Thread:

How much load is to much for the alternator??

Sorry if this has been asked befor but i did not find it in the search..

So i have two optimas on my boat (A #1 and #2 on a battery switch) and i charge them all the time, but my stereo is not that big and if i park and switch to one battery it last about twenty min. is that normal?
of coarse if i swicht to both batterys it will last longer but still....it shoulnt die that fast i am guessing

both batterys are brand new, 3 months old.

i am wondering if they are getting a full charge.
do all of your volt gauges show 14 volts when ideling?

Originally Posted by 28 stealth

Sorry if this has been asked befor but i did not find it in the search..

So i have two optimas on my boat (A #1 and #2 on a battery switch) and i charge them all the time, but my stereo is not that big and if i park and switch to one battery it last about twenty min. is that normal?
of coarse if i swicht to both batterys it will last longer but still....it shoulnt die that fast i am guessing

both batterys are brand new, 3 months old.

i am wondering if they are getting a full charge.
do all of your volt gauges show 14 volts when ideling?

20 min is quick but you may have more stereo than you think. Or the equipment is not very efficient.The 14 volts when at idle is from the alternator sounds normal.Turn key on without starting to see batt volts.Not sure witch Optimas you have but in todays world of stereo some would consider them starter batteries.Most shops now will go with at least a 1700 amp batt. Some wont put in a system without a 2150.

I would always recommend a 2150 odyssey battery or a 2400 Kinetik battery for any sound system. 20 minutes is too short of a time even for an optima. You must have very inefficient amplifiers. Which amps are you running?? We run 1 - Pdx1000.1 and 2 - Pdx150.4 amps with one 2400 Kinetik at 3/4 volume all day before it gives up and even then all we have to do is turn the bass down.

well you see my volt meter is rarly showing that its making 14 volts. at speed it shows full charge, but if iam ideling with the stereo on it makes about 10 volts.
not sure if thats a good thing
the batterys are only 3 months old, and they are the blue marine optimas.
i just dont know if it is the alternator that is acting up or just alot of stereo.
i realy dont think i have alot of stereo, it doesnt get that loud to make me belive i have a big stereo.

Use a volt meter to check the voltage at the battery. Don't always go by the meter on the dash. They are typically off by a volt or two. If you do not see a change from when the motor is not running to when it is then you probably have an alternator problem. If the batteries go dead within a couple days of not using the boat then you have a problem with the battery. I personally do not like the optima other than maybe to start the engine. They were never designed to work with stereo systems. Go with an Odyssey or a Kinetik battery for the stereo.

Originally Posted by thmper321

Use a volt meter to check the voltage at the battery. Don't always go by the meter on the dash. They are typically off by a volt or two. If you do not see a change from when the motor is not running to when it is then you probably have an alternator problem. If the batteries go dead within a couple days of not using the boat then you have a problem with the battery. I personally do not like the optima other than maybe to start the engine. They were never designed to work with stereo systems. Go with an Odyssey or a Kinetik battery for the stereo.

Thanks for the input,
what do those useualy run$$$ ??

Also, alternators are meant to maintain a charge on a battery, not bring back a battery from being completely run down.

Originally Posted by BOBALOO

I have 3 JL amps and run 4 batteries. 2 Odysseys and 2 Stingers. I cant play the whole day without recharging. I do tend to play on the LOUD side though. I like to be the sandbar DJ, at least around my boat.

I HAVE to charge the batteries every night and use 2 chargers, one DLS 55 and one DLS 75. They are made by Iota and have the IQ4 module built in. If you are relying on the alternator to charge ............good luck. It takes many hours to charge with a dedicated charger and you would have to run your boat prob 5 hours (not at idle) to charge yours when dead. At idle you are prob putting out 15 amps and at 3000rpm 55 amps.

You NEED to get some kind of separate charging system.

That's very good advice as well. The boat is always plugged into the smart charger as soon as its back at the house.

Multimeters can be bought cheap at home depot. Under 100.00. Its a good tool to have on a boat.

28 Stealth

You batteries would get a better charge if they were charged one at a time. By charging them both at the same time all of the time they are getting half of what they actually need. 10 volts is too low at idle for sure. The voltage should always be between 13.2 and 14.7 whenever the engine is running. Don't trust the volt gauge on the dash, have the voltage varified with a quality meter.

Boats take a lot more stereo than a car or truck to make them equally as loud. Your not that big stereo system may be a lot bigger than you think. ?