Battery Draining problem

[Clearancediver]

Check voltage while car is running. Alternator should be putting out 13.5-14.5 volts. If it's less than 13.5 volts it's bad... If it varies when the engine is revved up it's also bad.

If you charge the battery and then go drive the vehicle when the alternator isn't charging the car will run just fine. However it's using the stored battery charge to "fire" the spark plugs. It will run this way for quite some time until the battery voltage drops. The scenario you describe about 5-6 hours later battery being discharged... Do you mean the car won't start/is hard to start..... That also fits into the scenario I described where you've driven the car and later fine the battery discharged.


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[cj10jeeper]

I bought the battery in May last year - but I think that the lack of driving may have hastened it's demise. I have already asked for a replacement through Amazon let's see where it goes. Also it was a Bosch S4 which I now realise have a high failure rate.

What batteries are people using these days?

There's your issue. Don't worry about more complex stuff yet such as alternators, current drains, etc. just yet as they are nothing like as common as the battery just dying.

I suspect you've flattened it more than a few times, which normal batteries cannot survive. Put a meter on it and bet it's low 12's or even in the 11's indicating it's dead.

If you have a replacement on the way fine, but if not drop into a Halfords and they will test it FoC. don't have to buy one from them.

[jampudding]

Ok so this is what I tried today:

1.Battery was dead this morning
2.Jump started it
3. drove it for 40 mins at a steady 70mph (live right off the A3)
4. disconnected the battery and tested the voltage here are the results
11:15 - 12.25v
12:45 - 12.10v
13:55 - 12.07v
14:50 - 12.05v
16:05 - 12.04v
20:55 - 12.01v

Prevously by the last test the car would be completely dead.
So is the battery bad? - it's definitely had too many jump starts.
As the battery was completely dead this morning but now has a charge I assume the alternator is ok?

I have a returns authorisation from eurocarparts via Amazon, this is for a refund which I don't want as the battery is nearly £25 more than when I bought it - I just want a swap.
1. What courier's do people recommend for the return?
2. Has anybody been in this situation and managed to get a swap done at a store? - I don't have the original receipt anymore.

I will try starting it in the morning. I should also have checked the voltage when it was completely dead. Then I will try the test with no loads but the battery connected. Then I will check to see if any internal lights are not turning off. Then I guess the fuse's.

Thanks for all the input so far very helpful.

[cj10jeeper]

You're start voltage after a good drive is still low, however if the alternator wasn't working the battery would have been near flat after a 40 min drive so I'm confident it's the battery.

What I would do however is charge it on a proper charger overnight with leads disconnected and check the voltage. Leave it a few hours and see if it drains in which case it's the battery.

Had it on mine a month ago when left parked it would drop to high 11's after 3 days. Back to 12.x on the 20mile drive from airport to home and then drained again after a weekend. Just swapped the battery out as it had a dead cell and perfect ever since.

[jampudding]

Thanks for that. As the battery is under guarantee/warantee I'll do that first. And worry about the rest later. I'll try halfords on Monday I was too busy today and I assume Halfords is very busy over the weekend.

[Clearancediver]

If you can test the battery with a meter... You can test the alternator. It done by simply testing the battery voltage with the engine running. It's not complex and it should be the first thing you do when you have an issue with a new battery.

If you don't check the alternator voltage output as part of the fault diagnosis you are being... how do you say it.... Ahhh yes..less than smart. I've been working on cars for 45 years and have seen this more than once or twice.

[johnbirt]

I bought the battery in May last year - but I think that the lack of driving may have hastened it's demise. I have already asked for a replacement through Amazon let's see where it goes. Also it was a Bosch S4 which I now realise have a high failure rate.

What batteries are people using these days?

Don't Bosch batteries have a 3(4?) year guarantee? Last one I got for Boxster had. Probably need receipt though.

Thought Bosch had quite a good reputation.

[EdButler]

A Cars battery has the following resting (no current) voltages to denote charge: 12.7V = 100% 12.1V = 50% 11.6V = 0%

Due to the fact the battery is draining fastest at higher voltage, it would suggest it is bad. If the car was draining it, the discharge rate should be linear. You can always check this however, by removing the negative terminal of the battery, and connecting your multimeter leads into the Amperage (e.g. 10A) sockets and connecting the leads to both the negative battery terminal and the cars negative cable. The car would need to be using over 2A for that kind of discharge rate (~35h to fully discharge a battery from full).

My car has recently been rested 4 months and drained a brand new Exide battery to 1.5V! Silly me for not disconnecting it! I hope mine hasn't gone south, the little LED hasn't re-illuminated...

[HAL296]

When my battery went I was told by BMW that the number of short mileage journeys recorded on the computer was not enough to keep battery fully charged.

I only usually do 40 miles a week with 6/8 starts so I bought a small portable Solar Panel Charging unit that plugs into the cig lighter and rests on the dashboard. It has worked fine for over 2 years with the occasional mains battery charger boost in the winter when load on electrics is constantly high.

This may work for you as it saves disconnecting the battery and susequent computer reset if you are leaving your car outside for any reasonable length of time.

[jampudding]

Thanks for all the help. Some very interesting postings.

I exchanged my old battery for a new battery from Eurocarparts. As I had bought my battery through Amazon they had a copy of the invoice and sent it to me so I could exchange it in store. Not sure I would have kept the old invoice for that long.

I have not connected it yet to see if it was the problem but from the various posts I assume it was. It was 10 months old and must have been fully drained easily well over 40 times. I will update when I connect the battery. Although I notice a new M steering wheel up for sale so perhaps leave it disconnected until that is decided!!

[Clearancediver]

Have you installed the battery? Curious to see what was the real problem with the battery drain..... Bad battery ... alternator..or perhaps another issue causing a battery drain.


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[jampudding]

I will put the battery in tomorrow as I need to use the car. I think the long term problem for me is going to be the lack of use of the car. I will be loolking to get one of the solar trickle chargers.
I will be reconnecting the bonnet sensor too. I will then report back

[HAL296]

I will put the battery in tomorrow as I need to use the car. I think the long term problem for me is going to be the lack of use of the car. I will be loolking to get one of the solar trickle chargers.
I will be reconnecting the bonnet sensor too. I will then report back

I bought my Foldup Solar panel from http://www.solartechnology.co.uk and I see the price is still £25 so it's a cheap and easy solution to draining battery from low usage.

[jampudding]

Is this the one you got "Foldup Solar Panel, 12v 4w" and did it connect to the car battery or just into the cigarette lighter? The blurb says you stick it in both.

[HAL296]

Is this the one you got "Foldup Solar Panel, 12v 4w" and did it connect to the car battery or just into the cigarette lighter? The blurb says you stick it in both.

Yes that's the one. You get 2 wired connectors - 1 with claw clips on it for direct battery connection and 1 with standard cig lighter plug in. You can use either not both at the same time.
When plugging in make sure you keep the plug vertical and that the engine is not running as I have had a cig lighter fuse go once when I was a bit rushed to fit the unit.
I would had preferred longer leads as I wanted to put and keep the unit on the back shelf to get maximum sun but the supplier could not supply them - it still works OK as the unit charges even in low light so I just dismantle after use, fold up and store in box in passenger foot well, before I start engine and drive away.