Whats worng .how do i find a short when i drive the amp light is on than it will go off and start charging the batt than it gos back on i check the connections at the alt semed good and i cant find the voltage reg were is it at were could the short be
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Battery might seem fine on a routine check, but the crancking amp power is not there anymore, seems that your alternator is not charging it anymore, have the alternator checked and replaced if needed, the battery might need replacing too.
Ck your charging system with a meter at the batt posts. Charging range should be between 13.6v and 14.2v. The higher the voltage, the less the charging amps. You want it to be close to 13.6 if the batt is low and 14.2v if the bat is charged properly. It won't start with key because battery is too low. Good Luck
The batteries one gets today will not tolerate being stored for a long time and will fail internally.
If you check with a multimeter (cheap- under $20 US at Radio Shack or auto parts stores) you will probably find the terminal voltage even after charging will be below the 12.6 nominal and probably will fail very rapidly after the engine is off.
It likely has one or more shorted cells and each one is a loss of ~2 volts.
Being an expert in this Electronics field this should be fairly easy.
It appears your charging system is functioning OK as you did the
QUICKIE alternator/regulator test and that part appears to be fine.
Next - Never ASSUME you have a good, or NEW battery. I've seen brand
new batts fail a few months after purchase for no known reason at all.
Water level should be topped off esp during Hotter weather as water
level will drop as the batt ages.
AND - when in doubt - Always do a hydrometer test on each cell, and
make sure all cells read equally at approx 1.285 to 1.290 - indicating
a fully charged batt.
When doing a LOAD TEST with an external 100 Amp Load Tester make sure
you disconnect the POS terminal cable (or better yet both batt cables)
on the batt before doing a good Load Test on a fully charged batt.
Batt voltage on a good fully charged batt should never drop much below
11.4 to 11.7 volts doing a 10 second load test using a Load Tester
similar to say one bought at Harbor Freight Tools for like $15 when
they are on sale.
If the top of the batt is wet (for whatever reason such as dew-point or
leaky batt acid) this will cause the batt to self-discharge right
across the top of the batt. Just like putting a small light-bulb across
the batt posts and causing a drain. It happens more times than you care
to know. When I worked at SEARS I seen it day in and day out......trust
me I know!
Next - you'll want to check for a couple things at night, or else
daylight will work as well - if you have good eyesight. You want to
check and make sure your "backup lights" aren't ON when the Headlights
Switch is turned OFF and the Ignition Switch is OFF as well. Sometimes
a SHORTED Transmission Backup Light Switch will cause a battery drain
with everything shut off. Sometimes!
Also - If you have any Interior Lights left on when the SUV doors are all closed that will surely drain the battery down.
A radio/stereo left ON will do the same as well.
A shorted tail-light (or any marker light) will also cause a battery to drain over time.
Jeeps that have a under the hood light Mercury Tilt Switch for the
Engine compartment sometimes can have this switch mounting come loose
and when you shut the hood the light will actually stay lit thus
draining the batt down as well. Make sure you check it at NIGHT during
darkness as it will show up better.
If all this proves NOT to be the cause then you will have to do an
actual DVM inline amp meter test to see just how much current leakage
(shorting) you have. A fuse block isolation test will next have to be
done to isolate from which circuit leg the short (or current drain) is
Once that circuit is isolated then it's just a matter of finding the shorted device or shorted wire(s).
If you just added anything new electrical wise to the Jeep recently-
then that is a good starting point - for if the problem wasn't there
before that time, and now it is - then there is your culprit!
If you are using an external battery charging PV (Photo-voltaic) panel,
and it's bad for any reason - then it will drain your battery down as
well, esp if the blocking or back diode goes bad.
Also - If you have a dual battery system with a BATTERY ISOLATOR
installed you might want to double check all your wiring there as well
- as I've seen them go bad and cause many a battery problem!
It's gotta be something I just went over here - as I covered everything......