Leisure Battery Advice

[grasscutter]

We have owned our Hobby Van Exclusive for 2 1/2 years. Decided that I should investigate the leisure batteries etc.
Although We haven't had any problems we are retiring and hope to really start using the van and it may be prudent to sort out the batteries etc whilst we have a chance.
Having spoken with Carol the previous owner she said that they had an extra battery added at a later date.
So the system at present is two gel batteries. What may be an original 85ah and a second 65 ah battery.
The solar is I "think" an 80w roof mounted panel.
Pic photos of the system above.
Obviously the gel batteries have charged fine to date and I haven't removed the drivers seat to see what the engine battery is so I feel it may be best to replace the leisure batteries with gel batteries so that I don't upset any charging regime.
I would like the extra capacity of 2 X 100 ah/ 110ah batteries.
So any recommendations for batteries or foreseeable problems would be most appreciated.
Just to add the battery dimensions of both are 350l X 170w x190h.
TIA
Graham

 

[Boringfrog]

If they're 85ah I doubt you would fit 110ah in the same space. If your not have any problems yet I wouldn't bother changing them.

 

[scotjimland]

How old are the Gels ? (aprox).

Properly looked after and not abused they should be good for at least 10 years or more

I changed out a pair that were 14 yo .. Hymer OEM..
so personally I wouldn't bother.. wait until they stop holding charge or not performing well .

 

[Lenny HB]

The blacklooks like a Sonnenschein 78 a/h almost the same as an Exide, Sonennenchein make the Exide Gels, probably good for 6 to 10 years. Don't know what the other one is.
Probably worth separating them and running a controlled test on each battery.
Some re-wiring looks worthwhile the main cables to the batteries look far too small to me I would change them for at least 16mm sq cables.

Easy way to test is to do a controlled discharge on each battery separately like this:-

Fully charge the battery, let it stand for an hour then measure the voltage.
Then apply a load, for example if it's a 100a/h battery load it with a 5 amp load and run for 5 hours, this will represent a 25% discharge. (adjust load/time to suit the size of battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeate the the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged but not recomended for wet cell batteries.

 

[grasscutter]

Thankyou @Lenny HB . the black one is indeed a Sonnenschein .

^{_{Subscribers  do not see these advertisements}}

 

[hilldweller]

Forget the batteries, you are well under power for solar unless you (nearly) always hook up. Another 100W or more would improve things.

 

[TinaLes]

Gel Batteries are great, they may be lower amp/hour rated than AGM, but the fact that they can be discharged to much lower extent(25%) means that they can be charged up many times and last longer, well that's the theory anyway.
I would not dream of changing the batteries until I had done the suggested test that @Lenny HB has suggested, regardless of age your batteries may well have years of life in them yet.
Your vehicle battery is a different matter though as its probably a wet jobbie or an AGM, so will tend to need replacing a more frequent intervals.
Only you will know how long you will spend off grid with no hook up?, the existing solar panel may well be good enough in summer to keep the leisure batteries topped up while being stored, but not much use in winter with much less sun available.
If you haven't looked at "Battery Masters" yet, then consider one of those they are cheap, and will apply a small charge from the leisure batteries to the cab battery to keep them level charged when van is not in use also, or when on a site for a time without hook up. We bought ours from Vanbitz, but they are available from other sources and it is a doddle to wire up and install.
Good luck with the battery testing, enjoy your well earned retirement, safe and happy touring.
Les