voltage drop

I'm not sure what previous POST you're referring to so I have no idea what sort of vehicle you're trying to get the wires into the rear of......

A full one volt drop is waaaayyyy too much and means (in most instances) that the cabling is nowhere near heavy enough. However, what is the voltage at the battery when the fridge is on? If that too is down to 11.4v then it may mean the battery is on the fritz.

If you have a wagon (which I'm assuming as you talk about a shelf system), then there should be large rubber grommets in the lower rear inside panels that you can run cables up through..........at least that's how I do it in the Patrol.

Cheers

Roachie

>it reads 12.4V without the fridge plugged in, 11.4V with the
>fridge plugged in and turned on. is this an acceptable voltage drop?

I wouldn't be happy with it. That's about an 8% loss in the cable and/or fuse. From memory an Engel typically draws about 4A which is not a high current and something like 1.5mm sq. or 32/0.2 should do pretty well for short runs. Also check _all_ connectors and the fuse rating, about 10A should be OK. If you are planning to take more load than just the fridge off this circuit consider a larger cable.

Mike Harding

Howie. I've run twin 12mm squared cable to the back of the car & get a .2 of a volt drop between the battery & the plug on the fridge when it's running.(bit less than 4 amps)
Do the same. Measure your voltage at the batt & fridge when running not just at the rear. I would be disapointed with any more than .4 volt drop & suggest upgrading wires & fitting better quality plugs.
A full 1 volt drop would lead to a shorter run time with the fridge cutting out well before the battery was discharged.
Cheers Craig...
Trojan deep cycle batts, 30 amp Circuit breaker, 12mm wire, 32 volt clipsal plugs.
Autofridge

I would agree with the above posts and would also like to know what is the voltage at the battery and then at the fridge. Also is the battery fully charged to do this test ?

Regards Derek.

Howie, It may be a coincidence, however when my engel is running and the low battery cut out switch cuts off the power because the battery is flat, the volt level measured at the battery instantly jumps 1 volt. When I have played around switching the fridge on and off I find that there is a 1 volt difference when the fridge is running to when it isn't. This is with the fridge connected straight to the battery and the battery is FLAT. I was only doing it to set my low volt cut out at a level I wanted and have never checked on a fully charged battery.
Your situation is different as there is a difference between the battery and your plug which doesn't seem right, however I just found it interesting that as in my case you also have a 1 volt difference when your engel is running and when its not.

Tony

It is worth checking the article by Collyn Rivers regarding cabling sizes. You can probably get it from the archives. My advise is to put in as big a cable as you can. Yoy only ned about 6 metres and it is cheap compared to a warm beer somewhere along the track.

This depends a bit on how you are measuring voltage drop. I prefer to have one multimeter probe on the pos battery terminal and the other probe on the pos lead as it enters the fridge (I use a sewing pin thru the cable for this). You'll need one probe thats about 5 metres long - easily doctored up with a piece of wire. With the fridge turned off, voltage drop will be zero (unless you are running other accessories in the circuit) and with the fridge running you'll get an exact measurement of the voltage drop in that cable.

The reason I use this method is because its more reliable than spot readings. Tthe voltage in the battery itself falls while the fridge cycles, and comes up again when the fridge stops cycling.

Also, to interpret your voltage drop will depend on which series Engel you have. The current F-series has an amp draw of only 2.8amps while cycling - a voltage drop of 1 volt would be rather huge. The amp draw of most other engels is 5-6amps when cycling, and one volt might be almost acceptable.

Also, if you have the later engel, it will turn off and not work when the supply hits 10volts. If you have the earlier engel it will slowly chugg away at lower volts until it kills the battery and maybe itself!

Wiring is obviously important, but fuse holders and any other connectors are sources of voltage drop - particularly when they start to corrode. My method is to solder a blade fuse into the wire at the battery end avoid any additional connectors until I get to the fridge - then use something substantial like an Anderson plug. I actually use a thing called a Deans plug which is used in R/C cars. In the unlikely event that I would blow a fuse, I'd need to solder a new one in.

I earth the lead to a bolt on the body which has been cleared of paint and has a smear of vaseline to stop corrosion. And I also ensure that the 2nd battery has a substantial earth lead to both body and motor. To run an earth lead all the way back to the battery is a reliable alternative, but I think its unnecessary if you do the above properly. And a long earth lead will also have voltage drop.

Cheers
Phil