Changing charge voltage for Odyssey battery?

[SIO2GA]

Hi Everyone,
I have a 2023 Jeep Gladiator Rubicon Diesel but I'm posting in the Wrangler forum since the Gladiator is close to being a "Wrangler with a bed" and there's a lot more members here than in the Gladiator forum.
Like most people, when my Jeep turned three years old the stop/start aux. battery died and took the starter battery with it. My Jeep had the tow package and has a 240 amp alternator and a 700 CCA AGM battery. I went with an Odyssey performance series 94R H7 AGM battery, 80-amp-hour, 850 cold cranking amps, 155 RC.
The Gladiator charges the battery to 12.6 volts which is fine for a regular flooded battery but not fine with AGM batteries that have extra capacity and are "full" at 12.85 volts.
After doing a lot of reading I figured out that my Jeep quickly let the new Odyssey battery run down to 12.6 volts, or only 80% capacity. I also learned that if I don't charge my battery to full with an AGM charger at least once a month that my battery will become sulfated and lose capacity. Once sulfated you can't get the capacity back. I contacted EnerSys, who makes the Odyssey battery, and one of the research scientists answered my email and she told me to charge it once a month or even once every two months but that going longer risks the battery getting sulfated and losing the capacity.
As an aside, I have an Everstart Maxx 15 amp charger with an AGM mode and I also bought a CTEK 5 amp charger that is specifically made for Odyssey batteries and has an "AGM2" mode specifically for Odyssey AGM batteries. I realize that the 5amp is not ideal for an 80ah battery but CTEK, who makes charges specifically for Odyssey said that the 5 amp charger would work for my specific battery but would just charger slower. After paying $350 for the battery I didn't have $275 for the next step up, the CTEK Odyssey specific 15 amp charger. The next step up after that was like a 300 amp charger for around $800 if I remember correctly. So I paid $110 for the 5amp since CTEK said that it would work okay until I could get one rated higher.
There's a lot of opinions and even outright wrong info floating around about AGM batteries (and Odyssey batteries specifically) and chargers so I did reach out to both Odyssey/EnerSys and CTEK with questions. For those not familiar with Odyssey batteries, they are made differently and need higher charging voltage and float voltage when charging than regular flooded cells and even other brands of AGM's. It became obvious to me that when I charge up the Odyssey battery to full capacity at 12.8 volts that it will quickly run down to 12.6 volts in 1 or 2 days and then the extra capacity is gone. Since I have the tow package that came with an AGM battery I don't understand why Jeep didn't set the charge function to keep the battery at 12.8v instead of 12.6v. It should be the same amount of work to maintain the 12.8v instead of 12.6v except for when the battery is run down by winching or running a radio or acc for long periods with the engine not running.
This brings me to the reason I am posting and writing all of this: Does anyone know how to go about changing the charging setpoints so that my Jeep will charge to 12.8v instead of 12.6v? I'm guessing a Taser or J-scan or some similar tool would work? So I'm trying to find out what to use and what settings should be changed. Has anyone tried changing the Jeeps charging settings? Does anyone know what settings need to be changed and what they should be set at to maintain 12.85V for my battery? I know there are some really knowledgeable people here on the Gladiator and Wrangler forums, and some have a lot of knowledge on batteries and Jeep systems so I'm hoping someone will help. Thanks for any help or insight anyone can give me on this.
Rodney

Sponsored

 

[WranglerMan]

I think you can set some voltage limits under the IBS section of JSCAN but I have not changed anything on my duel Genesis Gen 2 setup.

 

[Terrymo]

Good Question

Cliff Notes for those of us at the back of the class.

Does anyone know how to change the charging system set points of my Jeep so it will charge to 12.8v instead of 12.6v with a Taser, J-scan, or any other device?

@THAW ?

 

[Wabujitsu]

Following, as I’ve noticed the same issue with the OEM H6 (replaced by the dealership last year).

 

[MPets]

also watching this one.

 

[THAW]

Good Question

Cliff Notes for those of us at the back of the class.

Does anyone know how to change the charging system set points of my Jeep so it will charge to 12.8v instead of 12.6v with a Taser, J-scan, or any other device?

@THAW ?

I don't know of any way to change charging voltage set points using JScan, but I've not looked into it.

@SIO2GA, how, when, and where are you measuring battery voltage? What are your driving habits?

Battery voltage readings and vehicle charging voltage can vary significantly based on battery temperature. Most of the voltage-based SoC charts assume 25° C (77° F) for the battery (not ambient) temperature; batteries in engine bays will rarely be at that temperature (especially during winter).

Remember, too, with the engine off and the battery connected to the vehicle, there is always at least a small load on the battery (the load gets much bigger when the dash is awake). A load on a battery will cause voltage sag; the bigger the load, the lower the voltage.

Finally, in general, automobile alternator charging systems are not ideal battery chargers, because (even if they were intended to be) vehicle use patterns rarely line up with optimal charging times.

 

[SIO2GA]

I don't know of any way to change charging voltage set points using JScan, but I've not looked into it.

@SIO2GA, how, when, and where are you measuring battery voltage? What are your driving habits?

Battery voltage readings and vehicle charging voltage can vary significantly based on battery temperature. Most (all?) of the voltage-based SoC charts assume 25° C (77° F) for the battery (not ambient) temperature; batteries in engine bays will rarely be at that temperature (especially during winter). Voltage can vary by up to a few tenths for every 5° C (9° F).

Remember, too, that while the battery is connected to the vehicle, there is always at least a small load on it (the load gets much bigger when the dash is awake). A load on a battery will cause voltage sag; the bigger the load, the lower the voltage.

Finally, in general, automobile alternator charging systems are not ideal battery chargers, because (even if they were intended to be) vehicle use patterns rarely line up with optimal charging times.

After reading about the Odyssey and seeing time after time where people where making comments that "a vehicle is never going to charge an oddyssey properly" I've kept a close eye on it the past two weeks. I have an ohm-meter and have been checking at the battery. Also, When I put the charger on it, it shows 12.6 volts and 75 - 80% charger level.
It only takes a day or two for it to run down. I can pretty much tell by the dash guage when it has run down because then I notice that the voltage goes up a lot once I slow down.
It seems that the only time it's really cranking the volts up is when I let off the accelerator and coast. From what I've read, Stellantis has set that charging scheme to increase fuel efficiency. Right after I charge the battery I notice that the dash reading is very low as far as voltage and this slowly creeps up over a day or two. Initially after charging when I left off the accelerator and coast the voltage is below 12.6 and it's not charging the battery. After 2 days I noticed a marked difference when coasting because it goes up to 14.7.
I understand that the voltage on the dash isn't accurate and that the electrical systems is always putting a load on it to some degree or another. However, some information can be gleaned from the dash gauge about the battery voltage and if it is charging.
The battery is new - I bought it Dec.24 - and I'd like to start out right with it. I'd like to find a way to keep the battery as nearly full as possible with the alternator alone.
My guess was that a tazer or J-scan could change the charging set points. I've seen people comment that it could be done but no one seemed to be speaking from firsthand experience.
Yesterday I was doing google searches on the topic and most times when I enter "Jeep" in the search it will lead me to this forum. Yesterday I was reading here in a discussion about changing the setpoints by using HP Tuners/PCM Tuning Services & Flyin' Ryan Performance. They had some screenshots where they had changed the charging setpoints. I gathered that the discussion was about radios and amps and that's why they wanted a higher voltage output. It was late when I discovered this so I didn't dig too deeply into. I did gather that you have to buy a tuner and pay to unlock tunes. I think the tunes are for engine performance and racing and it seemed like it would be very expensive to go that route just to change the charging set point up by 0.25 volts. So I will dig into PCM flashes as well as if a tazer/J-scan would work. I'd like to have a tazer anyways and that is probably a lot less expensive than getting a tuner, a tune, and flashing the PCM. So I'm trying to find someone that has done this or knows about it.
You asked about my driving habits. Usually I have a 4 hour roundtrip drive to a mine that I've been working at 2 to 4 days a week. I'm taking some time off for about a month and that means short 13 miles to walmart and back almost every day. But longer drives isn't going to keep the battery charged to 12.85v / full capacity though.

 

[OldGuyNewJeep]

Interesting thread.

My Odyssey gave up the ghost earlier than I would have predicted given its premium price point. Note that i regularly maintained it with an Odyssey 6 stage 20a charger (no longer sold).

Now I’ve got a Northstar in it - same company as Odyssey.

 

[SIO2GA]

Interesting thread.

My Odyssey gave up the ghost earlier than I would have predicted given its premium price point. Note that i regularly maintained it with an Odyssey 6 stage 20a charger (no longer sold).

Now I’ve got a Northstar in it - same company as Odyssey.

Out of curiosity, how long did it last and how often did you maintain it? I ask because I may want to try maintaining it more often than you did as hopefully some insurance. I sure don't want to have to buy another battery for at least 5 years minimum. Ultimately I hope to be able to set my Jeep settings to keep the SOC / state of charge at 12.85 volts so that I don't have to charge it once or twice a month.
Odyssey did discontinue some battery chargers but do sell Odyssey branded batteries made by CTEK. They have a 5 amp @ $110 (which is what I bought), a 15 amp @ 275, and a 25 Amp Charger @ $327. ODYSSEY BATTERY CHARGERS DIRECT What I like about these is that they have an AGM2 mode that is specifically programmed to charge only Odyssey AGM batteries. They sure are expensive! After shelling out $350 for the battery I could only afford to get the 5 amp for the time being. For the price that they sell these for it would seem that it would have a display panel showing the charging rate, amps, volts, % charged, etc. As it is, one doesn't have a clue what it's actually doing and how far along in the charging process that it is.
CTEK has these chargers for sale without the Odyssey branding and without the special AGM2 mode for the same high prices and I am really curious what differences - if any - that the special AGM2 mode has in charging.
The Odyssey-branded "OBC-5" 5A charger that I got is seemingly well made and has some heft to it. It's made to be bolted under the hood as an onboard charger and it has permanent leads that you can connect to the battery posts instead of clamps. It has a simple way to disconnect the charger clamps and connect to the installed permanent battery post leads.

 

[THAW]

@SIO2GA, Tazer doesn't have features related to charging voltage.

And, I think your quest to alter voltage set points for allegedly better battery maintenance is the wrong approach - one possibly rooted in old info for vehicles not factory spec'd with AGM batteries and Intelligent Battery Sensors.

The way AGM batteries work, they can take hours at low absorption charge acceptance rates to achieve true 100% SoC. Vehicles are essentially just blunt-instrument chargers, since the average passenger vehicle trip time is ~30 minutes and engine bays get hot. So, for the vast majority of use cases, overriding voltage to "beat the algorithm" (were it even possible) is unlikely to meaningfully improve charging and could cause more harm than good. And, for use cases that already include the regular, hours-long operating times important for proper charging, the battery is likely maintained fairly well.

Thus, as you are apparently aware, occasional external charging is likely the surest path to longest battery life.

In any case, to get a better sense of CR[an]K battery condition and JL charging, JScan exposes IBS data including SoC percentage and real-time charge current under prevailing temperature and voltage conditions.

 

[SIO2GA]

@SIO2GA, Tazer doesn't have features related to charging voltage.

And, I think your quest to alter voltage set points for allegedly better battery maintenance is the wrong approach - one possibly rooted in old info for vehicles not factory spec'd with AGM batteries and Intelligent Battery Sensors.

The way AGM batteries work, they can take hours at low absorption charge acceptance rates to achieve true 100% SoC. Vehicles are essentially just brute-force chargers, since the average passenger vehicle trip time is ~30 minutes and engine bays get hot. So, for the vast majority of use cases, overriding voltage to "beat the algorithm" (were it even possible) is unlikely to meaningfully improve charging and could cause more harm than good. And, for use cases that already include the regular, hours-long operating times important for proper charging, the battery is likely already maintained fairly well.

Thus, as you are apparently aware, occasional external charging is likely the surest path to longest battery life.

In any case, to get a better sense of CR[an]K battery condition and JL charging, JScan exposes IBS data including SoC percentage and real-time charge current under prevailing temperature and voltage conditions.

Thanks for that info. as that puts me a step ahead. Getting a Tazer is high on my list. When I go back to working at the mine it'll be a 4 hour round trip commute daily to the mine, 2 to 4 days a week.
As far as what bugs me about the Jeeps charging, after I charge the battery the system seemingly draws the voltage down on purpose within 2 days - that's based on the dash gage reading low voltage for two days after charging until it seemingly thinks the voltage is "right" and starts back charging. After the battery is drawn down It mostly seems to only ever be over 13.6 volts except for when it is coasting to a stop when it goes to 14.7. It seems that Stellantis wants a tiny bit of improved gas mileage over the battery being charged. That right there is why I have the idea that the charging can be improved based on stellantis doing the wrong thing with charging to improve fuel efficiency. They worry about the MPG number and not if a customer is going to have to buy a battery more often than necessary..

 

[THAW]

Thanks for that info. as that puts me a step ahead. Getting a Tazer is high on my list. When I go back to working at the mine it'll be a 4 hour round trip commute daily to the mine, 2 to 4 days a week.
As far as what bugs me about the Jeeps charging, after I charge the battery the system seemingly draws the voltage down on purpose within 2 days - that's based on the dash gage reading low voltage for two days after charging until it seemingly thinks the voltage is "right" and starts back charging. After the battery is drawn down It mostly seems to only ever be over 13.6 volts when it is coasting to a stop when it goes to 14.7. It seems that Stellantis wants a tiny bit of improved gas mileage over the battery being charged. That right there is why I have the idea that the charging can be improved based on stellantis doing the wrong thing with charging to improve fuel efficiency. They worry about the MPG number and not if a customer is going to have to buy a battery more often than necessary..

I love my Tazer, and think they're totally worth it.

I highly recommend JScan as well. If nothing else, it'll help you see more of what's going on with your battery so you can figure out how to best charge it.

 

[zouch]

hey Randy,

your charging system is getting up to 14.7'ish (when coasting down); isn't that doing the job of avoiding sulfation?

sounds to me like a 2-hour trip a few times a week is doing a great job of keeping this battery charged and in a good state of health, and the IBS is protecting it from excessive heat by overcharging when it's not needed.

 

[OldGuyNewJeep]

Out of curiosity, how long did it last and how often did you maintain it? I ask because I may want to try maintaining it more often than you did as hopefully some insurance. I sure don't want to have to buy another battery for at least 5 years minimum. Ultimately I hope to be able to set my Jeep settings to keep the SOC / state of charge at 12.85 volts so that I don't have to charge it once or twice a month.
Odyssey did discontinue some battery chargers but do sell Odyssey branded batteries made by CTEK. They have a 5 amp @ $110 (which is what I bought), a 15 amp @ 275, and a 25 Amp Charger @ $327. ODYSSEY BATTERY CHARGERS DIRECT What I like about these is that they have an AGM2 mode that is specifically programmed to charge only Odyssey AGM batteries. They sure are expensive! After shelling out $350 for the battery I could only afford to get the 5 amp for the time being. For the price that they sell these for it would seem that it would have a display panel showing the charging rate, amps, volts, % charged, etc. As it is, one doesn't have a clue what it's actually doing and how far along in the charging process that it is.
CTEK has these chargers for sale without the Odyssey branding and without the special AGM2 mode for the same high prices and I am really curious what differences - if any - that the special AGM2 mode has in charging.
The Odyssey-branded "OBC-5" 5A charger that I got is seemingly well made and has some heft to it. It's made to be bolted under the hood as an onboard charger and it has permanent leads that you can connect to the battery posts instead of clamps. It has a simple way to disconnect the charger clamps and connect to the installed permanent battery post leads.

I got 4 years, almost to the day. Symptom it was bad was anti-lock brakes engaging on their own. Fun. See: https://www.jlwranglerforums.com/fo...ults-i-feel-the-brakes-briefly-engage.160589/

I have this charger, and it was expensive. I think it's great, though: https://www.energy-xprt.com/products/odyssey-obc-20a-amp-battery-charger-917729/

You won't want to hear this, but a 5a charger isn't going to cut it. See: https://www.jlwranglerforums.com/fo...acement-question-for-the-experts.66343/page-6

I throw my charge on once a month in warm weather, bi-weekly (or more often) in cold. How do I decide? I keep alternator voltage as my default view on the dash. First trip of the day will always show 14.4-14.6, even on a freshly charged (or even brand new) battery. The second trip it will go down to 13.x. The longer I drive on that second trip, the more it falls. So long as I see it get to 13.1-13.4 I know my battery is healthy and adequately charged. Now, as the battery ages or when it's really cold I'll never get out of 14.4-14.6.

When it never gets lower than 14.6 no matter what, battery is done. That's my anecdotal observation, anyway.

If I were you I would return the CTEK (they are very nice) and get something heftier, even if you go with a lesser brand (e.g. Noco). Or, if you're lucky, you might find the one I have second hand. It really is a gem. Shame they discontinued it. (I never bothered to check if it was just a rebranded one like they now do with CTEK.)

 

[WillysMeow]

Very interesting discussion, I've had AGM batteries for years...one Odyssey that lasted not even 2 years and friend's lasted slightly longer...I'm done with that company's batteries.

Sponsored