Quick Question on Charging Different Battery Types

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Irish Reiver

Oct 24, 2015
Orlando, Florida
Happy Holidays everyone,

I currently have a dual battery set up which used a flooded battery on the starter and flooded deep cycle battery for my house battery. I have just added an Odyssey PC680 AGM to the rear quarter panel storage shelf I got from @NLXTACY. I plan to hook these up via a Morningstar solar controller but for the moment I don't have the solar panel fitted so I have just wired the Odyssey directly to main power being supplied by the house battery.
Is there anything different I need to do to protect the smaller AGM battery from being over charged or am I good to go? Also would it be OK to use a battery tender when I am out of town.


AGM/SLA etc charge at a nominal 14.4V (alternator output). Putting multiple batteries in parallel just means the alternator has to share its output current across batteries, it still pushes out 14.4V (if the total amps is less than the alt max output).

Nothing is getting 'overcharged' in this scenario...

but AGM batteries require certain amount of charge at certain amount of amps ?

AGM will be happy enough with alternator output - if that wasn't the case then a whole slew of different AGM batteries would have a serious problem when used in vehicles, which obviously is not the case...

Vehicle sized AGM/SLA etc etc batteries have no issue charging from a standard vehicle alternator. They can take more than a typical alternator's output current and so we're just left with how they deal with nominal 14.4V charging voltage, and they deal with that just fine :)

Thanks George. I finished the wiring last night and hooked them up to my charger and let them charge overnight. This morning the charge was in maintenance mode and all batteries were showing the same voltage. Truck is now at the airport so happy days..:)
Oh where's your truck going?

AGM's will take a higher current but charge at a slightly lower voltage. The regular battery mode on my ProNautic charger starts at 14.8 - 15.1, and the AGM mode starts at 14.7 - 14.8 (but is safe up to around 15-15.2). The alternator in my 80 starts charging at 14.8-15V when first started.

Long story short your batts will be fine. :)
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