Anyone know apx. how much power the car drains from the battery when driving?
It looks like I have to pick up a car about 1,5 hour drive from here, but it has a dead alternator..

I thought of bringing with me a battery or two, since I dont have a spare altenator atm, but not sure if that would be enough? (apx 90Ah)

 

hmm, it gave me about 15 minutes of driving last I remember having my alternator bad in 2006

 

Ouch, just tow it home then.

 

If you have a fully charged 65 AH battery in good condition at the start of the trip, you should be able to reach home in 1.5Hrs with no problem as long as you don't use any lights, fans, air-con, windows, audio etc

 

Well, he apparently has a few batteries so if thats the case then he should be fine. I had an Optima RedTop when this happened but then again it might've been low on charge by the time I was driving it.

 

Ok, ill take with my two batteries, fully charged and see how far I get, if they run out, i'll tow it the rest.

 

To extend the life of the battery on the trip back home, turn OFF all electrical systems and that includes the radio (yea I know it will be a boring trip) and don't open/close the windows more than necessary. Also don't turn off the car, once it's running leave it running. Starting the car drains a lot from the battery.

I've driven on a bad alternator a couple times and like LvR said, you should be fine to make it home if the battery is in good condition unfortunately mine weren't

Good Luck

 

you should be fine, my alternator went late last year and i had a battery full of corrosion and other stuff, got a boost from AMA, drove the car home from downtown (15 minutes), ran into the house leaving it running for a few minutes, and another 15-20 minute drive to the garage to get a new alternator

and yes, i got a new battery afterwards lol

 

turn off everything unnecessary blower fan, radio, foglights, interior lights etc....the less draw the more time you have!

 

Autos might consume more - mine definitely lasted much less: ~40 minutes.

 

ITO the maths and only with reference to my own auto 3rd gen VG - I have a Fluke DC current clamp and the vehicle consumes around 15A with everything (alt belt removed) off with the motor running and auto box in D ............sure its quite a lot but @65AH battery capacity surely 1.5Hrs should be a doddle

 

Thank you for providing this number, my old multimeter ends at 5A and I was never bothered enough to measure it using low ohm resistor.

There were multiple factors here which contributed to much shorter time in my case, the most important - lead battery capacity is shown while discharged by 1/20C current - around 3A for this battery. When discharged by even 15A it will show only about half of it. As I did discharge it fully I saw that reduced value which is still supposed to be around 2hrs. Other things made it even worse:

1. battery was couple years old
2. it was winter and it was cold
3. I live in Canada where we have 'day running lights' law - no way to turn low beams completely off short of removing fuse.
4. it was VE30DE which might be slightly higher in power consumption

 

All relevant yes.

I normally prefer to use the reserve capacity figures on batts to determine survivability in these situations because its an indication of actual time to be expected from the batt when under quite a heavy load - in my NS70 battery's case http://www.sinetech.co.za/printdocs/royal.pdf I can expect around 110min when loading at 25 A when the batt is new and still in good charge condition - guess you can probably derate that by 10% for age but if push comes to shove 15A should be a breeze

 

I think, you're right - he should be fine. My time was shorter but the conditions were very different too. It's just being stranded once I can't easily forget it even when the logic says it's OK.