Replaced RV’s batteries but converter won’t charge them. Now what?

Dear Dave,
I upgraded my RV’s batteries from regular 24 series dual-purpose deep-cycle to 2 AGM 6V golf cart batteries, Rolls 220AH. I did not realize the turmoil this would cause. These batteries require a different charging voltage and charger, 14.7V, and, of course, my converter will only do 14.4. I am in the process of finding a converter that does AGM. I found one power max which is adjustable to 16.5, but it may not have the proper voltage for the other stages. Also, no alternator output will go to 14.7, so that is another issue.

I was able to adjust my solar controller to 14.7 so that is the only thing so far that has worked. The battery company, Rolls, says 0.3 of a volt lower will cause sulfating, therefore shortening the life of the batteries. For an $800 investment, I need them to last as long as possible.

I did not realize all of this before I bought the batteries. The store did not advise me of this; otherwise, I would not have bought them. What are other people doing in this situation? I’m assuming people use these batteries in RVs. They have great capacity, but I’m not sure it’s worth the aggravation! I’ll be interested to know what you think or have done. Thanks. —Dave, 2008 Forest River Lexington 300SS GTS

Dear Dave,
I was not familiar with the Rolls brand of battery, so I did a little research. They have been making batteries since 1935 as Surrette Battery Company. They have been based in Springhill, Nova Scotia, since 1959. According to their website, they are predominantly in the renewable energy, marine, and railroad market.

I did not see a 220AH model listed so I called technical support at Surrette and talked with Steve, who was a wealth of information and familiar with your situation. He stated that you most likely had two 6-volt AGM batteries connected in series. Yes, they do require 14.7 volts to achieve the ultimate performance. Even a 0.1 drop in bulk stage charging will cause sulfation and shorten the life of the batteries.

Rather than replacing the converter/charger in your rig, he suggested the Victron 22-12/30. That is a 12-volt charger with three voltage settings: normal – 14.4V, high – 14.7V, and Li-Ion – 14.2V. You can connect it direct to the battery and plug it in. However, he recommended using a SmartShunt, as shown in this diagram.

You can then download the Victron Connect Bluetooth app and dial in the absorption charge of 14.7V and the float charge of 13.8V, which is acceptable for the batteries that you have. The short amount of time you will be driving and towing the rig should not have much affect on the batteries, as the alternator will put out a limited voltage and the solar controller can help limit the lower charge time.

You can find the Victron IP22/30 on Amazon here.

Your situation is very common in the RV industry, i.e., lack of education and knowledge of the products by store salesmen, for example. We see a lot of turnover in the RV industry and when we start purchasing products from other industries, there is even less knowledge of how things work.

According to the warranty records at Surrette Battery Company, you purchased the batteries at Total Battery. That is a discount retailer and not the most knowledgeable distributor in the industry when it comes to RVs and charging the batteries. That is why I have always maintained that if we are not replacing components with like product or something totally new, we really need to research thoroughly rather than just take it for granted that the sales person actually has done the research. If they have not installed the product in several RVs and don’t have a history of what the customer is experiencing down the road, we cannot assume it will work and last as intended.

Steve from Surrette Battery Company stated: “We are not in the RV business as every time we have worked with RV manufacturers and purchasing agents it has been a race to the bottom!” Well put!

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My batteries don’t charge when connected to shoreline power. How can I test my converter?

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My converter does not appear to be working. My batteries are not being charged when plugged into shoreline power. How can I test/check to verify an inoperative converter on my Airstream? —Jay, 2020 Airstream Classic 33

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

Read more from Dave here. 

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