Some data on batteries and current drain 1500 Hemi

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just_me

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Hi All,

After chasing down what appeared to be more than a dead battery, i measured and learned a bit an opted to share here (after fightnig with the very unintuitive registration process).

2020 Hemi 5.7 1500

First, the battery, after digging around and comparing to similar vehicles, is modestly undersized. So when a cell fails or it is partially discharged, it wont crank.

Second, according to several sources, many FCA batteries die within 3 years. Yikes!

But here's what i measured:

1 battery voltage, no load, stable: 10.4V or 5/6 cells. One cell dead. Apparently common. FYI a healthy battery should be about 2.1V/cell or 2.1 x 6 = 12.6V (not charging). Charging ought to show > 14V

Current drain:
___________

Note this is current - there is no such thing as voltage drain. I saw a lot of references to that myste4rious and non-existent measurement. Voltage is the, well voltage, the potential difference between the two terminals. Current is the volume of electrons (ok, holes for those physicists out there) that migrate (flow). To flow a lot of electricity a battery needs sufficient voltage and a low output impedance. A dead battery will fall in voltage under load because it has a hgih resistance and cannot deliver the current. And no joy comes of that.

If i disconnect and reconnect my battery ground terminal, with a ammeter in series to measure current flow here's what i get:

~ means "about"
1 immediate draw ~ 4A (yikes!)
2 After ~ 1 minutes ~ 2A
3 after ~ 5-10 min ~0.7A
4 after 10-15 min ~ 0.16A (160 mA)
5 After ~an hour+ ~ 0.050A (50 mA) --> ok, now it getting reasonable
6 after ~ a day ~ 0.03A (30 mA)

So it can be misleading, but this was a consistent pattern. Patience! This is normal and very low.

I will take FCAs free warranty crap-O battery, but after that i will but in the Diesel rated larger batter, AGM. Costco sells them for < $200

I hope this is helpful to others.

You lose some settings but nothing bad happens when you disconnect the battery.

If it is too low, you cannot get the darn truck to shut off and some stuff cycles until its good and dead. Ask me how i know :-(
 

crash68

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First, the battery, after digging around and comparing to similar vehicles, is modestly undersized. So when a cell fails or it is partially discharged, it wont crank.
and you derived that the OEM battery was undersized how? Hopefully not just comparing it to other similarly sized vehicles. There are lots of variables that need to be considered when the OEM sizes the battery for a vehicle.
As for a failed cell not allowing a vehicle to start that goes for just about all vehicles nowadays, the ECM/BCM won't function correctly with too low of voltage.
You should be able to upsize the battery to an H8 and a changing to an AGM type is a given.
 

Wild one

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and you derived that the OEM battery was undersized how? Hopefully not just comparing it to other similarly sized vehicles. There are lots of variables that need to be considered when the OEM sizes the battery for a vehicle.
As for a failed cell not allowing a vehicle to start that goes for just about all vehicles nowadays, the ECM/BCM won't function correctly with too low of voltage.
You should be able to upsize the battery to an H8 and a changing to an AGM type is a given.
The biggest variable when it comes to OEM batteries is the bean counters trying to keep costs down.The battery box with a bit of modding takes the H8 which is probably what the engineers originally spec'd,otherwise the box wouldn't be big enough to accept the bigger battery.
 

crash68

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The biggest variable when it comes to OEM batteries is the bean counters trying to keep costs down.The battery box with a bit of modding takes the H8 which is probably what the engineers originally spec'd,otherwise the box wouldn't be big enough to accept the bigger battery.
There's other factors like the same part fitting multiple platforms and situations, much like the EcoDiesel using the H8 in that battery tray. Cost can be kept down by using one part number, less paperwork involved. It's just a hold down clamp that get moved to accommodate the larger size.
 

Wild one

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There's other factors like the same part fitting multiple platforms and situations, much like the EcoDiesel using the H8 in that battery tray. Cost can be kept down by using one part number, less paperwork involved. It's just a hold down clamp that get moved to accommodate the larger size.
The only thing is the battery box was designed long before the ecodiesal was installed in the trucks. I stick with my statement,the engineers probably originally spec'd the bigger battery,but by the time the bean counters were done cutting corners/costs the gas powered trucks got the smaller battery.Very seldom is there any downside to a bigger battery,unless you're an accountant who's only priority is to cut manufacturing costs,and they spec'd the smallest battery that'll just barely get the job done.
 

turkeybird56

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The only thing is the battery box was designed long before the ecodiesal was installed in the trucks. I stick with my statement,the engineers probably originally spec'd the bigger battery,but by the time the bean counters were done cutting corners/costs the gas powered trucks got the smaller battery.Very seldom is there any downside to a bigger battery,unless you're an accountant who's only priority is to cut manufacturing costs,and they spec'd the smallest battery that'll just barely get the job done.
Want to have fun, which I am sure U know, the RAM takes forever to power down all the added stuff. I can hook up a multimeter, shut down truck, lock doors, and just watch the draw on the battery as the systems slowly shut down. MY 2019 has a particular issue: when Dealership flashed 5 modules after second battery in 4 months, updated the modules BUT, gave me an issue with my USB HUB under radio: Which stays powered in truck after I turn off. I can literally shut down the truck, and watch from outside and see HUB go dark, wait 45 seconds, and that sucker powers up for an hour (timed it for chits and giggles). Dealership has no clue, PUT in a STAR CASE. So yeah, there is always a draw on batteries ne way between passive security system, radio system, RF hub, etc. If I was parking for a long time and no run, I would put a tender on the battery. Just my Opinion.

ADDED: I replaced my OEM battery with Duralast Platinum H-7. I could have gotten an H-8, just did not feel like playing with Battery Box (lazy Boird).

ADDED: I had the same problem with my Harley Davidson with it's security system and fob. Let that sucker sit too long, battery not turn over. Luckily my Honda Wing is a 2006, and not got all the extra stuff drawing on battery. But I do put a tender on it if sitting long. I have an HD tender plug wired in and use my HD tender for the Honda, lol.
 
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DILLIGAF

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FCA are in the business of making money. so they stuff the cheapest crap available in your truck. Factory batteries are a joke at best.

There's a reason we all switch to H8s
 

turkeybird56

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FCA are in the business of making money. so they stuff the cheapest crap available in your truck. Factory batteries are a joke at best.

There's a reason we all switch to H8s
Luckily I normally do not have the extremes you have up North, so I can get away with a good H7. My biggest problem is the "heat", not the cold, so I still have to think replacing every like 4 years, as the heat cooks the heck out of the batteries also.

Heat gets to my MC also, as I have an AGM on the Bike. When riding in summer, it can be 100-110F on the highway, not counting the heat off the roadway, not sure if bike gets cooked more or dis BOIRD, lmao. (My 4 by 50 mph minus the winders gets a lil warm, lol). (I find as these old bones get older, it is real hard to ride over 100F, just too dang hot. OK if riding highway, rural, but not good with stop and go in town, OH HECK NO).
 
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