AGM Batteries Versus Deep Cycle Marine Batteries

[ksa8907]

Originally Posted by Piwoslaw

My new e-HDI engine has an AGM battery for the Start&Stop feature. I'm looking for info on how to charge it to keep it healthy.

I have been using a CTEK Multi XS 3600 charger on the previous lead-acid. As those batteries like to be charged "low & slow", I used the "Motorcycle" charging mode on the charger - 0.8A @ 14.4V, instead of the "Car" mode of 3.8A @ 14.4V. Apparently AGM batteries need a higher voltage, and this charger has such an option. It's called "Cold" mode - 3.8A @ 14.7V. The instructions state that this charger is for any kind of lead-acid battery, including AGM, but does not mention whether any specific mode is better for AGM.

What do you think? Is 3.8A @ 14.7V better for my new AGM battery than 0.8A @ 14.4V?

Higher charge voltage will help reduce oxidation but you will definitely need a charger that can step down to a float charge. AGM batteries can handle higher voltages but with any lead acid battery you need to use a charger that can adjust the charge rate.