What power 4pole 240v single fase motor?

[swissJohn]

Hi all. I hope someone on here can help.

Last year I bought a refrigerated box off an ex Sainsburys delivery van to replace the very old cold room at my farm shop. 12 volt DC powered so I thought it would do fine. It has been running great but with one big problem. I have it powered by a very large gel marine battery and had a 25Amp battery charger constantly charging it. As the DC motor is rated at 65Amps there wasn't enough power to run it fast enough. So I bought a larger charger - a 40amp one. This made it run faster but still not enough to get the temperature down quickly. It was sort of ok though so I persisted with it. It lasted about 6 months before it went bang! I sent it back under warranty and while I waited for it to come back I bought a BIG one. Rated at 90Amps max this one was the business, or so I thought! It lasted 4 months before it blew its 110Amp fuse and has now been returned under warranty. I'm back to using my little one which has not a hope in hell of doing any good in the temperatures we've been having.

Anyway, some of these boxes have a 240v standby and I know that mine has all the wiring and every thing else that goes with it to run a standby motor and on checking the wiring diagram that I got with the box I now know how to connect one up. My question is - How big a motor do I need to match the 65Amp output of the DC motor which runs at 1400rpm?

Sorry for being so long winded but I just wanted to give you the background to my problem.

Any advice greatly appreciated.

Many thanks. John

 

[Andy™]

well 65a at 12v is 780w...

 

[ProDave]

Are you sure it is 12V?  If it came from a lorry, it is far more likely to be 24V which might explain the slow running / poor performance?

65A @12V is 780W so play safe and get a 1KW motor.
 

 

[apprentice87]

You do not seem to know much about mechanical stuff... Anyway, the motor you have does not have a 65 amp output, that is its input.. You talk as though the fridge powers the motor and not the other way about...

I presume the fridge has two motors then?? One of 12V for when it is on a vehicle, and a 240V motor too??

Or do you want to swap the 12v motor for a 240 one?? How you going to control the motor?? what sort of drive is it?? a belt?? gears?? flange mounted??

Not at all sure what you are trying to do here. Also, the battery charger might say "90 amps" or whatever on the side, but that does not mean it can actually churn out 90 amps for more than a few minutes at a time.. If you CAN fit a different motor, it will only be a squitty little thing, so that might be the best

Photo be good if you can get the admins to let you post one..

john..

 

[Phoenix]

I am very suprised that the unit is designed to run on 12v dc from the truck when out and about, as I can't see 780w doing much cooling, thats about 1 horse power.
These things in my experience are diesel powered and run on red from a separate tank, when parked at depot, normally they are provided with a 32A three phase outlet to plug into. I am probably thinking of bigger vehicles than yours though?

 

[Andy™]

im thinking its from a small 3.5t van that would be 12v... truck mounted ones would usually be either PTO or their own engine and run on cherry

 

[swissJohn]

Thanks very much for your replies guys and sorry about the spelling mistake in the title. Phase it should have been as you already know.

The box is off a Sprinter van and it definitely is 12v. The 12v motor says 65Amp and being a decent mechanic (ex Army Air Corps helicopter engineer) but not an experienced electrician I'm just trying to explain what I need.

The chiller is designed to run off 12v when the vans engine is running but stops when the engine is turned off and they sometimes have a 240v standby (optional extra) for when the van is parked up for the night with stuff onboard that needs to stay chilled. Running off 12 or 240v it is set to chill to +2 degrees. Now that the box is not on a van anymore but in my warehouse I thought that I could keep it running in the way I described in my original post. This is not working as well as it could be and is costing me money by having to replace battery chargers which are not up to the job. Probably because battery chargers are not designed for 24/7 running. Which is why I want to change to 240v. The control box with its built in computer is equipped for both 12 and 240v so will be a straight forward job once I have a motor. I just need to know what power motor to buy and as a couple of you have said, it looks like I need a 1kw one.

If there are no more ideas then that is what I will buy.

Many many thanks for your help and apologies if my original post was not clear enough. I will definitely come back here if I need any more electrical help.

Cheers. John

 

[swissJohn]

Many thanks Canoeboy for your reply. Sounds like that's what I'm after.

Cheers for that. John

 

[binky]

sounds like my campervan which has a small fridge. Runs off battery when moving, when on site runs off 240v supply. have you got any details of the make of unit / manuals / any other info?