Battery losing its charge overnight

[Barry/Dot]

It’s happened twice now, overnight, where we have had to have a jump start in the morning. Running the vehicle for 10 minutes in the afternoon seems to keep the vehicle with enough charge to start it the following day. We have a transporter T6.1(2021 plate). Any suggestions to fix, as we are touring at the moment, would be appreciated.

 

[David and Sally]

Either the battery is knackered or you have a parasitic drain going on.
If you are only starting for 10 mins the chances are you are not putting back what you have taken out by starting.
Have you got a multimeter you can put across the battery terminals to check voltage at various times?

Visit a decent battery shop and get them to do a proper battery check.

 

[Jimbohorlicks]

If you have an inverter make sure its turned off when not in use.

 

[Barry/Dot]

Either the battery is knackered or you have a parasitic drain going on.
If you are only starting for 10 mins the chances are you are not putting back what you have taken out by starting.
Have you got a multimeter you can put across the battery terminals to check voltage at various times?

Visit a decent battery shop and get them to do a proper battery check.

Thanks very much for your quick reply.
We were wondering if somehow the fridge was not switching the EHU when we plugged in on site. The battery is only 18 months old and the van has only done 6k. The problem literally appeared overnight, no issues prior.

 

[pappajohn]

Batteries are like light bulbs.
They can last for extremely long times or they can fail at any time.
Just because it's only 18 months old is of no relevance.

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[Barry/Dot]

We don’t have an inverter, just a leisure battery and solar panel. We always use EHU.

 

[Jimbohorlicks]

If on ehu your leisure battery should be charged.for the starter battery you need a battery master connected to keep the starter topped up. Assuming that is the battery is in good shape to start with. As said you have a drain on the battery, is it a cab radio for example .

 

[David and Sally]

Thanks very much for your quick reply.
We were wondering if somehow the fridge was not switching the EHU when we plugged in on site. The battery is only 18 months old and the van has only done 6k. The problem literally appeared overnight, no issues prior.

The fridge should not run off the starter battery until you start the engine and the alternator tells the fridge to switch over. Otherwise it should run off the ehu as its first choice. The fridge display should show you what it is running on.

Sometimes a poor earth strap connection under the bonnet can cause starting issues. Some people run a separate earth strap.

Battery terminals tight and clean?

 

[autorouter]

You need to take a few voltage readings if possible, and that will tell you if it is the battery or not. This starter battery draining is a common problem, and there are several solutions depending on whether there is any form of charging available. But normally it takes a week or so to drain a starter battery at least, not overnight.

If you are always on EHU, then a small intelligent mains charger is a good option. It can be connected permanently, so it comes on automatically whenever the EHU is plugged in. It won't overcharge the battery even if left connected for months. When not on EHU it can stay connected, and doesn't cause any problems. I use a CTEK MXS5.0, which can charge at 5A, but a smaller Optimate battery maintainer at 0.8A is quite popular. They are used to keep the batteries of classic cars and bikes in good shape.

Another option is a battery maintainer that works from the leisure battery. A BatteryMaster for example connects between the leisure battery and the starter battery. It will keep a starter battery topped up if the leisure battery is being charged by some method - EHU, solar etc. This is very good if you have solar, because it keeps the starter battery topped up whenever the panels catch the sun, parked on the road, for example.

If you have solar, then another option is to get a solar controller that has two battery outputs, like the Votronic Duo. You can program it to send a large percentage of the solar into the leisure battery, and a smaller percentage into the starter battery to keep it topped up.

But first you need to find out what is causing the battery to drain so quickly. It could be a defective battery, or it could be a defective device somewhere that's not switching off properly. The radio/entertainment head unit is the favourite for that. Do you have a multimeter that can measure voltages?

 

[Brains]

I suspect your van may not have a [Broken Link Removed] fitted.

It's an automated switch that will allow electrical power from either the solar panel or EHU to charge up both batteries equally.

Your fridge should only run on 12v power when the engine is on
(and for 15 mins after it's switched off, so that the gas does not come on when filling up in petrol stations)
Otherwise the default is gas if there is no 12v or 240v EHU.
If EHU is available, then it will run on main power over gas.
The lights on the top of the fridge should tell you what is is running on.

I'd be looking for a parasitic power draw, the radio, the alarm, a cupboard light, a parking light? something on standby ?

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[bigtwin]

I use a CTEK MXS5.0, which can charge at 5A, but a smaller Optimate battery maintainer at 0.8A is quite popular.

CTEK do an MSX0.8 too (I have a couple of their 5A chargers and one of their 0.8A versions (could you guess that I have more than one motorcycle ).

Ian

 

[Old Cyclist]

We don’t have an inverter, just a leisure battery and solar panel. We always use EHU.

Had a similar issue. Turned out that the solar controller was faulty with the solar panel draining the battery during hours of darkness. A quick fix was to disconnect the controller. We were too were on EHU at the time. Worth checking this out if all else fails.

 

[Clive Mott]

Lift the negative of the starter battery and connect an ammeter in series. With everything turned off and doors all shut measure the amps. Hopefully no more than 30 milliamperes. But if you have an aftermarket alarm. tracker, rear view camera then these are frequently the culprit. Measurements come first and are better than guessing.

 

[autorouter]

The trouble is you can't see small drain currents. Even if you could measure all the voltages, you can only guess the drain currents by watching the voltages gradually fall over time. So as Clive Mott says, measurements are needed.

Measuring voltages is relatively easy for a beginner, and not much can go wrong. Measuring current (amps) is a different matter. With a standard multimeter the wire needs to be disconnected so that the current flows through the meter. This can be a problem for a user that is not very confident. Also disconnection disturbs the circuit under test, and can cause problems for the inexperienced user (loss of radio codes etc).

However there is a way to measure current (amps) without needing any disconnection, using a clamp meter. This has a loop clamp. The wire you want to test is put inside the loop, and the meter measures the amps flowing by measuring the magnetic field that the amps produces. No disconnection needed, no electrical connections needed, just clip the clamp around the wire.

Clamp it around the battery negative wire to look at the total amps going into/out of the battery. If it's more than you expected, clamp around the wire to different devices until the culprit is found. Then at least you will know what the problem is.

If you are buying a clamp meter, you have to be careful. Many clamp meters are aimed at electricians that do house electrics, and can only measure AC current. You want one that can measure both AC and DC Amps, because automotive electrics are DC. Also you probably don't need one that measures large amps (600A for example), these meters sometimes are not very good for small amps measurements.

A good meter is the Uni-T UT 210E, which many on here, including me, use for this kind of job. It has a couple of sockets for normal probes too, so it will also measure volts, resistance, continuity etc, so it's a good all-round meter. It has a 2A range for small currents, as well as a 100A range if you need it.
Amazon product ASIN B00O1Q2HOQ

 

[Tigger-Tim]

I agree that the UNI-T is good value.

The other tool worth having in the tool box is a little ammeter that replaces a fuse - just plug it in instead of the fuse of the circuit you suspect may be causing the problem.

Available for standard and mini blade fuses.

https://cpc.farnell.com/tenma/ten01046/current-tester-automotive-std/dp/IN04874

https://cpc.farnell.com/tenma/ten01047/automotive-current-tester-mini/dp/IN05470

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[RV72 SAM 🏴]

Go to Halfords as they happily come out and drop test your battery on the spot Just make sure everything turned off, as this can spike electrical components, but not if they "Off"
Also just double your control unit, is it a Truma as these have an 'A' mode for power to auto switchover, as if not on Auto it will stay on anything you left it on i.e. battery etc !