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Jeep will only start at 11 volts or lower

S

Sirtedybear

NAXJA Forum User
Location
Long island ny
Hi i have a 2000 xj with California emissions and im having an issue when the voltage is above 11 volts it will not crank at all but if i drain the voltage down to 11 or lower it will crank and fire up with no problem. It will also fire up if i jump the starter relay as well. I do not have any cel on and when its running it drives and operates fine.
I have check all fuses, checked and cleaned all grounds, all the relays work, I have also changed the battery terminals too.
Any help is greatly appreciated thanks in advance
 
Sirtedybear said:
The battery tested good and its only 3 months old. Its just strange that the car will only start at 11 volts or lower
Click to expand...

you had it correctly load tested? not just checking voltage on a multi meter.
 
This is a bizarre problem. Normally things don't work when the battery voltage is low. Where did you read the 11v? Gauge Cluster or at the battery?

How did you drain the voltage down to 11v? What made you try this?

Are you trolling?
 
Good call, Tom. According to my sources, anything below 11.8v on a lead-acid battery is considered to be dead, and will not crank over a vehicle. I've seen batteries test fine for voltage, but fall flat on amperage when a load is applied, an indication of a shorted cell.

The omission of the "testing"performed in his original post is the knee-slapper here.

My Grandfather once said, "believe nothing you hear and half what you see." He would have enjoyed this one.
 
Last edited:
Going by whats in the cluster and by draining i turn the lighys on radio on turn on my efan and when i see the guge go to 11v it will start anything higher and it wont turn over
 
Sirtedybear said:
Going by whats in the cluster and by draining i turn the lighys on radio on turn on my efan and when i see the guge go to 11v it will start anything higher and it wont turn over
Click to expand...

That's not testing it. Remove it, fully charge it. Take it to oreilly or whatever parts store near you for a LOAD test that requires a specialty diagnostic tool.
 
The battery came out of a runing car and i had it in the jeep for a few days had no problem with it untill yesturday

I have to drain the battery down with all my accessories on till it hits 11 volts or lower or it will not start
 
In my many years of doing mechanic I have never heard of this. Used to be that batteries at 11 volts were put on a charger to bring it up, or in an emergency one would pull out the jumper cables ,... This is a good one.
 
How many lead plates would need to be removed from the battery to keeping it from producing more than 11 volts? It would be a little bit easier to put resistors in front of the starter, huh?
 
Sirtedybear said:
The battery came out of a runing car and i had it in the jeep for a few days had no problem with it untill yesturday

I have to drain the battery down with all my accessories on till it hits 11 volts or lower or it will not start
Click to expand...

Where did the battery come from? History? Did it sit unused for weeks or months?

It may be sulphated and or have a bad cell. I have had similar data on a battery that sat too long, and sulphated the plates making them non conductive enough to NOT start the vehicle. Cycling the head lights on clean the plates slowly then recharging got a few days or weeks out of some, but most were DOA in a day or days.
 
techno1154 said:
In my many years of doing mechanic I have never heard of this. Used to be that batteries at 11 volts were put on a charger to bring it up, or in an emergency one would pull out the jumper cables ,... This is a good one.
Click to expand...

Today's batteries have such tight spacing on the plates with only a tiny plastic membrane film between the plates, they can intermittently short some and recover till they short out big time, and then burn out a plate to plate connection inside at which point they are DOA, or loose one cell.....

I do not recall trying to start one with only 11 volts post to post. I knew better. But I have had ones that read 12.7 volts, did not crank with three tries and read 0 volts after those 3 tries. They would not charge, they pegged the charger, dead short inside.
 
Sirtedybear said:
It wont even make an attempt to crank unless its at 11vlots on the gauge
Click to expand...

Do not trust the dash gauge. Use a volt meter at the battery posts, post to post to get the real battery voltage. Pull the clamps, clean them and make sure they are tight when you reconnect them. What do the clamps and clamp wires look like?
 
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