MGB Register Forum

Hi all
Thanks for all your tips. Fully charged on 5th/6th & left for 4 days. Started 1st time and 1st time every day for next 5 days without any re-charge driving. No indication of any drain. Battery now showing ''green'' as good. There appears to be no problem now. Still keeping one eye on it but maybe I left something on? Have not used the radio throughout and intend taking it out at some time for checking/replacing. If needs be I may fit the anti-drain key as mentioned. How much should that cost?
Thanks for all your help.

Hi Tony,
have a look at these - https://www.holden.co.uk/displayProduct ... r+Switches

I would recommend one with a removable key. The £9.29 one is perfectly adequate for a basic installation (that's what I have),

Ian F

Thanks Ian - I shall procure and fit.

There are two types of these switches. One as shown in the link to the picture above and another often described as an FIA Battery Isolation Switch. The first is perfectly suitable for a road car providing you remember NEVER to use it whilst the engine is running. If you do and you have an alternator this will be badly damaged by the high voltage surge which destroys the rectifier bridge. ALWAYS switch off the ignition first and wait until the engine stops then operate the cut out switch. The FIA version uses a resistor to prevent the voltage surge and can be used to isolate the electrics when the engine is running. This is necessary in cases of an accident during races or rallies. The same goes for the switch Tony has found under the dashboard, although I suspect this just switches off the low tension side of the coil wiring which will have the same effect as turning off the ignition.

One other point is the red key is widely available and they are all the same, so it is a minor inconvenience to a thief rather than an anti-theft device. Useful though as they would probably give up quickly if the car didn't start using the good old hot wiring trick!