Car will ONLY start while getting juice from another battery

Not sure how to word it sorry.

98 sunfire 2.2L

Basically the only way we can get my car to start is by hooking another battery up to it. Like, we plugged the tractor's battery up to it as we were going to jump it, but we didn't turn the tractor on. Then my car would start. The second we take the jumper cables off my battery it will die though. One time it did hold a charge for a minute or two before shutting off.

Also, my battery light is constantly on, even when hooked up to another battery, like the tractor one.

We replaced the alternator today (got a brand new one) thinking that was the problem but still no dice.

What else could it be? Could it be my battery that's less than 7-8 months old? It shows 11 volts when we put the meter on it. The new alternator is also showing that it's getting charge.

Thanks.

My batteries show 12.7v-12.8v when not running. Sure you dont have a dead cell in your battery?

Is there anyway to check if there is a dead cell?

Starting to think it may be a corroded battery wire. I really hope that's the case. Gonna mess with it tomorrow, an alternator swap has turned into an 8 hour day.

fully charged battery should be 12.66 volts.2.11 volts per cell on a 12v battery.you could check each cell voltage with a digital multimeter and a junk set of leads.also check specific gravity of each cell.I would have battery load tested.autozone and advance auto does this for free.

Obviously, the battery is run down, because the alternator is not charging......when a battery is really discharged, you do not recharge it by jumping and starting the car, and making the alternator work overtime trying to recharge it....

A fully charged battery should be 12.6 volts......so have the 7 month battery fully recharged first......now start the car.....should easily crank and start with a fully charged battery....now check alternator output......If below 12.6 volts, that new alternator is not charging......

Assuming the new one is good, one of two things......the large read cable on the back of the alternator is protected by a fuseable link.....it could be open.....

Also the harness connector to the alternator could have a bad connection in the harness connector(won't "turn on" the alternator), or the wire(s) to the harness is/are open.....

Alright, we checked the read cable and I believe it is not open. My battery is showing 10.7 volts I believe so it doesn't provide enough juice to start my car. We took the battery to a shop today and they said the battery was fine. Have to get a charger from someone tomorrow so we can charge the battery.

I've got some pictures this time around. Basically to get the car started, we bring the tractor next to the car. Connect the jumper cables to the tractor's battery and then connect the other end of the jumper cables to my battery cables w/o a battery in my car - http://i.imgur.com/2DtLSAu.jpg

The car will start off the tractor's battery. If I turn my headlights on, and rev the engine up a bit, my alternator still won't get any charge and that's what concerns me. The alternator will sit at 11.7 or so volts no matter how much revving or turning on headlights I do. Could this be because my battery cables are not making direct contact with a battery and are being jerry-rigged via jumper cables? That's what I've tried to tell my grandpa but he thinks everything should be fine while hooked up to his battery in the tractor via jumper cables (he's probably right, but I like to make sure).

Also, my grandpa thinks the problem is with this box - http://i.imgur.com/URM88rP.jpg Particularly with BATT1 and BATT2. He thinks something is jacked up in that box. Also, if you notice where it says GEN 10A in the diagram, there is no fuse where there should be (perhaps that's for a different model?). It would be really nice to know if this panel of fuses and whatnot is not causing any problems because my grandpa won't leave that alone and thinks that's the real issue.

Here's some pics of the alternator, maybe we didn't check the fuselink and caps and whatnot correctly.

http://i.imgur.com/Lbgelhc.jpg
http://i.imgur.com/OBGy7BH.jpg

Sorry for typing so much. This issue is really frustrating, thanks for the advice so far and thanks for reading.

Do you have another connector on the back of the alternator? Most have an "exciter wire" to tell the alternator when it should charge. And 2nd wire going to the gauge. I mention this because of your "batt light" on. Normally indicating "no charge". Hard to see on your pics.

Check out this video. Look at the connector and the wiring. Those are the wires I am referring to. around the 1:50 mark

http://www.youtube.com/watch?v=FF-FD8-T1Gg

You can see the control wire harness in the first picture.....

Let's check out the the large red cable first.......with car not running, attach a grounded test light to the positive battery cable....should be bright......now touch the large red cable nut on the back of the alternator.....should be the same brightness.....if it isn't, or doesn't light, check the fuseable link.....

The control harness(exciter harness) has two wires coming from the PCM which controls the output of the alternator.....

My fault for taking the badly angled picture. The exciter wire harness is connected and properly on there. We rechecked both that and the red cable connected to that bolt going into the alternator.

Really confused as to where the fuseable link is. I guess my grandpa will know what it is.

Will have to go buy a ground test light. We don't have one.

Thanks.

Link is usually attached at the starter......

Didn't get to test anything today. We do have a ground test light. Going to mess with it tomorrow hopefully.

You can see the control wire harness in the first picture.....

Let's check out the the large red cable first.......with car not running, attach a grounded test light to the positive battery cable....should be bright......now touch the large red cable nut on the back of the alternator.....should be the same brightness.....if it isn't, or doesn't light, check the fuseable link.....

The control harness(exciter harness) has two wires coming from the PCM which controls the output of the alternator.....

Brand new alternator(not used, it's straight up new and cost almost $200) was not getting any juice when we did the test with the ground test light.

So the fuselink is that small black cover between the small red wire and the small black wire right?

http://i.imgur.com/92az9eS.jpg

I dunno I guess my grandpa didn't have that test light with him but we used a voltmeter to see if the fuselink was getting any power and it was.

This is something that was strange though. With the ground cable screwed in the negative terminal on battery we were getting like 1.5 volts from the battery on the meter. When we unhooked the ground wire and took the screw out and then touched the end of the voltmeter to the battery w/o wire plugged in we got 8 or 9 volts. What's that mean?

Should we check the ends of all the cables in the car for corrosion.

OK, let's start again.......

Did you remove the positive and negative cables from the battery? Were they clean of corrosion? Was there any evidence of the battery leaking(white corrosion) at either connection of the battery? If the bolts were corroded, just replace them.....

Was your battery recharged? After recharging did it start the car?

With the battery connected, what does your voltmeter show across the two terminals?

What does the voltmeter show, when the key is turned to "on"?

What does the voltmeter show when the car is cranking?

If your voltmeter is showing above 12.0 volts, with the key on, turn the vehicle off, remove the key, close the door and have NOTHING on........ground your test light to the negative terminal of BAT, and probe the positive terminal of BAT with the other end....Is it bright?

If yes, now with the test light still grounded to the neg terminal of BAT, probe the RED wire nut going into the back of the alternator.....Do you have the SAME brightness as you had when you had the test light across the battery?

If yes, then with a new alternator that is not charging, you have a problem with the control circuit to the PCM....

If you do not have the same brightness, then you either have a bad fuseable link(yes that is it in the picture), OR the connection at the starter is so bad, that there is a voltage drop due to corrosion......disconnect the negative BAT cable first, and then disconnect the nut at the starter and clean those connections.....then reconnect, and then reconnect BAT cable....recheck with test light.....if still dim or no light at all, replace the fuseable link.....

Thank you for the reply. I've got everything printed out of what you said. I don't know when we'll be able to check these things, we still have to put the alternator back and whatnot. It may even be weeks, summer is busy with garden upkeep. Thanks