Mysterious power drain.

[Citysafe]

I have a Euromobil 810.

We benefit from a previous owner having fitted a high spec inverter and charging unit. It also has 3 x 110 amp hr static batteries.

we have never had a problem and lasted a week off grid with a top up from a small 20w solar panels.

Recently the battery capacity on the meter which shows as a percentage drops - after 24hrs to 90% and then down to flat after a couple of weeks. The control unit says there is no amp loading being consumed. Tracker and alarm are linked to vehicle battery.

I have taken the 3 batteries out and load tested then with a heater coil battery gauge and they all drop from 13.2 to 12.7v after a 10sec high load.

Does anyone know what my issue is. My next test is to take batteries out and leave them on bench for a week and see if they drop. I assume a good battery shouldn’t drop much at all unless really cold.

The strange thing is the solar panel used to keep them topped up without hook up although the van is alway left on the EHU with the internal conditioner on.

The after market controller shows a power drain of 0.3amp yet the Van control unit shows 0.

Any methodology to figure this out gratefully received.

 

[Lenny HB]

I have taken the 3 batteries out and load tested then with a heater coil battery gauge and they all drop from 13.2 to 12.7v after a 10sec high load.

That doesn't mean anything on a leisure battery you need to do a controlled discharged test.

First charge the battery fully and leave it to settle for an hour then:-

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.

 

[Citysafe]

Thank you. This is a great answer. What is the usual method for putting a controlled load on a battery ?

 

[Lenny HB]

Easiest way is to leave one battery connected in the van and turn some lights on, TV on etc until drawing around 5 amps, you need to test each battery separately.