Leisure Battery Current Draw

[sotal]

We had a new Yuasa LB this year as the old one had failed.

However when camping the new one doesn't seem to hold its charge as well as the old when did when it was still good. Even when not camping the LB seems to drop its voltage quite quickly.

It might just be a duff battery but I thought I'd have a quick check with them multimeter to see.

I have moved the normal stuff to the LB, so it has the radio, the blinds, the tap, the 12v sockets etc.

Initially connecting it up it was drawing 0.85A but that is because the radio kicks straight in after being disconnected. Switching the radio onto standby drops this to 0.26A.

So when it is left on standby for 15 hours it should use only approx. 4 Amps - this shouldn't make a dent. However measuring the voltage - in that time it will drop from 12.8/12.9v (immediately after switch off) to around 12.1v.

When camping we use an inefficient 12v cool box which draws around 4A on its own. We have been using EHU this year so it has been on charge all the time we are there but when out for the day it needs to last for a few hours at a time. Perhaps 6 at most - this would draw 25Amps, which should be less than the 50% of the 80AH capacity. However - when left like this it will drop to about 11.7v over that time.

Does that sound right? With the old battery we used to be able to do a few nights away without EHU, we would keep the coolbox running in the day but unplug it at night when it was cooler and pop it outside. The battery would normally get charged every day as we would normally drive somewhere every day.

[g8dhe]

Yes it sounds quite normal, voltage is not a very good indicator of actual stored capacity, also remember that the "capacity" of a battery whilst quoted as say 80 AmpHours if you take 80AmpHrs out of it will NOT do it any good - stick to no more than 40AmpHrs if possible i.e. 50% of rating if you want the battery to last.

Its also a good idea from time to time to measure the voltage drop along the cables easiest way is measure the voltage at the battery terminals themselves (actually on the lead posts- not the clamp) and then measure the voltage as close as possible to the fridge (largest current draw most likely) between its +ve and -ve wires if the difference in readings is less than 0.25v your well and good if its more than 0.5v then start hunting the corroded connector/switch/fuse! I recently noted that I had an intermittent voltage drop and finally tracked it down last week to what looked like a perfectly good and tight crimp connection on the ring connector on the -ve of the battery terminal!

[sotal]

I have also found out that the USB charger that I installed in the dash, draws 0.1 Amps with nothing plugged in. The standby load drops from 0.26A to 0.16A when I unplug it. Might need to put a switch in to turn it on and off. I realise it isn't a huge amount but was more than I thought it would be.

Will do a voltage drop test.