I was going to connect my charger to the XJS and there is a warning sticker on the battery mount - disconnect from car before using high speed charger - which isn't a particularly helpful message - what consitutes a high speed charger (pretty much anything today compared to 1987 I'd guess).

I have three potential chargers I can use, a CTEK MXS3.6, a CTEK MX10 and a Ring RSC612, I'd really rather not disconnect the battery every time I want to feed it but I've no desire to fry hard to replace electronics either.

So what constitutes high speed other than a 2 year old with a sugar overdose.

 

I have had one of these for a few years now. Used it on all the classics I have owned Triumph Stag, P38s Range Rover and now the XJS. Works fine and I don’t disconnect the battery.
Rob.
https://www.ebay.co.uk/itm/264802953413

 

Do you leave it connected all the time or just do periodically ?

 

Connected all through the winter. Keeps the battery in perfect condition. Through the summer now and again as and when needed. I didn’t get my charger from eBay it came from Lidl I think it cost about 15 quid.
Rob.

 

A CETEK can be left connected all the time, no bother. I use one like Robbo's no bother either.

 

I've had a bad experience with the CTEK on the SV8 and it has shattered my confidence in them a little, I used to swear by the CTEK's (thats why I have 2 of them) brand new battery had to be returned after less than 3 months, vendor said the battery was faulty but I don't know if the CTEK caused it, that said the XF is just about the worst car I've ever had for power consumption / management so fears may be unfounded. I know the Ring can get carried away - I've seen it pump out 8+ amps - the CTEK you've really no idea what it is up to.

In all the years I've had the CTEKs though I don't think I've ever seen the LED's trip over to maintenance mode.

 

I think by "high speed" they mean some professional shop type chargers that are capable of several hundred amps. An ordinary charger that is up to 8 amps will be fine.