Battery Replacement

[BC-ClassC]

Hi All,

On a recent camping trip (with no hookups) with the weather dipping near freezing overnight we ran the furnace on our 2019 Thor Four Winds 28E from around 9pm until 8am. This motorhome comes with 2 lead acid 12V deep cycle batteries at 80AHP. It also has the stock charge controller and inverter setup for solar but I haven't attached the solar panel yet. Despite ensuring the batteries were topped by running the generator (from 6pm to 8pm), by the morning the batteries were drained. I'm looking at replacing the 2 stock batteries with 2 new AGM 100 AHP batteries. Are the AGM's that much better? and are they are direct swap or will I need to change my charge solar charging set up?

Thanks!

[BC-ClassC]

One additional question, the current batteries are dual purpose as I'm assuming they are used as an emergency backup to start the motorhome (switch on the dash). If I replace these with AGM deep cycle batteries, can they still be used for an emergency start?

Thanks!

[Beau388]

Originally Posted by BC-ClassC

One additional question, the current batteries are dual purpose as I'm assuming they are used as an emergency backup to start the motorhome (switch on the dash). If I replace these with AGM deep cycle batteries, can they still be used for an emergency start?

Thanks!

AGM is simply another way of manufacturing lead-acid batteries and belong to the Valve Regulated Lead Acid (VRLA) battery group. The chemistry is exactly the same with the same charge/discharge requirements, except AGM should not be equalized or fast charged. Any deep cycle battery is not meant to be used as a starter battery, as currents above 13% of the batteries capacity will degrade the battery's cycle life. That said, if you use the emergency start switch properly, it should not degrade the battery's life. There are marine batteries than can serve a dual purpose but they are really a compromise between starting and deep cycle and they are available in flooded, conventional VRLA, AGM versions. I personally believe the VRLA marine battery represents the best value per amp-h but many others disagree because they dry camp more than we do.