Electrical-Battery Dilema

[Super_Dave]

Here is the history: (I am like Sgt. Schultz on Hogan's Hero's... "I know nothing, nothing!" - about electrical)

Project: BABA YAGA! (Can be viewed in my signature)
1. Newly professionally built 355 SBC.
2. New one wire alternator.
3. Electrical was fine for the past two years.
4. Four weeks ago battery was stone cold dead.
5. Checked battery and found the Hot terminal cable 3/4 of the way unbolted.
6. Tightened cable... truck fired right up. Weird. Almost like someone was trying to steal it.
7. Two weeks ago, had a new stereo professionally installed.
8. During installation, the new alternator was cranking 18 AMPs!
9. One week ago, battery was stone cold dead.
10. Checked cables and they were tight.
11. Checked date on the battery and found it to be 6 years old.
12. Replaced old battery with a new 800 AMP unit from NAPA. Truck cranked right up.
13. Yesterday, new battery was stone cold dead.
14. Jumped the battery and drove to the stereo shop and asked them to triple check their installation for any wiring that would drain my battery.
15. They disconnected the stereo to see if it would drain again over a couple days.
16. They checked the alternator and it was cranking normal AMPs. Assumed the 18 AMP reading on the old battery was because of the old battery was extremely low on water.
17. Drove the truck around on Saturday without incident.
18. Today - Sunday - had a buddy who does body work stop by. Tried to fire the engine and the new battery was stone cold dead.

So... something is draining the battery. I don't think it's the disconnected stereo, as the issue did seem to start before the stereo and with the old battery but still ran fine for a few weeks after the initial incident.

Could the alternator not be charging the battery even though it was reading around 14 AMPs on Saturday? Does it sound like the new alternator is bad?

I will hook up the battery to a trickle charger and see how it does over a few days. It might not have gotten enough of a recharge from driving around on Saturday, but it did start every time I fired it up throughout Saturday, so I don;'t think that was the issue... really confused at the moment.

I am getting a new, complete harness and hope it will solve the issue but it will be a few weeks, so I would like to try and trace down the issue.

Any thoughts, suggestions etc. are GREATLY appreciated.

[kwmech]

The diode pack in the alt may be going out. What is the amp rating on the alternator? I think at the minimum a 1 wire alternator would be at least 65+ amps

[Super_Dave]

Originally Posted by kwmech

The diode pack in the alt may be going out. What is the amp rating on the alternator? I think at the minimum a 1 wire alternator would be at least 65+ amps

Is this reparable or should I be looking to get another alternator. I have also been experiencing slow wipers when idling or going slow. Once I speed up they reach their normal rate. I was told by a repair shop that it could be the voltage regulator or bridge rectifier. Parts are available but given this alternator has less than 3K miles in two years on it (and is out of warranty) and is having issues, I might as well pony up for a new one.

Do you think all these issues could be interrelated?

[VetteVet]

Do a key off drain check.
Get a test light and remove the negative battery cable, connect one end of it to the negative post on the battery and the other end to the negative cable. Make sure all the truck lights are off especially the interior lights.

Does the light come on?

If it does, disconnect the large wire on the back of the alternator. Light on or off? If the light goes off then the alternator is draining the battery.

If it doesn't go off then start looking for a stereo wire that's still connected.

[Super_Dave]

Originally Posted by VetteVet

Do a key off drain check.
Get a test light and remove the negative battery cable, connect one end of it to the negative post on the battery and the other end to the negative cable. Make sure all the truck lights are off especially the interior lights.

Does the light come on?

If it does, disconnect the large wire on the back of the alternator. Light on or off? If the light goes off then the alternator is draining the battery.

If it doesn't go off then start looking for a stereo wire that's still connected.

I assume I need to have the battery charged to do this, correct? Interestingly, I had just downloaded the info on doing this test from the sticky section...

Also, see my questions above about other potential alternator issues... your thoughts?

[VetteVet]

Originally Posted by Super_Dave

Is this reparable or should I be looking to get another alternator. I have also been experiencing slow wipers when idling or going slow. Once I speed up they reach their normal rate. I was told by a repair shop that it could be the voltage regulator or bridge rectifier. Parts are available but given this alternator has less than 3K miles in two years on it (and is out of warranty) and is having issues, I might as well pony up for a new one.

This is one of the fallacies of the one-wires, they have poor voltage sensing abilities. Where do you have the large red wire from the alternator connected? If it's right to the battery then your alternator could be missing the voltage drop sensing that occurs downstream in the circuits. This means that you may only be pushing 10 volts into the wiper circuits and possibly the headlights at idle. When you speed up the alternator increases output and the voltage drop lessens so the wipers get 12 volts.

Do you think all these issues could be interrelated?

Originally Posted by Super_Dave

I assume I need to have the battery charged to do this, correct? Interestingly, I had just downloaded the info on doing this test from the sticky section...

It will show a drain much better if it's fully charged

Also, see my questions above about other potential alternator issues... your thoughts?

If you do decide to get a new alternator, get a 12 SI or a CS 144 and I'll show you how to hook them up.

[Super_Dave]

Originally Posted by VetteVet

This is one of the fallacies of the one-wires, they have poor voltage sensing abilities. Where do you have the large red wire from the alternator connected? If it's right to the battery then your alternator could be missing the voltage drop sensing that occurs downstream in the circuits. This means that you may only be pushing 10 volts into the wiper circuits and possibly the headlights at idle. When you speed up the alternator increases output and the voltage drop lessens so the wipers get 12 volts.

Well, I was WRONG! I have a two/three wire (Red, Brown and Yellow) coming out of the alternator (I believe it's a 10SI). The Red wire (and other two as well) runs from the back of the alternator, behind the HEI and into the cab through the main wire loom hole.

The battery has a second ground wire (small black) that goes from the (-) terminal, around the battery and to the core support.

So how does this change the landscape?

Originally Posted by VetteVet

If you do decide to get a new alternator, get a 12 SI or a CS 144 and I'll show you how to hook them up.

Thanks for the assist!

[Super_Dave]

Okay... here is what I have to date:

Battery Readings:

11AM

Engine OFF: 12.3
Engine ON-Idle: 13.6
Engine ON-RPM: 15.6

Alternator Readings:(LOAD meaning several electrical components -lights, heat, etc... are turned on)
NEGATIVE: (Negative Terminal to Alt. Case)
Ground Side: Load at Idle: .03
Ground Side: Load at RPM: .09
(Seems the resistance is too high, especially under load?)

POSITIVE: (Positive Terminal to Alt. Positive on back of Case)
Positive Side: Load at Idle: .20
Positive Side: Load at RPM: .60
(Again, it seems the resistance is too high on both tests?)

Battery Readings:

3PM (After Battery Charged for 2 hrs.)

Engine OFF:12.56
Engine ON-Idle:13
Engine ON-RPM:13.6

Alternator Readings:
NEGATIVE:(Negative Terminal to Alt. Case)
Ground Side Load at Idle: .02
Ground Side: Load at RPM: .03
(Now appears normal under load?)

POSITIVE: (Positive Terminal to Alt. Positive on back of Case)

Positive Side: Load at Idle: .2+
Positive Side: Load at RPM: .2+
(Now appears normal under load?)

Battery Readings:

4PM (After the 3PM Tests)

Engine OFF:12.7
Engine ON-Idle:14.7
Engine ON-RPM:15.6

5:30PM (After another 1.5hrs on charger)

Engine OFF: 13.56 AMPs (Still on charger)

7PM

Engine OFF: 14.3 AMPs (Still on charger... needle reading '6')

===================================

I put the charger on the Battery because the initial reading when the truck was off was: 12.14v
After 2 hours on the charger, the needle had moved from 8 to about 6, so I did another set of tests and got the 3PM numbers.
After the 3PM tests I ran the Battery and Voltage Drop tests again and got the 4PM numbers and put the charger back on and the needle was all the way to 8 again.
I just went back out and checked the battery again and and got the 5:30PM Battery reading and the charger needle is down to 7.

So, given this new info, I am not sure I really have a parasitic draw when everything is turned off? Also, why does the battery charger show that the battery is a long way from 100% even at 13.56 Volts?

I know only what I have read and watched on YouNoobTube... but it seems that the Alternator might be fine, and the Battery is new, so do I have connection-ground issues somewhere?
I really need to solve this to get the project back on schedule.

[VetteVet]

I'm not sure how valid those tests are with the engine running and the alternator charging.
The variables aren't that far off. As to the battery with the engine running you are going to read whatever the alternator is putting out not the state of charge of the battery.

The battery when charged fully will read over the max voltage into the 13s because the charger will put a surface charge on it and after a short while it will drop back to the normal reading.

I don't see any way you can pinpoint a battery drain by testing it like you have unless you had seen a voltage drop of more than 2 volts somewhere.

The small wire off the negative cable is the radiator shroud and should go to the sheet metal in front of the battery. It provides ground for the front lights.

I re-read your posts and didn't see what year truck we are working with.

[Super_Dave]

Originally Posted by VetteVet

I'm not sure how valid those tests are with the engine running and the alternator charging.

Should I test with the engine off? What and How? The vid's I watched showed them with it running. I will do whatever I need to do to get the accurate numbers. What do you suggest?

Originally Posted by VetteVet

The battery when charged fully will read over the max voltage into the 13s because the charger will put a surface charge on it and after a short while it will drop back to the normal reading.

Should I just take it off the charger?

Originally Posted by VetteVet

I re-read your posts and didn't see what year truck we are working with.

It's a 1974 C20

[VetteVet]

Your readings indicate that the alternator is charging OK so now you have to find out if you have a drain on the battery. Since you have a meter, take the negative terminal off the battery and connect the meter leads between the negative post and the negative cable with the meter on amps. 10 amps is the setting to use.

Make sure there are no loads on the system, lights, radio, memorys, etc.
You should read not more than .004 milliamps. Or .4 amps .002 would be best but you probably wouldn't kill the battery at .4.

If you get more than that you'll have to find the drain by isolating the circuits.
It's a key off drain so it shouldn't be hard to find. The alternator is the first culprit. Take the reading and post back and we'll go from there.

[Super_Dave]

Originally Posted by VetteVet

Make sure there are no loads on the system, lights, radio, memorys, etc.
You should read not more than .004 milliamps. Or .4 amps .002 would be best but you probably wouldn't kill the battery at .4.

If you get more than that you'll have to find the drain by isolating the circuits.
It's a key off drain so it shouldn't be hard to find. The alternator is the first culprit. Take the reading and post back and we'll go from there.

Okay...
Battery is at 12.5+ volts after sitting overnight.
The negative draw between the cable and post under no load conditions is .52

[VetteVet]

Originally Posted by Super_Dave

Okay...
Battery is at 12.5+ volts after sitting overnight.
If it was disconnected then that is good and if it was connected then that is still good but it should have been lower because that is too much draw.


The negative draw between the cable and post under no load conditions is .52

That's too much, so you have a drain, so the first step is to reconnect the meter the same way, and watch it as you pull the alternator plug. Does it get smaller?
If not check the white wire in the plug for voltage. Key off zero-key on 12 volts.
If it checks then disconnect the large red wire on the back of the alternator.
Does the amp draw get smaller?

Post back.

[Super_Dave]

Originally Posted by VetteVet

That's too much, so you have a drain, so the first step is to reconnect the meter the same way, and watch it as you pull the alternator plug. Does it get smaller?
If not check the white wire in the plug for voltage. Key off zero-key on 12 volts.
If it checks then disconnect the large red wire on the back of the alternator.
Does the amp draw get smaller?

Post back.

Just got back from putting new wheels and tires on BABA YAGA!

Here are the numbers:

Checked the Negative Draw Key Off before disconnecting the plug = .44
Checked the Negative Draw Key Off after disconnecting the plug = .44

Alt. Plug - Yellow Wire - Key Off = 12.95
Alt. Plug - Yellow Wire - Key On = 12.91

Alt. Plug - Brown Wire - Key Off = 12.95
Alt. Plug - Brown Wire - Key On = 12.91

Checked the Negative Draw Key Off - Red Wire Off - Alt. Plug Out = .5+
Checked the Negative Draw Key Off - Red Wire Off - Alt. Plug In = .5+

[Dead Parrot]

If you can, get an assistant to watch the meter. Connect the meter to measure your negative draw. Start pulling fuses one at a time. Check the meter between each fuse pull. Replace each fuse after each meter check. I would start with all fuses related to the new stereo. Hopefully, you will find one that when pulled, will have the meter go to near zero. If so, then something on that circuit is your problem.

Make sure you have a few extra fuses just in case one breaks or flips somewhere and vanishes from the known universe.

[Super_Dave]

Originally Posted by Dead Parrot

If you can, get an assistant to watch the meter. Connect the meter to measure your negative draw. Start pulling fuses one at a time. Check the meter between each fuse pull. Replace each fuse after each meter check. I would start with all fuses related to the new stereo. Hopefully, you will find one that when pulled, will have the meter go to near zero. If so, then something on that circuit is your problem.

Make sure you have a few extra fuses just in case one breaks or flips somewhere and vanishes from the known universe.

Sounds like a job for Super Wife!

I am easily confused when it comes to electrical... clearly. I stopped by my racing buddy's carb and tune up shop to chat and we touched on this issue. He grabbed his metering and diagnostic tools and did the same tests I was doing. He said he could not detect anything wrong.... Hummmm, maybe my NAPA meter is on crack?

I am wondering if, after the initial dead battery before pulling the stereo, I didn't charge the battery enough driving around on Saturday, so that's why it was dead Sunday afternoon?

That and my crack-head NAPA meter is not reading properly or my crack-headed self was using the crack-head NAPA meter wrong?

It has not had any discharge issues since Sunday... Maybe I should check myself and my crack-head NAPA meter into rehab...

[Super_Dave]

Well, BABA YAGA! got the 700r4 installed but upon starting the truck to break in the trans and dial in the speedo, the 355 would not keep running and would choke itself out. Then the wiring harness on the firewall started smoking... so it was towed to the race shop and a new, complete AAW CLassic Upgrade Harness is on the way, along with a new 87-91 Blazer 25 gallon tank to replace the spare tire carrier.

Needless to say, I have a better than average chance of solving the initial issue and isolating whether the ALT is the problem. It's a God Thing that the old gas tank polluted the filters and idle mixture screw seats... otherwise I might have been sitting on the side of the road watching BABA YAGA! burn to the round. Made me re-prioritize my project schedule.

[Super_Dave]

Had a local CL "Restoration Shop" (saw photos of 'Ace's' work... not what you would call restoration) respond to my request for installing a made-to-order AAW Harness... wanted more than what it cost to R&R my TH350 with a custom built 500HP capable 700r4!

Another shop quoted 75% less but wants the truck for at least 2-4 weeks. You betcha chief...