cranking battery

[h1x71]

I am new to bass boat's and have a question about the batteries. I have a 1976 70hp johnson motor with 2 batteries, the first battery is a reguler 12v car battery "I think", for cranking. The other is a 12v trolling motor battey. My question is how can I tell if I have a alternator on the boat to charge the cranking battery or do I have to charge the cranking battery before each trip out? Where would the alternater on the boat be, on the motor?

thanks don

[Ann-Marie]

Put a volt meter on the battery and watch the voltage after starting.  It will drop a little while starting but then it should rapidly get above 13 volts if you have an alternator.  If it stays below 12.8 volts you don't, or it is not working.

[Jayson]

hello Don,

I have a 1979 70hp merc 2- stroke and I also wondered about that to. I found out by watching your battery gauge on the dash and seeing what Ann is saying about the volts get above 13 then your in good shape.

I also wanted to ask you, how is that 70 treating you? does it run good? I found out where I live There's really nobody thats wants to work on that old of an outboard and plus being a 2-stroke:(. I need to maintain that motor till I can afford a decent 4-stroke (California )