Battery Problems

[Ade B]

Wondering if someone could offer some sage advice for fixing my '91 300CE 24V.

Tried to fire it up last week and it wouldn't turn over but all the idiot lights came on, presenters kicked in, seats adjusted etc.. Next morning it was totally dead which suggests something is draining it.

Fired up the car with a remote battery and ran it for a bit to get some charge back in. My dad measured 30A going back into the battery which then dropped to 6A after 20 mins which he reckons shows the alternator is putting the charge back and the battery is in ok shape..

Ran the car fine for a couple of days (albeit on short journeys) and then yesterday found it dead again..

After charging it overnight with a weedy optimate (0.6 a/h), the battery is showing 11.17V which seems low and having gone through the fuses with a meter I'm registering a 0.06A current through fuse C which protects the following:

rear roof light, trunk light, rear door locking system, safety belt handover arm, seat back arrester, (central locking system, door lights, reading lamps, aut. antenna, control unit seat adjustment).

When I took the fuse out to measure the current there is a click from the black box behind the fuse box (anyone know what this relay is? - bloody Haynes won't tell me...)

So...

Is a 0.06A drain enough to knack a battery over a period of days - it doesn't seem much?

All the electrical bits work as normal (except the passenger head rest), how do I trace the offending component?

Are there any other fuses I can check elsewhere?

Or is it a simple case of replacement battery required (it is behaving exactly as my R1100S did when its battery was kaput).


BTW, there is a scorpion alarm fitted but I switched it off ages ago, could this be the culprit?

The car has been running perfectly until this, typically it starts to act up the week before I plan to go away in it.

 

[IBIZA]

0.06A is less than half the current drawn by a single dashboard light, and could be something like your clock even (although a little high for that).

My guess would be a new battery.

The easiest way to check is - give it a decent run to charge it - then swap it with your dads.

If you are a nice guy, you can even tell him you swapped it

 

[BTB 500]

After charging it overnight with a weedy optimate (0.6 a/h), the battery is showing 11.17V which seems low

11.17V means completely knackered. A 12V lead/acid battery is fully discharged at 11.9V.

New battery time.

 

[television]

I would think that the battery has a faulty cell that can go high resistance after a stand of a couple of days. Cells can and do go parcial short circuit giveng the same result.

The voltage is down anyway at 11,75 volt, it should be 12.5

My V70R did the same thing two years back, once started or battery charged it was fine for the time it was being used, but left for 2 days and dead.

Your car has no known faults for this and there are no wake up circuits on the car.
Do not buy a house brand, make sure it is a Varta,Bosch,Exide,Banner,Lucas, and not a Halfords special, they are useless. Cosco or a motor factor are the best

 

[Ade B]

Cheers for the replies, I'll leave the optimate on for longer as it delivers such a slow charge to see if it picks up at all.. at least enough to get keep me going.

Will get a new battery.

My dad was down for the weekend to help us do the kitchen and is now back up north... he's a retired electrical engineer and has all sorts of gadgets for measuring electrical stuff, he brought down a spare battery pack and a hall effect type ammeter - unfortunately he took both back.. which also means I can't nick his battery..

Ade.

 

[Ade B]

BOSCH BATTERY TYPE 075 60Ah 360/640 242Lx175Wx175H 0/1 B13
BOSCH - 075

From Euro Car Parts - £56.

Anygood. The current MB branded battery is 100Ah and doesn't fit in the tray.... will this be an issue?

Ade

 

[IBIZA]

I would guess the standard one is the Bosch 1AN which is probably the longer 355mm size - heights and widths are normally 175 or 190mm.

In the past I have found Costco and Makro can often even beat wholesalers for batteries. Costco only do Bosch (who have their own numbering system, with the first number being the first number in the Ah value. 1 = 100Ah+, 9 = 90-99Ah etc)

100Ah/60Ah is the amount of power stored in the battery - so your 075 battery would power your present 0.06A current loss for 1000 hours. What you might be better looking at is the CCA(SAE) figure which is is the amount of current a battery can provide at 0 °F (−18 °C). The rating is the amperage a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). So try to get one with a CCA value the same or higher than your present one, as diesels and cars with over 4 cylinders take more effort to start.

Lastly - as a suggestion, its always worth while having an extra battery from a breaker that you can use as a back up and put in when you may have an electical fault which might save you frying a new battery.

 

[Ade B]

Update...

Well I bought a new battery (Varta) and all was well for a bit, then this too started to play up.. going flat within 2 days..

This afternoon poking around with multimeter in the fuse box, traced the cuprit to boot light.. Its not switching off (I know as I closed myself in - luckily my wife decided to let me out )

The switch works when you close it by hand, but appears not to shut off when the boot shuts.

Can this be adjusted or has something fallen off?

Ade

 

[television]

Mark where the switch plunger hits the rear part of the boot, if there is nothing there to adjust, then glue something on that point about 4mm thick, any bit of plastic will do, a self adhesive sticky chair leg pad will do.

Sorry about the battery, though with the winter coming on, not a bad thing to have.

I am pleased that you can trust your wife

 

[KillerHERTZ]

By the looks of it, thats sticking too far out.

You can turn the bootlight off by pulling them out normally, that looks like the switch mech has been damaged perhaps?

 

[Ade B]

Sorry about the battery, though with the winter coming on, not a bad thing to have.

Not to worry, I bought another halfords job as a spare as well and have been rotating them for the last month

The current draw was 0.6A not 0.06 as originally stated..

Will stick a block to the boot sill - boot light is currently disconnected hopefully that'll be the end of it.

Most irritating thing was my Dad guessed the boot light was the culprit first time round and I decided that as the switch worked it couldn't be the case.. Took climbing in to confirm it..

I guess parents know best...

Ade

 

[Ade B]

By the looks of it, thats sticking too far out.

You can turn the bootlight off by pulling them out normally, that looks like the switch mech has been damaged perhaps?

the switch looks ok and functions smoothly, the grey bit has flat surfaces on which look like they can be used to grip to adjust the length - I couldn't do it by hand so I thought I'd check here before I tried the molegrips

When I lay in the back I could see its missing the cill plate by a bit - checked the alignment of the boot lid which looks ok, which made me wonder whether there was a rubber foot or similar which has fallen off...

You can see a wear mark on the cill where the switch used to contact.. most peculiar..

Ade

 

[recycled]

can you just not take out the bulb?. it may probably give out a bulb failure light inside

 

[Ade B]

boot light is currently disconnected

temporary fix..

Ade