12v question

[Seafarer_Bob]

I'm thinking about connecting my 36v trolling motor batteries to my 12v house for more capacity, anyone do this? The 36v / 60AH batteries are parallel so they'll add 360AH at 12v which should all but eliminate low voltage alarms when I'm not running. Right now the 36v batteries a're connected via a 50a breaker to "common" on the switch. "A" goes to the TM and thinking I'll connect B to a 36v to 12v /20a stepdown transformer, to a 20A inline fuse, to the positive house bus bar. Is this a bad idea or any concerns about grounding etc?

 

[Hookup1]

You don’t use a transformer to reduce DC voltage. Transformers require AC. You would have to use a power converter which is an expensive “fix” for low voltage alarms. Check engine charging and replace 12 volt house battery would be my recommendation (fixed mine).

If you do go the power converter route it should be fine for 12 volt house load. Grounds would be connected together. When you say the "batteries are parallel" which is what I would expect then you say "I'll connect B to a 36v to 12v /20a stepdown". With parallel batteries it wouldn't matter which battery positive you connect to.

If you are using heavy duty dredge reels like 12 volt LP's a power converter is not recommended.