Battery voltage

timothyd · **Joined:** Wed Feb 20, 2019 2:58 am **Posts:** 90

I am suspicious that my 1 year old (7 year warranty) battery is already dead. Resting voltage is only 12.0V which is not good, but I was curious if anyone knows what a correct cranking voltage should be as well? I have been having hard starts even in ~55F temps which is not normal.

flman · **Posted:** Fri Jan 31, 2020 6:44 pm

12.7 V is great, 12.4 should be the minimum.

flman · **Posted:** Fri Jan 31, 2020 6:44 pm

12.7 V is great, 12.4 should be the minimum. Swap it in for warranty.

flash7210 · **Posted:** Sat Feb 01, 2020 12:20 pm

If in doubt, get your battery load tested.

Jay ne Ohio · **Joined:** Sun Dec 12, 2010 5:49 pm **Posts:** 216

It could be a bad battery. What is the voltage with the engine running? You should be around 14 volts with the engine running.

If less than 14 volts running, it could be either a bad decoupling pulley or your alternator. I just replaced a pulley on one of my CRD's that was slipping due to failed decoupler. Alternator was turning slowly due to some friction in the pulley, but not fast enough to keep it charged. I put a Gates 37018P from Amazon for $48 which is the same as the Litens 920834A from Advanceauto.

layback40 · **Posted:** Sat Feb 01, 2020 2:26 pm

flash7210 wrote:

If in doubt, get your battery load tested.

This should always be the first.
Mention is made by OP that he has been having starting problems "hard starts", if its cranking slowly, chances are it is not being charged properly by the alt. If its just cranking for a long time then the battery was probably good & there is some other problem.

WWDiesel · **Posted:** Sat Feb 01, 2020 2:43 pm

Only by watching battery voltage on a test meter while placing battery under a load test can tell it's true condition. Anything else is purely subjective.
I have seen plenty of batteries that would hold good 12+ volts readings while at a standstill (no load), but as soon as you put a load on the battery, the voltage drops below the 8 volt level indicating a bad cell or a weak battery.

You used to be able to check the exact state of a batteries charge status using a hydrometer, but since most batteries are now sealed or have gel in them, that is no longer possible.
Load testing and checking the voltage charge rate at the battery with the engine running is about all you can do nodays.

Also making sure you have real good clean battery connections is something else to check.
Bad or corroded cable connections can cause high resistance which can prevent full charging voltage from getting to the battery from the alternator.

timothyd · **Joined:** Wed Feb 20, 2019 2:58 am **Posts:** 90

Turns out it was the water level, I have not tested an over night voltage or start but the water level was about 1/2 inch below the top of the cells. Topped it off with distilled water and voltage after an hour or so is resting in the 12.6 ish range, might be higher once it gets a good driving charge on it.

This does bring up the question, how does a year old battery vent that much water. Charging voltage was 14.0-14.25 over a few minutes right after topping it off which seems right to me.

TKB4 · **Posted:** Sat Feb 01, 2020 8:45 pm

First a load test is best after the basics like checking the water level. I fully charge the battery first . If the voltage is less than 12.6 volts fully charge there is some degradation of the battery. Also if it starts normally after you charge the battery it either isn't getting fully charged by alternator or there is a parasitic draw somewhere in the system. Do the load test just after you fully charge the battery if possible. Of course the starter could be dragging etc. can't evaluate without fully charged battery. As covered generally the alternator should charge at 13.8v-14.8v.

The question was voltage under load though. I personally would like to see over 10 volts under load but it could be as low as possibly 9 volts while trying to start vehicle but of course the higher the better.

Our CRDs are very sensitive to low battery voltage not just for starting.

timothyd · **Joined:** Wed Feb 20, 2019 2:58 am **Posts:** 90

Finally got around to getting the battery tested, passed with flying colors. Things to note for the hard start is that it is happening on days into the 50's or even 60's, so I am not sure it is temperature related. Any over night start unless its 70's and above is producing white smoke. The colder it is the worse it is for sure, low 30 degree starts are longer and and produce much more white smoke on start. Also I have a pretty noticeable miss for only a couple of seconds after the rev down that clears up and idles just fine. Could that slow churning start be the starter?

flash7210 · **Posted:** Tue Feb 18, 2020 4:49 pm

timothyd wrote:

Finally got around to getting the battery tested, passed with flying colors. Things to note for the hard start is that it is happening on days into the 50's or even 60's, so I am not sure it is temperature related. Any over night start unless its 70's and above is producing white smoke. The colder it is the worse it is for sure, low 30 degree starts are longer and and produce much more white smoke on start. Also I have a pretty noticeable miss for only a couple of seconds after the rev down that clears up and idles just fine. Could that slow churning start be the starter?

What I get from all this is that:
1. the starter has no problem cranking but the engine just wont start.
2. the glow plugs aren't working or something worse is going on.

First, make sure the engine is getting fuel. Before starting, check the plunger on the fuel filter head.
Is it firm? If not, pump it up, then try to start.

Second, I know for a fact that my engine will start in 70F weather without any glow plugs. I tested
it by pulling the glow plug relay. Started up just fine without any hesitation or white smoke out the
exhaust.

So...
Are you noticing any mysterious loss of coolant?
Because your symptoms sound very similar to mine before I found that the head was cracked.
Coolant was slowly dripping into the cylinders overnight, making it very hard to start in the morning, and producing lots of white smoke out the exhaust.

timothyd · **Joined:** Wed Feb 20, 2019 2:58 am **Posts:** 90

I will double check coolant again but there hasn't been a drop missing since I last drained and filled it.

To summarize symptoms:

70F and above, normal start with no issues, fast cranking and no smoke, 1-2 rotations to fire

60F and below, slow chugging crank, puff of white smoke and a short duration of missing, 3-5 rotations to fire

~30F or below, slow chugging crank, large puff of white smoke and short duration of missing, 3-10 rotations to fire

Things I have checked:
Battery (voltage seems a little low but the battery tested perfect)
I have an in tank fuel pump and have not had any air in the system since
Changed the fuel filter less than 500 miles ago (symptoms before and after change)
Leaving key in on position for 1-3 20 second cycles (I listen for the fuel pump to stop priming and then cycle, this has made little to no difference in starting)
No CEL's

WWDiesel · **Posted:** Tue Feb 18, 2020 5:49 pm

What do you mean by: "Battery (voltage seems a little low but the battery tested perfect)"
Was the battery Load Tested? And if so what voltage did it drop down to during the load test. How old is the battery?
What voltage is the battery dropping to while the starter is spinning the engine over during the hard to start periods.
These vehicles do not like low voltages!

White smoke during a first startup after setting overnight is generally an indication of coolant getting into the combustion chamber. :cry:

timothyd · **Joined:** Wed Feb 20, 2019 2:58 am **Posts:** 90

Battery was bought from Les Schwabs, took it to them to do the test, they don't tell you much other than that it tested good and all the cells tested fine. I would assume a load test considering the cell health statement. For me it does seem off and I have not tested the batteries resting voltage after being charged and not plugged into the jeep, but below are my results when it is connected.

Resting voltage: 12.2-12.3

Key on voltage while glow plugs and fuel pump on: 11.4-11.6

Key on after the cylce is complete: 11.7-11.8 (I am not sure if this is normal but my headlights are always on when the key is on, its dimmer than the headlights being turned to the on position but they are always on)

Voltage when cranking: Varying in the low 10's

None of this has been tested on a 70F+ day.

TKB4 · **Posted:** Tue Feb 18, 2020 7:33 pm

The white smoke confuses things a bit but you also say chugging cranking so hard to tell . The 12.2 to 12.3 voltage after charged is definitely low though. I think I would take it and have it load tested at a parts store and see what they say if you don't have a tester. What group size battery its it and what CCA rating is it ? You should also check the voltage while the engine is running and it should be at least 13.8 volts. If its just a puff of smoke it could also be some extra fuel/oil in cylinder. The next thing I would do is a cooling system pressure check.

If the battery still checks good Make sure and check the battery cable connections at battery as well as at starter and ground.

WW he said battery was about a year old.

sportsbud · **Posted:** Sat Feb 22, 2020 8:41 pm

Curious just got my voltage tested at the local auto parts store and they said battery good. But when machine was left attached and cranked it registered bad starter solenoid and alternator.... Then said good Alternator. Voltage was 14.25v any reason their expensive machine would register a bad starter solenoid and alternator only at startup?

WWDiesel · **Posted:** Sat Feb 22, 2020 11:38 pm

sportsbud wrote:

Curious just got my voltage tested at the local auto parts store and they said battery good. But when machine was left attached and cranked it registered bad starter solenoid and alternator.... Then said good Alternator. Voltage was 14.25v any reason their expensive machine would register a bad starter solenoid and alternator only at startup?

Because it's a diesel? Maybe their machine's software is set up more for gas burners?

Just a guess....

sportsbud · **Posted:** Sat Feb 22, 2020 11:52 pm

WWDiesel wrote:

sportsbud wrote:

Curious just got my voltage tested at the local auto parts store and they said battery good. But when machine was left attached and cranked it registered bad starter solenoid and alternator.... Then said good Alternator. Voltage was 14.25v any reason their expensive machine would register a bad starter solenoid and alternator only at startup?

Because it's a diesel? Maybe their machine's software is set up more for gas burners?

Just a guess....

That's what I'm thinking... Maybe draws more amps than the machine thinks it should and causes it to go haywire...

That reminds me gonna upgrade that battery box also...

Battery voltage

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