Need to hook up a battery tender for this week. Will drop down to -15F. I've read so many posts about hooking up neg from tender to the post or to the ground stud next to the battery. Don't see the difference. Any quick help?

 

My Ctek connector in the boot (with LED lights to display battery condition) is connected directly to the neg battery post per their instructions.

 

I am not sure which C-Tek charger Abonano has, but my C-Tek MUS 4.3 smart charger specifically calls for the negative clip to be clamped to a grounding point on the chassis/engine block, not the negative battery post, which is the same protocol as when the car is jumped.

If the battery is removed from the vehicle, you can connect both clips to the battery posts.

Have I clamped the charger to the negative post? Yes. It didn’t cause damage, but it is good practice not to.

Make sure the battery is vented while charging and keep an eye on it especially if you leave the charger on for extended periods of time. What type of charger are you using?

Here is C-Tek’s explanation for connecting to a ground versus the negative battery terminal:

 

It will not matter in the boot on your XJ Mark. Either will be fine.

 

I also usually connect my Ctek on the negative post.
Never seen a spark. That would require the capacity to deliver a high current, something the Ctek is unable to do. Also the Ctek is an intelligent charger that certainly controls its output, e.g. it does not deliver current when you wrongly connect the cables (I know, I did it).

 

On both my jaguars it was recommended to connect the ctek to a ground point near the battery. The reason given was something to do with the battery monitoring system of the car sensing the battery condition or something like that so it could monitor charge in and current out of the battery.
Anyone else hear of this ?

 

Both the negative post, and both negative cable studs are so close to the battery, it isn't an issue.

 

Exactly, just like Box said but i will redact my original post.

Just checked instructions again - yes, connect to a ground point on the chassis, however, I'm not messing with those aluminum ground studs, nope...

 

The C-Tech instruction not recommend to connect to the neg. post just for the liability reason, so doesn't matter ground or neg. post.

 

Thanks guys

 

Installed my cteck and was much kinder to my battery at 20F below. Thanks for all the help.
Mark