www.jec.org.uk

Hi

Despite using a CTEK trickle charger, the battery on my XJ-S is now run down. Unfortunately, so is the battery on my other car!

I think that I need to “invest” in a starter power pack. I have had a quick look on Amazon - but I do not recognise any of the brands.

Can anyone recommend a starter power pack that will be good enough to start my V12 please?

Thanks

If your XJS battery is failing despite using a CTEK, it's time for a replacement battery to avoid the final ignominy of not being able to get home, even with a starter pack. When a failing battery drops below a threshold voltage, a car may start using a starter pack but it will only run until the starter pack is exhausted (i.e. not for very long). Very low voltages don't allow an engine ECU to operate properly and hence an engine won't run on the incorrect fuel mixtures generated by the ECU.

Most of the cheap starter packs (below £100) are made in the Far East and are typically capable of starting medium sized diesel engines, so an XJS with no other faults than a failing battery shouldn't pose problems. Nevertheless, if you want to be 100% certain of starting an XJS in extreme conditions (-20 degrees in the depths of winter), pay more for a heavy duty starter pack designed for commercial garage use. Mike.

Hi Mike

Thanks for the reply - interesting reading.

At this stage, I do not think that the battery is failing. The battery (Yuasa) is less than 2 years old and has always been kept charged up using the CTEK charger. I think that it is the CTEK charger that has failed because when I connected it to my other car - it also ended up with a flat battery and the red light on the CTEK charger not working.

Is there a brand for a starter pack that anyone can recommend? I am a bit reluctant to buy a Chinese brand that I have never heard of.

I am talking to CTEK and may well have to replace that unit - annoying but there you go.

All part of the fun - a constant series of challenges to solve!

Thanks

Remember that the V12 takes a lot of starting. Mine is an early facelift with the older small battery box, and I suspect the battery fitted is barely up to the job. Later cars got a battery box about the same size as my XJ TDVi, a pukka diesel, and a much larger battery. So I'd guess you need a power pack designed for big diesels. That said, I've no experience of these beasts. It's perhaps worth noting that the battery on my XJS is connected with 90mm area cables - I've just been buying replacement terminal connectors, and the supplier labels them "heavy duty truck", which is fair

Hi Paul

Thanks for that - yes I will definitely be going for a “beefy” starter pack when I settle on a brand.

I may look at what Halfords offer - in the past I have fund their tools to be very good.

Anyone have any brand recommendations?

Thanks

Peter

Peter,

As you will have realised, the development of electronics and the resultant pricepoint has changed enormously over the last 10 years and continues to evolve. Finding the right balance of performance, quality and reliability can be a challenge. I use CTEK MX5S battery conditioners, which aren't budget items. But I've also tried a very cheap (£16) conditioner that has even more features and it also appears to do the job very well, although reliability over time is still to be proved.

The same situation applies to power packs. You can buy an apparent 1000a peak output power pack for £15 if you look around! Will it do what you need, time and time again? I don't know. I carry a NOCO GB40 Boost 1000a powerpack in my car, and it's got me and many other people, out of trouble on a number of occasions. NOCO make a large range of Power Packs. I chose the GB40 on the recommendation of a colleague. and it's been fine for jump-starting everything including my Supercharged V8 Range Rover.

As with so many components, these days, there are huge variations in price and an enormous number of online retail options. So, whatever you decide to purchase, do look around carefully before you buy.

Good luck

Paul

Hi Paul

Perfect - thanks for your advice. I use the same CTEK trickle charger - I’ll now give that power pack a go.

Peter

I don't believe there to be much in the way of 'parasitic drain' on these cars, Vitally important that the main battery is good. I remember leaving mine a couple of months, started on the button. Even my X150 can stand for a month without use and still start first time (every time).

I don't believe there to be much in the way of 'parasitic drain' on these cars...

Ah, but if you have an aftermarket immobilizer, that can flatten a battery in a couple of weeks, particularly if it has ultrasonic intrusion detection. You can guess how I know.

Good point Paul - didn't think that one.

Hi Everyone

Well - I can now post a nice end to the story.

CTEK supplied a replacement trickle charger. I used this to charge up my BMW - which I then used to jump start my Jaguar. Once the Jaguar had been running for a while, I turned it off. When I then connected the replacement CTEK charger to the Jaguar, it operated as it should. It seems that I had two problems - the original CTEK charger was faulty and when I initially used the replacement one on the Jaguar it didn’t work. It turns out the battery needs to have a minimum voltage of 2V before the CTEK charger will work - I checked the Jaguar’s and it was initially (before the jump start) 1.105V.

So all is well that ends well - persistence, time and seeking advice paid off once again.

Thanks to everyone who read my original post and who contributed to this thread.

Peter

Glad it got resolved easily, Peter!

Paul