Leisure Battery Issues & Testing

Our NV200 has 2x “100AH” leisure batteries, and these are maintained via a 120W solar charger and CTEK D250S MPPT & B2B smart charger, and generally are maintained to a high voltage all the time and never flat. In the summer, the batteries are full by 9/10am from the solar even with compressor fridge. I designed the van so it’d run happily for a minimum of 4 days, even assuming no solar. (There is also a 240v 10A 7 stage smart charger, seldom used as rarely on hookup)

On our last 3 nights away over new year, with no solar, we were quite surprised when the power failed in under 48 hours….. Despite the batteries being full when we left. Yes, we were using fridge and heating, lights and charging, but still we expected double or more what we got. Very odd….. Starting the engine for 1/2 hour charged batteries enough and after this glitch all was OK. Batteries weren’t “fading” like old batteries, just quick death – but rapid charge

On the drive home, we put in 40AH charge (max) and the batteries were reporting full….. Hmmmm.

Anyway, here you have to remember, I installed the batteries quite early in the build, and then build the furniture around them, so they’ve never actually been out since they were installed. So, whilst I built the furniture with maintenance in mind, would it work lol! Once I remembered how to take it apart – yes. Phew. the wardrobe internals self-support and come apart in 5 mins. Then simply 6 screws to remove 2 panels, and within 10 minutes from starting the batteries are visisble and removable and they come out. Phew.

In tests, we found the smart charger “filled” the batteries in 3-4hrs and refused to put any more in. (A second smart charger and a dumb charger agreed they were full). This actually equated to 25-30AH maximum input……

Then in load tests, @ 10A discharge, each battery only gave out 20AH-25 before hitting empty voltage.

In summary then, both batteries both have massively reduced capacity, probably due to age, and maybe due to the first charger I installed whacking in 15.7v until I noticed. (It got returned!). But maybe that buggered the batteries, and as we normally have solar or move, not noticed reduced capacity. Regardless, new batteries needed.

Interesting points:-

  • The equivalent replacement battery is only rated at 75AH (C20) and 84AH (C100) tests – so clearly the “new” ratings are different and probably more realistic
  • Design your vans with maintenance in mind – removing and isolating batteries was trivial (phew)
  • Batteries fail…….

3 thoughts on “Leisure Battery Issues & Testing”

    1. Yeah – is a bit odd. The first charger I had (recommended by a supplier) whacked in 15.7v every time the fridge cut in, and took me a while to notice. Maybe that did damage? Dunno. Maybe the batteries aged? They were only £55 each…. so…….. lol

  1. A tip. I have had major problems with ctek’s chargers, it seems that ctek doesn’t keep the measure right. In the past, we used expensive chargers, ctek mx7 (000) for our leisure batteries and all of a sudden, ctek thinks it is wrong with all batteries except one. when i use a china charger it works without problems. last ctek charger died without warning about the day.

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