New batteries now low battery sign

[CRHardie]

So my original batteries in my 2015 finally gave up. Well one did. The other still tested good. Anyway I installed 2 new Exide AGM batteries and am now getting the battery low message on the dash. I have 14.10 volts on each battery at the posts and battery voltage on the dash bounces between 13 and 14. I never got this message when I had one bad battery and a no start. Does the charging system need to reset on these like I’ve read about on some cars with AGM batteries? I did some how manage to arc the positive cable on the passenger side which I removed it. Not even sure what it hit. They could have given us a little slack in the cables. Thoughts?

 

[seafish]

I suggest that you recheck the integrity of the crossover cable connections on each battery that you just installed.
And then go on to check each and every positive and ground connection.
If they are all clean and tight then likely the crossover cable has corroded or otherwise failed internally.

 

[Tuesdak]

I did some how manage to arc the positive cable on the passenger side which I removed it.

When you are working on the dual battery system in your pickup disconnect both negative terminals off the batteries first. This way when you touch the positive cables there is no circuit to cause an arc or worse a battery explosion. The ground isn't going to arc to the fender etc. when working on it. So after the battery negative cables are off you can work on the positive connections without concern if your tool slips it will arc something. It's not one battery or side at a time it's both negative cables off first. Then if you say change batteries out the negative cables go on last after you have hooked up both positive terminals.

AGM makes no difference to the ECM. A bad connection/cable dropping voltage during cranking maybe causing the message. Due to the arc you may have burnt or melted a connection.

I would load test both new batteries just to be sure you didn't get a defective one. Load test means disconnect one negative battery cable or a good battery will hide a bad battery when load testing.

 

[CRHardie]

When you are working on the dual battery system in your pickup disconnect both negative terminals off the batteries first. This way when you touch the positive cables there is no circuit to cause an arc or worse a battery explosion. The ground isn't going to arc to the fender etc. when working on it. So after the battery negative cables are off you can work on the positive connections without concern if your tool slips it will arc something. It's not one battery or side at a time it's both negative cables off first. Then if you say change batteries out the negative cables go on last after you have hooked up both positive terminals.

AGM makes no difference to the ECM. A bad connection/cable dropping voltage during cranking maybe causing the message. Due to the arc you may have burnt or melted a connection.

I would load test both new batteries just to be sure you didn't get a defective one. Load test means disconnect one negative battery cable or a good battery will hide a bad battery when load testing.

After 37 years making my living as a heavy diesel mechanic one would think I would do this properly. But as usual my stuff comes last because of working on others stuff to earn a living so I get in a hurry just before dark. Both batteries tested good with an actual OTC carbon pile battery load tester. Did that before I put them in

 

[sag2]

You have intelligent battery sensors on both batteries. There is a service procedure for disconnecting, connecting, and charging so as to not upset the IBS. It should relearn after driving for a couple of drive cycles. I'll send you a PM with additional info.

 

[CRHardie]

You have intelligent battery sensors on both batteries. There is a service procedure for disconnecting, connecting, and charging so as to not upset the IBS. It should relearn after driving for a couple of drive cycles. I'll send you a PM with additional info.

Thank you. That’s what I was thinking. I know my daughters Ford Escape has that

 

[AH64ID]

You have intelligent battery sensors on both batteries. There is a service procedure for disconnecting, connecting, and charging so as to not upset the IBS. It should relearn after driving for a couple of drive cycles. I'll send you a PM with additional info.

My previous 18 and 22 both only have one IBS on the drivers side negative terminal, did the earlier 4th gen’s have 2?

 

[sag2]

I thought there were two, but I have been wrong before. Too much to remember!

 

[CRHardie]

Just a follow up to help someone who reads this not be as dumb as I am I guess. I have discovered a couple things about this truck that I’ve owned for a year now. One I’m actually ashamed to admit but I just realized this evening it has dual alternators. Not sure why and I see no need for it but whatever. I’ve only put 5000 miles on it in the last year so that’s my excuse. Any way like I said in my original post in my hurry to change the batteries and not unhooking the grounds on both before I started I had an arc on the passenger side cable on something. Well that blew the 250 amp fuse on the alternator cable that I didn’t know existed. No power to the alternator no charge truck thinks it has a low battery. Mr Fluke and I saw 14.2 volts at the battery because the other alternator was still charging. Ordered a fuse and will install tomorrow night. Guess that’s what 37 years as a diesel mechanic gets you. My head is hung in shame

 

[AH64ID]

Just a follow up to help someone who reads this not be as dumb as I am I guess. I have discovered a couple things about this truck that I’ve owned for a year now. One I’m actually ashamed to admit but I just realized this evening it has dual alternators. Not sure why and I see no need for it but whatever. I’ve only put 5000 miles on it in the last year so that’s my excuse. Any way like I said in my original post in my hurry to change the batteries and not unhooking the grounds on both before I started I had an arc on the passenger side cable on something. Well that blew the 250 amp fuse on the alternator cable that I didn’t know existed. No power to the alternator no charge truck thinks it has a low battery. Mr Fluke and I saw 14.2 volts at the battery because the other alternator was still charging. Ordered a fuse and will install tomorrow night. Guess that’s what 37 years as a diesel mechanic gets you. My head is hung in shame

The batteries and dual alternators are tied together, so if only one alternator is working everything should have the same voltage.

 

[CRHardie]

The batteries and dual alternators are tied together, so if only one alternator is working everything should have the same voltage.

True but I’m assuming that because the alternator with the blown fuse had no load on it because it was not charging the battery the module that monitors that believed it had a low battery. The volt meter in the dash display said 13/14 volts when the truck was running but I was still getting the low battery message and light

 

[petersonj]

My head is hung in shame

No need for that. You figured it out and you let everyone know the solution. That is what this forum is about.

- John

 

[AH64ID]

True but I’m assuming that because the alternator with the blown fuse had no load on it because it was not charging the battery the module that monitors that believed it had a low battery. The volt meter in the dash display said 13/14 volts when the truck was running but I was still getting the low battery message and light

Was it the passenger side alternator fuse that was blown?

Just went and played with my truck and found the following…

Disconnect the drivers side alternator charge cable and I get a low voltage light and low voltage. No clue why the other alternator didn’t pick up the load.

Disconnect the passenger side alternator charge cable and I get a low voltage light with proper charge voltage, so it picked up the load but the ECM sensed the disconnection and warned me.

Learned something new

 

[CRHardie]

Was it the passenger side alternator fuse that was blown?

Just went and played with my truck and found the following…

Disconnect the drivers side alternator charge cable and I get a low voltage light and low voltage. No clue why the other alternator didn’t pick up the load.

Disconnect the passenger side alternator charge cable and I get a low voltage light with proper charge voltage, so it picked up the load but the ECM sensed the disconnection and warned me.

Learned something new

Yes it is the passenger side