Battery output

[HoosierJeeper]

Been noticing that the KJ has been cranking a bit slower...got the battery tested and it's putting out 12.47 volts. I can't remember...is the optimum output 13.6 or 14.5? Both numbers ring a bell, did a quick search on here and couldn't find a concise answer. Guess in either case it's bad.

Thanks!

 

[eemain]

Are you asking what the voltage should be when the Jeep is not running?

12.6+ is a full charge, 12.4 is on the low end.

 

[HoosierJeeper]

When it is running (under load)...sorry should've said that.

 

[Dave]

My scan-gauge reads 14.5 most of the time when driving.

Dave

 

[tommudd]

Mine as well according to the scan gauge

 

[tjkj2002]

Anything between 13.2 volts(min to charge battery,must do very long drives) to 14.7 volts(little high,may cook a battery in high heat) is good.


Ideal is between 14.2 and 14.5 volts.If you have a AGM battery you must have 14.5 volts through 14.9 volts otherwise the AGM battery will not charge correctly.

 

[profdlp]

My scan-gauge reads 14.5 most of the time when driving.

Mine as well according to the scan gauge

I have the Garmin ecoRoute add-on and it agrees with both of the above.

 

[eemain]

When it is running (under load)...sorry should've said that.

Sounds as if your charging system may not be working.

 

[Cardhu]

Whats the voltage on terminals when at idle?

 

[Billwill]

Check that your battery connections are clean and tight, the negative cable going to chassis is clean and tight and the cable grounding the engine to the chassis is clean and tight.

With the battery leads across the terminals, at the time of cranking the voltage should not drop below about 10 volts if your battery is good.

 

[TwoBobsKJ]

Man, I'm glad you electrical experts are here. I've never been good with electrical stuff and knowing I can get a clear answer here is awesome. Thanks!

Bob

 

[HoosierJeeper]

Got a new battery, it tested bad (Jeep not running) again.

 

[eemain]

HJ the 12.47v reading has me confused.

12.47 would be an OK V for the battery without the Jeep running.
If your reading that with the Jeep running there is a problem in the charging system. Could be as simple as a loose or corroded connection causing a V drop.
This could also have gotten worse over time causing the battery to work harder to supply current to CRANK the Jeep. Though if you were running 12.47v for long your battery would have died on you at some point.

An Amp clamp would allow you to see if the battery is charging and holding that charge.

 

[Billwill]

Have a look at the "voltage regulator/PCM" post that Sebastian has just posted...I contributed some advise there which may also be relevant here.

 

[HoosierJeeper]

HJ the 12.47v reading has me confused.

12.47 would be an OK V for the battery without the Jeep running.
If your reading that with the Jeep running there is a problem in the charging system. Could be as simple as a loose or corroded connection causing a V drop.
This could also have gotten worse over time causing the battery to work harder to supply current to CRANK the Jeep. Though if you were running 12.47v for long your battery would have died on you at some point.

An Amp clamp would allow you to see if the battery is charging and holding that charge.

Hm.

I took it to Sears to get the battery replaced and they had to check it again. The battery test bad and they also found a loose connection...one of the cables was effed up. I did notice a month or so back the Jeep was cranking slower, that's why I took it to Autozone first just to see if I was imaging things.

Thanks for the help everyone!

 

[eemain]

Hm.

I took it to Sears to get the battery replaced and they had to check it again. The battery test bad and they also found a loose connection...one of the cables was effed up. I did notice a month or so back the Jeep was cranking slower, that's why I took it to Autozone first just to see if I was imaging things.

Thanks for the help everyone!

Glad to hear that!!!!

 

[profdlp]

Loose battery cables are probably the best electrical problem to have. Probably the cheapest to fix, at least.