Battery issue

MOJO

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Another problem. On mains since Sept but our Hymer engine battery shows flat on the control panel though its supposed to receive a charge from mains. I have not started the engine since Sept on advice its better not to protect exhaust system as can not drive it anywhere to get high enough temperatures. Leisure battery is fully charged.
No alarm on so what could have been drawing from the battery is anyone's guess.
I will have to remove and trickle charge for when it will be needed April/May hopefully. That will be eight months not running the engine! Any thoughts on the reason?
 
I don't suppose the electric windscreen blind opened and closed each day takes its power from the engine battery? Anyway it should still charge enough to cover that.
 
There are several devices that could be drawing small amounts of power even when turned off, including the engines ECU. This constant drain is usually very small but after a few weeks it adds up. It is called quiescent current and is needed to maintain the electronic circuits, sometimes it is described as parasitic but this is misleading because the power is usually necessary.

Some car radios draw current when off so this might be worth checking but you may lose the memory and codes if you disconnect it completely. Also alarm systems and trackers use power but best to check with you insurer before disconnecting them.
 
Just checked ignition. Red warning battery/alternator. Then all lights started flickering on & off. Flat battery for sure.
Have received some advice to use the jump start probe under the bonnet to connect charger and clip negative to body. Have jumped this van like that before. Would save getting to the battery?
 
Will check 4 fuses.
EBL29 - internal charger module 20A yellow
EBL29-Auxilary charging unit 20 A yellow
EBL29-AES refrigerator 20A yellow

Starter battery 20A yellow (refrigerator)

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Update. Checked all fuses yesterday. All OK but it began to charge again. I assume a poor connection through cold or damp. Next job will be to see if it holds the charge.

IMG_20210124_150514.jpg
 
Test today seems to confirm it's holding charge. On mains 13.17. Unplugged for 1 hour it read 12.6.Plugged back in it slowly rose back to 13 +. My conclusion is a dodgy connection on the fuse. The act of removal and refitting seems to have made all the difference
 
MOJO said:
Test today seems to confirm it's holding charge. On mains 13.17. Unplugged for 1 hour it read 12.6.Plugged back in it slowly rose back to 13 +. My conclusion is a dodgy connection on the fuse. The act of removal and refitting seems to have made all the difference
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Sounds hopeful but remember that holding charge and achieving normal voltage readings may not mean the battery is undamaged. Sulphation of the plates can happen if the battery is left discharged. If this happens the undamaged parts of the plates can behave normally but the capacity is reduced, so a 100Ah battery may only have (say) 40Ah capacity left in it. Think of it like a water tank which has half filled up with scale, it still has water in it but less than when new.

However don’t worry, if the battery still starts the engine when you need it to that is good enough.
 
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