Optima battery alternative.

[turbostang]

Well, it seems my charging problem is self inflicted and no fault of the batteries.

Since my car was completely rewired, somehow I've managed to fuck up the alternator wiring and I'm not quite sure what's happening there.

The batteries took a charge using pep boys' nuclear powered charger. No dead cells, passed a load test fine etc. The alternator shows 14.2V out the back stud, and tested fine on the bench... but only 12.2V at the battery. (charge wire directly connected). I've replaced the charge wire, redone the ends, and tested about every way possbile. Since my car doesn't have the stock voltage guage, I've put a 560ohm resistor inline to simulate the guage - which seems to have made no difference.

The only thing I can think of is that the ground on the frame isn't adequate..

[green1995gt]

Well, it seems my charging problem is self inflicted and no fault of the batteries.

Since my car was completely rewired, somehow I've managed to fuck up the alternator wiring and I'm not quite sure what's happening there.

The batteries took a charge using pep boys' nuclear powered charger. No dead cells, passed a load test fine etc. The alternator shows 14.2V out the back stud, and tested fine on the bench... but only 12.2V at the battery. (charge wire directly connected). I've replaced the charge wire, redone the ends, and tested about every way possbile. Since my car doesn't have the stock voltage guage, I've put a 560ohm resistor inline to simulate the guage - which seems to have made no difference.

The only thing I can think of is that the ground on the frame isn't adequate..

Add more grounds!!!
bigger to frame and an extra from block to frame.

[sspstang]

Well, it seems my charging problem is self inflicted and no fault of the batteries.

Since my car was completely rewired, somehow I've managed to fuck up the alternator wiring and I'm not quite sure what's happening there.

The batteries took a charge using pep boys' nuclear powered charger. No dead cells, passed a load test fine etc. The alternator shows 14.2V out the back stud, and tested fine on the bench... but only 12.2V at the battery. (charge wire directly connected). I've replaced the charge wire, redone the ends, and tested about every way possbile. Since my car doesn't have the stock voltage guage, I've put a 560ohm resistor inline to simulate the guage - which seems to have made no difference.

The only thing I can think of is that the ground on the frame isn't adequate..

I have a aftermarket ground strap kit, The smaller one is missing but the rest of the kit is there. If you are interested.

[Acrotom]

Turbostang,

The difference in voltage between the alternator post and the battery terminal brings up two likely possibilities:

1). The wire from the alternator post to the battery positve terminal has a high resistance (causing the 2volt drop), or

2). The resistance in the ground path is high.

It sounds like you have already eliminated cause #1, so #2 is probably the problem.

Many gremlins in electrical systems are caused by inadequate grounds. I have found that the best way to eliminate ground problems is to run large ground cables from the negative battery terminal to the engine block, frame, and body.

It may sound like overkill, but three different cables to the negative battery terminal from engine, frame, and body will ensure that the ground potential is uniform throughout the car.

Doing this ensures that you are using high quality copper conductors for the current return path, and not relying on the steel in the frame and body.

It's also good practice to connect a cable from each cylinder head to the ground cable leading to the battery - spark energy needs a good return path, too.

A lot of people get by with using the frame, or roll cage, or body to complete the circuit back to the negative battery terminal, but sometimes it just doesn't cut it.

Good luck,

Tom

[turbostang]

Turbostang,

The difference in voltage between the alternator post and the battery terminal brings up two likely possibilities:

1). The wire from the alternator post to the battery positve terminal has a high resistance (causing the 2volt drop), or

2). The resistance in the ground path is high.

It sounds like you have already eliminated cause #1, so #2 is probably the problem.

Many gremlins in electrical systems are caused by inadequate grounds. I have found that the best way to eliminate ground problems is to run large ground cables from the negative battery terminal to the engine block, frame, and body.

It may sound like overkill, but three different cables to the negative battery terminal from engine, frame, and body will ensure that the ground potential is uniform throughout the car.

Doing this ensures that you are using high quality copper conductors for the current return path, and not relying on the steel in the frame and body.

It's also good practice to connect a cable from each cylinder head to the ground cable leading to the battery - spark energy needs a good return path, too.

A lot of people get by with using the frame, or roll cage, or body to complete the circuit back to the negative battery terminal, but sometimes it just doesn't cut it.

Good luck,

Tom

Thanks for the input Tom, I'm relatively sure your #2 is the culprit. I've tested the voltage drop with two different wires, and two different sets of ends on each wire... I'll know more later tonight..and update the build thread... after that, i'll get it bck on the dyno.

[Rustang]

I don't know how much of the factory harness is there, but don't forget there is a fusible link in there too. It just looks like a piece of wire, but can cause the problem if popped. You would show full charge at the alt, but only battery voltage at the other end.

[turbostang]

For the records, I added a ground strap from the block to the factory sway bar mount. (ground down to metal etc..) I also re-cleaned the ground point from the battery cable where it connects to the frame (in the back of the car).

This was a definite improvement, but still not 100%. Now, idleing, it's showing 13V at the battery, where before, it showed 12.2V.

If I check the power lug on the back of the alternator, it's 14.3V when grounded to the alternator case. So, it appears there's still a ground issue somewhere. Likely still on the battery's end. Tonight I'll add one more ground from the battery to the body and see how that does.

[Rustang]

Do you still have 14.3 at the lug if you ground the meter to the frame or other grounds? If not, alt ground is bad. Positive wire from alt to battery could still be a problem.

[line-em-up]

...

Just test the voltage along the path from the alternator to the battery to see where it is dropping at. I would suspect maybe the ignition switch, relay or connection point.

I would also test the voltage between the positive battery terminal and the alternator output terminal. Then test from the negative battery trminal to the alternator housing to see if the voltage is dropping on the + or - side of the circuit.

[turbostang]

Just test the voltage along the path from the alternator to the battery to see where it is dropping at. I would suspect maybe the ignition switch, relay or connection point.

I would also test the voltage between the positive battery terminal and the alternator output terminal. Then test from the negative battery trminal to the alternator housing to see if the voltage is dropping on the + or - side of the circuit.

My car doesn't have stock wiring in it, so it's not going through the ign switch - technically, stock wiring doesn't either. Only the exciter wire does. The big black/orange wires go straight to the starter solenoid.

in my case, it's one big red 4 guage wire that goes all the way back to the cutoff switch (on the battery's side).

The wire is new and tests fine, the alternator stud shows 14.3V tested at teh frame and the alternator case. Before, the battery showed 12.2V idling, grounded to the trunk floor and battery terminal. Now, it's 13.0V idling grounded at both places. It's definitely ground related as evident of the voltage improving after adding a ground strap at the head.

Next, the last part, will be adding a ground wire from the battery negative side to the body/floor/sheetmetal.

[kingjason]

When you do need another battery get a Die Hard Platinum. The are re badged oddysey dry cells. My die hard gold was nine years old in my Jeep and just started to taper off when it would dip into the 20's. The new Platinum makes it sound like I put two in there.

[VaderTT]

I had a braile racing battery that I used in 4 different e36 bmws that worked great, it only died when the last car was wrecked.

[8mpg]

I know you dont need it....but the Die Hard Platinum AGM batteries are on sale (30% off):

coupon code: SEARS2012

[turbostang]

Nice, thanks for the heads up Tim.

After some additional trouble shooting last night, it appears that my alternator is spent.

Now, after the additional grounds - it at least references voltage correctly, at the end of the alternator charge wire. It's seeing 12.8V with everything on (One Taurus fan, one electric trans cooler fan, ECU, fuel pump, lights etc.)

I ran an additional power wire just to test, and it added .3V to the overall measured voltage at the battery.

I'll likely test this alternator again, and sell it with my other good optima battery. I have a new 250A alternator on the way.