JK Wrangler Unlimited Cargo Area Auxiliary Battery Shelf

[Expedition Essentials]

Nice Job

 

[mmaattppoo]

To evaluate the voltage of my aux battery and the power draws associated with my fridge, LED strip lighting, RTT power feed (when connected), and the 12V wash down pump I installed a GT Power Watt meter...

This small inline meter should allow me to monitor the overall power draw of the accessories that run through my panel from my aux battery.

 

[mmaattppoo]

After the first couple camping trips this summer it became apparent that a 75 AH deep cycle AGM battery (Northstar) is only good for about 2 days of continuous fridge use before reaching approximately 12.1 - 12.2 volts (a little less than 50% SOC). Remaining stationary for >2 days required idling the engine for at least an hour a day to avoid running the battery flat...not ideal since 1 hour of idling really doesn't fully recharge the battery, is not an efficient use of fuel, puts wear and tear on the engine, and has the added benefit of attracting mosquitos from miles around (CO2 and warmth of the exhaust/engine is very effective as a mosquito attractant).

The solution was to take advantage of the D250S' inbuilt MPPT solar charge controller and add a pair of 75 Watt monocrystalline solar panels for an installed total of 150 Watts (under ideal conditions). This setup should easily feed the ~450 Watt•hr consumption of the fridge over a 24 hr period (primary power consumer) plus the minor draws from LED lighting and a fan inside the RTT overnight. With 150 Watts on tap I should be able to makeup the power used by the fridge and sundries overnight within ~3-4 hrs, and run the fridge over the course of the day, and have power to spare.

Here's a picture of the panels unfolded:

Here's a few photos of how I'm planning to connect the panels to the D250S:

I'll post a photo of the completed setup tomorrow after I bypass the charge controller that came with the panels and connect them to the D250S (with a fused +ve line) per the installation instructions from CTEK.

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[TheDriver]

Nice work on the whole install - I may use your idea for the external solar connection location! I had my extinguisher setup like yours for a long time and finally changed it to a quick release setup:

https://www.summitracing.com/parts/sdk-firexmntdag

It takes up a bit more room as it stands off the roll bar but it's a lot more secure (no rotating around the bar or need for velcro straps on the bottom end) and comes out fast. I don't think it would clear your electronics the way they are but maybe you have room on the right side roll bar.

Cheers!

Chris

 

[mmaattppoo]

Here are a few photos of the finished product in action (testing not camping):

Output voltage of the panels in full sunlight (2pm PDT) after everything stabilized fluctuated between 17.15 and 17.20 volts. The sky was completely cloudless with an ambient air temperature of 28°C (82°F)

Voltage across the +ve / -ve lugs of the D250S solar input while charging in full sunlight fluctuated between 16.60 and 16.80 volts and a regulated output voltage of between 13.85 and 13.95 volts across the battery.

There is a measured voltage drop of approximately 0.6 volts (3.5%) at the end of the combined: 10 ft of 14 ga wire that came with the panels, 30 ft of SOOW 14/3 cable (neutral third wire not used), an Anderson style connector, an Amphenol military circular connector, and a short run of 12 ga primary wire to the D250S. This voltage drop seems reasonable to me considering the ability to move the panels around to optimize their ability to collect light. Wouldn't want much more than 3.5% drop though.

Everything seems to be working. I'll be putting the completed system into action in the coming weeks.

EDIT (2016 07 21):

So upon further testing today (under similar lighting and air temperature conditions as yesterday), but for a longer duration (3 hrs instead of 30 minutes), it seems that the D250S and panels are capable of the following voltages once the end of the bulk charging stage is reached and the absorption stage of the charge profile begins...

Panel Output: 19.2 - 19.3 volts
At the D250S' +ve/-ve Lugs: 18.8 - 18.9 volts
Regulated Charging Output to Battery: 14.29 volts.

During the initial desulphation stage of the D250S' charging profile the voltage applied to the battery jumps up and down until it reaches the bulk charging stage where voltage gradually climbs until it reaches the maximum voltage at which point the absorption stage takes over. Yesterday's test run wasn't long enough to complete the desulphation and/or bulk charging stages...hence the lower voltages.

I really need to install an in line shunt/ammeter to see what's really going on based on the charge current entering the battery.



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[mmaattppoo]

Nice work on the whole install - I may use your idea for the external solar connection location! I had my extinguisher setup like yours for a long time and finally changed it to a quick release setup:

https://www.summitracing.com/parts/sdk-firexmntdag

It takes up a bit more room as it stands off the roll bar but it's a lot more secure (no rotating around the bar or need for velcro straps on the bottom end) and comes out fast. I don't think it would clear your electronics the way they are but maybe you have room on the right side roll bar.

Cheers!

Chris

Glad you like the installation details! Post some photos of your setup when you finish the installation. I always like to see what others do to improve on things.

Indeed. I really like those quick release fire extinguisher mounts; however, I have run out of real estate in the cargo area save for the space for camping gear. I carry a 5 lb CO2 cylinder on the right side of the roll cage.

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[rjcj-8]

Hey I really like the setup.
OT from the battery tray, how do you like the bestop pet barrier? I've been looking around at them and that is the only one that I like how it installs.

 

[mmaattppoo]

Hey I really like the setup.
OT from the battery tray, how do you like the bestop pet barrier? I've been looking around at them and that is the only one that I like how it installs.

The Bestop pet/cargo barrier has been great. A very solid barrier that you can mount things to (e.g. an axe and shovel). Here are a couple of links to threads where I posted a couple of closeup photos of the barrier installed and the fridge/action packer and cargo slide:

http://expeditionportal.com/forum/showthread.php?p=2106845

http://expeditionportal.com/forum/showthread.php?p=2031184

The only drawback I've encountered with this barrier is that simply folding down the back seat to accommodate large/bulky items is lost; true of all cargo barriers I suppose. The barrier can be removed if absolutely necessary but it's not something I'd want to do too often. Other than this one issue it's rock solid.



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[pdxfrogdog]

Wow, I'm glad to stumble into this thread! Kudos on your very clean aux battery & solar install. Lots of good ideas going on in there.

I've been recently contemplating how to install a CTEK D250S on my JKU and was going down the angle bracket path... but VHB tape sounds like just what I want. Mind sharing a bit more about what you are doing with the solar/battery monitor that shows up in your recent picture? Curious about what it is, where you purchased and what you think of it.

 

[mmaattppoo]

Wow, I'm glad to stumble into this thread! Kudos on your very clean aux battery & solar install. Lots of good ideas going on in there.

I've been recently contemplating how to install a CTEK D250S on my JKU and was going down the angle bracket path... but VHB tape sounds like just what I want. Mind sharing a bit more about what you are doing with the solar/battery monitor that shows up in your recent picture? Curious about what it is, where you purchased and what you think of it.

Glad you like the battery/solar build! It's been over a year in the making but has turned out quite well.

VHB tape is spendy but totally worth the cost. I've used it in many of my builds and it's worked every time except when trying to join or attach things to polypropylene. PP is just too slick and does not bond well to the VHB tape I bought. I think 3M makes several types of VHB tape including varieties that adhere better to PP.

The power meter I've installed between the battery (source) and distribution panel where all my accessories are attached (load) is made by GT Power and available on Amazon for less than $20. The GT Power meter is used in RC hobby DC power applications to monitor the performance of LiFePO4 and LiPO batteries in helicopters, cars, boats, and planes but works equally well for monitoring any DC load less than 130 amps and 60 volts; easily accommodating the nominal 12 volt 15 amp max load the combined draws from my ARB fridge/freezer, onboard pressurized water system, and power to my RTT LED lights and fan could ever draw together...not likely to ever happen.

NOTE: Even at the 11-14 volts a typical lead acid battery will operate at I would not want to approach the 130 amp stated current rating of the meter. Heat and fire would likely ensue given the 12 AWG wire used in the meter's leads.

A few additional notes about the GT Power meter (and similar meters) are:

1) the meter draws power from the system it's connected to. Remove the power and the meter loses the stored values it datalogs. Not a big deal but something to be aware of.

2) the meter only measures current and current related parameters (e.g. wattage) in one direction... from the source to the load. This means you will need two meters if you want to monitor power consumed from the battery (source) by your loads (load) and a second meter wired inline between the D250S' voltage regulated outputs to the battery (source) and the battery being charged (load) (i.e. opposite to how the meter is wired for monitoring current and power drawn drop the battery).

A second monitor is what I'm looking to install to monitor the current actually making it into the battery to charge it up...the main thing I'm interested in to know how well my solar panels are working.

An alternate means of measuring current would be to use an inline DC shunt ammeter. However, I've been quite happy with the GT Power meter's performance and will be buying a second meter shortly.

Hope the above details provide you with the information you were looking for.

Cheers!

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[rjcj-8]

Thanks for the reply back I'll check out the links.

 

[pdxfrogdog]

I appreciate the additional detail on the power meter. I'm still researching what sort of unit I'll go with and it's nice to see additional (and less expensive) options.

 

[mmaattppoo]

I finally got around to installing a second inline DC power/ammeter to monitor charging input to the house battery. I can now monitor charging inputs and draws on the house battery so I can determine if the solar charging inputs are making up the power consumed by my fridge and other accessories.

Upper meter monitors loads on the battery and the lower meter monitors charging input to the battery.

Voltages monitored by the two meters are within approximately 0.02 V. Currents measured by the two meters are within approximately 0.1 - 0.2 amps when compared to current measured with a UNI-T 210E DC clamp meter. Good to go in my books.

I can finally monitor the continuous current drawn and power consumed by my dash cam that's hardwired to the house battery. After startup the dash cam draws between 0.3 and 0.4 amps.

I'll have to experiment with my solar panels and running a couple loads...like my fridge and the fan for my RTT.

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[evaliquette]

If you run out of room in the back, you could relocate your fire extinguisher. Mine looks smaller but there is room


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[evaliquette]

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