Battery Charger Backup

[Seighlor]

My boat has two 12v chargers. The smaller 25 amp charger is dedicated to maintaining the generator starting battery. The larger 80 amp charger maintains the main engine bank and the house bank.

I have had ongoing problems with the 80 amp unit… back and forth to the manufacturer for six or more weeks during which time the only way to charge the two large banks is to run the engine.

The small charger has the capability of charging three battery banks. My thought is to install a 1-2-All-Off rotary battery switch on the smaller charger as a standby and backup for any time the large charger might be offline.

Would appreciate any thoughts on the proper way to wire the switch

[a64pilot]

Just hook it up to the other bank as well, with no switch. Multiple battery chargers play well together. I have three on my bank, two 110V and one Solar, they all are connected to the same bank, and cause no problems with each other.

[smac999]

you wouldn't use a 1-2-all for a charger.

you need to fuse it anyways. so just get a 30a thermal breaker near the house bank and run a 2nd wire to it. you can turn the charger on and off via the breaker. I wouldn't really worry about the engine battery. though if you really wanted, then get 2 breakers and run wires to both.

[Seighlor]

I didn't know it could be that easy. Many thanks to a64pilot and smac999 for the speedy response to my query.