mystery544

So I tried what you said - checking the amperage, and it showed nothing. There doesn't seem to be a draw anymore. Maybe it was the battery. This makes no sense to me (this is my 3rd battery in a month) but last weekend I redid a lot of wiring. So maybe that plus the battery? I hate electrical stuff

Gun Jam

well does your radio stay powered up?


when you touch the - battery cable to the post do you see a little spark?

Worth1

You're being too critical, no difference between 12.34 and 12.5, you are likely to get a different reading every time you check it. Also someone said it should never go below 13.5 running, and that isn't always true, if it idles too slow for the alternator to keep up with whatever load you are giving it. it can go down to battery voltage or even less. If you kick it up to 1000 to 1200 rpms, it should show a + charge.

mystery544

Radio and lights stay on, it's just too big of a draw for the alternator to keep up. I just checked the battery and it was at 12.06 I might have to go through some more wiring again - my header switch sparked yesterday after I got the car detailed. I don't think they got it wet, and it didn't look like anything was touching wire to metal. And there's no scorching on the switch leads.

I'm honestly thinking about just going and buying a 150 amp or higher alternator

Worth1 - yeah I understand the more it's able to rotate, the better its able to charge and faster as well. I'm pretty happy it's just finally staying in the 12's now

08'MustangDude

I put my A/C on, radio on, lights on, and I don't go below 13.5. It can drop at idle, sure,
not not while driving. I have a digital volt meter to the battery, and it never goes below 13V
even at idle. If you had an underdrive pulley, it will go down to 12.8 idle with all that on.
Whatever, you all can believe what you want to, but continuously being under 13V is bad.

mystery544

Yeah I believe you guys, I just don't know what could make my radio and lights draw so much amperage. It's not draining when it's off anymore, but it could still be a short? I'll try and redo the wiring under the dash tomorrow

Gun Jam

If I take what you give me as fact then we can come to the following conclusions with very high certainty



1) there is very little chance that you could pull more than a 100A alternator would give up (even at 900RPM) without setting the car on fire. So you are almost certainly not exceeding the alternator



2) The battery is charging over 13v the alt and its charging circuit are working and NOT being exceeded. Its normal to see battery voltage slowly drop after the car is shutoff it will sag to is nominal voltage of about 11.9 to 12 pretty quickly even with no parasitic amp draw. it will not hold 13v for long at all.



3) The radio stays powered to keep memory then you have at least some current draw so that should have shown up on your meter. Its set to the wrong scale or test type or wrong test lead positions..ect if its reading zero amps. You can youtube how to test amperage with meter.. your amp draw exceeds zero but we dont know if exceeds normal limits so an issue could be hidden here...we dont know.


If testing amp draw doesnt work for you then I suggest the following options.



1) Blame it on the old battery (this one is new right?) and tell yourself its good to go...technically it checks out good...dice roll on it.


2) check battery voltage each time you go to start it does it start to read much below 12v like 11.5 after 1 day or 11v after 2 days and 10.5v after 3 days of not running? Or does it hang pretty close to the upper 11.8s after a few days? If its the former then its back to the amp meter.


good luck!


-Gun

mystery544

I just checked it after I turned it off and it was down to 11.7 (had to use my headlights on the drive back) - forgot to test while it was on though.

I actually set my radio + fuel pump up on a kill switch, and the kill switch to the ignition because the radio previously was an issue.

When I tested the amp draw (remove the negative, test between the stud and cable) it was 0.

I wonder, if its struggling to charge the battery, could the starter solenoid maybe have something to do with it? All power goes through that right? But at the same time, that doesn't change the fact that something has to be shorting in order to have such a draw?

That being said, I had plugged the voltage regulator back up earlier this week - I'm gonna see about unplugging it and seeing if that does something. (self regulating alternator doesnt need it, but my buddy told me he has his hooked up anyways and to try it)

Gun Jam

okay well if the radio is on a switch and you feel that you did set the meter up right yes I can believe that there is no amp draw..its plausible.


the battery cables are new and clean yes? and they are tight to the battery yes...you cant wiggle them?


I run the same alternator its a good piece of equipment.


I was curious about this my car has the radio hooked up and has been sitting for a bit over 24hrs (which is rare) I have 12.7v but I also run an AGM deep cycle.


11.7 is quite low after having just been driven so yes I agree there is an issue here.


but you said you get 14+v in a previous post. If you turn the radio on and the headlights on and the map lights on and stand on the brake do you still get 14v at 1000 rpm or more? You should if you dont this would be an indication of corrosion or a poor connection like a loose ground cable or strap not necessarily a bad alternator ( o really? autoparts can check the alt for you...but thats not likley the issue)


It seems like the issue is either intermittent or load based for example it makes 14v when it just runs the ignition but when you demand 20 or 30 amps from it the charging circuit falls on its face.



so test the voltage at just above idle with all the stuff running like I mentioned...still 14v??

mystery544

I tried it this morning after my car died last night. It seems that the alternator stopped charging (even with all the lights and radio off). It wouldn't go higher than 11.16 even when revving it up. I replaced the ground cable 5o the battery in case that was the issue. It didn't help.. Maybe that diode mentioned before? I noticed when starting the car there's a surge that caused both blinkers to flash on, I'm wondering if there's a bad ground in my dash, but I doubt that would cause the charging issue