Non-boaty car battery question.

[jwilson]

Two months ago my Volvo was driven 200+ miles and parked overnight. Next morning (and nothing left on) battery dead as doornail. Green Flag put meter on and got about 4 volts, then had to put TWO jump-packs on to get it started - it was a big battery. Recovery mechanic said ".... batteries these days just sometimes do this - die completely very fast." Once started didn't turn off till parked at a battery/tyre place that definitely had the right battery to swap.

 

[lw395]

I don’t know. My dad used to have a garage and one of the mechanics used a plug in cigarette charger to maintain voltage when battery disconnected

That doesn't work on my car, the poxy lighter socket turns off with the ignition.

Most car dealers seem to let batteries go flat and then jump start using a Li-Ion battery pack these days?

Some people connect a second battery to the jump start connections while changing a battery, it avoids recoding the radio and allows lcoking/unlocking the car.

 

[PaulRainbow]

Do you know of any verified cases of an ECU being damaged by removing power? Which vehicles?

Yes. Peugeots are notorious for damaging BCM which will need replaced or/and initialised. Some cars will loose immobilizer. It's not recommended, you might get away with it, but it's not worth the risk, it could cost £100s to fix.

I personally had a Peugeot that completely crashed the BSI. Couldn't start the engine, lock the doors, turn the lights on etc etc. Luckily, i knew someone that was able to re-install the software on-site, otherwise, big bills.

Disconnecting batteries can also cause issues with things like ABS, air bags, traction control etc. More often than not, these systems will detect the battery removal as a problem and shut all of those systems down, illuminating an array of failure lamps on the dash. Hopefully they'll all go out after you drive the car a short distance, allowing all of the sensors and ECUs to sort themselves out. If not, it's a trip to a dealer for a diagnostic reset.

It's common practice when removing batteries from modern cars to keep some power supplied to the systems, often by a small battery connected via the cig lighter socket or via the diagnostics port.

 

[PaulRainbow]

That doesn't work on my car, the poxy lighter socket turns off with the ignition.

Leave the ignition switch in the on position. Or use the diagnostic port.

Most car dealers seem to let batteries go flat and then jump start using a Li-Ion battery pack these days?

Some people connect a second battery to the jump start connections while changing a battery, it avoids recoding the radio and allows lcoking/unlocking the car.

Most modern cars (10 - 15 years old) have the onboard entertainment system coded to the ECU, so no need to enter any codes.

 

[vyv_cox]

When I leave my car for extended periods I leave the bonnet unlatched so that I can charge the battery if needed. If the battery was completely dead the doors would be locked and no possibility of opening the bonnet.

 

[VicS]

When I leave my car for extended periods I leave the bonnet unlatched so that I can charge the battery if needed. If the battery was completely dead the doors would be locked and no possibility of opening the bonnet.

I can unlock the passenger side door with the key. It would be very useful if it was the drivers side 'cos would then be able to get in without unlocking both plus tailgate. French car I suppose. Most things French seen to be cack handed

 

[dom]

Leaving the battery to go flat, not using the car for a month is not a warranty issue, it's self inflicted.

Dear oh dear, you do come out with some nonsense at times.

Is that nonsense? It could save the OP £20-40 on wasted carriage.

Improper usage, sulphation, inappropriately deep cycling, over-charging, under-charging, etc., are routinely excluded from warranties. In practice, all that is covered are short circuits, faulty cells, internal disconnects, and other manufacturing problems. This is consistent with the Consumer Rights Act.

And most suppliers charge carriage for returns, only refundable if claim is accepted.

 

[PaulRainbow]

Is that nonsense?

I think it's nonsense to say that "Leaving the battery to go flat, not using the car for a month is not a warranty issue, it's self inflicted."

A good battery should not go flat and be beyond charging just because the car was not used for a month.

 

[dom]

Hoping the warrantied battery will make a full recovery, but I am mystified how it can go from starting the car fine to reading such a low voltage in what seems like three weeks. I'm sure no lights were left on or whatever.

I think it's nonsense to say that "Leaving the battery to go flat, not using the car for a month is not a warranty issue, it's self inflicted."

A good battery should not go flat and be beyond charging just because the car was not used for a month.

Okay, I see the problem; there is really no such thing as a "good battery" and one must always purchase the correct battery for an intended application. In this case, that spec will have included neither deep cycling, nor being left entirely discharged for such a period.

We don't even know that the battery was fully charged at the start of the month, only that it was "starting the car fine". A few weeks later, for reasons unbeknownst to us, the battery was completely flat.

So in this case lw395 is - sadly for the OP - almost certainly right. It seems overwhelmingly likely that any consequent claim will be rejected unless a manufacturing defect is found.

 

[KellysEye]

You might consider the latest CCA battery a Calcium one. A calcium battery is a lead acid battery with no antimony in its grids. Instead, a calcium component (around 1%) is added to both the positive and negative plates. This works to reduce water loss through gassing in the battery and allows the battery container to be fully sealed and maintenance-free.. Halfords sell them and check for other retailers.

 

[lw395]

I think it's nonsense to say that "Leaving the battery to go flat, not using the car for a month is not a warranty issue, it's self inflicted."

A good battery should not go flat and be beyond charging just because the car was not used for a month.

Unfortunately, the issue is that the car AIUI, hasn't really been used for 3 months.
In that time the background loads on the battery will often flatten it.
A few minutes charging a couple of months in doesn't really do enough.
It's 2000 hours times whatever the ecu, remote lock receiver, immobiliser, radio etc. draw.

That's why the owner's handbook for my car advises removing the battery if it's not going to be used for a long time.
They don't mention the inconvenient detail of needing to leave the boot open, I guess they assume it will be in a nice dry, secure garage?

By the way, some years ago, I had a Peugeot. When the exhaust blew, it upset the calibration of the fuel injection, air getting to the lambda sensor I expect. The way to reset the ecu was to disconnect the battery for a minimum of 15 minutes. ISTR those cars were randomly fitted with electronics from Bosch, Marelli and some French brand which I forget. That's kind of a previous generation of cars to the OP's though.

 

[PaulRainbow]

Unfortunately, the issue is that the car AIUI, hasn't really been used for 3 months.
In that time the background loads on the battery will often flatten it.

Your original comment was posted on the basis that the battery had been left for one month, as per the original post. My comment related to that. It wasn't until later the OP suggested it hadn't been used for 3 months.

I used to own a used car dealership, i can assure you that cars were left standing for longer than three months, with batteries of varying vintage. Rarely did one go flat in a few months and if it did, it was usually knackered and we replaced it.

The battery is less than a year old and is likely a decent make, it has a 5yr warranty, if it went flat from normal discharge it will almost certainly charge back up again. If it won't it's a rubbish battery and should be replaced under warranty.

 

[PaulRainbow]

By the way, some years ago, I had a Peugeot. When the exhaust blew, it upset the calibration of the fuel injection, air getting to the lambda sensor I expect. The way to reset the ecu was to disconnect the battery for a minimum of 15 minutes. ISTR those cars were randomly fitted with electronics from Bosch, Marelli and some French brand which I forget. That's kind of a previous generation of cars to the OP's though.

If it was one of the models affected by BSI failures when the battery was disconnected, there was a particular procedure to follow to prevent the BSi crashing (hopefully). Fact is, it's not good practice to randomly disconnect batteries, unless you know your car will be unaffected by doing so.

 

[lw395]

Your original comment was posted on the basis that the battery had been left for one month, as per the original post. My comment related to that. It wasn't until later the OP suggested it hadn't been used for 3 months.

I used to own a used car dealership, i can assure you that cars were left standing for longer than three months, with batteries of varying vintage. Rarely did one go flat in a few months and if it did, it was usually knackered and we replaced it.

The battery is less than a year old and is likely a decent make, it has a 5yr warranty, if it went flat from normal discharge it will almost certainly charge back up again. If it won't it's a rubbish battery and should be replaced under warranty.

I guessed from the OP that 'travels' implied more than a month.
I wouldn't be surprised if the OP got a new battery for free, the retailers can probably afford it, but the simple physics is probably 2000 hours of >25mA beats 50Ah or whatever.

 

[FairweatherDave]

Lots of good tips for leaving a car here, plus more electrical debate as expected. The good news is the car got through its MOT and the car started no worries after a reconditioning charge over night. Long term health of the battery, and why it discharged (or if it discharges again) we shall see. I never needed plan B, the Yaris battery. No adverse effects from disconnecting the VW Fox battery (but I haven't tried the radio yet ).

 

[FairweatherDave]

Note. In the good old days I would have used the car while she was away, but parking permit schemes and not having a driveway make that impossible. I'll be glad to get rid of her car out of the front garden and reinstate the Wayfarer in its rightful place. Much more attractive!

 

[Oletimer]

I bought a little solar panel that I sit on the dashboard and plug into an 'always on' power outlet (I have an old Fiat Multipla that has 3 power outlets built in as standard) it doesn't matter how long I leave it the battery gets sufficient charge to keep it useable. I think the panel cast about £20 from ebay, never let me down in the last 2 years.

 

[Iliade]

My 2007 VW T5 would flatten its battery in about a fortnight to a level below which it was capable of starting the engine. It did this without fail every year when I went on a month long work trip abroad until I bought a float charger. Nothing wrong with the battery, it was just that the alarm was quite power hungry. Switching off the ultrasonic sensor helped, but invariably someone would open it for something or other, lock it again and the sensor would default to on. Our current T5.1 is better, but still imperfect.

I bought a cheap car starter battery pack from Halfords and was pleasantly surprised at how we'll it starts a 2l diesel. It regularly does sterling service when I leave the lights on or the doors open (21 * 21w interior lights do get through the battery surprisingly quickly! I recently changed most to LEDS which helped.)

My BWM motorbike has similar issues and will run the battery down unless it is plugged into one of those motorbike battery maintenance chargers (~£20 from eBay.)

My '05 Ducato based motorhome has an aftermarket alarm and will flatten the battery in a fortnight or so. That has no sophisticated radio so I just fitted a clip on type of battery terminal and disconnect it when I leave it. Problem solved and thankfully the ECU has yet to complain. It gets used monthly or so.

I originally tried one of the Sealey solar 'trickle chargers' but that didn't seem to put out enough amps to keep the 'dub happy. I then tried it on the boat and it didn't help there either, the battery was dead flat when I came back a few weeks later, so maybe the panel is not perfect. I still have it and it still produces a voltage when measured across the terminals while open circuit but I have not checked to see if it can discharge against the diodes.

All in all, if mains is available, I would recommend the motorbike maintenance chargers and they do come in car sizes. I suspect that a cheap bike one would be fine for a car, but they do give battery sizing info so maybe not officially.

 

[lw395]

^ Wot he said.
I had a BMW bike which would lose enough charge in a week for the ABS lights to flash madly due to the low volts when started.
So I'd have to ride it a mile, stop switch off and restart. But that was 80s/90s technology, old K series 'brick'.

I have a couple of little Ctek chargers for my bikes and RIB. They do a neat adapter with some LEDs built in. When it stops blinking green, it's that bike's turn on the charger.
The 1.2A chargers will charge a car battery, it just takes a long time.
Ctek are not cheap, but IMHO they are the best of these things.
There are some very cheap (£5) alternatives on ebay which don't really work. I've not got around to trying the mid price Chinese offerings.

 

[oldmanofthehills]

I think it's nonsense to say that "Leaving the battery to go flat, not using the car for a month is not a warranty issue, it's self inflicted." A good battery should not go flat and be beyond charging just because the car was not used for a month.

Just returned from Brittany after 4 weeks and newish battery dead as the proverbial. AA man suggested it was the phone charger left on. As he said "diddly squat over 4 weeks mounts up". The Corsa has had several such lapses but usually near home where jump leads available rather than down remote country lanes by moorings. Will remember to unplug charger next time, though it might just be alarm systems etc.

If its beyond charging that's another matter