My battery will not stay charged. I put on a new alternator, did not help, what else should I look for.

What's the voltage at the battery with the car running ? Testing an not guessing is the way to do proper diagnostic's ! Battery light staying on , is there B+ voltage at the alternator connection's ? A new alternator won't make a bit of difference if no power to the alternator . Looking at a wiring diagram an testing the electrical circuit ,doing voltage drop testing , plus checking for DTC'S - diagnostic trouble code's . Some vehicle's charging systems are computer controlled . And looking at a wiring diagram i see your vehicles charging system is computer controlled . If you have done so already , take it to the dealer

Have you put a meter on the back of the alternator to see if it is putting out voltage but not making it to the battery ?

Maybe it wasn't running long enough to charge up the battery?
Stop trying to jump it, when you are having problems with it dying, take the battery off and have it charged. And/or buy a $20 voltmeter to see what the battery shows. If it says less than 12 volts, it is discharged, and needs charging. A good battery that is not run down should have at least 12.5 volts. A new battery that is charged should have very close to 13 volts, maybe 12.8 volts.
When you have the truck running, check the alternator for charging. You put the voltmeter right on the battery and check it again. This time, with truck running, battery should show at least 13.5 volts. That shows the alternator is working. A good alternator will put out about 13 or 14 volts-the regulator will keep it from going any higher to prevent problems, like a melting battery or electrical parts burning out.
I would say get the charging system working right, then address the problem of dying at stop lights. That could be a carburetor problem, if the alternator is working.

either that cable going to the battery is shorted to ground somewhere (maybe on the body of the alternator) or the alternator is defective. there is a chance that you put one of the wires wrong on the alternator and you are forcing it into full field mode. that is a mode we use to test the full output of an alternator. if an alternator stays on full field too long (more than ten seconds) it could fail.

The alt should charge at around fourteen volls , any ways, yogi need to put another battery. A weak alt will kill a good bat.and vise versa

the battery wont stay charged? if youre putting in a fully charged battery and your car runs, but then the battery slowly dies, the problem will be your alternator. the alternator is what maintains a car batteries charge. try replacing the alternator. hope this helps.

Replace the large wire on the back of the alternator,with a new one,it comes off the back to the positive side of the battery,leave the old one on the alternator.

I am guessing that you put in a new battery drove it for a day at most and went out the next day and it wont start. Well if this is true then you will need an alternator, your battery is not being charged. Your car can start a run without this but you wouldn't get that far and eazy way to figure this out is either charge your battery or have a friend jump, be sure to let it charge for 3-5 min. before trying to start.
If it starts than remove the jumper cables and let the car tun for another 2-3 min and turn it off. If you cant restart it than you will need a new alternator

Check with dealer there are recalls on the 2000.

Mazda Mpv 2000 I also have the same problem, the alternater is testing good- 14.12Amp, so what is the problem the battery light will not go off.