I am new to AGM batteries and have done a lot of study prior to purchasing them as a replacement for my coach batteries. My charger has a specific algorithm for charging them when plugged into shore power so I have no concerns here. What has been nagging me is what happens when I take off on a long (several 100 miles) drive starting out with fully charged batteries. During this drive the battery separator will deliver alternator power to the batteries for the whole drive. Should I be concerned? Should I add a switch to disable the battery separator under these conditions?I would appreciate any thoughts or ideas.

Don't see why. My truck has AGM batteries.

Peteponic wrote:I am new to AGM batteries and have done a lot of study prior to purchasing them as a replacement for my coach batteries. My charger has a specific algorithm for charging them when plugged into shore power so I have no concerns here. What has been nagging me is what happens when I take off on a long (several 100 miles) drive starting out with fully charged batteries. During this drive the battery separator will deliver alternator power to the batteries for the whole drive. Should I be concerned? Should I add a switch to disable the battery separator under these conditions?I would appreciate any thoughts or ideas.My only concern would be that the charging voltage of the vehicle voltage regulator may be set at a higher voltage for conventional lead/acid batteries. This could lead to possible over charging.

Like you, I start out with fully charged batteries (both house and chassis batteries) from being plugged in. Instead of a switch to turn off the charging voltage, I run the fridge off the inverter while driving. It keeps the voltage at the house batteries just below 14 volts during the drive. From memory, I think it is 13.9 volts which is a bit better I think than hitting them with 14.4 volts for hours when they are already fully charged.If your fridge has a DC option then that might also keep the voltage at the house batteries at a more acceptable level.

I've also wondered about possible overcharging of AGM batteries while driving. Since the 2 original equipment AGM batteries in our Sprinter seem to be fine after 7 years and 90,000 miles so apparently the problem is not too significant.

14+ Volts is just fine. I suspect the Amps are very low. I wouldn't worry, I am 100% AGM and my youngest battery is in its forth year.HTH;John

AGM batteries, overcharging on long drives | Good Sam Community

markopolo
Explorer
Apr 15, 2013
Like you, I start out with fully charged batteries (both house and chassis batteries) from being plugged in. Instead of a switch to turn off the charging voltage, I run the fridge off the inverter while driving. It keeps the voltage at the house batteries just below 14 volts during the drive. From memory, I think it is 13.9 volts which is a bit better I think than hitting them with 14.4 volts for hours when they are already fully charged.

If your fridge has a DC option then that might also keep the voltage at the house batteries at a more acceptable level.
loving_retireme
Explorer
Apr 15, 2013
Peteponic wrote:
I am new to AGM batteries and have done a lot of study prior to purchasing them as a replacement for my coach batteries. My charger has a specific algorithm for charging them when plugged into shore power so I have no concerns here.
What has been nagging me is what happens when I take off on a long (several 100 miles) drive starting out with fully charged batteries. During this drive the battery separator will deliver alternator power to the batteries for the whole drive.
Should I be concerned? Should I add a switch to disable the battery separator under these conditions?
I would appreciate any thoughts or ideas.

My only concern would be that the charging voltage of the vehicle voltage regulator may be set at a higher voltage for conventional lead/acid batteries. This could lead to possible over charging.
2oldman
Explorer II
Apr 15, 2013
Don't see why. My truck has AGM batteries.

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AGM batteries, overcharging on long drives

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