Battery Tender - Issue with 2016 GT ?

[plresultsman]

Getting ready for winter nap, and my Schumacher SC1303 battery tender doesn't appear to work on new-to-me 2016 GT Mustang 'vert with 15k miles. I tested it on a 2017 Subaru and it seems to work fine. On Mustang it lights up and recognizes battery type and charging, then turns off totally dark - unlike on Subaru. I tried both the battery negative terminal, and the suggested frame negative spot from Mustang owner's manual, for the tender negative. The car sat recently for two-ish weeks and the battery went dead after one start, but I was able to jump it and charge it with a brief ride. It appears to be the original battery in the car.

Note that in the Mustang:
- see pics below. There is a red small light that burns just above the 'above' the battery near the firewall - anyone know what that is?
- several smaller wires are running off of battery - again, anyone know what those are?

The car has a Shaker stereo, Roush Stage 1 Supercharger and Magnaflow exhaust (non-active exhaust) - but is otherwise stock. No aftermarket electronics.

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[WildHorse]

Well if it works fine on the Subaru, but not on the Mustang with a bunch of 'unknown wires'.. what does that tell you ?

 

[plresultsman]

Well if it works fine on the Subaru, but not on the Mustang with a bunch of 'unknown wires'.. what does that tell you ?

It appears to shut down when connected to Mustang. Why would that be?

 

[WildHorse]

appears to shut down when connected to Mustang. Why would that be?

Probably because you have a bunch of unknown wires going to God knows what. Disconnect the positive and negative leads on the battery, hook the tender to the battery, and see what happens.

 

[plresultsman]

Not God-knows-what - The only additional equipment on the car is the supercharger.

 

[WildHorse]

Not God-knows-what - The only additional equipment on the car is the supercharger.

Did you not type all this :

- see pics below. There is a red small light that burns just above the 'above' the battery near the firewall - anyone know what that is?
- several smaller wires are running off of battery - again, anyone know what those are?

That's 'God knows what'.

I gave you a very simple task to see if that's the problem. Can't help any further cause I hate guessing games.

 

[plresultsman]

Did you not type all this :


That's 'God knows what'.

I gave you a very simple task to see if that's the problem. Can't help any further cause I hate guessing games.

Thanks for the 'help'.

 

[Laztug]

The battery tender is shutting down as a failsafe.
I can armchair mechanic with the best of them, but you really need to figure out where those wires lead to.
Someone with poor craftsmanship, no motivation, and at least 1 bad eye tossed that mess together.

 

[ORRadtech]

Simply put, chances are very good that you have a dying battery.

*A 5-6 year old battery
*Dead after sitting 2 weeks.
*Driving a short distance will NOT properly charge a dead battery, it will barely put a minimum charge on it.
*14.4V in your picture is reading the charging system, not battery voltage.
*That rats nest of wiring and random red light belies your claim there are no added electronics.
*A decent maintainer that shuts itself off after ID'ing the battery.

Nothing in this bodes we'll for the battery...

 

[Dana Pants]

Get a new battery before diagnosing further.

 

[Hidalgo]

You got yourself a bad battery.

 

[Cobra Jet]

The battery tender is shutting down as a failsafe.
I can armchair mechanic with the best of them, but you really need to figure out where those wires lead to.
Someone with poor craftsmanship, no motivation, and at least 1 bad eye tossed that mess together.

 

[ORRadtech]

Probably because you have a bunch of unknown wires going to God knows what. Disconnect the positive and negative leads on the battery, hook the tender to the battery, and see what happens.

Thanks for the 'help'.

Like it or not he stated the truth and made a very valid troubleshooting suggestion.

 

[StangTime]

I would want to know what that box is doing. It didn't come from the factory that way and it sure didn't come with that green and grey wire either. Looks like you have more than just one after market device connected to the battery. I would find out where they go. I'm guessing GPS tracker installed somewhere.

Also, the battery tender should not be attached to the battery ground. It need to go to the ground wire on the strut tower.

This is likely not the reason your charger shuts down. Have your battery tested at a shop or parts store. They will tell you if your battery is done.

 

[CrimsonRocket]

My tender wouldn't charge a fully depleted/dead battery. Tried everything. When i finally got a new battery everything worked fine. Took the dead battery out and kept the tender on it. It finally started charging after 3 days.

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