i'm with gun on that one. get a multimeter and measure. only this way you find the problem without guessing. you will need that thing more often than you think. i couldn't check any electrical problem without one. at least not properly

if your problem is a crappy battery that doesn't hold charge then the multimeter would have been a waste of money, but you'll use the thing more often than you think once you have one.
At least you can verify what you are doing

Kalli

Seamus: really depends on how your radio is hooked up. some people hook up radios so they don't get any power with key not in ignition or on left. as well it's unclear "testing current". either you measure voltage which is done in parallel or you measure amps which is done inline.

Since gun already mentioned radio in conjunction with flat batteries. You want to measure how many amps the thing is sucking while its off. because this is what gives problems. The general idea is to measure with key out of ignition switch and measure inline between the battery - and the cable that usually goes to battery - (remove the cable, and measure amps inbetween). if something is drawing cuirrent then remove a fuse and see what happens. this way you should find the culprit circuit. In old cars like that it's usually a radio/clock or interior lights stuck in on position. And if something is drawing energy (like a radio) and the connection inbetween is bad then it will use even more.

 

If you wanted to measure just the amp draw of the radio while its running you can't do that from the battery because that's the root source it powers all systems so you don't know which one you're measuring and depending on whats running amp draw could be up around 30+ amps (way more than a simple multi meter can read with the inline test method)

To measure a single systems amp draw disconnect the power lead from that device Then one end of meter goes to the lead the other end goes to the post that lead connected to you use the meter to make the circuit. Most multi meters can only read up to 10 amps so make sure you dont test something with more than that. You should be safe with testing the head unit.

-Gun

 

good advice , gents. Anything more than 500 milliamp should be considered as a drain. Less than that will kill a battery if it sits for a while.

 

I dont usually drive at night but I did notice today that my interior lights will do that. It did crank up today after letting it charge for about 20 minutes yesterday after it wouldnt crank.

 

I bought a digital multimeter tonight for $17. My lights wont even come on anymore but I was just messing around and my battery showed 5.3 I even tested my dd to see what it read and it was 12.96 (it would jump around when the terminals got a better connection with the post). Btw, I took my battery to an auto parts store about 2 weeks back and they said it tested: Replace. I didnt buy a new one yet because if something wasnt charging it or if something was draining it wouldnt it test bad anyway? If something is draining it or its the altenator and I get it corrected wont the battery get charged back up and be okay?

What would I need to do to start checking to see if the battery or altenator is bad and/or if something is draining it?

If I crank the car and pulled the + post off and the car continued to run wouldnt that mean the alternator is good and bad if the car cuts off? I heard I could do that to check the alternator..

I know I would want to have it on the 12v -Batt to check the battery but what would I want to have it on to check to make sure nothing is draining it while everything is off? Would I want to have it on AC or DC? I have never used a vm

Sorry for all the questions.

 

Okay, I connected one terminal to the post and the other to the battery cable (with the cable not connected to the post) and the amp reading was 0.05 to 0.06. I then cranked the car and messured the voltage with the cable attached to the post and it was 14.14.

Would this lead me to believe that it is the battey that is bad since its hold a good charge with the car running?

 

Looking at the scales on your meter and your description, that would indicate that you have minimal current drain. The voltage at 14.14 is showing us that the alt and Vreg are working, a little low, but still working. Change the battery!

 

If I have everything off in the car (i even unhooked the radio) would it still even have a minimal drain of 0.05? Would that be enough to kill a battery? I just want to make sure I dont go buying another battery and something killing it to.

 

If you're on the 1 amp scale 0.05 is 50 milliamps. It would take months to drain a battery. Since most batteries are in the hundreds of amp hour ratings for energy content.

Batterys will also self-discharge thru internal resistnce in the design so no battery is going to last charged for an idefinate amount of time. Based on what you've told us, your safe in buying anew battery. if you don't dirve your car often either start it every couple of weeks or pull the pos cable end off for storage and then 1every month or so connect it back up and start the car and rechage the battery.
jlg

 

10-4.

Thanks for all the help. I am def. glad I spent the $20 on a multimeter to be sure.