Charging a flat battery.

If it's a "normal" wet cell, it's probably cactus if it won't hold a charge for a couple of months.

I would disconnect it to try recharging, but since it's totally flat it may never recharge at all.

Good luck.

Charge away and as soon as possible Toolman. It would have been a good idea to have someone either run the engine or put on a charger several times during your absence. Batteries don'rt like being discharged. By that I mean that their potential life is substantially shortened by a complete discharge. Even "deep cycle" suffer damage from discharge - they are just somewhat more substantial and therefore withstand it better and suffer less damage.

The Nissan Patol handbook suggests to disconnect the battery if it isn't going to be used for a month or more. There is always some drain on the battery with the newer vehcles.

Anyhow I'd discconect the battery before I charged it, to be sure to be sure to be sure??

Hi

Disconnect the battery and pull it out, i dont think it would be too great for the car to be connected directly to a charger, especially if it's an old one as you never know what might happen. Also go to an auto store and get a tester to test the cells that usually gives a good indication if the battery is cactus.

Hi Toolman
If you regularly have to leave your vehicle parked up for extended periods maybe it would pay to invest in a "Charge & Maintain" battery charger. I have used one for years and never had any problems.
Regards
Dave

It's perfectly OK to attach the charger whilst the battery is still connected to the vehicle. The electrical system of the vehicle is designed to withstand a higher voltage than the charger is designed to produce.

Having said that: there is always the slight possibility that (I may win Tatts Lotto :) your charger goes haywire, manages to overcome the barrier of an isolation transformer and stuff 240V into a place which would make your battery's eyes water :) Personally I don't bother to remove a battery terminal but it's a simple process in order to be totally safe however you may loose radio and clock etc settings.

Mike Harding

My thanks to those of you who replied with advice. Your comments have been very helpful and I now have a fully charged battery. I did disconnect the + cables before charging.

Also, call me ungrateful, but I have dismissed the appointed vehicle starter (my daughter) for her tardy and less than professional approach to her designated duties.

Toolman

Yes, as you say it's not surprising to find your 12v batteries are somewhat 'flat' after remaining connected and unused for a few months.

Obviously the batteries are not AGM's, as they would still be OK.