AGM battery question

[acdc96]

My boat has a single AGM battery in it now. It has a dual battery switch so I can have a two battery's. The AGM is a year old. I want to put a second battery in. But I don't want to pay the money for another AGM battery. Can I use a standard dual purpose lead acid battery along with the AGM?
I don't want to screw up the AGM battery.

 

[gm280]

Re: AGM battery question

My boat has a single AGM battery in it now. It has a dual battery switch so I can have a two battery's. The AGM is a year old. I want to put a second battery in. But I don't want to pay the money for another AGM battery. Can I use a standard dual purpose lead acid battery along with the AGM?
I don't want to screw up the AGM battery.

Are you looking to isolate them like one for cranking and the other for the trolling motor? Or are you wanting to run them in parallel?

If you are separating them, no issue there. If you are going to run them in parallel, then all you are accomplishing is a 12 volt source with a higher capacity... need more info to seriously help.

 

[acdc96]

Re: AGM battery question

Are you looking to isolate them like one for cranking and the other for the trolling motor? Or are you wanting to run them in parallel?

If you are separating them, no issue there. If you are going to run them in parallel, then all you are accomplishing is a 12 volt source with a higher capacity... need more info to seriously help.

the agm is strictly for starting and the lead acid battery is a house battery. the batterys are hooked up to a GUEST battery selector with 4 postion (OFF, BAT# 1, BAT# 2, and BOTH). Im not going to use them together unless if the motor wont crank over on one battery.

im more concerned about charging the batteries.

i use a digital battery charger when the batteries are off the boat. the rest of the time the engine/alternator charges the battery. i don't have an on board charger that hooks up to shore power.

1986 Mercruiser 260Hp V8 w/ alpha one drive

 

[alldodge]

Re: AGM battery question

the agm is strictly for starting and the lead acid battery is a house battery. the batterys are hooked up to a GUEST battery selector with 4 postion (OFF, BAT# 1, BAT# 2, and BOTH). Im not going to use them together unless if the motor wont crank over on one battery.

im more concerned about charging the batteries.

i use a digital battery charger when the batteries are off the boat. the rest of the time the engine/alternator charges the battery. i don't have an on board charger that hooks up to shore power.

1986 Mercruiser 260Hp V8 w/ alpha one drive

Since you don't have an onboard charger you can mix them. The AGM can be charged faster then the lead acid but this is not a big issue. Where you could get into an issue is with long term charging. The float level of the AGM is lower then that of a lead acid. The AGM would be damaged being charged over a long period with an alternator. During the winter, make sure you charge them separately.

 

[UncleWillie]

Re: AGM battery question

My boat has a single AGM battery in it now. It has a dual battery switch so I can have a two battery's. The AGM is a year old. I want to put a second battery in. But I don't want to pay the money for another AGM battery. Can I use a standard dual purpose lead acid battery along with the AGM?
I don't want to screw up the AGM battery.

For the house battery, a Deep Cycle Battery will give you the best performance.

Charging the Deep Cycle in Parallel with the AGM is not a problem, as the AGM will not take as much abuse and need to be treated a little gentler. Once the AGM is fully charged the float voltage needs to be reduced below 14v for the long haul.
The Deep Cycle will appreciate the gentle care. Once it is full, if you continue charging the AGM at 14+ volts, like the typical alternator supplies, It may develop gas bubbles in the matting faster than the chemistry can reabsorb them. Not Good!

The real claim to fame of the AGM is that it does not spill acid when turned upside down.
This is a real plus in military aircraft and race cars that tend to roll over on occasion.
My Motor cycle has an AGM in it. It is necessary because the battery is mounted sideways.
If your boat ever goes inverted, I am sure there will be plenty of water available to dilute any spills.

Many here will claim that the AGM is is the best thing since Sliced Bread.
It is your Money, Spend it wisely.

 

[acdc96]

Re: AGM battery question

Ok... Now I understand.

Yeah I take the battery's out of my boat for the winter and charge them fully then store then in my basement checking them mounthly.

I had my AGM battery come flying forward after hitting a big wake and slowing down. The strap broke but no damage or spilled battery acid. . Was fine tuning the engine at that time with no engine cover or panels.

Thanks all.