Best backup for starter battery

[Dockhead]

Originally Posted by Kettlewell

I replace the start battery about every 5 years before it poops out. Problem solved. But, with my LA house bank I can also use it to start if I need too.

This. Why overcomplicate this? You would buy a BACKUP to a battery that you think is dying, and worry about keeping it charged?? Just change it, same cost, job done.

If it ever runs down or flakes out, jump off the house bank. Anything more than this is a waste of time, space on the boat, and money.


On my boat my start batts are completely separate from house bank, with their own alternators. One start batt each for main engine and generator. Jumper cables just in case. I have once in a blue moon jumped the generator off the main engine start batt. Never had to use the house bank.



15 years with this setup and zero problems.

[NorthCoastJoe]

KISS. Replace the start battery and be done. If you want to be fancy put in a switch to draw from the house bank for emergency use. Otherwise jumper cables.
I have seen many ways over think and over do simple tasks.

Having less is better, except for money.

[Fortytwo]

NOCO Boost X GBX45 1250A 12V UltraSafe Portable Lithium Jump Starter, Car Battery Booster Pack, USB-C Powerbank Charger, and Jumper Cables for up to 6.5-Liter Gas and 4.0-Liter Diesel Engines
https://a.co/d/0hif583b