I'm thinking my alternator in my RX7 is just about completely shot. Without running lights, radio, etc about how long can a car run on a fully charged battery alone? I know this is vague, just looking for a ballpark estimate.

 

Take ur alternator belt off and go drive around your neighborhood close to your house, cmon... it'll be fun.

 

Get a DVM & clip it on a convenient place like the cigar lighter.
Use it like a gas gauge.
You should be OK down to around 10 volts.

Be aware that the voltage drop will not be linear.
When it gets down to 10, it will drop off fast.

And carry some jumper cables to recharge/restart it.

 

When my alternator belt died on the highway @ 3 a.m. I made it home on the battery with the headlights. Th distance from when it happened to when I got home was about 5 miles. The car did start to warm up though (alternator belt and water pump belt = same) so I drove a bit faster (80 mph) and coasted as much as I could until I hit about 60 mph to stay off the gas and not generate more heat. When the temps cooled after a few secs from outside air, I got back on the gas at about 80 until they started to creep up a bit. Gauge never got past 1/2. I changed the alternator belt the day after and the car actually started without a batt charge!!

 

15-45 minutes....it depends on the condition of your battery.

 

i went about 25 miles once when i didnt know my alternator belt had come off, when i got to my street the car was losing power pretty fast and was almost done.

 

I went 35 minutes on a new battery when my altenator jumped up to 16V and than to 12V (12V Being the battery reading), and also with the lights on. I was in Montana at the time so I was booking serious *** to get home. It was like 50 miles or so I had to go. I thought for sure I was going to be stuck on the side of the freeway, but to my suprize it made it to the off ramp to were i was living.

SureShot is right, once the voltage meter got to 10V it died, almost instantly.

 

My belt popped twice had to get it replaced each time... but i went about 3-4 miles from ful voltage when it popped the second time.. the first time i had to have it jumpstarted i had to wait til the battery was at 14 to turn it on and drive across town to get it fixed..

You can drive quite a bit when it pops but get it fixed right a way... or risk the lost of power..

 

happened to me once coming from a friends house if at night with lights on and gauges lit prob 5-6 miles but if you drive with lights off 10 miles i ws driving down the highway at 1am with no lights and i just made it home as the car was stalling out.... get it fixed asap i recommend

 

Drove it 30 miles with stereo, A/C, dash lights, headlights, and driving lights all on. Lights were still bright when I pulled into my driveway.

 

one time I broke my alternator belt , and I drove about
half mile and the car die.

 

How did you come to this conclusion? Are your Idiot Lights displaying? Have you brought out your DMM? The Battery will run for a short time before you fully discharge It. This pends on how strong your Battery was to begin with.

 

Coincidentaly, I lost my alternator belt when I was 75 miles from home. I drove the entire time (mind you this was at night) with lights on to the nearst wallmart). Was abotu 50 miles. Went in, bought a new battery. After I was walking out of wallmart, It started to rain. I said **** installing it, and drove the remaining 25 miles home. Next day I got up and drove to napa to get all new belts.

Drove about 85 miles on the battery with no alternator.

Pretty crazy eh? old battery was a wallyworld cheapy (but ******* amazing) battery about 8 months old.

 

BTW, doing this is very bad for standard starting batteries. They can only handle a few deep discharges (<12V) before they are junk.