Battery drain - what is causing it?

[DenisM]

When I first took delivery, I charged the dual battery set up several times following low readings and used the "recondition" function on a Victron 15A smart charger. It's operating normally now. That was 18m ago. The vehicle doesn't do many kms at the moment so I charge it once a week to maintain it.

 

[TheDocAUS]

When I first took delivery, I charged the dual battery set up several times following low readings and used the "recondition" function on a Victron 15A smart charger. It's operating normally now. That was 18m ago. The vehicle doesn't do many kms at the moment so I charge it once a week to maintain it.

A good practice as a smart charger maintains and charges the battery(s) better than an alternator.

A solar panel with the CTEK CTEK250SE does a good job as well, if there is sun around.

 

[Dschubba]

Further to last post.
I got a Victron ip65 25A, gave the battery a full recharge and sulphation condition. Then I had to go away for a week. I had installed the BLM voltage monitors, so here’s the pictures.

It’s interesting to see how the ctech 120 keeps topping up the main battery, then just preserves itself once it gets to 12V. At that point you can see the main battery voltage dive fast, and towards the end was in a real death spiral at .5V a day loss.

The car screen display is what showed when I turned the key on. I videoed the ctech 120 module during the start and I can see it used the auxiliary battery as main battery failed to start it. (Thanks Rok instructions guide)

Also of note was that when I started the car the voltage shot straight up to 14.9v. That would indicate to me that the battery has a high internal resistance.

So to summarise the main battery wouldn’t last 7 days after being given a full charge with the car being locked and untouched.

For interest what’s the consensus for how long you should be able to leave the car without charging it?

Thanks
Sean

 

[TheDocAUS]

Thanks great information.

When I went away for 2 weeks recently, both batteries were is good condition upon my return, but not fully charged. This was because of the CTEK250SE and solar panel topping everything up.

I suspect both batteries would be fully charged in summer, however, the shorter winter days means less solar charge going in. The car was not driven on 26 May onwards. The voltage drops on 24 and 25 May are the car being started and driven.

It seems clear the main battery was benefiting a great deal during the day from the solar panel. The aux which was fully charged to begin with was allowed to supply power and drop voltage (you can see this in the 7 day graph), but on 1&2 June was recharged again and the pattern of supplying power to the main battery repeats. On 2 June both batteries were being charged in a similar way until the aux battery was topped up (see 1 Day graph below).

A bit of difference between our graphs, ignoring my graph is for 2 weeks (first 2 graphs).

NOTE: My graphs use different colours between my first screenshot and 2nd and 3rd screenshots- the app picked up a battery box as I walked around.

2 weeks

@Dschubba

7 days

1 day, being 2 June were both batteries were charged

 

[ADVAW8S]

I went away and my car was dropped off at dealer for work. It was not driven around. I have a single battery. Left with the screen saying 98% charge. Picked up 11 days later, battery was at 93%. The work done was software update, new safari window seals, coolant pipe and coolant reservoir replaced. Limited engine needed to run.

 

[Tenac]

I went away and my car was dropped off at dealer for work. It was not driven around. I have a single battery. Left with the screen saying 98% charge. Picked up 11 days later, battery was at 93%. The work done was software update, new safari window seals, coolant pipe and coolant reservoir replaced. Limited engine needed to run.

I've been out in travel past 4 weeks got home on Thursday my dual battery system read 92% and is now back at 98%, I didn't drive it very far.