Jag battery died

[Deleted User 4828]

Yup, it's dead, not a bean from anything, I got into the car and opened the bonnet. The voltage at the jump points in the engine bay is 5.6V.

Going to make a up a jig/tool to pop the tailgate in order to get to the battery, I managed to remove the back parcel shelf so I can get access to the green pull handle for the boot emergency exit. Them measure battery with gnd disconnected, I expect the same voltage tbh.

btw the fuses in the jump box were ok

More later.......

[RPSN]

Yup, it's dead, not a bean from anything, I got into the car and opened the bonnet. The voltage at the jump points in the engine bay is 5.6V.

Going to make a up a jig/tool to pop the tailgate in order to get to the battery, I managed to remove the back parcel shelf so I can get access to the green pull handle for the boot emergency exit. Them measure battery with gnd disconnected, I expect the same voltage tbh.

btw the fuses in the jump box were ok

More later.......

You can open the boot (even when it's closed and the battery is flat or disconnected) by using the jump starting points underneath the bonnet as explained here.....viewtopic.php?t=4896

[Deleted User 4828]

That's the first thing I tried actually, the weird part is that even with jump leads connected the voltage at the jump terminal was still 5.6V!! go figure, that's why I need to get into the boot. So unless the AGM battery is that bad it's just sinking anything that gets connected to it. I'll work it out I'm sure, I already have a replacement battery on it's way.

[RPSN]

Strange?

Going back a while ago the positive connection popped off my car’s battery after I’d gone out for a spin and parked the car up. At the time I had nothing with me to get the boot open so a friend brought along a Ring Lithium portable jump starter. I tried this and it was no good no matter what. Luckily he also brought a good pair of jump leads which at first didn’t work but after a bit of fiddling with the connectors all was ok and I was able to open the boot to reconnect the battery positive lead.

[scm]

Sounds like the battery has an internal short.

[Deleted User 4828]

It does doesn't it or something is. If a bad short then I would have expected a fuse to blow and end up not measuring any voltage (this car does not have the aux battery btw). I have made my tool now and will get to the Jag with another good battery. I plan to disconnect the battery, measure it and see. Then connect up spare 12V lead acid battery to see if it does come alive, without starting etc. First experience with an AGM battery issue.

Again, new later on my findings

[scm]

An internal battery short wouldn't blow fuses - just make the battery give much a lower voltage. Hopefully a new battery will sort everything out!

Did you order the battery from Tayna, using YouTuber Number 27's discount code?

[Deleted User 4828]

An internal battery short wouldn't blow fuses - just make the battery give much a lower voltage. Hopefully a new battery will sort everything out!

Did you order the battery from Tayna, using YouTuber Number 27's discount code?

I would say that is down to where the short is and the power rating of where the problem is. The fuse is there to protect the wiring after. Otherwise you can end up with a fire...just like the TR7's in the very early days Update to follow.

[Deleted User 4828]

Ok so I got into the boot measured voltage first across battery, it had gone up to 10.7V, press start button, nothing. Then as I was starting to disconnect the battery I heard it ping to life and die! voltage had now dropped to <7V.

So I continued to disconnect battery and put in place my charged 12V lead acid battery. Bingo! The car came to life and pressing the start/stop button car came up with no faults. Stereo came on widows worked all ok. I did not try and start it. Now it's alive, I have left that battery in it, awaiting the new battery.

My tool worked a treat. The original AGM battery was still down at about 7V so I am confident when the new battery arrives it will be ok. So happy there were no reported faults.

Bought this battery with 5 year guarantee

[gasgas]

new battery will be a great starting point, i had issues a couple of years ago all sorts of lights on the dash, new battery and all is good