Charging problem???? Need help...
 

Twice now, I have had issues with my batteries getting sucked almost dead when I have idled for a prolonged period of time. When I'm underway, both are charging at 13, and if I run hard for a bit, I have no problem at all restarting.

I have Optimas and run with my Perko switches in the "BOTH" position all the time. Any ideas?

Just guessing bad batteries have them tested. I would also put a meter on the batteries and see what they are really charging at. !3 volts is low.

Optimas that were put in last summer...

belt good and tight I'm assuming.

Yes. I am not a fan of them for that reason. Seen a LOT of them go bad fast.

Yup...both of them. And this is the big reason why I'm having trouble with this...BOTH are acting the same way. Even with the batteries...I just can't see having two fail that miserably...maybe its just my luck? :drink:

Run the switches so that each engine charges one battery, not both to both. That will help isolate the problem and is better for the alts and batts.

Yeah what he said :D
Picture two pumps trying to supply water through the same tube to two different tanks....while they do work properly in the begining over time you will see one pump eventually supply more then the other pump......in the case of alternators you will eventually back feed the other alternator and cause all sorts of problems...
Best thing to do is let each Alternator do it own thing with its own battery....

Check the charging voltage at idle. Also, make sure that your alternator has enough output to run all of the accesories that you are using at idle. If the voltage is below 12v at idle, I would consider increasing the pulley diameter or rebuild/replace your existing alternator. The only downside to increasing the pulley size is the possibilty of slinging the belt at high rpm. Hope this helps some.

Thanks guys.

I wonder if I may have already created the "backfeed" problem...I've been running this boat with the batteries on "Both" since I bought it.. Perhaps it's time for some rebuilds...

It should be on both while running to charge both, when you stop overnight switch to house bat and cut off engine bat. remember if one bat goes down it will kill the other soon after. Thats why when you change bats you should change both.

http://bluesea.com/viewresource/684

13 volts is def. to low.
The altenator should put out atleast 13.8 volts .
Also i never had a problem with OPTIMA .
And yes each engine should charge 1 batt.

Mike, if you take your Alts off and take them to any of the auto parts stores like Napa, PepBoys, Murrays etc..they can test the alt to make sure its working properly. If you want to rebuild them i suggest MG Auto Electric 500 S Arthur Ave Arlington Hts ..they do some good work and quick turn around. 847-394-1698

Velocity Vector, You should run the switches only on each respective battery for each engine So if the Port side engine is No1 then that switch should only be run on position 1 when running and the same for the other side (alldepends on how the boats rigged) then if you need extra starting juice or have a dead battery switch to the other or to both postion....last thing you need to have one alternator fry out...then overload the other alternator and possibly even fry out the batteries! That link you posted to Blue sea also states:
"Port engine battery is connected to port engine circuit, starboard engine battery is connected to starboard engine circuit, circuits are isolated

Thanks Wally. My boat is rigged kinda weird...the guy that had it just chucked the 502s in it so he could trade up to a 42...I've monkied with the switch settings before, but always just ended up going with "Both" cuz it worked!