2 minutes ago, shawty1984 said:

From my understanding of that, it's detected it as a 6v battery and is no good? 

 

It keeps climbing to 5.7v and dropping to 4.4 then climbing again.

Ever heard of the saying, "a watched kettle..."?? Just give it time and stop staring at it.

1 minute ago, StephenFord said:

Ever heard of the saying, "a watched kettle..."?? Just give it time and stop staring at it.

See this is why I'm asking as I've never done it before. Reading the instructions tells me that it's not going to charge over 6v as it's stuck in 6v mode?

I think you're right about that. You need to somehow get it above 7.5V to be detected as a 12V battery. To be honest if it's been discharged that low it will likely have irretrievably lost some capacity.

The best way to get it above 7.5V would be an old-fashioned dumb charger if you can get access to one. Then you can finish off with the Maypole. If I was faced with doing this I have a lab bench power supply which has controls for setting the voltage and current limit but most people won't have one of those.

7 minutes ago, mjt said:

I think you're right about that. You need to somehow get it above 7.5V to be detected as a 12V battery. To be honest if it's been discharged that low it will likely have irretrievably lost some capacity.

The best way to get it above 7.5V would be an old-fashioned dumb charger if you can get access to one. Then you can finish off with the Maypole. If I was faced with doing this I have a lab bench power supply which has controls for setting the voltage and current limit but most people won't have one of those.

I've had it jump started, and its now charging at the correct 12v std. 

If it has lost capacity, how will this affect things? We will be selling it at some point soonish, so would rather not have to get a new battery if not needed, it will be sold to a garage rather than privately. 

15 minutes ago, shawty1984 said:

If it has lost capacity, how will this affect things? We will be selling it at some point soonish, so would rather not have to get a new battery if not needed, it will be sold to a garage rather than privately. 

Well, I don't recall anyone ever testing the battery voltage when I sold a car to the trade so if after a full charging cycle it starts and runs ok I'd let them sort it out.

You don't say if the cambelt had been changed or not so given its 10 years old I'd be more concerned that they might be clued up about that.

1 minute ago, Eric Bloodaxe said:

Well, I don't recall anyone ever testing the battery voltage when I sold a car to the trade so if after a full charging cycle it starts and runs ok I'd let them sort it out.

You don't say if the cambelt had been changed of not so given its 10 years old I'd be more concerned that they might be clued up about that.

Hasn't been changed. To be honest it's more a quick sale as father is ill and won't be driving again, so if they knock money off, not too bothered, or is it a case of they won't touch it? 

As long as it runs fine on the day, the buyer won't test the battery capacity. 

Depending on which type of garage is buying, they may knock a bit off for the cambelt overdue.  It is listed as a 'minor fault' on some of the online car buying websites when assessing condition for a valuation.

3 minutes ago, shawty1984 said:

so if they knock money off, not too bothered, or is it a case of they won't touch it? 

Probably only one way to find out! You'll be aware of the range of prices for the job from the many threads on here so at least you're forewarned. 

A friend of mine is facing a similar dilemma with a Fiesta now just short of 10 years old. They've had it from new (his daughter is currently using it) and wavering between chopping it in for another car or biting the bullet with the cambelt.

 

 

 

On 12/23/2023 at 9:52 PM, alexp999 said:

I was told by a neighbour who is a retired mechanic to use the donor car just as a portable battery. Have the donor car engine off, only start it once the the flat car is running and the cables have all been disconnected. That way it never sees a big spike in voltage from two alternators or from having a flat battery disconnected from its circuit.

 

Same charger will work on both batteries. Usually a Maypole gets recommended on here. 

I haven't read the entire thread yet so forgive me if this has already been said, but as long as you get the polarity correct on connecting your jump leads, generally jump starting is fine, the early ecu controlled cars had issues handling voltage spikes from jumpstarting, but computers in cars have come a long way and these days they generally can handle having a jumpstart just fine as the voltage spike isn't to disimilar to just connecting a fresh battery to a car that didn't have a battery in it

 

17 minutes ago, Neb_engineer said:

I haven't read the entire thread yet so forgive me if this has already been said, but as long as you get the polarity correct on connecting your jump leads, generally jump starting is fine, the early ecu controlled cars had issues handling voltage spikes from jumpstarting, but computers in cars have come a long way and these days they generally can handle having a jumpstart just fine as the voltage spike isn't to disimilar to just connecting a fresh battery to a car that didn't have a battery in it

 

A fresh battery is 12.8V. An alternator trying to charge a low battery is 15V.

An alternator trying to charge a parallel connected flat battery then suddenly not having it there could cause a spike. It’s safer just to keep the donor car off. 
 

It’s why the manual states to wait 3 minutes before disconnecting the jump leads to allow time for things to equalise as they suggest starting the donor car. Most people won’t wait that long. So it’s safer to just not start the donor car.

15 minutes ago, alexp999 said:

A fresh battery is 12.8V. An alternator trying to charge a low battery is 15V.

An alternator trying to charge a parallel connected flat battery then suddenly not having it there could cause a spike. It’s safer just to keep the donor car off. 
 

It’s why the manual states to wait 3 minutes before disconnecting the jump leads to allow time for things to equalise as they suggest starting the donor car. Most people won’t wait that long. So it’s safer to just not start the donor car.

I get that but I mean the origin of this was actually jump starting killed voltage regs on the dead car's alternator (modern cars are computer controlled voltage regulation). My personal experience after jump starting hundreds of vehicles including a double decker bus and a lorry (those both were airfield vehicles) I haven't had any issues from jumpstarting.

2 hours ago, shawty1984 said:

I've had it jump started, and its now charging at the correct 12v std.

Just caught up on this now, you did the exact correct thing. In the past I have used a 'dumb' charger before (bought in the 70s) so that it brings it over the threshold of 6v, then swap over to the smart charger to finish the job. Many ways to skin a cat... 😁

For future information, the NOCO GENIUS5

"Charge dead batteries - Charges dead batteries as low as 1-volt. Or use the all-new Force Mode that allows you to take control and manually begin charging dead batteries down to zero volts."

https://no.co/genius5

2 hours ago, YOG said:

For future information, the NOCO GENIUS5

I have one of these which I normally use on my wife's car which does low mileage. Seems to do a good job, but I've not (yet!)  needed to use the force mode (which I think I've mentioned on another thread).

The C-tek MXS 5 makes a similar claim, which, if true, would help justify the extra cost of these over, eg, the Maypole.

Just checked the car, it's showing green and full bars on the battery, sat at 12.4v. Is that high enough or should it be reading higher fully charged?

20 minutes ago, shawty1984 said:

Just checked the car, it's showing green and full bars on the battery, sat at 12.4v. Is that high enough or should it be reading higher fully charged?

Stop getting hung up on figures. Does the car start? If so, the issue has been dealt with as you are selling it anyway.

23 minutes ago, shawty1984 said:

Just checked the car, it's showing green and full bars on the battery, sat at 12.4v. Is that high enough or should it be reading higher fully charged?

As long as if the car has stop start, the car not being annoyed with battery health it'll be fine

2 hours ago, shawty1984 said:

Just checked the car, it's showing green and full bars on the battery, sat at 12.4v. Is that high enough or should it be reading higher fully charged?

That's about the 80% SOC which is all the standard "intelligent" charging system on cars  attains these days. You could always use your chargers "maintenance" mode to keep it there until you get it sold, if you're concerned.