Dual power sources to Lithium batts, do I need extra device?

[JimmyDarci]

Tipping my hat to electrical guys in advance. I have Lithium batts and solar with proper Victron MTTP. Also have newer 25 HP high thrust OBs that kick up to 18 amps through spinners when they are running. I am told these Yamahas have a regulators built in. Question is do I need some sort of extra device to manage the amount of current that runs from the engines directly to the batteries?

I generally have no issues running as is BUT last year, I did have incredibly sunny days where an afternoon with engine use would cause the voltage in batteries to go excessively high. They are wired (4) in parallel and I received an excessive charge indicator message on two occasions. Thereafter, I would turn on additional electronics and shut off the solar to balance but this is not the right way for the long term fix, obviously.

I have called Yamaha and their response is that they have regulators built in and (ready for this) Yamaha does not recommend use of Lithium battery with their engines.

Is anyone aware of a separate regulator or other smart device that will help me to minimize overcharge stress on battery system? I have thought about wiring a separate starter battery for the OBs but I would not want to forego the ability to charge batteries via the engines on a series of cloudy days while cruising.

Thank you again for your responses (admitting in advance that electric systems are admittedly not my strength. Will say that solar is running great and each of batteries (BattleBorn) have safety sensors to prevent overcharge.... but seriously hoping for better fix than manually shutting off solar and turning on devices to drain excess charge while cruising under power in sunshine)

[Pete7]

Originally Posted by JimmyDarci

Is anyone aware of a separate regulator or other smart device that will help me to minimize overcharge stress on battery system? I have thought about wiring a separate starter battery for the OBs but I would not want to forego the ability to charge batteries via the engines on a series of cloudy days while cruising.

Jim, the standard method is a lead acid battery charged by the engine and then a DC>DC charger from the engine battery to the LFP bank. The DC>DC charger can tailored to the charging requirements of LFP. You don't really want 25A being drawn permanently from an outboard so perhaps join the two outboards together on one battery and use the combined charging.

Victron do one that is blue tooth enabled called "smart" with the adaptive charging profile https://www.victronenergy.com/upload...60-400W-EN.pdf

I am just doing this now with a Victron DC>DC. There are others, Sterling do one, just check the efficiency when looking at the specs.

Pete