2025 Devlin Snow Goose Thread

RM Anderson said:
Not to be that guy...but is your chosen outboard rated for a lithium starter battery? My Yamaha 40 hp was only rated for lead acid.
RM
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No, it's a good question. I've been planning to buy a Tohatsu, though that isn't finalized. As of a couple years ago they were advising against lithium, but that language seems to have dropped from their owners manuals. Having said that, I'm not aware of any OB MFR that has specifically said they're ok with lithium batteries (except for Mercury on a select few of their larger motors).

In my opinion, the issues that caused most OB MFRs to advise against lithium batteries was because the batteries (and their on board battery management systems) weren't really designed for cranking - resulting in voltage spikes and battery shutdown while the motor was running (killing the motor, and possibly damaging internal electonics). I believe that is less of a concern now that we have batteries and BMS designed and spec'd for the purpose.

In the end, when I buy my motor I'll have the conversation in earnest with my dealer - he's an old family friend and been in the business a long while and will give me an honest opinion about the real risks, and not just the MFR CYA line. If he strongly advises against it I'll consider a dc to dc charger or go with an AGM for the starter... but I may just take my chances. There are plenty of people using lithium starting batteries successfully with Tohatsus, Yamaha, Suzuki, etc.
 
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