Battery question?
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Senior User
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From: Walla Walla, Wa
Battery question?
My trucks been sitting at about 11.9v or so for the past few months and I’ve noticed over the past few weeks it’s been slow to start on Monday mornings after sitting over thr weekend. My batteries are a little over 3 years old and I’m thinking it’s about time to replace them, does anybody know if a group 31 battery will fit in the factory trays?
Hotshot
Joined: Jul 2005
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From: Middle Tn.
My trucks been sitting at about 11.9v or so for the past few months and I’ve noticed over the past few weeks it’s been slow to start on Monday mornings after sitting over thr weekend. My batteries are a little over 3 years old and I’m thinking it’s about time to replace them, does anybody know if a group 31 battery will fit in the factory trays?
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From: Walla Walla, Wa
Hotshot
Joined: Jul 2005
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From: Middle Tn.
A fully charged static battery will read 12.6 volts. You're too low. FICM should never drop below 47 volts.
Token Redneck
Joined: Jun 2007
Posts: 9,339
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From: Breckenridge, TX
^^^ this. You're stressing the alternator trying to charge undercharged/damaged batteries. Float voltage of 11.9V is too low like Mike said.
Bare minimum it's time to pull the batteries, charge them separately, strip the surface change and load test. $5 they both fail.
Bare minimum it's time to pull the batteries, charge them separately, strip the surface change and load test. $5 they both fail.
Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 26
From: Middle Tn.
^^^ this. You're stressing the alternator trying to charge undercharged/damaged batteries. Float voltage of 11.9V is too low like Mike said.
Bare minimum it's time to pull the batteries, charge them separately, strip the surface change and load test. $5 they both fail.
Bare minimum it's time to pull the batteries, charge them separately, strip the surface change and load test. $5 they both fail.
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Senior User
Joined: Apr 2010
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From: Walla Walla, Wa
I realized I’m causing undue stress on my alternator and whole electrical system having low batteries, hence why im in the market to have them replaced, my original question hasn’t been answered yet tho, will a group 31 battery fit in the stock trays?
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Logistics Pro
Joined: Nov 2004
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Just measure the tray.
My guess is that they won’t fit because the stock group 65 battery seems to just fit in my truck.
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Lead Driver
Joined: Jul 2004
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From: Foothills, CA
a 31 is longer and taller than a 65. I'd probably be more worried on the height as you likely can get it to sit on top of the tray edges. Here's the measurements, take a tape measure out and check...
BCI Grp 65: 12.0625"L x 7.5"W x 7.5625"H
BCI Grp 31: 12.9"L x 6.75"W x 9.27"H
I just put some Group 31s starting batts from Napa in our motor home, they were 950CCA...
Scott
BCI Grp 65: 12.0625"L x 7.5"W x 7.5625"H
BCI Grp 31: 12.9"L x 6.75"W x 9.27"H
I just put some Group 31s starting batts from Napa in our motor home, they were 950CCA...
Scott
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From: Walla Walla, Wa
I just started the truck and ran a data log on FORScan looking at FCIM voltage and it sat at 48.5, it did dip down to 48 a few times when I blipped the throttle bot only while the glow plugs were still on. Once they were off I hit the throttle a few more times and it sat at 48.5 the whole time. Should the half volt drops be concerning or no since it was only when the glow plugs were on and the FCIM was only seeing ~11.8 from the charging system at the time?
Hotshot
Joined: Jul 2005
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From: Middle Tn.
I just started the truck and ran a data log on FORScan looking at FCIM voltage and it sat at 48.5, it did dip down to 48 a few times when I blipped the throttle bot only while the glow plugs were still on. Once they were off I hit the throttle a few more times and it sat at 48.5 the whole time. Should the half volt drops be concerning or no since it was only when the glow plugs were on and the FCIM was only seeing ~11.8 from the charging system at the time?
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