Testing Coach Batteries

[mromberg1]

We are getting close to purchasing a used coach that's been in service for a little over three years. What the best way to check the overall health of the house batteries as I have no idea how the previous owner maintained them.

[LJowdy]

Usually there is a date on the batteries, check to see how old then have them load tested at a dedicated battery shop

[vsheetz]

If wet batter IU es check specific gravity of each cell. And do a load test.

I always assume when buying a used RV that batteries will need to be changed, and budget accordingly.

[mromberg1]

Yeah - probably best to just replace and know exactly what's gone on with them rather than get hit with surprises down the road. A good time to go maintenance free AGM's being we will store it away from home.

Originally Posted by vsheetz

If wet batter IU es check specific gravity of each cell. And do a load test.

I always assume when buying a used RV that batteries will need to be changed, and budget accordingly.

[Ivylog]

What ^^^^Vince said.

[Mark_K5LXP]

You can do a measured capacity test by applying a C/20 load and seeing exactly how many Ah they will deliver. The $64K question is just what this practically changes when contrasted to the cost of a 3 year old motor home. My take on it is to make an offer with the idea that the batteries would need replacing along with any other wear and tear consumable plus depreciation. When you get the coach you can replace the pack as a matter of course, or do a measured capacity test and decide if they're worth keeping around a while. Batteries being a consumable that isn't terribly expensive or difficult to replace, I wouldn't consider to be a significant issue or bargaining chip when considering the purchase of an RV.

Mark B.
Albuquerque, NM

[Reacher]

mromberg, to answer your question: properly testing your batteries is not difficult. This video lays it all out for you. Rather than sending you out half cocked ready to lay down big money on new batteries, 3 year old batteries should be less than half way through their useful life unless they were abused and neglected.

https://www.youtube.com/watch?v=EclPoCswaTw0

[Mark_K5LXP]

Voltage and SG measurements as shown in the video don't reveal anything about capacity or merit.

Mark B.
Albuquerque, NM

[Reacher]

Originally Posted by Mark_K5LXP

Voltage and SG measurements as shown in the video don't reveal anything about capacity or merit.

Mark B.
Albuquerque, NM

Right. But it would reveal a dead or damaged cell which is indicative of a failing battery. With that knowledge he would definitely need to replace them. Instead of replacing them anyway as some have suggested. It would also give him insight and confidence that he could do something about it himself rather than relying entirely on a professional.

[CountryB]

I doubt the OP has a battery load tester. And since he is looking at someone else's coach - it's unlikely he can take the batteries (or Coach) to a shop to have them tested.

Your (OP's) best bet is to look at the date on the batteries and check that the water level is correct (which indicates someone is providing some level of maintenance). If the batteries look clean, have water in them, and are not too old, then don't worry about them and move on to inspecting other items (like the tires).

If the batteries are at or over 5 years old, plan to replace them.

[mromberg1]

Very good practical advice...thanks!

Originally Posted by CountryB

I doubt the OP has a battery load tester. And since he is looking at someone else's coach - it's unlikely he can take the batteries (or Coach) to a shop to have them tested.

Your (OP's) best bet is to look at the date on the batteries and check that the water level is correct (which indicates someone is providing some level of maintenance). If the batteries look clean, have water in them, and are not too old, then don't worry about them and move on to inspecting other items (like the tires).

If the batteries are at or over 5 years old, plan to replace them.

[HJLowell]

I have this tester on my boat and one in the coach.
Maybe purchased 18 or so years ago.
I dont think this model is available anymore.
But I can find out real quick the state of a batterys health. Charge.
I cant say its 100 percent accurate?
But it saves me from hauling batteries in for bench testing.

[HJLowell]

Also must haves
I think.

[Ray,IN]

Originally Posted by Mark_K5LXP

You can do a measured capacity test by applying a C/20 load and seeing exactly how many Ah they will deliver. The $64K question is just what this practically changes when contrasted to the cost of a 3 year old motor home. My take on it is to make an offer with the idea that the batteries would need replacing along with any other wear and tear consumable plus depreciation. When you get the coach you can replace the pack as a matter of course, or do a measured capacity test and decide if they're worth keeping around a while. Batteries being a consumable that isn't terribly expensive or difficult to replace, I wouldn't consider to be a significant issue or bargaining chip when considering the purchase of an RV.

Mark B.
Albuquerque, NM

That is a practical thought process!