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24VDC battery storage in truck camper. Issue with high current 12vdc jacks

JyoungCJ

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Oct 30, 2021
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I created a solar setup in my truck camper based on the info on Will's website. It uses 2 Battleborn 12VDC 100aH batteries in series. It all works great with the exception of the truck camper jacks. These are the 4 jacks that are used to remove/install the truck camper from the truck. They run at about 40-50 amps when all 4 jacks are running at the same time, although that draw is load dependent.

I used the uxcell 552watt (40A) 24/12VDC buck transformer recommended in the website (actually, I selected the 13.8VDC output instead of the 12.0VDC, but essentially the same device). The controller shuts down when running a single front jack (heaviest load w/ a measured draw of about 15A). I believe the problem is the inrush current at startup is causing a low voltage condition that shuts down the controller (atwood 85439). I don't have the tools to measure the inrush current, but I suspect that is the issue.

I tried putting a 1 Farad power capacitor in parallel with the output of the buck transformer 13.8VDC output. I still have the same issue, although it seems to help with operation of the rear jacks with a lower load.

Do I need a bigger power capacitor, bigger power supply, or both? How big is sufficient? I don't mind a little overkill in the solution, but size and cost are best minimized.

Thanks for all input.

Jim
 
I'd try a 60A buck converter. uxcell has a 60A version for about $80:


Victron has a really high quality 70A converter ($141).

Higher current is usually more expensive.

Another option is throwing in a separate 12V battery just for the jacks. Not necessarily LiFePO4. Or there might be a way to safely hook the jacks up to the truck battery.
Thanks for the input. I considered both of those converters. Since a single high load jack draws 15A and that still shuts down the controller, I'm not confident a 60A (or a 70A) will have enough power when running all 4 jacks. It is rough since I don't know the inrush current.
 
Perhaps you can contact the jack manufacturer about the inrush current?

I personally would keep a lead battery for the jacks, separate from the lithiums. That way if the house battery is flat or otherwise fails you can still work the jacks.
 
Please keep the thread active til you find a solution.

Concern about problem you are describing is why I decided to stay with a 12V pack in my truck camper. If I decide to do significant runtime on my air conditioner, I may be forced to re-configure for 24V.

Those suggesting a separate battery for the jack may not understand the space limitations in a truck camper.
 
Those suggesting a separate battery for the jack may not understand the space limitations in a truck camper.
Which is why I also suggested using the existing truck battery for the jacks if possible. No extra space. Not used often. Won't kill the 24->12V converter.
 
It would probably work using the truck battery, but would require extended wires ..... It is necessary to jack up the camper and then back the truck under it .... and the other way around when unloading it.
 
Which is why I also suggested using the existing truck battery for the jacks if possible. No extra space. Not used often. Won't kill the 24->12V converter.
Use of the truck battery would solve the issue, but it is too far away from the controller. This would require large wiring and would not provide jack control when the truck is not present (or close enough to be plugged in).
 
If the camper has a generator, it might be possible to run it with a 12V converter while running the jacks. I have done that with mine when the old batteries were low. Or, maybe have a portable generator for that purpose..
 
I thought you said all 4 were 40-50A. But maybe they are 60A at 15A each. Cllena makes a 100A ($150):


BTW - I have no experience with the larger ones. I have the Cllena 24->12V 40A (basically the same as the uxcell). They also have 85A and 120A.
The front jacks use more current than the rear jacks (due to weight distribution).

120A may be enough, but I don't know the inrush current. This is not available from the manufacturer and it is load dependent anyhow, so my solution would be different from someone else. Assuming this is an inrush issue, if there was some sort of formula for steady state vs inrush I would have more confidence in the solution. BTW, the power capacitor was intended to solve the inrush current issue. It may be more efficient (cost and size wise) to use a bigger power capacitor. 3 and 6 Farad options are available. I know I likely need to increase the 12VDC supply amperage as well.

I don't want to keep throwing more money at it until I have confidence in the proposed solution.
 
If the camper has a generator, it might be possible to run it with a 12V converter while running the jacks. I have done that with mine when the old batteries were low. Or, maybe have a portable generator for that purpose..
It has both a propane generator and a 110VAC inverter. I could source the jack power from either 110VAC source or from the more than sufficient LiFoPO4 24VDC battery pack. It still leaves the question of how big of a 12VDC power supply is required.
 
It has both a propane generator and a 110VAC inverter. I could source the jack power from either 110VAC source or from the more than sufficient LiFoPO4 24VDC battery pack. It still leaves the question of how big of a 12VDC power supply is required.
My onboard generator and original converter handle the jack power just fine. Gotta admit I don't know the current rating of it off hand.
 
My onboard generator and original converter handle the jack power just fine. Gotta admit I don't know the current rating of it off hand.
My OEM 12VDC charger was Progressive Dynamics Model PD9245C (13.6VDC at 45 amp). I haven't considered trying this a the sole source for the jacks. It is bigger than I prefer for a permanent solution, but it would be a good data point for required power.

Are you using the output of the charger straight to the jack controller or is there a 12vdc battery in parallel?
 
My OEM 12VDC charger was Progressive Dynamics Model PD9245C (13.6VDC at 45 amp). I haven't considered trying this a the sole source for the jacks. It is bigger than I prefer for a permanent solution, but it would be a good data point for required power.

Are you using the output of the charger straight to the jack controller or is there a 12vdc battery in parallel?
I have the battery in parallel with it .... only needed to do that with my old tired FLA batteries. It would be easy to try with nothing lost except time if it doesn't work.
 
I have the battery in parallel with it .... only needed to do that with my old tired FLA batteries. It would be easy to try with nothing lost except time if it doesn't work.
I tried my OEM 12VDC 45A charger from Progressive Dynamics as the sole and direct power source to the jack controller. It provided enough to run a single front jack. Not enough to run two jacks (even 2 rears with a lower weight load). The addition of a small battery would provide the additional required amps, but at the cost of another maintenance item and more space. I'll keep trying with a bigger power supply and possibly a power amp until I find a combo that works.
 
I'm still guessing at inrush current, but I did find the following formula on the Cllena Amazon site:
Questions:
How to choose the correct current for loads?
For example, if the max current of your load device is 10A, then choose 10A/0.8=12.5A at least for resistive loads according to international standard.
If the load device is motor or compressor, then you may choose 10A/0.5=20A according to real testing result since the motor and compressor starting current may be 2-3 times than nominal current.


It is a starting point. I'll post updates as I try more options.
 
I tried my OEM 12VDC 45A charger from Progressive Dynamics as the sole and direct power source to the jack controller. It provided enough to run a single front jack. Not enough to run two jacks (even 2 rears with a lower weight load). The addition of a small battery would provide the additional required amps, but at the cost of another maintenance item and more space. I'll keep trying with a bigger power supply and possibly a power amp until I find a combo that works.
If it were me.
Since I own one of these https://www.kleintools.com/catalog/clamp-meters/acdc-digital-clamp-meter-auto-ranging-400-amp
I would test with a starter battery and see what the locked rotor amps value is and then add a margin.
 
I tried my OEM 12VDC 45A charger from Progressive Dynamics as the sole and direct power source to the jack controller. It provided enough to run a single front jack. Not enough to run two jacks (even 2 rears with a lower weight load). The addition of a small battery would provide the additional required amps, but at the cost of another maintenance item and more space. I'll keep trying with a bigger power supply and possibly a power amp until I find a combo that works.
I posted this in the other thread but it bears repeating here. Below is my truck camper running completely off the AC to DC converter and all 4 jacks running and raising the camper. My jacks are Happijac, I know you mentioned you have Attwood which Lippert no longer sells. Peak initial inrush current is 30 amps, running all 4 jacks for any extended time is just under 24 amps.

45 amps x 4 jacks = 180 amps. You would need a battery cable to the jack control if this is the case. Possibly yours was made that way with no gear reduction on the motor. But that is a large load. I do believe if your heads are gear reduction, then you have the thrust bearings dragging in the jacks. The Attwood hasn't been produced since 2018. You can go with Rieco-Titan replacement but it is not cheap. Those are a gear reduction motor. I've always had Happijac and been quite pleased with them. Perhaps you could locate a used set, either manual and add motors or find a full power set. Jacks raising camper.jpg
 
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