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Charging AGM House Battery

Richard Guess

New member
Center console with twin Yamaha 150s, two start batteries and a house battery. Looking to replace my old flooded acid house battery with an AGM, but concerned that the charging system might need updating. My alternators put out max 35A each. Both of my start batteries are wired to Blue Seas ACRs and then to my house battery. The ACRs won't regulate charging, just act as an on/off switch according to Blue Seas rep. I've attached a diagram of my system. The only update to the diagram is a cable running between the negative terminal of the house battery to the negative of one of the start batteries. I appreciate any help.
 

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The ACR's are on off switches, They sense voltage, They turn on when the voltage drops and off when it comes up. 35amp alts are enough.

FYI.... Yamaha alternators will maintain a good battery bang, They are not designed to charge a dead battery.

Tie all battery Negatives together, (Common ground)
 
Just be aware that AGM batts prefer higher charge voltages than normal flooded cell batts. Your alternators will likely produce flooded cell voltages which will work OK on the AGM's but not maximize their performance. I would suggest that you connect them to an AGM charger periodically if they are likely to come home partially discharged.
 
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