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JK Write-UpsBulletin board forum regarding useful installation write-ups, budget fixes and homemade solutions for the Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X).
Another side discussion. I found out it really sucks when you drain your battery after the doors have been locked and the alarm is turned on. When I jump started it, the alarm started going off, which seemed kind of ridiculous to me since the key was in the ignition, in the on position with the engine running. Not wanting to turn off the engine, I was frantically trying to disarm the alarm with my key fob in the ignition and no button pushes worked. I had to go back in the house (with the alarm still blaring mind you), search for a backup key fob, to then turn the alarm off. I'm sure my neighbors loved me since this entire process took about 15 minutes with the alarm blaring before I got it turned off. Good morning neighbors! Sorry.
This does sound pretty hysterical. I have a pair of the Odyssey batteries and still managed to almost murder one while doing the month-long HID retrofit with the Jeep parked in the garage. I unwittingly had been doing all the test operations off the cranking battery and I was reading the accessory battery voltage during checks. The cranking battery had dropped to about 4V by the time I finished and tried to fire it up. It took me forever to figure it out. I ended up piggybacking in the accessory battery to fool a hobby battery charger into pumping some juice into it until the voltage was high enough to charge regularly. After that it's been 100%. That was a deeeeep cycle. Aside from the attempted murder, I've had zero problems with the Odysseys.
Ok, inquiring minds want to know what you used and how you took all those measurements?
I'ld like to do the same on my current Sears DieHard Platinum.
My JKU is now coming up on being 10 years old. Stock battery lasted 2 years before I replaced it with a Sears DieHard Platinum. That one lasted for 2.5 years and replaced it with another Sears Die-hard Platinum which is what is still installed. So I'm around 5 years on this 2nd one. Over the past 3 years, every 6 months I put the micro controller charger on it to make sure it's fully topped off. I'm currently crediting the additional life on the 2nd one due to using the micro controller charger on it. I wish I had that charger when the 1st DH Platium battery died, probably could have revived it. Although hindsight 20/20, it was probably a good thing I didn't since I likely would have missed my window of opportunity to purchase the 2nd DHP.
Last month I completely drained my current DHP after I forgot I left a device plugged into the OBD2 port overnight. It was drained pretty well, I couldn't unlock my doors with my key fob but I easily jump started it with one of those Lithium ion jump packs to get me on my way to work. Which BTW I feel is a better solution than a dual battery setup when you have one of these types of higher performance AGM batteries.
Another side discussion. I found out it really sucks when you drain your battery after the doors have been locked and the alarm is turned on. When I jump started it, the alarm started going off, which seemed kind of ridiculous to me since the key was in the ignition, in the on position with the engine running. Not wanting to turn off the engine, I was frantically trying to disarm the alarm with my key fob in the ignition and no button pushes worked. I had to go back in the house (with the alarm still blaring mind you), search for a backup key fob, to then turn the alarm off. I'm sure my neighbors loved me since this entire process took about 15 minutes with the alarm blaring before I got it turned off. Good morning neighbors! Sorry.
"...frantically trying to disarm the alarm with my key fob in the ignition and no button pushes worked." Too funny! My 90+ year old mother-in-law lives in a nice quiet mobile home park, and had similar happen a few times over a month before I fixed it -- A new way to get to know the neighbors!
Regarding the instrumentation:
For battery CCA (cold cranking amps) I use a Large Current Pulse analyzer from Argus -- Which was sued out of business by a competitor (Midtronics if I remember correctly) over patent infringement. Here's a https://www.amazon.com/Midtronics-PBT300-Battery-Charging-Starting/dp/B000K38UN6/ref=sr_1_3?crid=3AV9YPV45PP0&keywords=midtronics+battery+tester&qid=1559410752&s=gateway&sprefix=midtronics+battery%2Caps%2C308&sr=8-3. For accuracy and repeatability, the key point with these instruments is having clean terms, and direct connection to the battery terms themselves rather than through clamps. Takes only a few seconds, doesn't drain the battery, and the results on mine are repeatable. This test emphasizes cranking performance; but for a given battery as CCA's reduce so does the AH. This is a meter that gets used often.
For AH (amp-hour) testing, the measuring device is https://www.amazon.com/RC-Electronics-Inc-Watts-Analyzer/dp/B001B6N2WK/ref=sr_1_2?gclid=Cj0KCQjwxMjnBRCtARIsAGwWnBPA0xA9fqv5eidzcmPRB07zBA4ZS3XA2cOEbBfSdkCsUSt1dcjJmFgaAvJrEALw_wcB&hvadid=241938057982&hvdev=c&hvlocphy=9032843&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=10591898006012057900&hvtargid=kwd-128422222&hydadcr=24661_10400817&keywords=watts+up+meter&qid=1559411155&s=gateway&sr=8-2 It's a current shunt type ammeter plus voltmeter, and it calcs AH and several other measurements. Can't remember how accurate it tested against a Fluke, but it's plenty accurate for this sort of testing. I've got a resistive load bank with fans, but headlamps work too. The problem is that it takes a long time for a test, the test itself can take some life out of the battery, and the voltage should never get <10 or the battery can be damaged. Despite the potential issues, this test says a lot about the battery's ability for a deep draw down.
For the battery impedance measurement I have a https://www.amazon.com/AideTek-Portable-Internal-Resistance-Voltmeter/dp/B01L6IC8A4/ref=sr_1_4?crid=1PPGPDK8341VO&keywords=battery+impedance+tester&qid=1559412446&s=gateway&sprefix=battery+impedance%2Caps%2C422&sr=8-4 -- But this measurement is the least useful, measuring CCA with a large current pulse/conductance type of meter is getting the same information a better way.
One more thought Red... Normally I take the Argus Battery Analyzer to the store and test the battery right at the counter in front of the sales person, only takes a few seconds. I've seen a few that were significantly less than expected-rated, even with my limited use for family, friends, and neighbors.
One of the batteries that read low, and I accepted anyway, was a Diehard Platinum -- And it didn't last that long. Despite that, it's probably paid for itself over the last ~10 years just by verifying new batteries are at least close to spec.
One more thought Red... Normally I take the Argus Battery Analyzer to the store and test the battery right at the counter in front of the sales person, only takes a few seconds. I've seen a few that were significantly less than expected-rated, even with my limited use for family, friends, and neighbors.
One of the batteries that read low, and I accepted anyway, was a Diehard Platinum -- And it didn't last that long. Despite that, it's probably paid for itself over the last ~10 years just by verifying new batteries are at least close to spec.
Great idea! I was trying to think of a good use for this device if I decided to pick one up other than filling my curiosity for a one-time use.
It's been 5.3 years, and unfortunately the CCA on the Odyssey battery was down to 425 A (exactly half of rated). It still started the engine fine, no noticeable symptoms yet. It's life was shorter than my previous experience with Odyssey, but that's the way it goes sometimes.
Next up is a group 34 Diehard Platinum AGM from Autozone. Autozone owns the Diehard brand now, and Clarios manufactures them. A step down from Odyssey, but the price tag is way lower, less than 2/3 the cost. It's rated at 60 AH and 740 CCA and it measured 800 CCA before installation. Curious how long this one will last!
On a side note, I'm raising the alternator voltage by 0.18 volts (to 14.45 @ 26 C) using HPTuners. There's a temperature sensor near the battery, and the alternator voltage varies with temperature (about 18mv per deg C) via a 4 point curve. Hoping this slight voltage increase will reduce sulfation and add some life for an AGM battery.
Last edited by Mr.T; 11-09-2021 at 12:28 PM.
Reason: typo
Alternator voltage adjustment -- More AGM battery life???
Here's how simple it is to change the alternator's voltage at various battery temperatures in HPTuners. First pic is a voltage table with temperature (deg C) in the far left column. Second pic is a graphical view. Unrelated, but worth noting, are the coolant temperatures and conditions for the fan speeds on the left. There's a lot to HPTuners besides the hard-core engine tuning that it's known for.
As mentioned in the previous post, increasing the voltage by 0.18 throughout the range (new values shown in the table in the pic) might just be the ticket to increasing AGM battery life a bit. The basis for this is that running the higher end of Odyssey's recommendations for alternator voltage (14.2-14.5V at 25ºC with 18 mv per deg C temperature compensation) should tend to reduce sulfation. Note that charging with a multi-stage AC powered charger has a slightly higher max recommended voltage, which drops after the battery is almost completely charged -- The typical alternator doesn't do this, hence the lower max voltage for an alternator vs a multi-stage charger.
Last edited by Mr.T; 11-09-2021 at 12:28 PM.
Reason: typo
Got a question about the battery temp sensor. I cannot find one in any of my wiring diagrams and I know there was not one attached to the battery tray like the older Jeep’s. Any idea where the PCM is reading this temp? I worry that it could use the ambient air temp in front of the radiator that actually measures pretty accurately but under hood where the battery is located is going to be much warmer(hotter). I am considering bumping the charge voltage for the same reasons you did but am worried that may actually cause more loss of longevity by potentially overcharging.
Got a question about the battery temp sensor. I cannot find one in any of my wiring diagrams and I know there was not one attached to the battery tray like the older Jeep’s. Any idea where the PCM is reading this temp? I worry that it could use the ambient air temp in front of the radiator that actually measures pretty accurately but under hood where the battery is located is going to be much warmer(hotter). I am considering bumping the charge voltage for the same reasons you did but am worried that may actually cause more loss of longevity by potentially overcharging.
I was hoping no one asked this . Never found the sensor either, despite mention of a battery temperature sensor in the charging system description and the tables in HPtuners that appear to work as though there is a physical battery temperature sensor. For instance, the voltage gradually decreases as the engine warms up on a long drive even though ambient stays the same, and the voltage corresponds approximately to what the battery temperature measures with an IR thermometer.
Here's my take, battery temperature is a calculated value within the PCM, just like the fuel temperature and cat temperatures are. It's probably based on ambient temperature plus the factors that affect under-hood heat like engine temperature, MPH, fan operation, calculated cat temperature, calculated exhaust temperature, run time, etc.
Makes sense. I’ve been watching my charging voltages compared to engine and ambient temp and they do adjust roughly as expected but am on the low end of the spectrum at 30-50 degrees ambient.
How is the increased voltage setting working for you so far?
I've raised the voltage at the higher temps a bit more. I like what I'm seeing so far. Planning to check the CCA with the meter at least once a year to see to see how the battery ages.
06-01-2019, 05:33 AM
Odyssey batttery replaced...
. Never found the sensor either, despite mention of a battery temperature sensor in the charging system description and the tables in HPtuners that appear to work as though there is a physical battery temperature sensor. For instance, the voltage gradually decreases as the engine warms up on a long drive even though ambient stays the same, and the voltage corresponds approximately to what the battery temperature measures with an IR thermometer.
