My 1985 battery keeps going flat

I think you are on the right track with replace the battery.

Have the alternator tested, any Autozone does the test for free.

ok thats a really little bit of information there in order to make a good assestment. I'll be a bit general but if your issue dont fall into that please respond with these answer..

1.) Please describe the situation.
2.) how old is the battery ?
3.) is it discharging over night ?
4.) Did you have the charging system checked and whats the charging voltage ?

BATTERY DRAINS or Runs out over night, vehicle runs fine once started..

This occurs because of a defective battery. Usually a cell is damaged. To verify this, run the vehicle so it recharges the battery. once you get home, remove the negative pole from the battery. leave it overnight reconnect in the morning. It it starts then there is something in the vehicle draining power. If it doesn't you have a bad battery. If its a sealed battery get it replaced. If its one with the caps pop the caps and make sure it has enough electrolyte, jump the vehicle and look into the cells to see if its bubbling or smoking. If so replace the battery. If there is none, then it just needed electrolyte.

There is no power from the Alternator to charge the battery,, VEHICLE DIES WHEN BATTERY DIES..

go to a repair shop as soon as possible or if you have the skillets replace the alternator.

keep me posted.

ok get power to truck turn key to on position pull plug off altenater one of then should be hot its call an exciter wire to excit the altenater to starg charging but first before all that check the alt. fuse inside your truck

hi, it sounds like the alternator is playing up this would need testing to see wht voltage it is putting out if its to high then this would ruin the battery and if it was to low then this would cause the battery to not charge.

If your only driving for say 10min at a time then this wouldnt charge the battery up enough and would cause the battery to keep going flat.

Its also worth checking the earth leads from the battery you should have one going to the cars body work and one going to the engine it would be a good idea to undo these and give them a good clean and remove any corrosion from under neath the wires ensuring their is good connection as this can cause the problem your having.

If the battery is going flat over night then you need to look at things like the light in the boot not switching off or if you have a light under the bonnet then you need to check these are switching off when they are shut as sometimes the switches fail leaving the light on and flattening the battery.

Let me know how you get on or if you need further assistance ok

start engine and get someone to hold rpm at 1500 then disconnect battery and if engine stops replace altenator ,if it keeps going then warning light control is U/S but to repair will nesitate removing the altenator and stripping it to change the brush /regulator unit and this can cost nearly as much as a recon altenator ,if it charges then leave it alone it could run for 50.000 miles or more like this

What is the tester that you are using? It sounds like your charging system is not working. Instead replacing batteries, charge them with a small charger over-night. Once the battery is charged, start the car and measure the battery voltage with a voltmeter. At fast idle, the voltage should be from 13.5 to 14.5 volts (DC). If it reads only 12.6 volts, the charging system is in trouble. The first suspect is the alternator which is driven by the belt. It is controlled by the voltage regulator, so either unit is suspect. If you take the car to an auto parts supplier, they will usually check your alternator and regulator for free in the hopes that you will buy any needed parts from them. Good luck!

first you need to make 100% sure it isnt the battery .when you park it for the night take your battery cables off and leave them off until the next day.when you go to start it put them back on and if it starts up then its probably not a battery issue.(some batteries get weak and will not hold a charge overnight). if it starts then its probably a short in your wireing.also when you put the cables back on listen for a crackling poping sounds as you putting the cables back on the battery.a good indicator thats there a short in your system.i hope this helps thanks jeff

I am having a similar problem on a 2003 Volkswagon Passat 1.8L 4 cylinder manual engine. My batter (after 10 years of service) died about a month ago. When the engine is cold and I start it up the engine (if I do not carefully add gas to rev the engine) will idle at around 200 to 400 RPM and then stall. The problem does not occur after the engine has been going for more than about 90 seconds. No check engine light is on. Ideas anyone?

Alternator might be bad, or is going bad. I assume you're using a stand-alone batter charger to recharge the battery? If so, you'll need to replace the alternator, as it's not performing the function of recharging the battery. If you take longer trips, the battery might run out of juice and the engine might stop.

If not the alternator, you definately have a short somewhere else that needs addressing.