Morris Minor Owners Club

I fitted a modern radio in "Aunty Mable" and I had to change the polarity to negative earth, I only drive her at weekends, which means she is garaged most of the time.
Since fitting the stereo the battery wont keep its charge, She was fine before I fitted the stereo, anyone got any ideas what the problem could be?
Mark & Aunty Mable(1961 2 Door)

Did you re-polarise the Dynamo??

If you did then perhaps it hasn't worked so try it again....

Bear in mind that (depending how you've connected it) some radios draw current to maintain settings even when turned off.

but that is a teeny weeny bit of current, sounsd more like an electrical leak or something

V true, just trying to help! If there's not much juice in the battery to start with...

then you got a fair point. Check your battery fluids too btw, you never know

Might be stating the obvious here, but a good idea to switch to a substitute battery, if possible. At least then you could eliminate the battery as being dodgy.
My radio needs a constant supply for memory settings, but it's only a trickle current that shouldn't affect the battery.

I had to take the radio out of my traveller for the same reason, and that was after having a new battery, the polarity on all bits checked and the wiring checked as well.
Fablovely

I just can't imagine what type of radio would draw such a heavy current when in standby mode.................

Think about radios,

I have -ve earth moggie with an old(ish) radio/casette in it. There is one power lead, and one "memory retention" lead.

The power lead is expected to be from the "accessory" tag on the ignition switch (which moggies don't have).
The "memory retention" lead is connected to "always on" - i.e. fuse box - live.

The power lead supplies power to the radio/casette, speakers AND the aerial (either motor or power amplifier). I've fitted an on/off switch under the dash so that I can make sure there's no power drain when the radio's off (I have an internal antenna with a power amplifier).

The "memory lead" takes virtually no power. Maybe that solution would remove the problem?

Colin

I just can't imagine what type of radio would draw such a heavy current when in standby mode.................

A faulty one?

Ray's right, doesn't matter how it's connected, when it's switched off it will only draw a trickle through the permanent live lead for the memory.

It's possible you could help the problem by running a much bigger battery, helps starting too.. I use a battery that's rated for a 1.8/2.0 engine.

Sounds like your dynamo isn't charging (re-polarise) or it's possible it could be knackered, perhaps the brushes are shot?? Anyone else heard of this happening when converting from -ve to +ve?? I've heard of points & fuel pump contacts giving up the ghost before...

Have you tried putting a meter on the back of the dynamo to see what the output is?? Try at idle & also with a few revs.

I dont wish to ask the obvious but how old is the battery ?

Really unlikely suggestion:

Is it actually switching off? If it's a modern radio and you're just using it as a tape player, when you eject the tape, if it's got no arial it may silence the hiss, but still actually be on. So if it's fitted under the seat or somewhere else where you don't look at the display it could still be on, despite producing no noise.