Test load 6 Volt RV Batteries Need Advice

[MiniVistaCruiserJack]

Hi everyone,
I’m new to the forum. Just bought a pre owned 2009 Mini Vista Cruiser about a month ago. So far been enjoying overnight trips with it here in San Jose California.
I’m going to load test the house batteries. They only last about 6 hours with just house lights and occasional use of water pumps.

1) Do I need to disconnect the batteries individually to do the load test on each of them?
2) The load tester I’m using from Amazon will ask me to enter the CCA for the battery. I can’t seem to find the CCA written on the battery. I attached photos of battery and specs.
3) What’s the amp/hr capacity on these batteries? There a 2 ratings for amp/hr and 2 ratings for Reserve Capacity. I don’t fully understand them.

I’m somewhat of a DIY guy but new to RVs. More than happy to read up on technical reads on batteries. Thank you in advance for any advice on these questions. I’m new to all these

 

[Kevin D Pem]

Before load testing will give useful results the batteries must be fully charged.
How did you determine they were fully charged?

 

[MiniVistaCruiserJack]

I used a multimeter. It was something like 6.05 volts. I can’t remember exactly. Batteries have been hooked up in the coach all these time. Did a 1.5 hour drive then checked with a multimeter. Should I fully charge each battery with a 6 volt automotive charger then do the load test? How many hours do you recommend charging the battery using a 15amp charger?

 

[Kevin D Pem]

My experience tells me you might as well load test, as a 12v battery (2×6 in series)! Why? Because if one is bad, both should be replaced. Goes back to the "don't mix and match " warnings on most battery operated devices. Size doesn't matter!

So your flooded 12vdc battery should read 12.67 full charge, after sitting for 24 hours. To calculate 6vdc that would be 6.335 vdc. However, my above statement still applies. 12vdc replacement not 6vdc replacement.

I am not advocating changing to 12vdc batteries. Every battery is composed of a grouping of cells in series to produce the voltage required. So how you choose to configure your bank is based on other factors not spoken of here. It is simply a matter of not mixing old with new. (Balancing is the issue).

So your telling me you are load testing the battery when it is lower voltage than a lead acid battery voltage it should ever see! 50% soc should read around 6.15vdc. I would bake the battery with that 15 amp charger for 3 or 4 days and see if it will come back. Honestly I would put the battery back in 12v configuration to see if they would equalize!!!

Hope that helps.

 

[MiniVistaCruiserJack]

I see. Thank you for all the information. I will charge the batteries.
On the other hand, these batteries seem like they are an overkill for me. They each weigh 50lbs and I only do overnight camping. We usually drive back home the next day. I’m thinking of possibly replacing all the batteries with the one I attached an image of. Would 100Ah battery suffice to run house lights and water pumps for an overnight trip? Also what does 100Ah/20HR exactly mean?

 

[Kevin D Pem]

100ah at a 20h discharge rate. As a point of reference, the 100 ÷ 20 gives the load on the battery to accomplish that rating. If discharging at let's say 1h the rating may only be 50ah.

If you go to their website you will find a graph that will help you chose the battery based on the load you plan on exposing the battery to.

 

[MiniVistaCruiserJack]

Thank you. I’ll check out their website.
Also after I change the batteries, is there anything I need to reset in the coach? I asked the technician at the dealership and he said there’s nothing to reset. Just be sure to observe polarity. I just want to confirm there’s nothing to reset after I change the batteries.

 

[TheLooks]

Maybe. You need a different convertor unless you have one that can charge lithium. It will charge them, but not fully. Most say it will prolong the life of the battery to undercharge it to about 85%. With Lithium you can do this as they can be discharged so much lower then lead/acid. Just get one that has enough capacity to do what you intend and maybe a little extra.

 

[Kevin D Pem]

Well! AGM batteries can and will boil dry. They can't have water added to them.

They have voltage levels in the literature that need to be followed. Make sure you take heed to their warnings on charging voltage.
Renogy has what they call a hybrid battery. It is AGM with carbon technology. The people I know with them won't go back to a standard AGM.

MY HARBOR FREIGHT TOOLS battery charger has an AGM setting, would be my comment about needing special settings.

FYI all my batteries are AGM or Northstar Blue hybrid Lead acid carbon AGMs. So use that statement to see how I buy.

 

[Kevin D Pem]

Maybe. You need a different convertor unless you have one that can charge lithium. It will charge them, but not fully. Most say it will prolong the life of the battery to undercharge it to about 85%. With Lithium you can do this as they can be discharged so much lower then lead/acid. Just get one that has enough capacity to do what you intend and maybe a little extra.

The picture is of an AGM.

 

[TheLooks]

You are correct, good catch.