Single wire alternator question
 

My voltage guage is indicating no charge is happening. The guage works properly as it moves when accessories are turned on and off. I started the engine and pulled the negative cable, the engine continued to run (Thus MSD ignition is running off the alternator). Does that mean the alternator is acutally charging? How should I proceed to debug this?

Re: Single wire alternator question
 

Put a volt meter on the battery and check voltage before and after you start the engine and note the change in the voltage. Usually a single wire alternator has to reach a certain rpm before they "turn on".
Robert

Re: Single wire alternator question
 

Did you rev the motor up to get it charging? You have to reach a certain RPM for a certain time before the field will excite itself. Mine are around 1800-2000 rpm for a couple seconds and they go to life.

Jon

Re: Single wire alternator question
 

No change after revving the motor, will put the meter on the battery tonight.

Re: Single wire alternator question
 

Sutphen30 - I wish but it's a single wire. This is its third year in the boat. It's worked perfect up to now.

Re: Single wire alternator question
 

Do a search on the net for one wire alternators.. I did this yesterday and found some sites that had replacement parts, etc.. my one wire alt will start as soon as it sees about 800rpm..

Re: Single wire alternator question
 

What do you mean it is indicating no charge is happening? Are you saying that the voltage is not increasing when you rev the engine? If so, this could be indicative of a failing battery, in that the voltage is not increasing due to increased charge load from the battery. If the engine runs without the batt connected, the alternator works. Does the boat not crank properly?

Re: Single wire alternator question
 

I just replaced mu Mando 65 amp alternator with a 135 amp from this company. The site shows it as a 105 amp but the alternator was stamped as 135 when it arrived.
http://4alterstartcom.verizonsupersite.com/marine/
First water test last night. This one starts charging at 1000 and stays charging once idled down a bit. It will put the gauge at 13.5 even with a very low deep cycle. The Mando would take 20 minutes before it would show 13.5 because the battery was taking all of the charge and needing more. You may want to ohm out the + from the alternator. If it was an aftermarket it may be a higher amperage and your wire could have burned through. I ran a #4 from the alternator to the common post on the battery switch as the the stock #8 would have a hard time carrying 135 amps.