the engine can fry the Lithium BMS. I have experienced this a couple times (can’t remember the brands, sorry).

There are a few brands that advertise as safe for cranking. Up to you if you want to trust them.

Good point there, I wasn’t sure how they handled cranking (haven’t dug too deep yet as its a ways back on the priority list).

In one of those long threads, Sheldon talks about the new stators he replaces because someone hooked up lithium to an outboard.

I called and talked to Dakota battery a couple weeks ago about deep cycle (and combo) batteries for replacing my trolling motor batteries. Lithium needs 14.7 volt charge. I would have to replace my MinnKota onboard charger with the new “Precision” charger – made for lithium. Most “regular” chargers are not 14.7 but some Noco chargers have that output.

I didn’t ask about outboard motor charging system. But a quick phone call could answer your questions.

I just found this: 12v125ah 900 CCA Ionic Lithium Marine Cranking Battery for $779 on sale. It is the best price and cranking amps that I have seen. If your motor can charge it up it would be great or you would have to charge it at home with a lithium charger to get it fully charged.

James Almquist wrote:

I just found this: 12v125ah 900 CCA Ionic Lithium Marine Cranking Battery for $779 on sale. It is the best price and cranking amps that I have seen. If your motor can charge it up it would be great or you would have to charge it at home with a lithium charger to get it fully charged.

I have this battery as a starter for a 2007 90hp suzuki. Never had a problem going on 4th year