Is my Ctek faulty?

[blueST]

My car has been laid up for few months now and I keep it on CTEK mxs5. I spotted the other day that the Ctek was showing an error on stage 5, which indicates a battery that wont hold a charge. I pulled the battery, brought it into the garage and thought id try a reconditioned charge before I condemn it. Because I'm curiousI put my multimeter on it at the same time. Resting voltage before charging and nothing connected was 12.3v. It a standard wet cell battery.


What I noticed is that when the Ctek gets to stage 4 it holds the voltage at 14.7v to 14.8v instead of 14.4v stated in the manual. It does this on both standard charge and recon charge. This is the figure for an AGM not a wet cell battery. I checked it with abother meter and it reads the same eliminate any inaccuracy there.

Is my CTEK faulty and will this damage my battery?

Edited by blueST on Sunday 11th January 15:10

[blueST]

I may have solved this. I asked Gemini and it says the voltage at stage 4 might be raised in low temps. Its nippy in my garage today.

[bigandclever]

I have the same unit. If it's cold enough it will change to 14.7V. Naturally I can't find what the switchover temperature is, though for it to work 'best' that's why you keep the charger as close to the battery as poss.

[trickywoo]

A lead acid battery reading 12.3v is goosed.

[blueST]

trickywoo said:

A lead acid battery reading 12.3v is goosed.

Could be. Even if it's been sat for a few weeks in a car with an immobiliser?

[Panamax]

trickywoo said:

A lead acid battery reading 12.3v is goosed.

Sounds like it to me. You could make certain by charging it indoors (room temperature), then take it off the charger and leave overnight and if the voltage next morning is 12.4 or less it's new battery time.

Under the conditions mentioned above a "good" battery would show 12.6v or more.

[fooman]

If it's charging high when cold, it won't hurt not to charge for a few days, unless battery is already dead!

[blueST]

Im.going to leave on the ctek on the bench for a day or so now, then let it sit and see what happens to the voltage.

[blueST]

The battery was showing fully charged and I left it on the ctek for about 48 hours. Its now been sat disconnected for a further 48ish hours and the voltage is still 12.9v so maybe it's not unhealthy.

If so, why was the ctek erroring at stage 5? Could a parasitic drain on the battery fool the ctek?

[Panamax]

blueST said:

further 48ish hours and the voltage is still 12.9v so maybe it's not unhealthy.

I've not read back in the thread but unless that's a very fancy, brand new battery I suspect you've got a dodgy voltmeter.

[blueST]

Why is that? 2 meters agree.

[Panamax]

Then I'm probably wrong, but I do know the Radio Shack brand hasn't been on sale in UK for a long time.

I guess so long as the car works fine it's all irrelevant anyway.