Battery voltage drop to appliances

[Marcus and Jude]

Hi, Our Bailey Adamo has had this problem since we bought it 2 years ago and we have not been able to find anyone to fix it yet! There is a voltage drop from the Battery to the Appliances of 1.5 to 2.5v - tested by two MOHO mechanics, but they don't know why! We mainly use the battery to watch TV which draws 2.3amp and with a 90amp battery it should last about 15 hours but only lasts for 5 to 6 before switching over the to vehicle battery and running it down. Also, the fridge and heater will not work from the leisure battery (not that we would normally do this as we use EHU or Gas for these, but it should which might be part of the problem?). We believe the issue is with an electrical component between the battery and the appliances but no one has been able to tell us which one this might be. It has been suggested the BCM might be at fault but not being electrically minded and I understand this has more than one function I haven't a clue how to proceed. Would anyone on this forum be able to help please?

 

[ChrisL]

These devices are useful for testing leisure batteries, the device is powered by micro USB, attach leads with crocodile clips to the battery and the green terminal block, set a load and a voltage you want the test to stop and then run the test it will count the amp hours used and display the voltage thereby indicating the batteries capacity.

Pardon our interruption...

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In this case the battery voltage dropped to 8.84 volts immediately with a 2 amp load indicating the battery was shot, the voltage prior to running the test was 12.8.

 

[AdrianChen]

These devices are useful for testing leisure batteries, the device is powered by micro USB, attach leads with crocodile clips to the battery and the green terminal block, set a load and a voltage you want the test to stop and then run the test it will count the amp hours used and display the voltage thereby indicating the batteries capacity.

Pardon our interruption...

www.ebay.co.uk

In this case the battery voltage dropped to 8.84 volts immediately with a 2 amp load indicating the battery was shot, the voltage prior to running the test was 12.8.

View attachment 973730

Out of interest, how high can you set the load on that? To test my battery bank at C20 (which is how it is rated) so I can see how far gone it is I would need 21.6amps - Luckily I chose two in parallel so I could separate them if needed?

 

[ChrisL]

Out of interest, how high can you set the load on that? To test my battery bank at C20 (which is how it is rated) so I can see how far gone it is I would need 21.6amps - Luckily I chose two in parallel so I could separate them if needed?

I think that one is 4 amps but I think there are ones capable of heavier loads. One thing to note ìs it relies on a cut off voltage to turn the test off (maybe 12v for a lead battery) so if using it with a lithium battery it might be better to set a timer instead.

 

[pappajohn]

A 90a battery should deliver 45a....discharged to 50%.
Therefore, if nothing else connected, it should power the 2.3a TV for 20 hours.
Can you put a different battery on temporarily to test.
I suspect your battery has lost considerable charge capacity.
If it has reduced capacity it will show fully charged but as soon as a load is applied the voltage will drop considerably.
Renewal is the only real option.

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[autorouter]

We believe the issue is with an electrical component between the battery and the appliances but no one has been able to tell us which one this might be. It has been suggested the BCM might be at fault but not being electrically minded and I understand this has more than one function I haven't a clue how to proceed. Would anyone on this forum be able to help please?

If you think the BCA unit is at fault, I don't know the details of the BCA unit, but it should be easy to check. It will have an input from the leisure battery where you can measure the battery input voltage.

It will have an output to the circuit for the TV. There will be a fuse that protects that circuit, and the wire will come from one of the connectors. If the connector pin number is not detailed in the manual, you could find it be trial and error. It will show about 12V with the fuse inserted, and about zero volts when the fuse is removed.

Once you've found the wire, with the TV working and drawing its usual power, measure the voltage on the wire as it leaves the BCA unit, right at the pin. Then straightaway measure the voltage at the BCA leisure battery input. If they are almost the same, then the BCA unit is not the problem. If there's a big voltage difference, you've found the fault, it's inside the BCA. Assuming the BCA battery terminal is good and tight, of course,