JK Battery?

[vtsoundman]

Oh yeah..I skipped an important point. I don't have dual batteries under the hood because of the reasons that both you and I mentioned above. I have a standard lead-acid battery up front and a 120 amp hour group 31 in the rear (much like you mentioned). The use I described was for one night of average, actual camping with no winching. The group 31 is housed in a National Luna Power Pack, so it disconnects the starter battery almost immediately after you begin to use power (I think at 12.5 volts...don't quote me on that though).

In the morning I would find that the group 31 had dropped to 12.1 or 12.2 volts, which is just about as low as I want to go for lifecycle reasons. To be fair, I could discharge it quite a bit more for another night (most likely). I have made it through two or three nights by running the engine for 120 minutes each afternoon, but it is kinda of a pain to be worrying voltage about it all the time.

I use a "Fanstastic Fan" meant for RV use. On low it supposed to pull about 1.5 amps per hour. As for the National Luna fridge I've read that it averages 1.6 per hour, but have never verified that. Could be a bit more or less. The fridge is housed in a "Jeep Kitchen" and has appr. 1.5 inches of clearance all around it with vents in the cabinet.

Please take my post with a grain of salt. I am no expert. I do however pay attention to the voltages when around the camp fire, and honestly, if I had known just how much money, attention, and inefficiency is involved with 12 volt power going in, I would have continued to buy ice for the cooler and D batteries for a fan.

Oh yeah..I skipped an important point. I don't have dual batteries under the hood because of the reasons that both you and I mentioned above. I have a standard lead-acid battery up front and a 120 amp hour group 31 in the rear (much like you mentioned). The use I described was for one night of average, actual camping with no winching. The group 31 is housed in a National Luna Power Pack, so it disconnects the starter battery almost immediately after you begin to use power (I think at 12.5 volts...don't quote me on that though).

In the morning I would find that the group 31 had dropped to 12.1 or 12.2 volts, which is just about as low as I want to go for lifecycle reasons. To be fair, I could discharge it quite a bit more for another night (most likely). I have made it through two or three nights by running the engine for 120 minutes each afternoon, but it is kinda of a pain to be worrying voltage about it all the time.

I use a "Fanstastic Fan" meant for RV use. On low it supposed to pull about 1.5 amps per hour. As for the National Luna fridge I've read that it averages 1.6 per hour, but have never verified that. Could be a bit more or less. The fridge is housed in a "Jeep Kitchen" and has appr. 1.5 inches of clearance all around it with vents in the cabinet.

Please take my post with a grain of salt. I am no expert. I do however pay attention to the voltages when around the camp fire, and honestly, if I had known just how much money, attention, and inefficiency is involved with 12 volt power going in, I would have continued to buy ice for the cooler and D batteries for a fan.

Ah ok... those are estimates.

12.0-12.1V was that voltage resting? Any load will depress the battery voltage and give an artificially low values.

Fridges are worth their weight in gold...I've never looked back. I honestly find the system to be relatively care free...

 

[jacobconroy]

Ah ok... those are estimates.

12.0-12.1V was that voltage resting? Any load will depress the battery voltage and give an artificially low values.

Fridges are worth their weight in gold...I've never looked back. I honestly find the system to be relatively care free...

Yup, just estimates. I've been using the built-in voltage lights on the NL Power Pack. The few times I checked them...they seem to be on-the-money. I am glad that I have a fridge. Particularly the freezer (which I use quite a bit to have ice in my drinks).

 

[big_willy_wanderer]

what kind of dual battery system do you guys run? I have an ARB 50 and just have been running it off the starter battery and usually don't sit for longer than 20 hours when out camping. It makes me nervous tho.

We run Dual Battery Systems that include DC to DC Charging units and battery monitoring. The missing link for most people, is that without a DC to DC charger in the mix, performance/deep cycle/hybrid batteries never charger to 100% In fact, most of them wont get over 80-85% without a high-output alternator or a DC to DC charger. In addition, most vehicles built in the USA after 2006, have smart alternators which will dial back the charging power of the alternator, when the first of the two batteries starts to top off and have problems hitting the second battery like they should.

 

[vtsoundman]

We run Dual Battery Systems that include DC to DC Charging units and battery monitoring. The missing link for most people, is that without a DC to DC charger in the mix, performance/deep cycle/hybrid batteries never charger to 100% In fact, most of them wont get over 80-85% without a high-output alternator or a DC to DC charger. In addition, most vehicles built in the USA after 2006, have smart alternators which will dial back the charging power of the alternator, when the first of the two batteries starts to top off and have problems hitting the second battery like they should.

We run Dual Battery Systems that include DC to DC Charging units and battery monitoring. The missing link for most people, is that without a DC to DC charger in the mix, performance/deep cycle/hybrid batteries never charger to 100% In fact, most of them wont get over 80-85% without a high-output alternator or a DC to DC charger. In addition, most vehicles built in the USA after 2006, have smart alternators which will dial back the charging power of the alternator, when the first of the two batteries starts to top off and have problems hitting the second battery like they should.

Only 80-85%? Hmm....sure if you don't let the Jeep run long enough, but a DCDC will have the same issue.

The JK alternator will produce 14.3-14.6V and higher (at times, temps) which is almost perfect for most AGMs/ deep cycle batteries. (Perfect is up to 15.2V when adjusted for cold temps).

The Jeep will also will produce up to 165A at around 2500 enigne RPM. Two batteries placed in hard parallel will look like a single battery to the PCM - in my experience, it keeps that voltage high until the current into the battery drops to a few amps.

The charging protocol in a Jeep is actually quite good.

The missing link is time - the Jeep has to run long enough to get full charge into the battery - which is a problem for a b2dc as well.

Getting the battery over 92/95 to 100% is where the issue is - most large quality AGMs need 2-4hrs of absorb time...couple that with the bulk charge requirement, and charging could take 6hrs or more...and this leads to PSOC and deficit cycles in large batteries in vehicles. This is why most people should be using an AC charger to keep those batteries topped off after a long run.

I've taken my batteries way way down on many occasions and the JK alternator has done an damn good job getting them charged backup...if I give it the time it needs.

Edit:
Forgot to mention, I am a big user and fan of DC converters - they are in my Jeep, Sprinter and Mini Countryman - only if they can be adjusted for the battery and have a temp comp probe (CTEK cannot be adjusted - so that's out. REDARC is very limited, so that depends) ...the Jeep can get by without one, but not possible in the Sprinter.

 

[big_willy_wanderer]

My Jeep is a 2016 JKU the alternator puts out 14.4 max. The charge time issue is not what I'm referring to. The voltage output is the issue and the smart alternators in most modern vehicles (when talking dual battery.) If the Voltage that the alternator is putting out doesn't reach into the region of 14.7 or 14.8 the battery will not fully charge and there are multiple references to the 80-80% that I quoted. I cant speak about your Sprinter , or RVs, or HO Alternator equipped vehicles-- but regular trucks like Tacoma, Tundras, Jeeps and just about everything else, using the alternator alone, will not charge the deep-cycle battery/ or hybrid past about 80% The top 20% will not charge and will eventually become near useless. Look at the charge profile available from the manufactures and most of them show the requirement. This is a non-issue on a starter battery, but on house/accessory batteries , it can be significant.

The "gate" is the lover than 14.7 or 14.8 volts. Its like a line on a sign that says "You must be this tall, to charge 100%" If you aren't 14.7 volts tall -- you aren't going to charge all the way.

The other issue is the smart alternators. With two batteries hooked up-- the current hits the first battery and starts charging (the deficit is large) solidly and quickly. Then the "ECO/GREEN" settings in the alternator power it back/reduce its output to compensate for the high voltage (as the charge nears its upper threshold) and the second battery suffers for the cause.

I'm not making this up. If you are willing to put in the time and do the research, you'll find that what I'm saying is fact. Not sure what you're referring to about the probe. There is a temp probe on both the ctek and the RED ARC-- what exactly are you looking to do?

Side Note: I have a full CTEK D250SA/Smarpass system with Solar. It all works fine. My house battery charges 100% . . .It did not before this setup

Dave

 

[jadmt]

I just did some research and it sounds right. your car battery gets charged fully and the alternator cuts way back so your house battery really never gets fully charged.

 

[vtsoundman]

My Jeep is a 2016 JKU the alternator puts out 14.4 max. The charge time issue is not what I'm referring to. The voltage output is the issue and the smart alternators in most modern vehicles (when talking dual battery.) If the Voltage that the alternator is putting out doesn't reach into the region of 14.7 or 14.8 the battery will not fully charge and there are multiple references to the 80-80% that I quoted. I cant speak about your Sprinter , or RVs, or HO Alternator equipped vehicles-- but regular trucks like Tacoma, Tundras, Jeeps and just about everything else, using the alternator alone, will not charge the deep-cycle battery/ or hybrid past about 80% The top 20% will not charge and will eventually become near useless. Look at the charge profile available from the manufactures and most of them show the requirement. This is a non-issue on a starter battery, but on house/accessory batteries , it can be significant.

The "gate" is the lover than 14.7 or 14.8 volts. Its like a line on a sign that says "You must be this tall, to charge 100%" If you aren't 14.7 volts tall -- you aren't going to charge all the way.

The other issue is the smart alternators. With two batteries hooked up-- the current hits the first battery and starts charging (the deficit is large) solidly and quickly. Then the "ECO/GREEN" settings in the alternator power it back/reduce its output to compensate for the high voltage (as the charge nears its upper threshold) and the second battery suffers for the cause.

I'm not making this up. If you are willing to put in the time and do the research, you'll find that what I'm saying is fact. Not sure what you're referring to about the probe. There is a temp probe on both the ctek and the RED ARC-- what exactly are you looking to do?

Side Note: I have a full CTEK D250SA/Smarpass system with Solar. It all works fine. My house battery charges 100% . . .It did not before this setup

Dave

In general, I am in favor of B2DC converters. The main beef I have with most of them is their inability to change the charging profiles, alter tail current/aborb times (as when to end absorb and head to float), change float current/bulk current thresholds (when running loads).

I never said CTeK or Redarc dont have temp sensors - it is their inability to tune the charging curve that bugs me. Most use voltage and a timer, which is an awesome way to be fooled by sulfation caused by PSOC....

Toyotas are known to have low voltages and aggressive voltage reduction schemes - they are a different animal than a Jeep.

Much of what you say about the PCM backing off the voltage on an alternator is true - however, given sufficient time, most AGMs will charge to 100% SoC at 14.3--14.4V. The absorb phase is greatly reduced if one can increase the current (by increasing the voltage) to a set limit - sometimes as high as 14.7V. Do that with a Lifeline on a regular basis and you run the risk of drying out the plates...

Another reason to push higher voltages is to reverse the effects of PSOC and deficit cycles that plague marine and auto industries. Hence the reason that many resorted to connecting a shore charger from time to time...

Part of what you're referring to with smart alternators is the next generation of ECO savings being phased in where the alternator voltage is truly reduced to the mid 12s. Many vehicles drop to an intermediate level now - usually in the mod 13V. I see an early version of this behavior on Sprinters (they periodically drop the alternator bus voltage) and see the most aggressive flavors on new German vehicles (nearly turning it off altogether - it will get worse, just wait!)

In my 07 JK, batt voltage remains high if there is sufficient current draw on the system - that leads me to believe that PCM is looking at voltage, current draw (via field current) and time when determining when to dial back the alternator. I've seen this behavior on other vehicles as well.

Regarding charge voltage :

One cannot use a broad brush to paint the voltage requirements.

AGMs vary from mfr to mfr - Lifelines prefer less voltage (around 14.3) than Full River (around 14.7). Odyssey is on the high side... (This is all at STC of 25C)... In fact, Odyssey suggests limiting charge current at 14.7, but at 14.2, there is no such limitation (at STC). Some batteries mfr even want a certain c-rate to maintain battery health too...

My cheapy Deka / Duracell Group 31 under the hood from Sam's Club prefers a slightly lower curve - I've run it down below 50% many times and the alternator does a good job bringing it back up provided I drive long enough. My Group 31 Universal Battery - another cheapy, will be fine as low as 14.4 at STC...

 

[big_willy_wanderer]

All great info... you're still not getting a 100% charge on a deep cycle or performance hybrid...with a regular alternator butting out 14.4 volts.

 

[vtsoundman]

All great info... you're still not getting a 100% charge on a deep cycle or performance hybrid...with a regular alternator butting out 14.4 volts.

Hmm ok.

AGMs vary from mfr to mfr - Lifelines prefer less voltage (around 14.3) than Full River (around 14.7). Odyssey is on the high side... (This is all at STC of 25C)... In fact, Odyssey suggests limiting charge current at 14.7, but at 14.2, there is no such limitation (at STC). Some batteries mfr even want a certain c-rate to maintain battery health too...

 

[Cedo Nulli]

I don't run double batts, but I do run the Odyssey. I'd recommend.

Related/unrelated, our club has noticed a trend of parasitic draw we haven't been able to pin point on the 2015 and 2016 JKURs running Odyssey and SPODs. Jeep sits for more than a week...she's dead. All three rigs are running essentially the same setups. Odd...but, I only bring it up because of the PITA of reconditioning an AGM battery.

 

[big_willy_wanderer]

I don't run double batts, but I do run the Odyssey. I'd recommend.

Related/unrelated, our club has noticed a trend of parasitic draw we haven't been able to pin point on the 2015 and 2016 JKURs running Odyssey and SPODs. Jeep sits for more than a week...she's dead. All three rigs are running essentially the same setups. Odd...but, I only bring it up because of the PITA of reconditioning an AGM battery.

Cedo, thats strange. I've seen more and more complaints on the Odyssey stuff. I run North Star up front and in back. I have an SPOD-- I don't get any parasitic draw-- again, wonder if its an Odyssey thing?

 

[Cedo Nulli]

I'm beginning to think it may be. I've switched out to a standard acid batt and haven't had near the problems with long-term storage as I was having with the Odyssey.

There still has to be a draw from somewhere though. Of course, could simply avoid by disconnecting, pulling fuse, or adding a batt kill switch...but, ideally wouldn't have to deal with any of that.

 

[jacobconroy]

The charging protocol in a Jeep is actually quite good.

The missing link is time - the Jeep has to run long enough to get full charge into the battery - which is a problem for a b2dc as well.

Getting the battery over 92/95 to 100% is where the issue is - most large quality AGMs need 2-4hrs of absorb time...couple that with the bulk charge requirement, and charging could take 6hrs or more...and this leads to PSOC and deficit cycles in large batteries in vehicles. This is why most people should be using an AC charger to keep those batteries topped off after a long run.

Good point. I'm not really an Overlander, just a car camper that likes to screw crap to his rig and stays within 100 miles of home. Therefore, I rarely ran the Jeep long enough to get 100% on the deep cycle. Solved it by installing a 2 bank NOCO charger in the Jeep. After getting home I just plug it in for 24 hours. Best money I have ever spent on 12 volt gear. Worrying about voltage at camp can really screw up a camping trip. Especially when you didn't have the battery topped off upon arrival at camp.

 

[vtsoundman]

I'm beginning to think it may be. I've switched out to a standard acid batt and haven't had near the problems with long-term storage as I was having with the Odyssey.

There still has to be a draw from somewhere though. Of course, could simply avoid by disconnecting, pulling fuse, or adding a batt kill switch...but, ideally wouldn't have to deal with any of that.

Killing a 63Ah battery in a week...that implies a 150-300mA draw...should be relatively easy to find.

Can one of you guys get a clamp-on meter and start looking for the parasitic (start pulling fuses until the draw disappears)...I've come across a few sPODs that developed a parasitic draw. They were way past warranty and we solved the issue by moving the tap to a switched ignition source. One was pulling current from the main feed - he pulled it out and tossed it in the trash and used custom built panel instead. Also, how many of you guys are running LEDs for interior lights? Some interior lights, if not CAN bus compatible, will continue to draw some current (esp the rear cargo light) even if it is 'off'. The JK uses FETs inside the TIPM instead of relays to control interior lights...

Odyssey's like voltage and a LOT of current when charging - if you really flatten them, this is where an adjustable B2DC really shines - they need 14.7-15.0V at STC to properly recover. There is a statement in the technical manual about having a min of 0.4C - for a 100Ah battery, that means they need a min of 40A. Odyssey behavior is quite DIFFERENT than many other AGMs on the market. Many AGMs actually suggest a limit on charging current...

Take a look at the top of P16 manual - http://www.odysseybattery.com/documents/US-ODY-TM.pdf You will see that one sample was charged at lower voltages while the other was charged at higher voltages & currents. The lower voltage battery had less life.

A standard lead acid or even a typical AGM battery will not suffer from deficit cycles (from PSOC) like Odyessys in mobile applications... ... because ... Odysseys need voltage AND current AND time to charge properly....something that is hard to do in a vehicle. (A deficit cycle is where the battery is partially charged and then discharged again...this leads to premature sulfation hardening (among other issues) within the AGM mat.)

 

[vtsoundman]

Good point. I'm not really an Overlander, just a car camper that likes to screw crap to his rig ...

We all were ... until people starting charging money for a badge and a number so you could be 'bound' for the outdoors...via a car to go camping & hiking ....and car camping became over landing ... and now goods & services carry the same tax as marriages & marine/boats. Just say overland or expedition and the price will double or triple.