New battery suddenly losing power with everything shut down!

Joined
Oct 4, 2022
Posts
207
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320
Location
Henfield, West Sussex
Funster No
91,710
MH
Autosleeper Broadway
Exp
Since 2021 (previous tent campers)
We’ve recently replaced our leisure battery after managing to kill the old one after a night away in the freezing weather.

It’s a Hankook 110ah lead acid.
After fitting we connected EHU to give it a good charge for a few days. Then disconnected and shut down the electrics with the black button.

In the past this has kept our battery at a steady voltage.
However after just one night, we checked the power and found the battery had dropped to 11.6 overnight!

We recharged, disconnected the battery and checked it over a few days. It held a charge of 13v unconnected.

Reconnected and overnight it again dropped to 11.9 with all electrics shut down.

What could be causing this sudden drain which wasn’t happening with the old battery?
 
As it only does it when connected there must be something connected that is draining it. Keep doing that and you will need another new battery.
Do you have tank heaters that are turned on?
If you have a multimeter connect it in series with the battery on the 10 amp range and see what current is being drawn.

Where abouts are you in Sussex, I'm in Lancing and have a Clamp meter, so you can check current without disconnecting.
 
Hi Lenny,
We’re in Henfield.

We do have tank heaters, but don’t think they’re working. They also wouldn’t work if everything shutdown with black button would they?

I’m off out to buy a multimeter as we’ve been checking with the van display.
Not sure what you mean by connecting in series with 10amp range will look into it..

Thanks
 
Seems you have something else that killed your old battery not necessarily anything you did.
 
It’s seems strange that it would suddenly start draining when it wasn’t before.

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Hi Lenny,
We’re in Henfield.

We do have tank heaters, but don’t think they’re working. They also wouldn’t work if everything shutdown with black button would they?

I’m off out to buy a multimeter as we’ve been checking with the van display.
Not sure what you mean by connecting in series with 10amp range will look into it..

Thanks

You’ve had a very good offer of Lenny coming round to sort it for you, he doesn’t live far and my advice would be to give him a nice bottle of wine and that’ll save you ten times over….

Give him a shout…. He is a nice man and very good at electrics …..
 
Thanks will do.
In B&Q at present getting a multimeter!
Will look at how to message him once home again.
 
We do have tank heaters, but don’t think they’re working. They also wouldn’t work if everything shutdown with black button would they?
Quite normal for items like heating & tank heater circuits to remain live with the panel turned off.
 
The clamp meter on offer from Lenny HB is a cut above the standard multimeter and means you do not have to disconnect one of the battery leads to put the multimeter in series. It 'clamps' its jaws to form a circle around the cable and by inductance accurately tells you how much current is flowing without touching any terminals or bare wires. Something like RS Clamp meter. In my opinion its well worth taking up the offer as I suspect by the question from you about series connection you have little understanding of electrical theory. Even with the correct tools you need a little understanding to use them and correctly interpret the results.
 
The clamp meter on offer from Lenny HB is a cut above the standard multimeter and means you do not have to disconnect one of the battery leads to put the multimeter in series. It 'clamps' its jaws to form a circle around the cable and by inductance accurately tells you how much current is flowing without touching any terminals or bare wires. Something like RS Clamp meter. In my opinion its well worth taking up the offer as I suspect by the question from you about series connection you have little understanding of electrical theory. Even with the correct tools you need a little understanding to use them and correctly interpret the results.
He has, poping up there on Monday.
 
I’ve made contact with Lenny.
Meanwhile I shall have a good hunt through the van looking for any possible draws on the power.
And try and work out this multimeter I’ve bought! meanders You are correct I am clueless! But willing to learn…
 
I have liked it not because you say you are clueless but because you are taking up Lenny's offer. . Everyone has to start somewhere, but even 12v electrics can be dangerous and cause fires for example.
 
I’ve made contact with Lenny.
Meanwhile I shall have a good hunt through the van looking for any possible draws on the power.
And try and work out this multimeter I’ve bought! meanders You are correct I am clueless! But willing to learn…

Better think of anything else that your not sure about and make the most of him..😆

You did know that I’m Lenny’s agent and I need my cut….😉😎
 
Bimble solar do a nice reasonably priced clamp meter, test dc and ac, resolution down to 1mv, and 10ma on the clamp.

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And try and work out this multimeter I’ve bought! @meanders You are correct I am clueless! But willing to learn…
If you've not used a multimeter before then measuring amps in the 10A range is not the best way to start learning. You need to first learn how to measure voltage - that's easy and unlikely to cause any problems. Then learn how to measure resistance and do 'continuity' checks.

Measuring milliamps or amps means disconnecting the circuit, putting the meter into into the circuit with the red and black probes, and allowing the amps to flow through the meter. Also to use the 10A range you probably have to pull the red probe cable from the 'V' meter socket and plug it into the '10A' socket.

You can avoid all that complication by using a clamp meter, which clips around the wire and measures by sensing the magnetic field generated by the amps in the wire. No disconnection or electrical connection required.
 
If you've not used a multimeter before then measuring amps in the 10A range is not the best way to start learning. You need to first learn how to measure voltage - that's easy and unlikely to cause any problems. Then learn how to measure resistance and do 'continuity' checks.

Measuring milliamps or amps means disconnecting the circuit, putting the meter into into the circuit with the red and black probes, and allowing the amps to flow through the meter. Also to use the 10A range you probably have to pull the red probe cable from the 'V' meter socket and plug it into the '10A' socket.

You can avoid all that complication by using a clamp meter, which clips around the wire and measures by sensing the magnetic field generated by the amps in the wire. No disconnection or electrical connection required.
I'm popping up there on Monday with my clamp meter.
 
Hi Lenny,
We’re in Henfield.

We do have tank heaters, but don’t think they’re working. They also wouldn’t work if everything shutdown with black button would they?

I’m off out to buy a multimeter as we’ve been checking with the van display.
Not sure what you mean by connecting in series with 10amp range will look into it..

Thanks
I think 🤔 it's possible that the tank heaters might very well work even with main control switched off, just like the boiler frost valve and electric step does so you do need to check, but as Lenny says there is definitely something taking power and to drain the battery overnight it's something that's taking a heavy current. 😉
 
If you've not used a multimeter before then measuring amps in the 10A range is not the best way to start learning. You need to first learn how to measure voltage - that's easy and unlikely to cause any problems. Then learn how to measure resistance and do 'continuity' checks.

Measuring milliamps or amps means disconnecting the circuit, putting the meter into into the circuit with the red and black probes, and allowing the amps to flow through the meter. Also to use the 10A range you probably have to pull the red probe cable from the 'V' meter socket and plug it into the '10A' socket.

You can avoid all that complication by using a clamp meter, which clips around the wire and measures by sensing the magnetic field generated by the amps in the wire. No disconnection or electrical connection required.
Could I ask that the excellent "Motorhome Tips and Tricks" does a feature on the use of a multimeter and its different functions, with some practical examples please. I for one would find it very useful.

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Our electric step doesn’t work when the system is shut down.
And I don’t think our tank heater is working at the moment (light doesn’t come on) it’s booked into the workshop to be sorted in April along with a few lights that aren’t working.
But I agree whatever it is it’s taking a heavy current to drain overnight!
 
Could I ask that the excellent "Motorhome Tips and Tricks" does a feature on the use of a multimeter and its different functions, with some practical examples please. I for one would find it very useful.
That would be very useful!
 
Another thing to be aware of if measuring current in series, is if the current being drawn exceeds the range of the multimeter it will blow the internal fuse of the multimeter if it has one, or fry the circuit board if it doesn't. Always better to use a clamp meter for measuring current in my opinion, the ones made by UNI-T are reliable and reasonably priced.
 
Electrics can be very complicated, when I had a Bongo I found it with bothe the starter and leisure batteries flat, never did find the fault, traced it to a relay sticking and not switching off when the key was removed, this then powered up the split charge relay and some of the vehicle too including the heater fan, but I was not able to find which relay was at fault when one stays live it powers up other relays and electricity flows in both directions along a wire.
I just checked everything had shut down every time I turned the key off and if not gave it another go until it did

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