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bad battery drain.


tom1946

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Hello folks, been a while through illness, hope your'e all well.

 

Ever since I bought my Motorhome almost 3 years ago (It's a 2002 Peugeot Boxer Starfire 1.9 Diseasal) I have had a problem with the car battery going flat after a few days, I thought I'd left something switched on but I haven't.

 

What I did each time we got home I had to disconnect the earth until we went out again. Which is not very convenient, so I called an auto electrician out and he connected an ammeter across the negative battery terminal and there is absolutely no discharge at all.

 

So there are two of us stumped here and I wondered if anyone on here might have a clue as to what's going on??

 

As we plan to go 'off grid' this summer this is going to become a big problem even when switched over to the habitat battery.

 

The Van battery is an almost new Lucas 95 a/hour.

 

Please help!

 

Tom.

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Could there be something like an alarm or tracker fitted which only turns on some time after reconnecting the battery so it does not show up immediately when inserting the ammeter? Try leaving the ammeter connected for a few hours and go and look at it every half hour or so.

 

Keith.

 

PS When you say "there is absolutely no discharge..." what discharge did the meter show?

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It's not showing a discharge, he said there is nothing that would completely discharge a big battery like that in two and a half days. We tried switching a few items on and off to make sure his machine was ok and it responded as it should.

 

No alarm or tracker fitted and it's a 2002 vehicle so nothing fancy electronically. It's a puzzle alright.

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tom1946 - 2019-03-06 11:56 AM

 

It's not showing a discharge, he said there is nothing that would completely discharge a big battery like that in two and a half days. We tried switching a few items on and off to make sure his machine was ok and it responded as it should.

 

No alarm or tracker fitted and it's a 2002 vehicle so nothing fancy electronically. It's a puzzle alright.

 

Tom,

 

What was the resolution of his ammeter? ie what was the smallest current it could measure, Amps or MilliAmps?

 

If it could only measure down to say 1 Amp then it would be missing the potential problem.

A 1 Amp discharge for two and a half days would be a 60 Ah (Amp Hour) discharge and would likely result in the problem you have.

Hence why I asked EXACTLY what was the discharge from the battery?

 

Keith.

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Hi Keith,

 

I couldn't see his meter properly while he was doing it so I don't really know. All he said initially was that the needle wasn't moving. I've just ordered a 'clammeter' that clips over any cable to see if that shows up anything, it was about £50 and does DC current down to milliamps so I'll try that when it gets here.

Thanks.

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This is most definitely a case for Poriot, and there appears to be some uncertainty over the accuracy of the diagnostics, but failing that and clutching at straws . . .

 

I’m assuming that the your auto electrician did his tests during the day so firstly, do you have dual charge solar fitted? I’m wondering if a faulty solar controller might cause a night time discharge?

 

Secondly, are you confident that there is nothing within your habitation area that is powered by the starter battery? I’m thinking maybe something that switches on when the temp or light levels drop?

 

The only other variable I guess is that the discharge tests would, I suspect, have been done with the bonnet open. Any possibility that closing the bonnet is causing a short somewhere? It could be as simple as causing some cable to flex. Easy to test, if the two items above have definitely been discounted then leave the bonnet open overnight and see if the starter battery discharges.

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tom1946 - 2019-03-06 12:50 PM

 

Hi Keith,

 

I couldn't see his meter properly while he was doing it so I don't really know. All he said initially was that the needle wasn't moving. I've just ordered a 'clammeter' that clips over any cable to see if that shows up anything, it was about £50 and does DC current down to milliamps so I'll try that when it gets here.

Thanks.

 

Tom, as others have said, you should see SOME current even with nothing switched on.

Although you would assume that the autoelectrician would know what he is doing, even experts make basic mistakes sometimes.

 

Common mistakes are -

Having the probes in voltage measuring sockets when trying to read current.

Trying to read DC current while set to AC current.

Faulty probes or blow meter fuse. When first connecting up, there is often a high surge current until the ECUs etc. settle down. This can be enough to blow the meter fuse (depends on meter)

If the meter really has a "needle" (haven't seen one of those for many years - was it an AVO8? :-D ) you could have the meter leads the wrong way around!.

 

I always do a "sanity check" when measuring anything (i.e do you get an increase if you switch something on?)

 

A DC clamp will be useful.

 

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Hi, forgive me but I havent completely understood what testing has been done.

you refer to "car battery"and "earth", so I have to confirm that you mean habitation battery, and negative connection respectively.

 

what is the state of the engine battery..ie does the engine start up,.

what are readings of voltage across the habitation battery terminals when the negative connection is disconnected from the battery. Ie is the battery holding a charge when no load is connected.

Have you checked each cell to see if there is any acid in the battery..

Measure the terminal voltage from habitation battery positive terminal to the vehicle chassis with negative terminal disconnected.should be no reading, but iff there is, then there is a sneak path somewhere, .

 

set your meter to measure current, and with negative lead disconnected from battery, measure any current flowing from battery negative to nearest. chassis earth point. With nothing switched on in the van, the only current flowing could be via alarm system if fitted, but I would expect alarm would normally be connected to starter battery system. If current is flowing, then check that ALL habitation equipment, lights, pump, water heater, radio or tv are all switched off. If current is still flowing, the look into fuse panel

and withdraw all fuses one at a time to isolate which circuit is responsible for current flow.

 

This should enable you to trace fault, if there is one. If you have a solar panel, pull out its fuse as well, to see if it loading battery instead of charging.

 

hope this might help

tonyg3nwl

 

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aandncaravan - 2019-03-06 11:18 AM

 

If he found zero discharge he was doing something wrong as there is always some discharge, like from from the Fiat body module ECU, etc?

 

 

 

 

One of the issues with some Auto Sparky's is that they are used to working on vehicles that get used every day. If they are not familiar with motorhome usage, i.e. it standing idle for weeks at a time, they won't be looking for the minuscule currents involved

 

We have been talking to a couple of owners recently about the issue of the Starter battery running flat.

 

One has very timely had his motorhome back from a Peugeot agent testing for drain on the Starter battery.and emailed the outcome at 13:21 today.

 

He writes,

"Hi Allan, Update for you.

Not got much further as they charged me an arm and leg and wanted to investigate more.............

 

Report was:

 

Investigated battery drain.

Installed AMP meter found drain of 0.20 amps removed F39 and drain dropped to 0.07amps. Found a 2a fuse for the tracker. Removed fuse and amps dropped further to 0.03 amps. Removed fuses leaving van to see if battery goes flat. Tested next morning battery okay. Refitted interior for customer to take away. Found dash lights illuminating. New dash pod required possibly causing battery drain.

 

Just spoken to the dealer again and they are going to do the dash POD under warranty but said they suspect that the tracker is to blame on this one?

Thoughts?

D."

 

 

A 0.2amp drain is effectively 4.8amps per day, or 48Ah (more than half most Starter batteries) in 10 days.

 

So you don't need much drain to make a big impact. I am guessing the Sparky was looking for amps, rather than milliamps?

 

You can see that even if the battery was perfect and was still able to deliver 100% capacity, days are all the battery will last without regular boost charging.

 

 

I think the dash lights glowing faintly are a red herring, although maybe account for up to 50% of the 0.2 amps depending on their brightness?

 

 

 

Tom, I hope your new meter shows some current draw, and you are able to identify the origin.

 

 

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tom1946 - 2019-03-06 10:26 AM

. . . I have had a problem with the car battery going flat after a few days . . .

 

Tom.

 

Alan’s post got me thinking, out of interest, what do you precisely mean by “a few days”.

 

Do you means 48hrs, or 7 days or 10 days?

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Wow, so much to respond to, thanks very much.

 

The leccy guy had what looks like a 60's grey box with a large voltmeter & and a large ammeter built into the top. All he did was to take off the negative from the van battery under the bonnet and connect his meter in between. I wasn't able to see clearly, I just assumed he knew what he was doing. Hence I've ordered this clamp meter to check myself.

 

I don't have any solar equipment so can rule that out. The habitation battery is always fully charged when I switch over and test it on the main panel.

 

He may have looked at volts instead of amps, I don't know. Let's wait and see what the new machine tells us, it should be here tomorrow, then I'll report back.

 

Thanks, Tom.

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If you don't get a handle on the battery drain, some of the early 2000 model Fiats had an issue with the body computer taking excess power, which can be a lot of money to fix, then this device makes isolating the Starter battery very quick and easy :

https://www.ebay.co.uk/p/Heavy-Duty-Battery-Disconnect-Isolator-Cut-off-Switch-12v-24v/14026959592?iid=172096775398

 

Fits on the Negative Pole, they only cost about £4, great anti theft device.

 

Just unscrew the Green wheel and remove it, just screw it back on to reconnect the battery.

1392675604_BatteryClamp3.JPG.aee8c8ac32dbcb5a0b55b250bd720d5e.JPG

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Hiya, back again.

Just received my new clamp meter so I put the clamp around the negative battery cable with the following results:

Using the up to 20 amp range it reads 00.21, it started out higher but each time I 'tried again' it dropped from .37 to .21 ?

 

Tried using the up to 2 amp range I got 0.162

I don't know what to think, it sounds to me about .2 of an amp?

 

I'm no electrician but that doesn't sound like anything like enough to flatten a big battery in 2 days.

 

Any thoughts?

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You haven’t provided details of the clamp meter you’ve purchased, but if you browse the internet for such devices you’ll find that their accuracy varies and (unsurprisingly) the cheaper meters tend to be the least accurate. As the ‘battery drain’ that you have asked about may be relatively low - though still plenty adequate to significantly discharge your motorhome’s starter-battery over a few days - the accuracy of any measurement device used becomes important.

 

Personally, in your position, I would not have used a clamp meter. As you’ve been habitually disconnecting the starter-battery since you bought the motorhome to avoid the battery going flat, I would have just used a common-or-garden good quality multimeter to take ‘amps’ readings.

 

It’s stating the obvious, but if the starter-battery is fully charged and (having been disconnected) is still well-charged after 2 months, but ‘self discharges’ badly over a few days if left connected, then, in the latter case, charge MUST be being lost. After confirming by taking a voltage reading that the battery’s state of charge (SOC) is ‘full’, if the battery were then left connected and voltage readings taken (say) every 24 hours, you should get a reasonable idea of how rapidly the SOC was declining.

 

There’s a fair amount of on-line discussion about this type of problem

 

https://tinyurl.com/y2yoy8rz

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Tom, as we noted above for for Dave Brown's issues,

"a 0.2amp drain is effectively 4.8amps per day, or 48Ah (that is more than half of most Starter batteries capacity) in 10 days".

 

48Ah out of a 90Ah Starter battery is an awful lot of power, I would guess that after 5 days a battery that wasn't perfect is going to struggle to start an engine let alone one left for 10 days.

 

 

Have you 'mapped' the battery voltage over a few days, for example what does your Starter battery drop to after the first day, second day, third day, etc.?

 

 

Now that we know the draw, the information on the battery discharge should give the other half of the puzzle.

 

 

I guess it is also possible that you have some other issue that limits the current going to the Starter battery, like a poor Earth, which only becomes apparent when the battery loses some of it's capacity.

We therefore need to know what the real battery voltage is when you describe it as flat?

 

 

Edit :

Sorry Derek, I must have been typing mine while you were typing yours, agree with all you say.

 

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The meter I used is this one:

 

https://www.ebay.co.uk/itm/72-2985-100a-True-Rms-Mini-Ac-dc-Digital-Clamp-Meter/143109450991?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

I think the main problem is that it is losing charge when connected. I now need to find out where it's coming from, someone mentioned that it may be the ECU, if that's the case why don't the batteries of our 3 cars go flat if they come on periodically?

 

I think I need to start disconnecting some items like the DAB radio etc' etc' and see if it is any of the accessories.

 

I'll let you know if I find it.

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If my reading of all this is correct then the battery is ‘flat’ after being connected for 48hrs.

 

Out of interest, when this happens (as per the last recent discharge) how did you go about getting it back to a full charge? I’m just wondering how fully charged your battery is before you connect it.

 

That aside, then if my reading of what Tom wrote is correct, then the battery is ‘flat’ after being connected for 48hrs. So presumably we’d be expecting to see the meter show a connected discharge of about 2+ amps.

 

Something definitely doesn’t add up.

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Tom,

I bought a similar DC clamp and find it very useful. I also have a high accuracy 6 1/2 digit bench meter that I checked it against and I found it surprisingly accurate for its cost. When zero'd correctly, it gives better than 10mA (0.01A) accuracy for the range of currents you are trying to measure. You also have to make sure that the jaws are fully closed.

 

On my starter battery, there is a fat braided earth cable and another 3 smaller wires attached to the negative terminal clamp. If yours is similar, you need to measure the current in all of these wires to get the true battery drain current (in addition to the main earth cable). As it is not easy to get all wires through the clamp at the same time, I would need to measure each wire in turn and then add up all the readings to get the total current.

 

Are you sure that the current doesn't change from when you measured it? (for example, is the heater on at night? does it increase when the alarm is set? etc.)

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I agree with Tom's commnets above, we've all been concentrating on discharge current with no mention of battery voltage.

 

Tom,

 

What is the make and specification of the starter battery, and how old is it?

 

And next, what is it's resting voltage before you leave it connected and voltage after 48 hours left connected?

 

Keith.

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BruceM - 2019-03-08 4:05 PM

 

If my reading of all this is correct then the battery is ‘flat’ after being connected for 48hrs.

 

Out of interest, when this happens (as per the last recent discharge) how did you go about getting it back to a full charge? I’m just wondering how fully charged your battery is before you connect it.

 

That aside, then if my reading of what Tom wrote is correct, then the battery is ‘flat’ after being connected for 48hrs. So presumably we’d be expecting to see the meter show a connected discharge of about 2+ amps.

 

Something definitely doesn’t add up.

 

Bruce, in his first post Tom talks of "going flat in a few days", which is more the 2 and could easily be 7. Confirmation of that exact time via battery SOC monitoring over days would be useful.

 

We also don't know what "flat" is. Is it 11.8v or is it a term used because it won't start the engine?

Just because a battery won't start the motor doesn't mean it is fully depleted, we already know from threads on here that other factors can impact a batteries ability to start an engine, even a battery that is 'Full'.

 

Without a map of the degrading battery voltages, from beginning of test SOC to 'discharged' SOC, there is too much missing information, IMO, to make even a guess at what is going on.

 

 

Edit after seeing the below reply :

If the battery is a Lucas and 18 months old, then I would be surprised if it has anywhere near full capacity, I would guess nearer 75%??

 

 

 

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Ok, battery is a Lucas 95a/h jobby, 18 months old.

 

I need to do more tests, clearly. I'll have to wait until the weather gets a bit warmer, my digital extremities don't function too well in the cold. I'll report back when I have some stable figures to report over the next few days and check out the earths too.

 

Speak soon.

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