Hey all

To start off, i bought a new battery, but hadn't driven the car for some time and stupid me didn't disconnect it! so the battery was practically dead! read 2Volts.
anyway i jumped it and all was good! now reading 14+ volts while running, so i am assuming alt is ok!
Now my mechanic has told me that the alt is to keep the battery charged, and when low it should take about 20 mins to charge up! (this is with most cars), however i have been told on this forum that the alt should not be used to charge a battery!

Anyway i thought i would try it so i left the car idling for about 10 mins, then it just shut off! wtf? could this be that the battery just couldn't cope, or the alt is stuffed, or that it may have got too hot and turned off(i wasn't in the car so not sure on temp)?

Anyway any help would be great! thanks

 

The purpose of the Alt. is to keep the battery charged. If you are saying that you unhooked the Alt and ran the car for 10 min and it died that would be about right. I would have thought you could have run it longer but it would depend on the charge of the battery

 

OK yes it charges it, but will the alt. bring a battery back to full charge from about 2 volts!

No i didn't disconnect anything, just ran the car then all of a sudden it died! and battery was enough to pwr window up, but no lights on dash!
Thinking the alt. maybe working intermittently? brushes worn out?

how much for a new alternator is the US?
Thanks

 

I agree that it is never a good idea to bring a fully discharged battery back up to full charge with the alternator. But! I've lost track of the times I've done it w/o a single problem so far. (However, I've got a battery charger (for some years now) and I don't push my luck anymore.)

At risk is cooking the diode pack (rectifier). Heat resulting from unusually high current load, is the issue. Charging a dead battery will the alternator's output capacity. Electronic devices deteriorate with heat, and if the rectifier is on it's last legs anyway, max output might put it over the top. And, if the ambient temperature is high (e.g., hot engine with the hood closed), the heat situation is exacerbated. So! In addition to a possibly injured battery, now you would be facing replacing/repairing the alternator!

If you did charge the battery with the alternator and the alt survived (probably would have), you're in luck - tho you might have aged the rectifier in the process. You might want to see if there is an excessive current draw when the car is not running - causing the battery to drain. (Something like 20 mA or less wouldn't concern me: 50mA would put a furrow in my brow, and 100+ would prompt me to pulling some fuses to isolate the leak! JMO)

I keep all my vehicles charged using a Battery Tender. There are several other good ones, and I've even built my own, on occasion. (My personal favorite is their 800mA waterproof unit.) More than just keeping the battery charged, they go a long way toward preventing lead sulfate from forming on the plates - the real killer of lead-acid batteries.

Hope this helps. Come browse the ZR1 Net Registry some time. All are welcome.

P.

 

Years ago I did some part time work for a local parts house. Sold bunches of alternators. Was required to tell each customer that the warranty was void if the alternator was used to charge a dead battery.

 

A fully discharged battery reads 10v- if it's reading 2v, then you have some dead cells.

 

I think that far too much is made of the "using your alternator to charge a dead battery will result in dire consequences" way of thinking. Think about it. If this were the gospel truth, why would jumper cables exist? If you are having to jump your car every time you use it, then yes, you are going to take out your alternator. A new battery is required. If your tires go flat every night then you are also going to prematurely wear out your compressor too. Occassionally? No problems. In the area I live, extreme temperatures in the winter of upwards of -40 drains the battery to some degree most times you start your vehicle. I have five vehicles and can't remember the last time I changed an alternator.

 

New Battery =

You can do it yourself by pulling part of the body behind the front wheel, specifically; the lower left front fender panel (with the vent).

A torx bit is required as some of these are torx screws and you don't need to pull it completely off, just loosen the screws on the front part behind the front wheela and remove the top and bottom bolts on the rear part, so you can get the battery past it sideways.

 

Paul Workman: Thanks some good info there! i too have many a time had to have my other cars jumped, and drove for about 30 mins or so and the battery charged fine! alt is fine too!
i agree not a good idea too often!

How can i check to see if there is a current drain?

The battery did not charge up at all as after the 10mins of running it it was barely enough to operate the pwr window!
I am thinking the alternator must have been gone when i bought the car

To all the other guys posting, my battery was brand new! AC delco, cost me $300AUD, was left in the car for only 3 months max and now needs a jump to start car! Yes i have swapped the battery over before, not too bad of a job!

Can these alt. be rebuilt, new brushes etc?

Thanks

 

Battery:

If the car has been sitting for an hour since being shut off, is cool, and the engine not running, the voltage across the terminals should be aprox 12.6 or so. There are (6) 2.2-volt cells in a 12 volt battery, and if you have a voltage reading that is low by approx 2+ volt increments, then you have a bad cell or cells. E.g., as mentioned, 10 volts on a battery that was recently charged is approx 2 volts low and probably one cell is definitely bad. At that point, the battery IS junk.

An otherwise healthy, but simply discharged (car) battery will still read 12 volts with NO LOAD attached. (Up to 20-25mA would be considered "no load", in normal circumstances.) However, the voltage across the terminals of lead acid batteries under significant load can go conciderably lower than 12 volts - ask anyone with a trolling motor! But, I digress...

Well, if the voltage measured between the battery posts ("cold") reads approx 14.6 ± a few tenths with the engine running and no accessories running, or about 13.5 volts after the car is warm and been running for 30 minutes (normal driving) or so, the alt = fine. That isn't a problem.

 

Pauls doing a great job helping you. Keep in mind, anything, even new, can be bad. 2v batt is alot of dead cells.

If you want some links to the parts (off a guy from the big auction site)- send me a pm. I just bought the brush kit, regulator and he threw in new bearings, for around $20. Even comes with the needle to install the brushes (pull the needle out of the little hole in the back after screwing down the brushes).

 

Paul Workman: Thanks so much mate! that info is awesome, you're a champ!

Well i guess my alt is ok then, that's a relief! will try and recharge the battery and see how that goes! and will check for any drain!

Wonder if i can take the battery back to the supplier? i have had it for over 3 months now, maybe more! but i am thinking it was down in cells when i bought it! ya see i live in Western Australia and there is not a lot of demand for those batteries, so who knows how long they have been on the shelves!

SoCalman: thanks mate for the offer, if it turns out that it is the alt, i might get that addy of you!