electrical drain...

[jimmyleeday]

hi all.
i recently wired up a new stereo in my '65 p1800. on the first drive out the stereo lost power after about 15 mins and turned itself off - i noticed at this time the horn had also stopped working. as i was nearly home i carried on and thought i'd investigate the following day.
the next day i discovered the battery was flat. obviously the stereo was incorrectly wired and so i disconected the stereo wiring from the car. started the car using jump leads and all ok. made a 35 minute journey to during which i noticed that the windscreen wipers appeared to be operating a bit sluggishly when i got caught out in a shower. i then noticed the horn wouldn't work. after that, about 15 mins into drive, i noticed that if i turned on my lights, the wipers didn't work. towards the end of my journey (30 mins) it got to the point where nothing worked, not even my indicators. on reaching my destination 1 shutt off the engine, i then tried to restart but battery was flat.
any ideas anyone please? must add that engine wiring is back in pre-stereo fitting state.
thanks in advance,
jimmy

[Alf ista]

Now, I am no expert, but it sounds like your alternator (dynamo perhaps?) is acting up. Your battery could also be knackered but I would have thought that once you are driving you would be ok. A troublesome alternator can actually drain a battery rather than charge it. It sounds like one or both of these is where you should be investigating. Now lets see what everyone else thinks. Hugh.

[TomTom]

Hi jimmyleeday,

Please give a few more details: do you have a dynamo or alternator (how many amps), how much power is the stereo drawing. I would suspect that your dynamo/alternator is on the way out and not charging the battery sufficiently (which may also be a bit old). To prepare for the cold wet period ahead, if you can afford it, get a good alternator (55 amp is normally enough), a new battery if yours is old, and enjoy brighter lights, faster wipers, and your lovely stereo.

Tom

[AidanC]

Hi
Where did you take the power for the stereo from? Have you got a multimeter? If so, could you check the battery with the engine running to see if its been charged? Sounds to me like a short circuit. Make sure that your fuses are the correct rating - you don't want to risk a fire

[Ron Kwas]

Jimmy;

All of your symptoms confirm nothing more than an electrical system with low voltage...this is likely as a result of a charging system which is not putting anything out...for a while, your battery (if in good shape) will run things, but eventually it will go flat as you found...then you have NO source of power at all in the vehicle...was your AMP Indicator ON indicating a failure of charging system?

I recommend you charge battery with a mains charger over night, then perform a load test on it to see if it is capable of storing charge, the start engine and monitor system voltage (at battery) while engine is running and charging system is presumable putting out...system voltage should be around 13.5V with elevated revs (if less than 12.5V charging system is not working).

Let us know what you find...I doubt the stereo had much do to with causing the problem...unless it's one of those ridiculously highpowered ones (especially those with "soft" power switches), its load on the E-system is quite small. Those awfull Lucas fuseblocks MAY be also contributing (see: http://www.sw-em.com/gastight_II.htm ), but in order to give useable help, you need to give us better symptom and operating conditions info.

Good Hunting, and Greetings from Connecticut!

[TomTom]

On a related question, should all the fuses below the top fuse be 8amp (white)? I tried to get some spares but the shop only had 16amp (red) and said these were fine. Is this right?

Tom

[AidanC]

On a related question, should all the fuses below the top fuse be 8amp (white)? I tried to get some spares but the shop only had 16amp (red) and said these were fine. Is this right?

Tom

You can get 8 amp ones in the likes of Halfords (they sell handypacks of four or five fuses for not a lot). The small 25 amp one is the tricky one to track down

[TomG]

I had a knackered dynamo for a couple of years and just ran the car on the battery, which it will run fine, unless you start usin ya lights/wipers/horns etc. If ya battery's not chargin, your AMP light should be on all the time, (well it was with mine). Also don;t forget, batterys do have a life span, and yours might well have come to it's end, specially if it's been run flat.

You can get 8 amp ones in the likes of Halfords (they sell handypacks of four or five fuses for not a lot). The small 25 amp one is the tricky one to track down

I've got a spare little 25 amp one out of my old fuse box if anyone ever needs it.