Did my C-Tek drain my battery?

[Louis Balfour]

No response on the marque-specific page, so I hope it's OK to re-post here:

My Bentley Continental had a battery trickle charger, that connected with a magnetic connector, but it wasn't working. So I used one of my C-Teks via the cigar lighter socket. Prior to this the car was fine, it was a precaution for the low use months.

The charger never reached showing a full charge, the full battery lamp was flickering.

Today I went to open the car and nothing worked. Not the boot, nor doors. I unlocked it manually and it started it (there is a second starter battery, which can also be engaged for ancillaries if needs be).

I assumed the car had just "gone to sleep" and would be fine once I had re-started it. Now, however, if I stop the car nothing works again. I get all manner of warning lights and occasionally a "low battery, start car" warning.

I have tried connecting a different charger - C-Tek MXS 5.0 - directly to the battery with clamps and will see what happens, however, have I had a battery fail by coincidence or has my old C-Tek flattened it / broken it somehow?

[Jap90s]

Sounds like the battery has a dead cell

Whether that's because of the constant charging / CTEK is impossible to say but it's definitely possible

Many now only connect a trickle charger periodically as you're far from the first person this has happened to

[Louis Balfour]

Jap90s said:

Sounds like the battery has a dead cell

Whether that's because of the constant charging / CTEK is impossible to say but it's definitely possible

Many now only connect a trickle charger periodically as you're far from the first person this has happened to

Hmmm this is what I fear. But I though the point of the C-Teks was that you connect and forget.

[Chubbyross]

I would start with a new battery and go from there. It’s possible the cold weather has finished it off over the winter. I’ve just had the same thing on my Boxster. It was fine and holding a charge and then…pff…battery finally dead.

[spikeyhead]

Have you had a power cut, even briefly? Older Cteks would need to be reset afterwards, without which they'd stop charging.

[Louis Balfour]

spikeyhead said:

Have you had a power cut, even briefly? Older Cteks would need to be reset afterwards, without which they'd stop charging.

Not that I am aware of.

I wonder if a clue was that the charger started at "half charged" and then never went to "full charge" the full charge light just constantly flickered.

I've had the car for 2.5 years and the only time it has given a hint of trouble is immediately after I used my C-Tek. It was connected for about 3 weeks.

[RicksAlfas]

Perhaps a daft question, but when cars have two batteries and you connect a charger via the lighter do both batteries get charged, or only one?

[Saudade]

Louis Balfour said:

Jap90s said:

Sounds like the battery has a dead cell

Whether that's because of the constant charging / CTEK is impossible to say but it's definitely possible

Many now only connect a trickle charger periodically as you're far from the first person this has happened to

Hmmm this is what I fear. But I though the point of the C-Teks was that you connect and forget.

It is, not sure what older model you are using, but my mxs 5.0 has a float mode once the battery reaches full charge.

I've left it on a battery for nearly 4 years now, starting the car maybe once every 3 months and moving it and the battery is fine. (Car won't pass and MOT and is a longer than intended project at this point).

Back to your topic, I didn't even know you could charge batteries via the 12v socket. Try putting the clamps on it to see what happens?

Also reading from the ctek website:

"One thing to note about this accessory, is that you will need your 12V socket to be live, even when the vehicle is turned off. So this accessory will not work if your vehicle has ignition shut off."

Edited by Saudade on Wednesday 18th January 08:18

Edited by Saudade on Wednesday 18th January 08:20

[Louis Balfour]

RicksAlfas said:

Perhaps a daft question, but when cars have two batteries and you connect a charger via the lighter do both batteries get charged, or only one?

I don't know!

[RicksAlfas]

Jap90s said:

Sounds like the battery has a dead cell

Whether that's because of the constant charging / CTEK is impossible to say but it's definitely possible

Many now only connect a trickle charger periodically as you're far from the first person this has happened to

CTEK supply an indictaor you can connect to the battery so you know when it needs charging.
This might be a better solution than leaving it plugged in all the time.

https://www.ctek.com/uk/battery-chargers-12v-24v/a...

[Louis Balfour]

Okay, just been out to check the C-Tek. I set it last night to "recond" and this morning it is showing "3" which is bulk charge.

Whilst I am still prepared for a battery replacement, it does suggest at least that the battery is trying to charge.

[alscar]

I doubt the CTEK itself would have killed your battery but equally it does sound a bit of a coincidence.
The MXS 5 is a pretty decent charger / conditioner unlike say the 3.8 which can cause insufficient power issues on a bigger battery / car.
I was going to say put on recd mode and leave for 24 hours and see.
I have had chargers fail even after say 3 or 4 lights appear but once that green light appears all should be ok.
I think the longest I’ve left one on to get working is 48 hours.
Obviously make sure the part you are charging to has a good connection although the charger will show red pretty quickly if it isn’t.

[Louis Balfour]

alscar said:

I doubt the CTEK itself would have killed your battery but equally it does sound a bit of a coincidence.
The MXS 5 is a pretty decent charger / conditioner unlike say the 3.8 which can cause insufficient power issues on a bigger battery / car.
I was going to say put on recd mode and leave for 24 hours and see.
I have had chargers fail even after say 3 or 4 lights appear but once that green light appears all should be ok.
I think the longest I’ve left one on to get working is 48 hours.
Obviously make sure the part you are charging to has a good connection although the charger will show red pretty quickly if it isn’t.

Thank you.

If it doesn't work I will run it down to Bentley. I bet they'll want >£1k for two new batteries fitted though...

[alscar]

LB , is the second battery a stand alone ( and chargeable by itself ?) or connected in some way to the main battery ?

[Louis Balfour]

alscar said:

LB , is the second battery a stand alone ( and chargeable by itself ?) or connected in some way to the main battery ?

I don't know how the electrics on the car are configured. However, there is a large battery in the boot on the right that, as far as I know, deals principally with the cranking. There is a smaller one on the left that deals with ancillaries.

If the ancillaries battery is flat, you can insert the key in the ignition and turn it left, then right, and it engages the cranking battery for ancillaries. Which is nice.

[GreenV8S]

It's very unlikely that the batteries would be cross-connected when not in use since that would defeat the point of having separate batteries.

If you need to maintain them you need to work out whether the car designers gave you a way to do that5 from a single point - if not, you may need to connect a battery maintainer separately to each battery.

Also note that any / all of these batteries could be damaged by a deep discharge and might need replacing now.

[996TT02]

You don't say how old the battery is. That's the starting point. If 4 years or so, particularly if your car has stop start, it's time is probably up and you would be flogging a dead horse. Not ever fully charging is a good indication of that.

Maybe a battery guru can advise whether a battery remaining on charge for 3 weeks as opposed to being on trickle, will damage it further and accelerate its demise.

[spikeyhead]

996TT02 said:

You don't say how old the battery is. That's the starting point. If 4 years or so, particularly if your car has stop start, it's time is probably up and you would be flogging a dead horse. Not ever fully charging is a good indication of that.

Maybe a battery guru can advise whether a battery remaining on charge for 3 weeks as opposed to being on trickle, will damage it further and accelerate its demise.

Cteks sense the battery voltage and revert to a trickle / maintenance charge when the battery is full.

[Dave.]

I'm pretty certain a constant "half charge" light and a continuous fast flickering "full charge" light means there's a break in the connection.

That's what my old ctek does anyway.

ETA, is the lighter socket a permanent live with no key in the ignition? It might take a while to shut off after the key is removed and the car " goes to sleep".

Edited by Dave. on Wednesday 18th January 12:20

[littleredrooster]

Dave. said:

ETA, is the lighter socket a permanent live with no key in the ignition? It might take a while to shut off after the key is removed and the car " goes to sleep".

^ ^ This. I'd be mildly surprised if the socket is permanently live.