Coach Battery Replacement

My Roadtrek which I could name "Tried and true" or "Rock steady" continues to perform. But there is maintenance to do. Some of this is preventative.

It became apparent that I needed to replace the coach batteries when one of them dropped to 0 volts. It had shorted, I guess, because the bank was at 6.5 volts, which was the voltage across one of the batteries and also the voltage across both. One battery seemed to be doing okay and the other was a tag-along. Just like America, 50% are doing the work and the other 50% is contributing nothing. beyond lip service.

I was aware that the batteries were not able to deliver the designed capacity. Capacity is the ability of a battery to provide the required power (watts) or ampere-hours for the required amount of time. My coach battery capacity prior to the 0 volt failure was below 50%, even though they measured suitable voltage on the indicator in the Roadtrek.

My batteries achieved a life of 4 years. Well maintained AGM batteries can go for 6 years, or more. I use a 50 watt solar panel with de-sulfating controller to maintain the batteries when off of the grid. My measurements indicate this is sufficient when storing the Roadtrek. On a sunny day the batteries will reach peak voltage. After a couple of cloudy days the voltage might decrease to about 80% as an indicator of "state of charge." I take my measurements early in the morning, prior to sunrise and after sufficient time to dissipate any "surface charge."

I'd done a lot of research including opening a discussion via the FMCA Roadtrek International "cyberrally" email.

I'd also designed a LiFePO4 system, should I want to upgrade to a lithium battery system. However, I decided at this time that going with AGM battery replacement was the prudent thing to do. More on that decision in a future post.

I was spending some time in the Tucson AZ area, so I found a distributor who carried the 220Ah 6-volt AGMs I was interested in and would install them for an additional $30. The total price was irresistible.

One thing we observed was the ends of the crimp connectors showed some oxidation. Is that a problem? The oxidation is higher resistance than bright copper, and over time that oxidation will creep up the wire. Resistance is a voltage loss and a source of heat. After cleaning, the ends were again shiny copper.

The installer then applied liquid plastic via a glue gun to seal the end of the connector. This should prevent further oxidation.

The new batteries included lifting means. One of the reasons I didn't do this was the fact that the old batteries didn't have such a means. I was faced with either purchasing a strap, or wrestling with 63 pound batteries. I've stored the lifting means in the compartment with the batteries.

Here's the completed installation:

After several weeks of monitoring the battery voltage, and with the solar panel connected, it seems the new batteries are doing well, achieving maximum terminal voltage and sustaining it into darkness.

My Roadtrek which I could name "Tried and true" or "Rock steady" continues to perform.