Battery or Alternator?
Thread Starter
Instructor
Joined: Jul 2017
Posts: 196
Likes: 10
From: Marietta Ga
Battery or Alternator?
trying to determine battery issue. Bought a battery tender Jr. it charges fine and changed from red to solid green. Drive the car around today and the voltmeter shows between 13-14. Got home and hooked the battery tender back up and shows red (less than 80% charge). Could this be a bad battery or alternator? Thanks for any help.
Melting Slicks
Joined: Oct 2016
Posts: 3,340
Likes: 2,084
From: Lehigh Valley PA
Its normal - mine does that too.
Now you should notice that the tender gets back up to fully charged much quicker than when your battery is low... If not, then yes you have a problem.
My tender needs maybe 2 hours to show GREEN again after a drive... If its low it could take all day and most of the night - big difference in time.
Now you should notice that the tender gets back up to fully charged much quicker than when your battery is low... If not, then yes you have a problem.
My tender needs maybe 2 hours to show GREEN again after a drive... If its low it could take all day and most of the night - big difference in time.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
trying to determine battery issue. Bought a battery tender Jr. it charges fine and changed from red to solid green. Drive the car around today and the voltmeter shows between 13-14. Got home and hooked the battery tender back up and shows red (less than 80% charge). Could this be a bad battery or alternator? Thanks for any help.
a good way to measure battery life is to measure the battery voltage after its been sitting for several hours and then measure it every day and see what the voltage does. if it goes down or stays the same.
if it goes down compare it to a battery voltage chart from a google search. it will let you know if the battery is good or not. assuming no parasitic loss.
Racer
Joined: Sep 2016
Posts: 252
Likes: 103
From: O'Neill (Home of St. Pat's Weekend) NE
battery tenders are a good tool but they can mislead you in a bad way as I keep my cars on one all the time that way they are not low when I go to drive them. EG we went to town the other day and the car started right up all day but on the way home we stopped for coffee and gas, well when I went to start the car all I got was a clunk and nothing else. The battery tender showed a good charge when we left and if we didn't have it on the car "might have" shown symptoms of a bad battery before it totally went bad. LDK Just my experience?
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
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Melting Slicks
Joined: Oct 2016
Posts: 3,340
Likes: 2,084
From: Lehigh Valley PA
I see Harbor Freight sells a few models...
$22 model - 100 AMP
https://www.harborfreight.com/100-am...9888-9191.html
$50 model - 500 AMP
https://www.harborfreight.com/500-am...ter-91129.html
$75 Digital model - didnt mention AMPS
https://www.harborfreight.com/digita...zer-66892.html
Which one is needed to test car batteries? Is a digital model worth the extra money?
$22 model - 100 AMP
https://www.harborfreight.com/100-am...9888-9191.html
$50 model - 500 AMP
https://www.harborfreight.com/500-am...ter-91129.html
$75 Digital model - didnt mention AMPS
https://www.harborfreight.com/digita...zer-66892.html
Which one is needed to test car batteries? Is a digital model worth the extra money?
Le Mans Master
Joined: Sep 2016
Posts: 6,480
Likes: 555
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Melting Slicks
Joined: Sep 2012
Posts: 2,219
Likes: 789
From: Fort Myers Beach Florida
I see Harbor Freight sells a few models...
$22 model - 100 AMP
https://www.harborfreight.com/100-am...9888-9191.html
$50 model - 500 AMP
https://www.harborfreight.com/500-am...ter-91129.html
$75 Digital model - didnt mention AMPS
https://www.harborfreight.com/digita...zer-66892.html
Which one is needed to test car batteries? Is a digital model worth the extra money?
$22 model - 100 AMP
https://www.harborfreight.com/100-am...9888-9191.html
$50 model - 500 AMP
https://www.harborfreight.com/500-am...ter-91129.html
$75 Digital model - didnt mention AMPS
https://www.harborfreight.com/digita...zer-66892.html
Which one is needed to test car batteries? Is a digital model worth the extra money?
Melting Slicks
Joined: Jul 2015
Posts: 2,294
Likes: 232
From: Round Rock Texas
Dont just buy any alternator either they are only certain one that will work in the vette or you will be posting " I am getting charge system faults"
Autozone, NAPA, Advance does not have the correct one. Better to get it rebuilt or do it yourself
Autozone, NAPA, Advance does not have the correct one. Better to get it rebuilt or do it yourself
Last edited by sirdano; Oct 29, 2017 at 11:49 PM.