Replaced Main Battery Yesterday

[Reddout99]

Jeep wouldn't start a couple days ago, so I jumped it and took it to my trusted shop'
He tested both batteries and said the main battery needed replacement but the aux battery was pretty good. He said they charged the aux battery since they had access to it. Buttoned it all back up and I was good to go.
Now the weird part. The PO of my JT had disabled the start stop which was cool, no dash lights or anything. I assume he used a Tazer to do so, I only have the JScan app. When almost home, about 20 minutes later, coming to a stop light the engine shut in typical start stop fashion. I can still press the dash button to kill it.
What do you think was the cause? The PCM relearning after the battery swap?
I don't mind pressing the button on the dash, just wondering what caused it to come back on.
Thanks

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[Lost1wing]

Perhaps the ess saw an issue ( battery charging) preventing a stop start event. Charging the Aux and replacing the main would have corrected the issue and stop start would then begin to function normally. Just my guess. Is there a Tazer still connected under the dash, above to obd2 port?

Glad you got it going anyway.

 

[Brahmajoe]

My Battery has been showing 15v on the cluster when driving, is this considered normal. I feel like it’s Hella high.

 

[Pismo61]

Id replace both batteries,one will drain the other if one is bad.15 volts seems high dunno on that one.Also not a fan of the Tazor,but many have with no issues and is the Tazor been updated.Some have had to do that to prevent it from draining the batteries.

 

[SoK66]

Really should replace both batteries. An old aux battery combined with a new main battery is a future problem lurking. JMHO, the shop saw what was going to be involved in replacing the aux battery and punted.

 

[Hootbro]

My Battery has been showing 15v on the cluster when driving, is this considered normal. I feel like it’s Hella high.

If it is a sustained 15Vdc for long periods of time, I would say that is high and the batteries are struggling to maintain a state of charge.

Going into the winter months and increased use of heated seats, steering wheel and rear window/mirror defrost functions will put higher electrical demands on the battery and will struggle to maintain if the batteries are getting marginal.

 

[Brahmajoe]

If it is a sustained 15Vdc for long periods of time, I would say that is high and the batteries are struggling to maintain a state of charge.

Going into the winter months and increased use of heated seats, steering wheel and rear window/mirror defrost functions will put higher electrical demands on the battery and will struggle to maintain if the batteries are getting marginal.

I have been using my seats and wheel as of often. Maybe that’s why

 

[Reddout99]

Perhaps the ess saw an issue ( battery charging) preventing a stop start event. Charging the Aux and replacing the main would have corrected the issue and stop start would then begin to function normally. Just my guess. Is there a Tazer still connected under the dash, above to obd2 port?

Glad you got it going anyway.

No Tazer. I think the PO might have made the change

 

[Reddout99]

Really should replace both batteries. An old aux battery combined with a new main battery is a future problem lurking. JMHO, the shop saw what was going to be involved in replacing the aux battery and punted.

No they had access to it but couldn't get an aux battery for it in a reasonable amount of time. He said bring it back in the he summer to replace it.

 

[Reddout99]

Going into the winter months and increased use of heated seats, steering wheel and rear window/mirror defrost functions will put higher electrical demands on the battery and will struggle to maintain if the batteries are getting marginal.

First thing I've been doing is flipping on the heated seats and steering wheel whenever I jump in. I'm sure it was the original battery. I was at 41k miles.

 

[Lost1wing]

No Tazer. I think the PO might have made the change

If they removed the Tazer, I would think the vehicle would return to the state it was before. If unmarried anyhow.

You mentioned Jscan. Couldn't you just set it back to always off with that?

 

[Lunentucker]

My Battery has been showing 15v on the cluster when driving, is this considered normal. I feel like it’s Hella high.

Mine typically runs at 14.5-14.9 ever since I bypassed the lawn mower battery.

 

[Lunentucker]

No they had access to it but couldn't get an aux battery for it in a reasonable amount of time. He said bring it back in the he summer to replace it.

Keep a very close eye on things. If that aux is bad it'll suck the life from your new main battery.

 

[Brahmajoe]

Mine typically runs at 14.5-14.9 ever since I bypassed the lawn mower battery.

Mine is still connected could it possibly mean the aux is on its way out?

 

[chorky]

If it is a sustained 15Vdc for long periods of time, I would say that is high and the batteries are struggling to maintain a state of charge.

Going into the winter months and increased use of heated seats, steering wheel and rear window/mirror defrost functions will put higher electrical demands on the battery and will struggle to maintain if the batteries are getting marginal.

I would mostly agree - but with an exception. If it is super cold. When I bought my JT new, soon as temps dropped below freezing charging was in the low to mid 14v range. Once temps fall below 0, I pretty much see a charge of 15v constantly. Granted that was with factory batteries before I opted for the Genesis kit and removal of the aux. Now I dont know if that is normal or not but I would assume so due to the cold temperature. It has acted the same this year as well with the Genesis kit - so no change from original.

Mine is still connected could it possibly mean the aux is on its way out?

It could. SOP in these situations is to charge both batteries independently of each other and independently of the vehicle (ie, disconnect things). Each one needs a full recharge cycle, usually half a day or overnight. Plus resetting the IBS. Before doing diag, batteries need to be fully charged to assess what is going on.

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