Charging issue...

[supraman7mgte]

Well I got some issues with my supra.
It seems that I have a draw on my charging system somewhere,or my alt is crap.
And sometimes when at a stop light,the voltmeter will drop around 10 volts.I roll down the windows and it g o e s s l o w ........
I had a high amp alt installed,and thought it might be the problem,so I installed the origional back in. Same issues.
I can leave the car for a few days and come back to a dead battery.:cry:

 

[mkiii222]

I can leave the car for a few days and come back to a dead battery.:cry:

Find the source of this problem and you should be set.

First I'd replace the fusible link, it's in the fuse box behind the battery and is bolted in from the bottom so don't yank it. For less than $5 and all the trouble a 'halfway dead' one can cause it's good maintenance anyway.

After that I'd check for draw.
Aftermarket alarm? Shorting out somewhere? gone bad?
Aftermarket radio/amp/sub... Disconnect amp wire from the battery for a couple days and see if you still have the problem.
Any other grounds look bad?

 

[92TealSupra]

You may want to check circuits of the car after everything is turned off. See if anything is making a draw. Fuseable links should not be bad - those are made to blow not having drawing issues. By the way a fusesble link does not pull energy to make something work, it just is there incase you have a huge surge of energy. Check your wires in the engine bay. Make sure there are no wires exposed. Main things to check Would be componets that are directly related to the charging system.

 

[Neil W]

It's really easy to pull off one battery cable, and connect it in series with an amp meter. More than 10A will burn most multi-meters so if the reading is 10 or more, don't hold it on for long.

If you have no current flow, or very little, your problem lies elsewhere. From what you are saying it sounds more like a bad alternator ground anyway.

 

[mkiii222]

By the way a fusesble link does not pull energy to make something work, it just is there incase you have a huge surge of energy.

I said replace the link, then check for draw. Not replace the link because of draw. It's more common to have a bad link or ground than it is to have draw in a stock car. If it's got aftermarket electronics, then draw could easily be a problem.

Fusible link can be damaged enough to cause charging problems without being visibly blown. If you don't think this can cause a problem, search a little.

 

[92TealSupra]

I said replace the link, then check for draw. Not replace the link because of draw. It's more common to have a bad link or ground than it is to have draw in a stock car. If it's got aftermarket electronics, then draw could easily be a problem.

Fusible link can be damaged enough to cause charging problems without being visibly blown. If you don't think this can cause a problem, search a little.

I am saying check the link, not visibly but with a dvom. I am sure the link is expensive I just want him to keep looking before any things get replaced.

 

[mkiii222]

You may want to check circuits of the car after everything is turned off. See if anything is making a draw. Fuseable links should not be bad - those are made to blow not having drawing issues. By the way a fusesble link does not pull energy to make something work, it just is there incase you have a huge surge of energy. Check your wires in the engine bay. Make sure there are no wires exposed. Main things to check Would be componets that are directly related to the charging system.

I am saying check the link, not visibly but with a dvom. I am sure the link is expensive I just want him to keep looking before any things get replaced.

Don't see where you say to check the link. But replacement is less than $5 from any parts store, not expensive considering you get a) a value meal, b) a gallon of gas, or c) a pack of cigarettes, all for roughly the same price these days.

Yes, if he has a meter he should use it, but if he doesn't and doesn't have a friend with one, he's better off replacing the link and knowing it's good before moving on.

 

[supraman7mgte]

Okay,as far as aftermarket electronics,I have a Kenwood head unit connected to a Crutchfield harness that goes to the stock radio harness,I do have 2 amps in back,disconnected at a fuseblock. HKS turbo timer and thats about it.
If it was a bad fuseable link,would my car start and run at all?
The link is to provide power from the alt to the battery,right?
And yes,I do have a meter,just trying to figure this out before tearing into my car.
The starter works fine,everything else electrically has been untouched.

 

[92TealSupra]

Don't see where you say to check the link. But replacement is less than $5 from any parts store, not expensive considering you get a) a value meal, b) a gallon of gas, or c) a pack of cigarettes, all for roughly the same price these days.

Yes, if he has a meter he should use it, but if he doesn't and doesn't have a friend with one, he's better off replacing the link and knowing it's good before moving on.

The fuseable links come in different types, and wouldn't you think he should know what one to get, also why spend $5.00 when the problem could easily locate the "real" issue. When posting you're suppose to point out many issues and where to start. It's never good to put people on a jouney just to find out the problem was simple.




Now about this problem, take the battery off the car and check the voltage come back in 5 hours and check it. Make sure you do not have a bad battery.

 

[92TealSupra]

Has your battery been checked? - and yes if your link is broken then yes you can't start your car.

 

[tlo86]

bad/old grounds?

 

[mkiii222]

and yes if your link is broken then yes you can't start your car.

If you're going to attack someone for trying to help, at least give correct advice when you try to help.

I'm sort of making an assumption that the battery has been checked if he has to take it to get charged as most places will run a check and tell you the battery is dead when they charge it.

Just in case though, SM7M, when you said you come back to a dead battery, are you taking it somewhere to get charged, or are you just jumping it off? If it's being jumped off, take the battery to a parts store to get checked/charged, and if they give it the OK, then pick up a fusible link (look at yours first as there were a couple different types used).

SM7M:
If the fusible link is dead, the car will still crank and run.
You are right in thinking the FL goes between the Alt and Batt. So you crank on battery power.
FL goes between the alternator and the battery, it blows to protect the battery from a bad alternator that spits out more current than the battery can handle. ($5 fuse blowing is a lot better than a $100+ battery blowing up)

The reason I suspect the FL is the fact that in the first post, you state you had an 'upgraded' alternator on the car. This would have put extra strain on the stock wiring.
You also said in the first post that your VM drops to 10 volts and the windows move slowly which points to it running on battery power, and the battery being weak at that. (is it the stock NA VM or is it part of your radio or turbo timer?)

I'm really thinking your FL has a hairline crack. Not enough juice to 'jump the gap' at idle, but when the alt provides more power, it's making it through.

Does your voltage go up over 12 at all? You should see 13.5+ only if it's coming from the alternator.

 

[supraman7mgte]

I have 2 batteries,1 red top Optima and 1 yellow top.
I'm going to take the higher amp alt to get tested just for shits and giggles. Like I stated,I put back in the og alt,and had the same prob.
Just started the car,it was charging at 14.5v according to the display on the HKS meter.
Can anyone tell me how to set my multimeter to check for current draw?

 

[xarewhyayen]

I wouldnt try to check for current draw with your multimeter, you'll likely blow the fuse, and its only one small part of what you need to know.

just take it to a shop and have them use a VAT machine to test everything. It doesn't cost much and you'll know its right. We charge 29.99 to do a complete starting and charging system check. Checks Alternator output and diode condition, Battery load test, Starter draw test, and sitting amperage draw.

 

[supraman7mgte]

Thanks!

 

[mkiii222]

That MM would be fine for testing current draw when the car is off. Set it on A DC 20 (I'm assuming you know which one is DC with a meter like that). Unless something is really wrong with your car it won't draw more than 20A with everything turned off. Just disconnect the positive battery cable and red wire to pos post, black wire to pos cable. If you see more than 1 amp you've likely got a bad piece of electronics or wiring somewhere. Trace it down by doing the same test but with different fuses pulled and see when it drops.

Getting 14+ Volts, it sounds like the Alt is fine. Especially since you have 2 different alternators and get the same problem on both. It's unlikely that 2 different Optima batteries went dead, but it is possible. I've had my red top going on 4 years and can leave the parking lights on overnight and still start the car 10 hours later.

The TSRM (section CH p2) recommends checking things in this order:
1) Belts (slipping belt can cause alt to run too slow to provide proper charging amperage)
2) Loose/Corroded Battery Cables
3) Blown Fuse
4) Fusible Link
5) IC regulator/Alternator
6) Other wiring

I get conflictng ideas based on your OP. Leave car for a few days and come back to dead batt suggests draw while the car is off. But, 10V while at idle suggests either dead battery or alternator (or fusible link).

 

[Neil W]

I wouldnt try to check for current draw with your multimeter, you'll likely blow the fuse, and its only one small part of what you need to know.

just take it to a shop and have them use a VAT machine to test everything. It doesn't cost much and you'll know its right. We charge 29.99 to do a complete starting and charging system check. Checks Alternator output and diode condition, Battery load test, Starter draw test, and sitting amperage draw.

Or you could use your multimeter to test your power off draw, and your alternator voltage output. If you really care you could take your 29.99 and buy your own battery load tester, but a power off voltage test is usually sufficient.

I think if you wanted to, you could answer every question that comes up here with "take it to the shop, then you know for sure". But don't forget the "watch out for people trying to sell you stuff you don't need". I would rather check the thing myself, and then I really do know for sure.