Bad Battery and/or Alternator???

[mustangaustin34]

I’m currently on business in the frigid Midwest this week and my 4Runner decided not to start this afternoon. I had my truck jump started and it has been fine all day (had a couple of stops and it turned over with no problem). I’m planning on getting a new battery tonight after work but I’m wondering if there is a problem with my alternator as well. For example, I was driving down a hill with my foot off the gas and all my dash lights, temperature gauges, and radio started to dim. Once I accelerated, the lights came back to normal. My question: is this obviously just the dying battery or could it be the alternator as well? Thanks for any insight!

 

[Clemsonfan15]

I'd go by a store like Advance Auto Parts and have them test your battery and alternator.

My bet would be on your battery though. When was the last time it was changed?

 

[mustangaustin34]

Clemsonfan,

I just checked my service records and I installed a new battery back in March 2004...it's obviously time for a new battery!

 

[JohnsD90]

Just a tip, If the alternator is shot once the battery dies your basically screwed, because you need a charge to keep the can running.

If the battery is hot it is a little easier to manage because you can atleast ride around using the electricity the alternator makes.

 

[fourwd1]

I’m wondering if there is a problem with my alternator as well. For example, I was driving down a hill with my foot off the gas and all my dash lights, temperature gauges, and radio started to dim. Once I accelerated, the lights came back to normal. My question: is this obviously just the dying battery or could it be the alternator as well?

The alternator puts out less current at idle RPMs, so if the demand exceeds the supply, things will dim. Normally. If the alt is bad usually the CHARGE and BRAKE lights come on. But it would be a good idea to get it checked out too.

 

[panzer]

Test

Only way to be sure is to have it tested. Typically your local Autozone, Pep Boys, Checker, etc. will check both your battery and alternator for free.

A word of advice, you may take your truck to at least 2 of these places for the check. The folks that work at these places are usually not mechanics (if they were mechanics they'd be making more money somewhere else) and may have trouble working even the simplest equipment.

I took my truck to 3 different places. All told me my battery was bad, but only the last 2 places told me my altenator was bad. If I'd just gone with the 1st shop's recomendation to change my battery then I would have had the same problem shortly thereafter.

I think our alternators put out around 80 amps if they are working properly. Ask the guy/gal who tests it how many amps your alternator is putting out. If they look at you like a deer in headlights when you ask this... move on to the next shop

I'm on my 3rd alternator. The factory one died at 40k, my Autozone replacement died at 80k and my 3rd is still in there. I bought the "lifetime" warrentee one from Autozone so I didn't have to pay for the 3rd (or any future) alternators. Luckily that is all I've had to replace on my truck so I feel pretty lucky about that

Good luck.

 

[panzer]

Test

Only way to be sure is to have it tested. Typically your local Autozone, Pep Boys, Checker, etc. will check both your battery and alternator for free.

A word of advice, you may take your truck to at least 2 of these places for the check. The folks that work at these places are usually not mechanics (if they were mechanics they'd be making more money somewhere else).

I took my truck to 3 different places. All told me my battery was bad, but only the last 2 places told me my altenator was bad. If I'd just gone with the 1st shop's recomendation to change my battery then I would have had the same problem shortly thereafter.

I think our alternators put out around 80 amps if they are working properly. Ask the guy/gal who tests it how many amps your alternator is putting out. If they look at you like a deer in headlights when you ask this... move on to the next shop

I'm on my 3rd alternator. The factory one died at 40k, my Autozone one died at 80k and my 3rd is still in there. I bought the "lifetime" warrentee one from Autozone so I didn't have to pay for the 3rd (or any future) alternators. Luckily that is all I've had to replace on my truck so I feel pretty lucky about that

Good luck.