Solar Battery Tender Thoughts?

[8ntruck 9,306]

I've had the check engine light come on a couple of times in our 2019 Jeep Cherokee.  This has happened after the car has been unused for several weeks.

 

The volt gage says 14.3 volts when running and 12.3 or 4 after shutting the car off, indicating a low charge to me.

 

I suspect that the 'idle' electronics draw is what is draining the (AGM) battery. I'm going to put a battery charger on it tomorrow for a few hours to see if I can get a fuller charge on it.

 

I think i have 2 preventative choices. 1) install a battery shut off to disconnect the battery when the car sits idle, or 2) put a solar powered battery tender on it when it is idle.

 

Comments?  Recommendations on a solar charger?

 

Thanks.

[adsm08 5,151]

44 minutes ago, 8ntruck said:

Comments

 

1) 12.3V is slightly to somewhat discharged, but not enough to cause problems. If the amperage is low enough to cause issues that indicates the battery may not be holding enough charge and needs replaced.

 

2) Do not install a battery disconnect, it will cause other issues. Particularly if you are in a jurisdiction that has emissions testing. Disconnecting the battery will reset the computer's memory, this means you are also wiping out learned adaptations that make it run smoother and shift better.

 

3) Modern vehicles are not meant to sit for weeks at a time not being driven. You either need to drive it at least once a week, keep it on a proper tender (not solar, 110 outlet) that is hooked up correctly to allow the battery monitor to see the proper power flow (the ground side of your tender needs to be hooked up on the body, not directly to the battery), or get rid of it and get something older with less constant draw on the system (I would suggest a brand not owned by Stellantis).

 

4) This vehicle is, by default, equipped with a fairly high amp battery. High amp batteries sulfate and die faster when sitting than low amp batteries do.

 

5) Have you actually checked to see what the codes are, or are you just assuming they two things are related?

Edited 22 hours ago by adsm08

[8ntruck 9,306]

 No, I haven't checked what the code is. Making a semi-educated guess here.  The check light seems to go out after driving the car a bit.  Probably left something in the memory, though.

 

Good point on the disconnect - I hadn't thought of that.

[squonk 48,142]

Are the batteries original? If so one may be junk and drawing off the good one.

[ri702bill 13,087]

8 hours ago, adsm08 said:

(I would suggest a brand not owned by Stellantis).

Ah, yes. Since Jeep's acquisition by Stellantis, they use their less than spectacular Fiat Electronics - that have proven to be a major source of their drivability and breakdown issues....

[WHX?? 58,200]

Read the engine codes that might yield some info. 

[Handy Don 17,486]

Good thread. My ’22 Volvo had a “low battery” message for me when I returned from a 10-day trip. Service team gave me @adsm08’s advice about the tender and so I’ve done that whenever the car will be unused for than a few days.

I also learned that this car “stays awake” for a time after shut down that depends on a slew of sensors--one being that the hood is open and another that it is unlocked! So, once the tender is on, I must close and latch the hood and lock the car lest the car’s “thinking” draw more current than the tender is providing!

Edited 8 hours ago by Handy Don

[ML3 2,513]

For sure the new vehicles after sitting a few weeks will cause a battery to go dead. If vehicle was originally equipped with an AGM battery be sure to replace it with the same. Most newer vehicles now have keyless remotes w/push button start. Be sure keyfobs are far enough away from vehicle,  definitely not being left inside it. Whenever they are "in range" they will be transmitting/communicating with vehicle theft/start modules therefore increasing battery draw. 

 

 

[My_horse 131]

Some cars with auto start/stop have 2 batteries. A regular sized one and a smaller one. 

[ranger 1,862]

If you use a solar panel with one of the separate controllers, you might need to fit a switch between the Panel and the controller, the eBay controllers I use require the battery to be connected to the controller first, then the panel. Disconnection needs the panel disconnecting first to prevent the panel from damaging the controller if no battery is connected. I think that this applies to most of the Chinese controllers? 
My wife’s old Peugeot had an airbag fault which showed on startup. It also locked all the doors. Every internet source said that one of the computers was at fault. The car always started first time on the key no problem? What it turned out to be was the battery voltage dropped when the starter operated to below the voltage threshold of whichever module which controls the central locking, and airbags. The car had been sitting doing nothing for quite a while, (Covld). About a year later, I fitted a new battery, problem solved👍👍👍 Before I retired, I used to get similar issues with VM diesel engines, they would spin over normally on the key, but would not fire. Crank position sensor faulty would display on the diagnostics. VM technicians stripped the engine, new wiring loom, sensors, ecu, everything, no joy? Turned out to be the starter motor. Although the old original turned the engine over as fast as the new one, it pulled the voltage down and the CPS was the first sender to drop out. A machine that had been in our workshop for a month, and had been virtually rebuilt, without a single pop from the exhaust, fired up on the first turn😵‍💫

[adsm08 5,151]

6 hours ago, Handy Don said:

Good thread. My ’22 Volvo had a “low battery” message for me when I returned from a 10-day trip. Service team gave me @adsm08’s advice about the tender and so I’ve done that whenever the car will be unused for than a few days.

I also learned that this car “stays awake” for a time after shut down that depends on a slew of sensors--one being that the hood is open and another that it is unlocked! So, once the tender is on, I must close and latch the hood and lock the car lest the car’s “thinking” draw more current than the tender is providing!

 

I like to install tenders with two-pin bullet connectors with rings on the other end, and run the connector out through the grill, so that you can plug in without ever opening the hood.

 

5 minutes ago, My_horse said:

Some cars with auto start/stop have 2 batteries. A regular sized one and a smaller one. 

Both should be replaced as a set.

 

Also, cars with this set up need a reset of the battery monitor when replacing the batteries so the charging profile updates and doesn't over-charge.

[ML3 2,513]

40 minutes ago, My_horse said:

Some cars with auto start/stop have 2 batteries. A regular sized one and a smaller one. 

True. My last Cadillac had 2 AGM batteries & it was $600 3yrs ago to replace them. It had the stupid start/stop. New Cadillac has 2 AGM batteries as well but I purchased a plug in bypass harness to permanently turn off start/stop. 

[Handy Don 17,486]

54 minutes ago, My_horse said:

Some cars with auto start/stop have 2 batteries. A regular sized one and a smaller one. 

Mine does, too.

The 48v “starter" battery’s only jobs are: a) spinning the engine at startup, 2) adding some noticeable torque at launch and acceleration, and 3) spinning the supercharger (when needed 😉). Charging is via brake-triggered regeneration. (I’ve wondered if there was ever any value in kicking a Kohler S/G to “starter” mode for a horsepower boost 🤣.)

Everything else, e.g. ignition, electrics, and electronics, is off the 12v AGM.