Flat battery in 3 days?

[Rich H]

OK a bit baffled...

The Esprit started and ran fine on Monday and Tuesday, nice wizz over as usual and rapid start to and from work, only short ish journeys ~10 miles each.
Thursday pm no start, one turn over then click click click...

Checked the charge and it's giving 13.8-14V
So put the multimeter in line with the positive lead and I'm getting a 5ma discharge - suspect it's the alarm as pulling fuses made no difference.

OK then reconnected it all then put the volt meter across the battery and got 12v but dis-arming the alarm (Opens the central locking) voltage drops to 9v!

Battery is ~18 months old motoquip thing, it's been allowed to run down a couple of times but most of the time lives on a accumate.
Cells are all full but it just doesn't seem to have any grunt.

Its on the proper charger and I've bought a new one for now.

What can cause a battery to just die? Has the accumate killed it?

ta
Rich

[Rich H]

Been on fast charge for 3 hours now and still looks like it's flat...

[renmure]

Can't offer any technical help (shock!!) ... but I have a few cars on accumates and haven't had one being killed by them. Elise has been on one without moving for donkeys at a time over the past 5 years with no issues.

[Rich H]

OK thanks, looks like it must be a duff battery.
I'll dig out the receipt see if it is in Warranty, it should be.

[Mr Momo]

Is there some kind of recovery setting ?

I borrowed Ali C's Accumate for a dead Banner for the Frog - opened to cells, topped up and left the Accumate to do it's job - seemed to remember nothing happening for >12 hrs whilst it was conditioning, then it started the charge cycle - did the trick.

[Rich H]

Nah it's on the big charger now.

[David]

Sound like a typical battery failure although 18 months is not long. Short journeys kill batteries - something to do with high cranking current being regularly drawn from less than full capacity. A battery will charge to 80% capacity in few minutes but then may take hours to reach 100%. Although a battery at 80% charge may operate without problems for some time, it does shorten the life considerably, usually resulting in the loss of a cell - typically a large voltage drop on load (12V off load, 9V on load).

[Rich H]

Sounds about right, it does go on long runs but I do take it to work regularly too.

[tut]

Normal usage should not affect a battery at all for years if it started out a good one. The Audi TT has had one new one in eleven years and has gone months without being driven. N1 stood for five years and was topped up with an Accumate now and again, and then started up first time. N3 has given continual problems until Craig fitted a new earth, now it is perfect.

It does sound as if you now have a duff battery or that something is pulling a charge from it. A quick check is to run a jump lead from the battery negative to the engine block and see if that makes any difference.

tut

[Rich H]

Done a check and it's pulling 5ma.

The flat battery has confused the alarm though, it now locks the doors when the ignition is on and it won't let me reprogram it... it works otherwise!

[Shug]

Dead cell in the battery - happens sadly. I've had one on the bike that was pretty new and just crapped out. May or may not be use-related.

[robin]

This may be related to trickle charging the battery or poorly regulated charging from alternator.

Lead-acid batteries hate two things: (1) deep discharge (2) overcharge. Overcharging by trickle charging is still overcharging. If you cannot prevent deep discharge you should always use a "marine" cell - these have gel electrolyte and don't disintegrate on deep discharge. Simpler is disconnect the battery from the car whenever you're not using it, but beware of secondary batteries in alarm systems, etc., that expect to be charged from the main battery - if you leave the main battery disconnected you might kill the alarm battery. Removing and discarding the pesky car alarm is a good fix for that

There is no work around for poor charging, though - both your alternator and your trickle charger must ensure that battery voltage remains within required specification otherwise they will destroy the cell. I think that the alternator charge voltage is higher than the trickle charge voltage. I'm sure Wikipedia has the answer, though I haven't checked.


Cheers,
Robin

[alicrozier]

I'm always wary of overcharging so switch off the trickle charger on the 211 once it goes green.
I have little option but to use a charger unfortunately as I have a tracker - battery disconnect would be dead easy and no alarm.

[Rich H]

The Accumate claims to be OK for permanent connection.

I do need a new alt belt as it squeals very occasionally, I suppose that won't help.

I'll also wire up a 12v gauge somewhere so I can keep an eye on it.

Ta
Rich

[whaleys]

I had a similar problem with a battery only lasting a few days from fully charged and it was down to a faulty regulator on the alternator causing excessive draw. This however was disguised by the battery as its frequent discharge knackered the battery.

Just a thought