battery charging

[grand2000prixgtp]

ok so on my boat we have 3 battery's and this year for some reason the alternator wont charge the battery's but when we turn them off, the boat still runs so that means the alternator is working. any idea as what this can be?

 

[TorqueAutoMotiv]

the lead from the alt to the bat? maybe something like that or the batt could just be toast?

 

[grand2000prixgtp]

the lead from the alt to the bat? maybe something like that or the batt could just be toast?

ill have to look at that lead. the batterys are brand new.

 

[PowerStroker]

There might/probably be parasitic draw on the batteries. With the boat off, check to see if there is anything drawing voltage (anything above .3v) with a multimeter. Check wires etc. from there!