Barn Door for JK factory hardtops

jscherb

Expedition Leader
Batteries...

I spent the last 10 days in Florida and on the way home stopped overnight in South Carolina. When I went to start the Jeep yesterday morning to continue the drive home, it wouldn't start. The battery could light up the dash and power some accessories, but couldn't supply enough current to start the engine. Nothing was left on overnight to discharge it, so I figured the battery had failed.

I've got the kitchen battery in the back, so I disconnected its positive lead from the relay under the hood that controls its charging and connected it directly to the battery terminal. It took about 3 minutes to make the change. The Jeep started right up. I left it that way for the remainder of the trip home and it the kitchen battery worked fine for every start.

This morning I tested the original battery and it was no definitely good so I went to Walmart to replace it. It's a Walmart battery but since I installed it in September 2016 it was out of warranty by almost 2 years. No problem, I bought another Walmart battery. A $119 battery that lasts a few months short of 5 years and can be replaced at Walmarts everywhere works fine for me.

The JKU is a 2013 so the factory battery that was replaced in 2016 lasted only about 3 years.

BTW the kitchen battery is a Walmart deep cycle battery that I bought in August 2018 for $99, so it's 2 months short of its warranty expiration. No problem though, it's still going strong. I parked the Jeep in Key West and forgot about it and it powered the fridge for about 18 hours in the 90+ degree Florida heat before the fridge shut down. Probably it was 110 or more inside the closed Jeep but I didn't measure that. I idled the Jeep for about 20 minutes, which recharged the battery completely. I'm very happy with this $99 battery, and if it fails just outside the warranty period it's still far less expensive to replace it than many other "better" kitchen battery options.
 
Hi Jeff - quick question for you. What size stock did you use for the tailgate hinge? I have below a mock up of what I am thinking but wanted to see if you have on hand the dimensions and stock type you used.

From what I can tell, 3x3x3/16 inch square tube is a normal stock (I would cut this in half for my body-side U-channel). For the tailgate-side arms, 2.5x1.25x3/16 inch rectangle also seems to be readily available (though 1.5" on the width would work as well). That would leave about 1/16 of an inch in either side if the tailgate-side arm to allow for a bronze bushing.

Does this check out, or should I be considering something different?


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Herbie

Rendezvous Conspirator
From time to time companies ask me to test and review products. For example, recently MORryde sent me a hitch stabilizer that's a new product in their RV line and asked me to test it for stabilizing Jeeps with roof top tents: https://expeditionportal.com/forum/...factory-hardtops.127687/page-313#post-2906304
Neat. I've seen the folding-frame version of those, (that just kind of wedge under the bumper, etc.), but not one that attaches via the hitch receiver. Thus far I haven't been able to commit to spending the weight/space budget for such a thing, but every time my kid starts flopping around in the upper bunk and the van is swaying, I wish I had one.
 

jscherb

Expedition Leader
Hi Jeff - quick question for you. What size stock did you use for the tailgate hinge? I have below a mock up of what I am thinking but wanted to see if you have on hand the dimensions and stock type you used.

From what I can tell, 3x3x3/16 inch square tube is a normal stock (I would cut this in half for my body-side U-channel). For the tailgate-side arms, 2.5x1.25x3/16 inch rectangle also seems to be readily available (though 1.5" on the width would work as well). That would leave about 1/16 of an inch in either side if the tailgate-side arm to allow for a bronze bushing.

Does this check out, or should I be considering something different?


View attachment 669300
The sizes you're looking at should work fine; I used 2.5 x 1.5 for the tailgate-side parts.
 

jscherb

Expedition Leader
Back from my trip, I'm getting set up to do the solar testing/experimenting. To accurately monitor the change in voltage and current output with various panel angles and sun conditions I visited my favorite electronics surplus store and picked up the parts to make a meter - a 0-30 DC volt meter, a 0-10 DC amp meter, a box and some SAE 2-connectors plus with 12-gauge wire.



The panel is sitting on the workshop floor and even though the workshop is lit with LEDs, the panel is showing some voltage...



Since both the solar panel output and the controller load output have SAE plugs, I'll be able to use this to monitor what the panel is putting out and what the load is drawing just by plugging the meters into the appropriate circuit.

If you're wondering why I'd go to the trouble of building the meters into a nice enclosure like this just for testing, it's not just for testing - I did it because this meter box could be useful in the field for aiming the panel.

I could do the testing with the fridge as the load, but the fridge cycles on and off and the current it draws varies so I'm going to build a constant load circuit to stand in for the fridge. Stay tuned.
 
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jscherb

Expedition Leader
I made up the constant load circuit for testing the output of the solar panel this morning.

I found some 10 ohm, 50-watt power resistors at the surplus store and they'll do. I really need a lower resistance to cause enough current to flow to approximate the load of the fridge but I can modify these resistors to a lower resistance by sanding off the coating and tapping into the resistance wire part way. I've sanded one of them in this photo:



I mounted them on a piece of blank circuit board and used hose clamps to secure wires to tap into the resistance wire. I added an SAE plug so it'll connect to the output of the solar controller.



I connected the load to my fridge battery through the meters and adjusted the position of the taps so that the load draws 4 amps, which is roughly what my fridge draws.

 

jscherb

Expedition Leader
I'm also going to experiment with two controllers - on the left is the Harbor Freight controller and on the right is one I found on eBay - the eBay one has adjustable settings for battery shutoff, charge level and a few other things. The eBay controller didn't come with the SAE plugs, I added them so its plug-and-play with the rest of the setup.



All the bits and pieces are ready to begin testing and experimenting but it's raining out today so maybe I'll start tomorrow. Yes I know testing in the rain would also be a good idea but I'll do that on another rainy day after I establish a performance baseline on a sunny day.
 

jscherb

Expedition Leader
Two weeks ago I posted that a company has asked me to test a few new items; today the 9-inch LEDs I agreed to test showed up. Haven't had time to do anything with them yet except pose them on the bumper for these photos.





I'll try to test these within the next week or two and I'll post a photos, maybe a video and my comments as soon as I test them.

And speaking of testing, tomorrow I plan a first real test of the solar panel. My plan for tomorrow is to run the solar and the fridge all day to see if the solar can keep the battery charged. The forecast is for some sun and some clouds and a possible afternoon shower, so it should be a good first test. I'll put the panel flat on the roof for this first test; in later tests I'll see what the effect of aiming the panel might be.
 

Jurfie

Adventurer
Maaaan, I wish I had a better understanding of electrical systems. I know the basics are relatively simple, but for some reason is just seems like sorcery to me. Both home and automotive electrical work is something I tend the leave to the professionals. :LOL:
 

jscherb

Expedition Leader
I'm doing a "simple test" of the solar panel all day today. By simple, I mean all I'm doing it setting the panel on the roof, running the fridge all day, and recording what happens. The setup:



At 8am when I started the test, I recorded the kitchen battery voltage so I can compare it to the voltage at the end of the day. At that time, the sky was overcast and the sun was maybe 20 degrees above the eastern horizon. At that time the panel was putting out about 1.5 amps.



The voltage shown on kitchen power panel is 13.2, which is higher than the battery voltage, so even in these overcast conditions the system is charging the battery. The "0. 8" (notice the missing digit) reading on the kitchen panel ammeter indicates two things: first, since the amperage is 0.08, the fridge isn't running at the moment. Second, since one of the digits is missing in the amperage display, apparently the controller manages the output as PWM (pulse width modulation). What that means is that instead of providing a constant DC voltage, it provides a square wave (rapidly switching the voltage on and off). I may pull out the oscilloscope later during the testing to verify that the load output is PWM. The fridge runs just fine on PWM power, and without the camera catching the flickering of the LEDs on the power panel, you wouldn't know it's PWM - the power panel display is steady to the naked eye, but the fast shutter of the camera catches the mulitplexing of the display digits.

At 9am, the cloud cover has cleared, and this is the status:



The amerage being shown on the kitchen power panel isn't captured by the fast shutter speed of the camera, but it was about 3.5 amps when this photo was taken, indicating that the fridge compressor is running at the time of the photo. The fact that the voltage on the kitchen panel reads 12.9 indicates that the solar panel is providing some power to the fridge, since 12.9 is higher than the base battery voltage. (Typically the kitchen power panel indicates a few tenths of a volt lower than the actual voltage of the battery due to the current draw of the running fridge.) The test meter indicates that the panel is putting out about 3 amps - this is full sun but the sun is only 30 degrees above the horizon, so not optimal aiming of the panel.

I expect the panel output amperage will be higher at noon if the sun isn't obscured, I'll report on that then.
 

jscherb

Expedition Leader
9:45am update. The sun is about 60 degrees above the horizon and the sky is clear. Panel putting out 4 amps. Fridge compressor isn't running as this photo is being taken; voltage at the output is 14.3, which is roughly what my JKU alternator runs at.

 

jgaz

Adventurer
Thanks for your efforts on this project.
This project could have the subtitle of “Solar for Dummies” (like me)
 

jscherb

Expedition Leader
Thanks for your efforts on this project.
This project could have the subtitle of “Solar for Dummies” (like me)
This simple test is turning out to be very interesting.

10:15 update. A cloud passed in front of the sun:



At that time, the fridge compressor wasn't running, and the current from the panel was about 1.25 amps:



But... a few minutes later the cloud has passed and the panel was back in full sun. The compressor still wasn't running, but the panel current output was only reading about 2 amps.

That suggests to me that the controller decided the battery was fully charged and wasn't passing much current to it, and the fridge wasn't drawing much current either so the draw on the panel was lower - when the panel was in full sun earlier the output was 4 amps. This is why I built the constant load board using those resistors - with that the current draw of the system will always be at least 4 amps (more when the controller decides the battery needs charging), so the draw on the panel will always be at least 4 amps. The constant load board isn't in the test today because this is a simple test (test for dummies?).

BTW I'm also monitoring the temperature inside the Jeep to get an idea how hard the fridge needs to work to maintain the 37 degree temp I've set it to. Outside temp right now is in the low 70's, but the temp inside the Jeep is about 95:

 

jscherb

Expedition Leader
I'm not going to do real-time updates all day long, but here's an update to the last post. The compressor just cycled on and there's a cloud in front of the sun. The current output from the panel rose to 2 amps. According to the kitchen power panel, the fridge is drawing 4.5 amps, so this suggests that the solar panel can't keep up with the fridge in cloudy conditions. That doesn't mean it won't keep the battery charged, because the fridge compressor will cycle on and off and when the fridge compressor is off, the battery will be charged from the solar panel.

I believe there will be a point of no return however, if the temp inside the Jeep gets so high that the compressor runs almost all the time, and the sky is cloudy, there won't be enough compressor down time to keep the battery charged.

Because I've got the prototype MORryde charging system installed for the kitchen battery, if the conditions are such that solar can't keep up with the battery drain, I can always idle the Jeep for a bit and charge the kitchen battery from the alternator. The other day in Key West when the battery got discharged to the point where the fridge shut down, idling for 20 minutes brought the battery up to full charge.

What I'm trying to understand with this testing are the conditions under which the solar will keep up with the load and keep the battery charged; the conditions under which I'll need to occasionally idle the Jeep to recharge, and as testing progresses, to what degree the angle of the panel affects this.

Once I understand that, and I've done some angle testing to see how that affects the output, I'll know enough to design a mount for the panel, which is the ultimate goal of the testing.

Next update will be after the sun reaches 90 degrees above the horizon.
 
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