Is my battery kaput?

[swee'pea99]

Just been out to test the battery and it's reading 11.13V. Can't open the central locking, much less start the car. A pretty catastrophic drop from last night's (itself useless) 12.3V - down from 12.54, 24 hrs earlier.

This is with the car parked up by the kerb.

Not the first time neither:

4pm 15 nov fully charged - 13.09V
6pm 16 nov - 12.78
10.30am 17 nov 12.6

On the 14th I measured a couple of hours after getting back from a drive - 12.67V. 24 hours later it had dropped to 11.93.

The battery's toast, right? I've been resisting this conclusion because it's only 9 months old, which to me reads 'New!', and it's a Bosch, which I bought though it was more expensive. Can you actually kill a 'new' battery by leaving it below-charge for extended periods?

The root problem is that since our dog died the car only gets used occasionally, rather than daily, so I suspect sometimes it drops significantly without being noticed (though I hasten to add it's never been allowed to go completely flat - it does get used, albeit often started with a booster pack, on at least a weekly basis).

I'm pretty sure there must be a parasitic drain, though an auto-electrician I took the car to assured me it wasn't so. I'm currently looking forward to the arrival of a dashboard solar topper-upper, to be installed more in hope than expectation. But in the meantime, any thoughts on the above would be very interesting. If anyone can draw any firm conclusions from those voltage readings, say. Or has ideas I could try out to find out, preferably ones that don't involve taking out the fuses one by one - it's a Honda Jazz, and it has about 114 fuses.

 

[numbnuts]

Sounds like you have a dead cell in the battery, get a new one and wire up the solar panal and you'll be good to go again

 

[Electric_Andy]

Sounds more like your alternator to me. When you're driving around it's not charging. When sat idle it's getting even lower. If you can charge the battery up, get the car running, measure with a multi-meter under load (lights and heater on) and you should be geeting 12.6V ish and should rise slightly when you rev the car. Could also be a parasitic drain somewhere. Or if in doubt find a reliable garage to test battery and alternator; one that won't just suck through their teeth and say you need new parts that is

 

[fossyant]

If the cars hasn't moved, pop your hand on the alternator. If its warm you've got a faulty alternator as its turned into a motor. This happened to the Aygo. I could hear a low hum, the alternator was warm, and could measure the current draw on the battery. Would go flat over 12 hours.

 

[Drago]

What is the date code on the battery?

 

[tyred]

I'd definitely get it running and check if it is charging properly first.

Check for silly things like the boot light being on that will drain the battery.

If the charging circuit is working okay, and the car is only used occasionally, you could make sure the battery is fully charged and then disconnect it (assuming it won't cause problems with radio security codes or whatever) and then see if the car starts when you reconnect it a few days later. If so, the car is somehow draining the battery. If not, the battery is not holding charge and needs replacing.

 

[Cycleops]

Multimeter on the alternator will reveal all. Should be 12.5-13.5v idling. Less than 12.5v something is wrong in the system somewhere.

 

[Fastpedaller]

There's a good guide on Tayna Batteries website. btw I've had 4 batteries from them over the years, great service and product, arrives within 24 hours by courier and (probably) about 20% lower price than the same battery locally! Is it ok to recommend? It's the opposite of 'naming and shaming'. I have no connection other than being a satisfied customer.

 

[CXRAndy]

I have several batteries which are quite old, one is 12yrs and the other one is 16 years old. Still in good order, because they are always on Ctek battery conditioners.

I've only bought one battery in 16 years.

A good battery should hold above 12.6 Volts. When the car is running, alternator should deliver 13.8-14.5 Volts for charging.

The other problem could be a parasitic drain, where some circuit or component is draining the battery. Modern cars usually have less than 30 milliamps battery drain/leakage and commonly around 10 milliamps.

If the battery is that poor take it off the car charge it inside, but vent the room incase of gas release. Refit once charged and test voltages as described above

 

[swee'pea99]

Thanks very much for all replies. I shall follow up on tests & suggestions over the next day or two and report back.

 

[Fastpedaller]

Not wishing to hijack the thread..... but are my (tiny) batteries kaput? The key fob for Wife's Ford has recently failed to work at first button push, so with it being 7 years old I thought a new battery would sort it. It's a CR2032, 3V battery. I found a couple in the spares drawer, and with the multi-meter they showed 3.08 and 3.09 volts. I removed the original, and it measured at 3.02 volts. Neither of the new ones would work. I replaced the original and it worked. Is it possible the 2 which showed a higher voltage are both kaput? Can small batteries (not unlike lead-acid car batteries) look to be ok with the voltage, but are too weak to take the load?

 

[Tenkaykev]

Not wishing to hijack the thread..... but are my (tiny) batteries kaput? The key fob for Wife's Ford has recently failed to work at first button push, so with it being 7 years old I thought a new battery would sort it. It's a CR2032, 3V battery. I found a couple in the spares drawer, and with the multi-meter they showed 3.08 and 3.09 volts. I removed the original, and it measured at 3.02 volts. Neither of the new ones would work. I replaced the original and it worked. Is it possible the 2 which showed a higher voltage are both kaput? Can small batteries (not unlike lead-acid car batteries) look to be ok with the voltage, but are too weak to take the load?

Check for a " bitterant " coating on the battery, or a fine peel-able cover on one surface. It's a safety measure to prevent children swallowing them.

 

[swee'pea99]

Check for a " bitterant " coating on the battery, or a fine peel-able cover on one surface. It's a safety measure to prevent children swallowing them.

Also probably worth taking a rub at all contacts with a bit of isopropyl on a hanky. You never know...

 

[Electric_Andy]

Neither of the new ones would work

I had the same issue with mine last year, I only buy Duracell batteries now but they still made my fob work intermittently and eventually led to me being unable to lock the car. It turned out that my fob had failed. I had to get an auto locksmith to order and replace one, and then code in the new fob at a cost of £140. Just for reference, the original fob was for a VW Passat and had lasted 8 years before it failed

 

[Gwylan]

The figures you quote don't look good.
Is there something running in the background?
Just dribbles away the battery. Had this on the camper.
I just isolate everything. Means I have to reset the date and time etc.
The solar panel top up might be useful precaution.