Ok Gang... I'm looking for a bit of help on diagnosing a charging issue. Been a busy day for fire calls today and on my way home from this last fire call I was noticing on the SG II my charge voltage is low and erratic. It still within spec of 13.5 to 14.5 volts but it bouncing a bit. With my lights all going its hover right at 13.5 to 13.6 which is usual for a charge voltage. Then it might bounce up to 14.0 to 14.1 then fall again... My first though is field brushes are wore out... Still running stock batteries 8 years old... No codes either... Now here is the kicker I need to do this without throwing a ton of money at parts guessin' I don't want to blow my Christmas Cash on repairs now... HELP!

Like "We" Professional techs like to say.................. "Run it and watch it",in other words.... let the problem develop a bit more. It doesn't sound like anything major. If you had them big ol lights on try without them and see if it changes. Could be a loose ground or other connection also.

Edited December 19, 200915 yr by Wild and Free

Well first off, you should check your voltage with the truck off and the grids on.. :wink:I don't know if I would jump to conclusions about the alternator. I run mine hard all winter and it's still stock and yours is 5 years newer. Are you sure your fancy overhead lights aren't turning on and off from a loose connection giving you a jumping voltage? Not sure if you can see them from inside the truck during the day or if this was at night or what. :confused: Does it jump with everything off driving along? I coulda sworn mine was at 14.2 no matter what but I'm only 95% sure.

Like "We" Professional techs like to say.................. "Run it and watch it",in other words.... let the problem develop a bit more. It doesn't sound like anything major. If you had them big ol lights on try without them and see if it changes. Could be a loose ground or other connection also.

Well That what I going to do I guess... But as for the lights... On or Off its still bouncing the voltage... I tried with everything on and with everything on... Just weird...

Well first off, you should check your voltage with the truck off and the grids on.. I don't know if I would jump to conclusions about the alternator. I run mine hard all winter and it's still stock and yours is 5 years newer. Are you sure your fancy overhead lights aren't turning on and off from a loose connection giving you a jumping voltage? Not sure if you can see them from inside the truck during the day or if this was at night or what. :confused: Does it jump with everything off driving along? I coulda sworn mine was at 14.2 no matter what but I'm only 95% sure.

The rocker switch has a LED light to alert me to it being on... As for the beacon light you can see it reflect off the road signs even in the daylight... Yeah it does bounce a bit... Like I was watching go up to 14.1 and then fall to 13.5 and back up to 13.8 then 14.2... Just all over the place... As for the grid heaters... It don't help leaving the fire radio on all night and coming out to a truck with 12.0V ... Grid pull to 11.2V and Pop up to 11.8V before starting... I wonder if a grid heater is stuck on??? :eek: ___________ Addon: I just went out and check the battery voltage and it falling since I got home 12.5V. I starting to think there is a internal short in the batteries and they are giving up. Yes everything is off!

Edited December 19, 200915 yr by Mopar1973Man

How does a battery reading 12 volts only drop to 11.2 and yet mine are all at 12.65 and drop to 11.1, all FOUR of them mind you! Now I don't know what to think. Jumping voltage seems so weird. I only took a 2 week crash course on motors, only learned parts. So I don't know, bad voltage regulator, bad brushes, belt slipping, :confused:

not sure if it applies to a disel but i believe a battery is a battery and while there are some other things pulling current off the batteries in a diesel as oppesed to a gasser ....it sounds exactly like my last gasser with all the F.D. lights on it....open cell in the battery....and for what its worth if it is the batteries....lay out the extra cash for the optima red tops

I was just at my local kragen/orilley and they had the red top 800cca for 149 ea. If that is the regular price it is a pretty good one. The 1000cca are 169ea. I would have to say even someone like you who is really on top of the maint on your truck is lucky to get that kind of time out of stock batteries. You get a set of the gel cel and never have to clean no corrosion and i think he said they have something like a 15yr typical life to them. I personally have used them since I found out they made them in 95. I have never had one go bad one me. Bonus is the dual terminal for those extra electrical connections. doing a little search I found this place that offers free shipping and some good prices. In your situation not being able to just drive 5 min to a auto parts store it might be worth looking into. http://bigtimebattery.com/store/optima_batteries.html?OVRAW=optima%20batteries&OVKEY=optima%20battery&OVMTC=standard&OVADID=27739516521&OVKWID=1206486521&ysmwa=oeatz1Uh-pRE4A_U8xiqca-vtlowvZk8EcY7QBFqBZO7BWXD0G5KK2maeDS8Q5cL

Edited December 19, 200915 yr by Howie67

sounds to me from what i have read here that you have one of your battery,s is developing a bad cell just my two cent worth

So, do you or a friend have a load tester? 8-year old batts are getting up there, but I don't see how bad batteries would jump your voltage up and down like this. When my batts went bad, my voltage would drop bad when starting and it would cycle up and down a lot until the charge got back. On the road, there were not real major ups and downs. Test the batteries with a load tester.

http://www.batterystuff.com/tutorial_battery.html

6. Battery Testing can be done in more than one way. The most accurate method is measurement of specific gravity and battery voltage. To measure specific gravity buy a temperature compensating hydrometer, to measure voltage use a digital D.C. Voltmeter. A quality load tester may be a good purchase if you need to test sealed batteries.

For any of these methods, you must first fully charge the battery and then remove the surface charge. If the battery has been sitting at least several hours (I prefer at least 12 hours) you may begin testing. To remove surface charge the battery must be discharged for several minutes. Using a headlight (high beam) will do the trick. After turning off the light you are ready to test the battery.

State of ChargeSpecific GravityVoltage12V6V100%1.26512.76.3*75%1.22512.46.250%1.19012.26.125%1.15512.06.0Discharged1.12011.96.0

*Sulfation of Batteries starts when specific gravity falls below 1.225 or voltage measures less than 12.4 for a 12v battery, or 6.2 for a 6 volt battery. Sulfation hardens on the battery plates reducing and eventually destroying the ability of the battery to generate Volts and Amps.

Load testing is yet another way of testing a battery. Load test removes amps from a battery much like starting an engine would. A load tester can be purchased at most auto parts stores. Some battery companies label their battery with the amp load for testing. This number is usually 1/2 of the CCA rating. For instance, a 500CCA battery would load test at 250 amps for 15 seconds. A load test can only be performed if the battery is near or at full charge.

The results of your testing should be as follows:

Hydrometer readings should not vary more than .05 differences between cells.

Digital Voltmeters should read as the voltage is shown in this document. The sealed AGM and Gel-Cell battery voltage (full charged) will be slightly higher in the 12.8 to 12.9 ranges. If you have voltage readings in the 10.5 volts range on a charged battery, that typically indicates a shorted cell.

If you have a maintenance free wet cell, the only ways to test are voltmeter and load test. Any of the maintenance free type batteries that have a built in hydrometer(black/green window) will tell you the condition of 1 cell of 6. You may get a good reading from 1 cell but have a problem with other cells in the battery.

When in doubt about battery testing, call the battery manufacturer. Many batteries sold today have a toll free number to call for help.

7. Selecting a Battery - When buying a new battery I suggest you purchase a battery with the greatest reserve capacity or amp hour rating possible. Of course the physical size, cable hook up, and terminal type must be a consideration. You may want to consider a Gel Cell or an Absorbed Glass Mat (AGM) rather than a Wet Cell if the application is in a harsher environment or the battery is not going to receive regular maintenance and charging.

Be sure to purchase the correct type of battery for the job it must do. Remember that engine starting batteries and deep cycle batteries are different. Freshness of a new battery is very important. The longer a battery sits and is not re-charged the more damaging sulfation build up there may be on the plates. Most batteries have a date of manufacture code on them. The month is indicated by a letter 'A' being January and a number '4' being 2004. C4 would tell us the battery was manufactured in March 2004. Remember the fresher the better. The letter "i" is not used because it can be confused with #1.

Battery warranties are figured in the favor of battery manufactures. Let's say you buy a 60-month warranty battery and it lives 41 months. The warranty is pro-rated so when taking the months used against the full retail price of the battery you end up paying about the same money as if you purchased the battery at the sale price. This makes the manufacturer happy. What makes me happy is to exceed the warranty. Let me assure you it can be done.

8. Battery life and performance - Average battery life has become shorter as energy requirements have increased. Two phrases I hear most often are "my battery won't take a charge, and my battery won't hold a charge". Only 30% of batteries sold today reach the 48-month mark. In fact 80% of all battery failure is related to sulfation build-up. This build up occurs when the sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to coat the battery's lead plates. Before long the plates become so coated that the battery dies. The causes of sulfation are numerous. Let me list some for you.

[*]Batteries sit too long between charges. As little as 24 hours in hot weather and several days in cooler weather.

[*]Battery is stored without some type of energy input.

[*]"Deep cycling" an engine starting battery. Remember these batteries can't stand deep discharge.

[*]Undercharging of a battery to only 90% of capacity will allow sulfation of the battery using the 10% of battery chemistry not reactivated by the incompleted charging cycle.

[*]Heat of 100 plus F., increases internal discharge. As temperatures increase so does internal discharge. A new fully charged battery left sitting 24 hours a day at 110 degrees F for 30 days would most likely not start an engine.

[*]Low electrolyte level - battery plates exposed to air will immediately sulfate.

[*]Incorrect charging levels and settings. Most cheap battery chargers can do more harm than good. See the section on battery charging.

[*]Cold weather is also hard on the battery. The chemistry does not make the same amount of energy as a warm battery. A deeply discharged battery can freeze solid in sub zero weather.

[*]Parasitic drain is a load put on a battery with the key off. More info on parasitic drain will follow in this document.

Also, if you have a volt meter, turn on your high beams / lights for a few mintues to remove the surface charge. After this, have someone start your truck while you have a direct connection to the altenator. Watch for alt cycling and listen for wining, etc. Our trucks all cycle with the grid heater, but your altenator should go off and turn back on in a consistent manner pushing about the same voltage during charging. An dropping or jumping in an extreme manner may indicate the volt regulator going south.....

It's your alt (or part of) or your batts... When batteries go bad, it beats the altenator simple. The vice-versa applies.

I know you don't live close to an auto zone, etc. They would be smiling to load test your batteries or test your alt... Is there a shop close by that you may be "buddies" with? :confused::confused::confused:

was the dash gauge jumping also or just the scan gauge?all good advice...but lets not forget what he can do at home...grab you digital VOM and and test each battery(they should be unhooked) while connected you could test the terminal connections(place one of the probes on the post and the other on the same terminal the is connected to the post. electricity takes the path of least resistance.if the DVOM gets a reading greater than 0.2, then there is a problem at that connection) i believe you might be able to test the alt similarly. the power of the cummins shakes screws loose and even has torn my dash to pieces. maybe a screw has come loose on some of your "aftermarket" wiring.you know i did my batteries earlier this year...because the starter contacts tricked me...but they were going so i guess i got them done early.

was the dash gauge jumping also or just the scan gauge?

Dash gauge sits right at 14 never really moves... ScanGauge is changing...

all good advice...but lets not forget what he can do at home...grab you digital VOM and and test each battery(they should be unhooked) while connected you could test the terminal connections(place one of the probes on the post and the other on the same terminal the is connected to the post. electricity takes the path of least resistance.if the DVOM gets a reading greater than 0.2, then there is a problem at that connection) i believe you might be able to test the alt similarly. the power of the cummins shakes screws loose and even has torn my dash to pieces. maybe a screw has come loose on some of your "aftermarket" wiring.

Yeap I guess I'll do some basic test and come back thanks for reminding me of these things...

you know i did my batteries earlier this year...because the starter contacts tricked me...but they were going so i guess i got them done early.

As for aftermarket stuff most all of it comes out to the driver side batter for hook up... Which I'm going to clean up in the near future... But all the cables and stuff have been kept clean and the positive cables and post are not oxidized (blackened).

any luck so far?

Well... I pulled both batteries out and charged both at 10 Amps for several hours to stir the electrolyte back up. Then gave the battery cases a wash in mineral spirit (degreaser) to remove the grime and gunk. Cleaned the terminals on the batteries and the cables. Stuck them back in the truck 12.8 Volts shown at rest. Key off. Short time later 12.5 Votls at rest. So I'm going to assume there is a dieing battery cell and the batteries are finally getting tried of cranking up this monster. Funny part is that during my re-prime process for my injector install the batteries held up fine. :confused: Cold charging volts is about 14.2 to 14.3 but warm then it drop to 13.9 to 14.0 but now its at least stable for the time.... Very well possible a bad cell is the cause of the unusual charging voltage.

Could be a parasitic loss through the alternator also if it has a bad diode ect. If you don't have a good meter to check it out with, disconnect the batt wire from the alt and see If it still discharges.

Edited December 22, 200915 yr by Wild and Free

A cell is bad if you have a 50 pt difference between any 2 cells on a battery. That is true even if it has good volts, it will not hold up in the long run. Learned that from my old auto parts selling days!

A cell is bad if you have a 50 pt difference between any 2 cells on a battery. That is true even if it has good volts, it will not hold up in the long run. Learned that from my old auto parts selling days!

what do you mean "50 pt difference"? how could you test each cell without opening the case,or do you?

Yes, you pull the caps off and test the specific gravity of the acid of each cell with a hydrometer.

you mean that eye dropper with the floaty balls? people actually use those things? live and learn.

I've only seen those for the antifreeze but I don't see why they wouldn't have them for the battery. Sounds like it would work :confused:

what did you have in mind to test "specific gravity"?what does the "hydrometer" look like?

I was thinking of something very fancy that you would see on mythbusters or something I can't find much other than the eyedrop things on youtube. Not sure on how accurate one has to be to measure from 1.265-1.120.