Strange electrical issue

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1BadDodge71

1BadDodge71

FABO Rice Hater
Joined
Aug 17, 2006
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Fort Collins,Colorado
Hello all,
Noticed something strange today with my 72 Duster.I noticed that when the engine is off and the key in the ACC position,when I turn on the lights,or even press the brake peddle or turn signals my radio will shut off and then come back on after I turn off either one.It never does it while the engine is running,only when not running in the ACC position.
I disconnected my stereo and hooked up my multimeter on DC volts and on acc,connected to the radio circuit,the meter drops from 12.65 volts to around 10 volts.I checked all the wires and non are broken or stripped.I'm wondering a voltage drop somewhere in the ground?Hmm.
I'll do some voltage drop tests.My battery is fairly new so I'm ruling that out.
I hate electrical problems :banghead::banghead:
 
Things I would suspect in no order:

Bad connection in the red / black bulkhead connector, ammeter wires

Bad connection at the ammeter

Rare but has happened........failure of the big splice in the black ammeter wire. This is in the harness under the dash, a few inches from the ammeter

I would also check out the ignition switch and fuse panel
 
Battery, Fairly new really doesn't mean much. Most modern electronic need the full 12 volts to operate. Lights and such would work but create enough draw to reduce voltage to the radio. Years ago wifes 93 Lebarron failed to start. I jumped it off and it ran. Pull headlights on or turn wipers on and shut the engine down. Yes I drove it home in a cold rain without lights or wipers or heat. Brake lights would cause skip / poor idle, but I got home. New battery cured it.
 
Ok,thankfully my battery is still warrantied.When I first bought it,I was wondering why it cranked the engine so slow.Like wrrrrrrr wrrrrr,lol.Anyway,I charged it,hooked up the multimeter and set in on MIN/MAX to record.I started it and let it run for a bit.
Not running,the battery read 12.75 volts,cranking,it dropped to 9.25 volts,running at idle,it read 14 v or so.Turned it off,cleared my multimeter and connected it to my battery ,set min/max and let it set.After 2 hours,the voltage dropped from 12.25 volts,all the way to 9.60 volts! Other than my dome light (which I disconnected),there is nothing that could be draining the battery,no clocks or radio memory.I did test it for a parasitic power leak and the multimeter didn't read anything.So,yeah I'm going to try returning this battery and get a better one.How many CCA do you guys recommend?
 
Tomorrow before I do anything,I'm going go through my wiring as well.On these cars,it's not much wiring.Maybe invest in some new battery cables.Check my grounds,the alternator,etc.But I cannot find any like the original ones.
 
CCA rule of thumb is equal cranking amps to engine CID + whatever extra you feel like paying LOL. "Used to be" a 50 month warrantee battery was pretty good. In today's world, batteries are chineseoated just like everything else.
 
The worst I recall, neighbors voyager minivan 12.3sumthin with nothing but dome lamp. When she tried to start it, immediate drop to 2.3 sumthin.
I have now purchased 2 of Advance Auto Parts Gold series batteries. Well pleased with both. At 150.00 + ( before discount codes applied ) they better be good ones.
 
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