Alternator woes need your advice

bristol321 · #1 (**permalink**) 10-05-2008

Hi all,
Just installed a new 60 amp alternator internally regulated. Anyway according to my gauges and multimeter she's putting out 15.6 volts at the alternator and the batteries are getting 15.2 volts. I was under the impression that the alternator should only put out around 14.7 volts......Is there an aftermarket external regulator that I can adjust this with? Is usage going to fry my two new batteries?

Zanshin · #2 (**permalink**) 10-05-2008

What kind of batteries do you have and what make is the alternator (some can also be externally regulated - which it looks like you might need)

camaraderie · #3 (**permalink**) 10-05-2008

How long are you letting it run when measuring...is this voltage at startup or after a while running? I understand they are new but what discharge state is your battery bank in...full/empty or somewhere in between? Have you measured amperage at this 15.6V??

bristol321 · #4 (**permalink**) 10-05-2008

I had the alternator built it has no name brand and using two new deka marine dual purpose for house, interstate starting battery all lead acid maint free

bristol321 · #5 (**permalink**) 10-05-2008

the resting voltage (no charger alternator or solar) is 13.3 volts on both batteries. they are at 90% charge the v oltage check was consistent at start up and after running 15 minutes

camaraderie · #6 (**permalink**) 10-05-2008

Resting voltage cannot be 13.3...that is surface charge from prior charging. Resting voltage cannot be over 12.7. Anyway....sounds like they are fully charged. Your alternator output after 15 minutes is WAY too high. Take it back to the shop as it will need to be either fixed for the correct output (not more than 14.7) or modified to take an external regulator.

Zanshin · #7 (**permalink**) 10-05-2008

According to their web site: Deka Dominator 14.1v, Deka Seamate 14.6v maximum charge voltage. As Mr. C. has already stated your alternator is putting out too much. Actually, are both being charged in parallel or do you have 2 separate batteries and dual charger? Some (cheaper) dual chargers will drop the voltage (usually unwanted, but in your case perhaps a possible solution).

NorthUp · #8 (**permalink**) 10-05-2008

Are you using a quality multimeter to measure these voltages? the (made in) china specials are not very accurate, and can be found inside meters with a more respected name from the USA or Europe.

timebandit · #9 (**permalink**) 10-05-2008

Quote:

Originally Posted by NorthUp

Are you using a quality multimeter to measure these voltages? the (made in) china specials are not very accurate, and can be found inside meters with a more respected name from the USA or Europe.

I agree.

I chucked 2 cheap multimeters from Harbor Freight because they read high.

Rick