Car battery is being drained

[viclord]

Hi all,

I have an issue with my D40. Over the last few weeks, my battery has been flat twice. After the first incident, I disconnected the dashboard camera that was wired to the battery directly, thinking that could be the culprit, however, the battery went flat again a few days later.

I bought the car back in April 2023 and at that time the previous owner replaced the battery with a new one, so it is about 6 months old. After the second incident, I took the car to Supercheap to check the battery and according to their report, the battery was Good and passed the alternator and starter test.

I have monitored the battery and I could see that it is not holding the ideal voltage (12.6v). After the car was parked, I could see that the voltage went from 12.67v to 12.55 in less than 4 hours.

So my theory is that something is draining voltage. The ute came with a second battery at the back which I was barely using (planning to change the whole battery setup at the back later on) so for now I disconnected it, although it shouldn't matter because I checked and confirmed that the ARB isolator is working near to the car battery.

Any ideas to track what could be draining voltage from the battery?

 

[Old.Tony]

Does it have a Couplertec rust inhibitor? What about a two-way radio? Is there live power in the trailer plug, and have ants or wasps left a gift for you inside the socket on the car?

If you put an ammeter between the positive battery terminal and the positive battery lead, how many amps does it read?

It is possible for a sulphated battery to self-drain (rapidly, if the sulphation is bad enough). C-Tek used to be one of the few companies that would make chargers that could reduce/remove sulphation, but now others (eg Century CC1212) do as well.

 

[viclord]

Does it have a Couplertec rust inhibitor? What about a two-way radio? Is there live power in the trailer plug, and have ants or wasps left a gift for you inside the socket on the car?

If you put an ammeter between the positive battery terminal and the positive battery lead, how many amps does it read?

It is possible for a sulphated battery to self-drain (rapidly, if the sulphation is bad enough). C-Tek used to be one of the few companies that would make chargers that could reduce/remove sulphation, but now others (eg Century CC1212) do as well.

Thank you @Old.Tony for your reply.

Yes, my D40 has a rust inhibitor and it seems like the fuse for it has developed some kind of corrosion, so I will need to clean it (or replaced).
Yes, I have a two-way radio but is always off and only has power when the ignition is on.
Yes, there is a live power in the trailer plug but going through an isolator and it is a recent one. I have checked and no visitors in there

When I checked the amps with the car off, I could see around 200mA, so I did some investigation and it turns out that the reading went down to 50mA after the fuse for the internal lights. I have turned them off and since then it seems like the battery is holding. The final test will be this weekend when I will leave the car for a couple of days and will check the battery voltage every 12 hours.