Truckfridge won't run off converter, why?

[Timber Wolf]

I bought a TF130 Truckfridge ($$$$$) for my birthday (I have been a very good boy) this year and am installing (shoehorning really) it in my Scamp. What a terrific piece of kit this thing is. Gets way cold, and dang fast too! No need to quaff lukewarm root beer with the Truckfridge on duty! But here is the sit-rep:

Runs fine on a battery, sitting in the garage hooked up with jumpers or in the Scamp. Even a sorry battery down under 12V (11.9V last time I measured).

Runs fine with no battery at all but with the Tow/Tug/TV providing power via the 7 pin.

Will NOT run, just cycles trying to start the compressor but soon kicks out, with the converter in the loop. This is with OR without a battery in the line. If the converter is involved the compressor WILL NOT start and run. This is even though I have 13.02V when the converter is on.

So, what the heck? Runs fine off LESS voltage from a battery but not at all with the converter? And yes, this is the 27 year old original, boat anchor converter in the Scamp that should be replaced. But I was hoping to put that off indefinitely and concentrate on the 12V side of things. Like two new 6V batteries and solar. Please advise what might cause this, and not "just change the converter" please.

[Bob Miller]

Voltage IS NOT available current. It sound like your wiring/converter is unable to provide the current needed to start the compressor.


Without seeing the exact wiring through the converter it's hard to guess what else might be a problem, but poor connections would be high on the list. I would read the exact voltage where the 12 volt line enters the device when it is trying to start and then work you way past each connection and find out where you are dropping voltage. But don't be surprised if it is at the converter. Some were rated as low as 15 amps when new and, between component breakdown, changeover relays etc, they do get tired.


BTW: Death, Taxes and replacing old converters are the three things that you can't put off indefinitely..... lol

[ckayaker]

I agree with Bob. Check all connections from the converter. Sounds like it isn't putting out the amperage needed to get the compression running.

[Bob in Mb]

If the unit is running and then turned off and you try to restart shortly afterwards it will not be able to start because it is still under pressure. Let it rest for a while and retry on converter.

[Darwin Maring]

Both Bobs are correct.
Also: The converter may not be putting out pure DC.
Personally, I would install a new converter that has the high enough amperage and the best battery charging ability.

I have purchased items from the following company and like their pricing.
Converter

[Bob Miller]

And their price for the PD-4045 isn't bad at all at about $172.00
progressive

[Bob Miller]

That refrigerator is 12DC/120VAC and has a built in converter to drop 120AC to 12VDC

[Timber Wolf]

It is 12V only, and runs fine on 12V from a battery. I did not spring the extra for the dual voltage 12V/120V model. I would rather put that money toward a new converter! My current plan is to go ahead and install a brace of 6V batteries, unplug the converter, and go camping. We have a 3 day trip coming up in a couple of weeks and I need to be ready.


It will be a good test anyway to see how the batts do running things for that short a time. I will take my good battery charger and if there is more draw than I think I will charge the batteries. I suspect that just running the fridge and a few intermittent 12V LED lights we might make all 3 days in the top 50% of the brand new batteries.


I will have more time to order a converter and get it installed when we get back. That and I am not looking forward to spending money and standing on my head to install it. Not that I mind spending money, OR standing on my head to work on stuff. Just don't like both at the same time!

[John Mohr]

i checked the truck fridge web page .on the bottom left corner of the page for the tf130 theres a message i believe this will solve your problem.

[Timber Wolf]

Originally Posted by John Mohr

i checked the truck fridge web page .on the bottom left corner of the page for the tf130 theres a message i believe this will solve your problem.

Link? Maybe here: http://www.truckfridge.com/tf130acdc.html I see what you may be talking about. Don't confuse an inverter with a converter. An inverter is 12V to 120V, a converter is 120V to 12V. And in any event I do not have the dual voltage model shown.

[Mike Magee]

It just about has to be a shortfall in amperage (current). Something is reducing the volume of flow. If the voltage reaching the fridge is as expected, you can still only be getting a trickle of it coming in.

[Darwin Maring]

I' m wondering if o e of those really large capacitors that the people connect to their car amps to supply the extra power required to make their bumpers rattle whild they listen to what they call music, that you can hear from a block away when you R driving down the road.

Used to just get the fridge started, then after the surge it continues to run.

[Bob Miller]

What's needed is the exact voltage at the refrigerator when it's trying to start.

The no-load line voltage is of little value if there is a voltage drop between the battery/converter and the appliance when it is drawing current.


There shouldn't be a need to add anything.

[Joe Romas]

Your problem is when connected to 120 volts AC your converter has a relay that switches most 12 volt circuits to rectified AC from a transformer that does not output pure DC. (rectified AC instead)

A cure is to run it off the battery directly.

Most Parallax converters have the right two or three fuse positions operated straight off the battery and not the rectified AC from the transformer.

Put your refer on one of those and it will work as long as you have a good battery.

If a large capacitor is added as mentioned above you will have way more than 12 volts. Been there, done that.

[steve dunham]

Your converter may not be able to maintain the proper output voltage when subject to the compressor's starting current . If the load on a DC power supply is greater than its rating the power supply will regulate
the voltage to get the current down to a safe level .The battery has no such regulation. As Mr. Miller suggested I would check the voltage at the refrigerator when the compressor is trying to start. "No load voltage is meaningless in this situation" I would speculate that the voltage at the refrigerator is enough to make the compressor hum but not enough to develop sufficient torque to get the compressor to turn/run.

[David B.]

Tim, I have the same refrigerator, and when I had our NOVAKOOL 12 volt danfoss style compressor refrigerator, the factory guy told me to hook it up directly to the battery (via a fuse).....I did and never had any problems. I didn't hook up our Truckfridge, as the Lil Snoozy factory installed it for me, but since the Lil Snoozy only comes with a battery charger, it must be hooked up directly to the battery. Hope this helps.
Dave & Paula

[frankcfx]

Specs say 60 watts input should be around 5 amps.

[redbarron55]

Here is a troubleshooting page:

https://www.isotherm-parts.com/PDF/s...leshooting.pdf

If when starting the voltage drops below the 10.4 volt level for even an instant then the compressor will lock out. Voltage has to be over 11.7 to reset.

Here is another troubleshooting guide:

http://www.dometic.com/QBankFiles3/E...uide_29020.pdf

This is one reason I got a (very) old swing compressor refrigerator- no starting surge. (noisy however!) The Engle uses swing compressors as well.