Can I start/charge my deep cycle from the alternator?

[muskyfins]

I have opened a can of worms on this battery thing, but this is a separate question.

If I'm on the hook for a couple of hours, can I start up the motor and charge up the deep cycle house battery? I guess I've seen where folks say this is a bad idea. I suppose I could get a dual purpose battery but they don't have the same capacity for running electronics.

Damn I hate electrical......:mad-new:

 

[UncleWillie]

I'll assume that you have a starting battery on the Engine/Alternator, and a separate Deep Cycle battery for the House loads.
If you have a 1,2,Both,Off battery switch that you place in the Both position while the engine is running, it will charge BOTH Batteries.
This is perfectly Valid.

If the House battery is significantly low you may need to operate the engine at advanced RPMs, Not at idle, for many hours to completely recharge the battery.
A shore powered charger is typically still needed to top off the battery but the alternator can be used to extend the day.
This is the recommended scenario for the installation of an ACR System.
If you do not remember when to select 1,2, or Both at the proper times if is possible to deplete both batteries and be stranded with 2 dead batteries.
An ACR takes all the thinking/remembering out of the equation.
It automatically selects BOTH when the engine is operating and Separates the batteries when stopped.
A shore powered charger may still be necessary, and it too will charge BOTH Batteries Automatically.

 

[muskyfins]

I'll assume that you have a starting battery on the Engine/Alternator, and a separate Deep Cycle battery for the House loads.
If you have a 1,2,Both,Off battery switch that you place in the Both position while the engine is running, it will charge BOTH Batteries.
This is perfectly Valid.

If the House battery is significantly low you may need to operate the engine at advanced RPMs, Not at idle, for many hours to completely recharge the battery.
A shore powered charger is typically still needed to top off the battery but the alternator can be used to extend the day. -Great! Saw some things in the corners of the internet that suggested this would damage a deep cycle battery
This is the recommended scenario for the installation of an ACR System.
If you do not remember when to select 1,2, or Both at the proper times if is possible to deplete both batteries and be stranded with 2 dead batteries.
An ACR takes all the thinking/remembering out of the equation.
It automatically selects BOTH when the engine is operating and Separates the batteries when stopped.
A shore powered charger may still be necessary, and it too will charge BOTH Batteries Automatically.

appreciate it. yes I have a 1, 2 both, off switch although I get nothing in the both position. Positions 1, 2 and off work properly as determined by testing individually. I will be replacing the switch.

 

[gm280]

Unless you are running/boating for hours on end, the alternator is not going to charge the house battery up to anything resembling a full charge if it was drained pretty much! A few minutes of charging from an alternator (from a boating run on the water) just doesn't have enough time to do the complete job. So to your question, the answer is yes and no. Yes the alternator can charge up the battery, but no it usually doesn't have enough running time to do it to full charge... And even using a ACR or a battery selector switch set to both, it will take even longer because it will be trying to service both batteries splitting the fixed alternator output across two batteries. Just the way electricity works. Supply and demand! JMHO!