I have put my xk8 back on the road for the summer. I alway disconnect the battery when idle for a long time. Charged battery used for a couple of day did about 50 miles no problems. Started car each day after to keep battery charged up no probs. Didn't start for 2 days tried to start car battery flat so jumped tt started no faukts have come up traction contol, gearbox fault cat eon't come out of p and stability contol fault. Any ideas do you think new battery might sort it out when computer re boots. Many Thanks Trev.

New development fitted new battery took to the road, drove 20 miles no stops. Get to place. Turn off engine. There 30 mins. Start engine fine. Drive 10 mins. Stop there 2 hours (pub) Start engine fine drive 15 mins. Stop 15 mins fine start engine. Dark now turn on lights drive 18 miles notice battery reding on dash has gone down to in to the red, then warnibg lights come on ABS Stability control, get home put in garage. Next morning Start car every thing fine. So decide to charge new battery, my charger has 4 lights 1 charging 2 50% 3 75% 4 fully charged. Been on now for 8 hours won't move from the charging light. So put on my other car to check charger shotsstraight up to fully charged. What does every body think Faulty Battery? Any ideas?

 

In the US the simple answer is to take the car to the nearest auto parts store and ask for a free charging system check. Don't know how that works in the UK.

Sounds like a defective new battery or failure of the car's charging system . . . or a drain on the battery with everything off . . . or supposedly everything off.

Leaving the key in the ignition with everything off will keep the car's modules 'alive' and eating current.

 

It sounds like a battery with a heavy sulfate buildup to me, where fully charged means that it's charging as far as it can go and the cells have lost most of their capacity. Disconecting the battery during winter storage helps with the hig current drain but over several months it's going to dischage to the less than 80 percent capacity level with causes hard sulfate buildups.

I would charge it as far as it will go and then go to an autoparts store that has a load tester. Or if you have a Hygrometer in your tool box, take a sample of the electrolyte and check the specific gravity.

If you search the boards you will find numerous articles relating to the electrical Gremlins that occur with a bad battery. Good luck... Jim

 

Trev,

The new battery is definitely the right spec? If so, I'd be going straight back to the supplier to have it checked and eliminated as a possible cause before doubting the remainder of the charging system.

Graham

 

Unfortunately the Voltage indicator is just as fake as some of the other displays.
For a quick and easy (and cheap) check of what your system voltage is doing you can plug in something like this 12-24V LED Display Cigarette Lighter Electric Voltage Meter for Car Battery TR | eBay

Will tell you the correct battery/charge voltage.

 

Hi TW, at times a bad battery can drive you buggy. Plates at the bottom of the battery will short out giving you a no start condition or it reduces the capacity greatly. Being you replaced the battery, I doubt you have a bad second battery. A good batt will rejuvenate itself a little by itself over night. Could be a heavy draw off the batt while sitting. take a volt meter, remove the positive cable from the battery. place one leg of your meter to the positive cable, the other leg of your meter to the positive side of the battery. If you have a hi amperage and or high voltage, 12 =/+ you have a short within the car that is draining you charge. Somthing is on all the x. ck trunk or glove box lamp. If all within specs, your alternator might not be putting out enough voltage or amperage to bring the battery to full charge each time you use the car. Usually the brushes are worn out. May need new alt. Hope this helps. I'd check the trunk light first. I've noticed mine gets stuck at times. Rich