Hello I am so glad I found this brilliantly informative site and I hope someone may be able to advise - our lovingly restored and decorated (yes I wallpapered it) elddis wisp caravan battery shows full charge until we switch on a light, the pump or the water heater when it shoots back to no charge and nothing works. Before realising this was happening we were advised to buy a new battery which worked for that trip. The next trip it showed no charge so we charged it overnight to full again , but when we turned on the pump and heater - no charge. We realised that it was showing full charge when nothing was switched on but as soon as we turn on something - no charge. We would be very grateful for some advice before we have to call an electrician as a last resort!
When you say the battery showed a full charge I take it you mean by means of the caravan voltmeter gauge. If so then this is only a guide to the condition of the leisure battery and needs to be checked with an independent voltmeter to see exactly what voltage remains in the battery. Now from what you have explained it sounds very much like the battery is not holding a charge which means a new battery will be required. However, before buying a new battery you need to confirm that the existing one is defective so you need to re-charge it fully to at least 12.7 volts and disconnect from the charger. Check the battery about 24 hours later and take another reading and again the day after. If the battery voltage has reduced over this period then it confirms that the battery is failing to hold the charge.
Thanks - yes I do mean through the caravan voltmeter. The battery in question is brand new - as the voltmeter showed it was down we recharged it and then charged the old battery which we thought was dead and that took a full charge as well - so we suspect that the old battery was not at fault nor the new battery but something happens when we turn on something - the switch for the pump, the heater or a light - then the voltmeter shoots down to nil.
Quote: Originally posted by LlaniDavis on 12/5/2017
Could also suggest there is a dead short somewhere in one of those circuits.
I would suggest checking each circuit carefully
It would have to be close to the battery as it affect all the circuits apparently. It could be a dodgy connection, and I would start with the battery earth. A short circuit would probably lead to a burning smell somewhere, I would have thought.
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our lovingly restored and decorated (yes I wallpapered it) elddis wisp caravan battery
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you wallpapered your caravan battery !!!!
stu
A dead short to earth would simply blow a fuse, leaving plenty of charge in the battery.
If you have those blue and red battery clamps,check them very carefully for corrosion. If present, ditch them as they are fiddly to clean and replace with the simpler side lever rather then top lever type.
even a 90% worn out battery from a voltage point of view can show a full charge.. a no load voltage test is pretty meaningless as regards testing the condition of a lead acid battery..
i have a fancy testing meter but the only other way to test the condition of a battery is to put a known load on it and see how long it takes to go flat..
a battery capacity is measured over a 20 hour drain.. a 100 amp battery with a 5 amp load should take 20 hours to go flat when fully charged..
a 10 amp load should take it down from fully charged to flat in say maybe 9 hours.. with a higher load the rated capacity is less..
this is when new.. with use the capacity drops off.. usually one hell of lot before folks buy a new one.. :)
but even a 90% worn out one will read the same fully charged no load voltage as a new one.. in a sense it is "fully" charged but even fully charged it has bugger all in it.. he he
trog
ps.. batteries dont just die.. they wear out gradually with use just like a car tyre does.. the only difference being with a tyre you can see the wear.. with a battery you cant..
you could do with an ammeter and put it in series between the battery and the load. That would tell you what is pulling what current - especially if you remove and fit fuses and play with the respective on/off switches.
You can pick one up from Lidl of Aldi cheap enough. (or maybe borrow one from a friend)
a quick and easy test to see if current is being drawn is to disconnect one battery terminal and gently touch it back on and off.. there will be a small spark if any current is being drawn from the battery.. if the battery has charge in it and there is no spark no current is being drawn..
ebay or maplins is the best place to buy an ammeter..
to properly test the battery as opposed to the vans electrics you need to remove it from the van.. charge it up from a separate charger and then work from there..
Thanks for all the advice - the battery in the van is brand new - it worked on our last trip for 3 days. This trip it did not work at all as described above, we took it out and charged it separately thinking it was flat, it then showed a full charge but still didn't work. I really think it is something past the battery that is at fault but have no idea what!
How long between the end of the last trip and when you next charged it?
You should either have a permanent trickle charger hooked up, or re-charge once a month.
If neither of these happened, then your battery can be damaged.
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Topic: battery problem
