Experimental findings-Current draw

[Albert Stall]

If anyone is interested, I did an analysis of the current draw of our EC 12 equipment.

Follow the link....Also check Rob Guyatts comments below.

http://picasaweb.google.com/Mywebpictur ... sJau3EsI8#

Al Stall

[s vernon]

Good info Albert.

I decided to look at my RMG booklets and I noticed that the stall current for the 280DL and 280EL (can't pass up a bargain) are listed at (ouch) 12 amps versus your measured 1.4 amps. I wonder how that wiring would like 12 amps.

The running current for the EL is 550 ma versus 450 for the DL.

I think Rob Guyatt comes around here now and then.

I wonder about the "slight discrepency" between 1.4 and 12 amps stall current.

Scott

[MichaelJ2K]

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by s vernon</i>

Good info Albert.

I wonder how that wiring would like 12 amps.

Scott
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

You'll find that electronics run on smoke.[:(!][xx(]

Mike Denest
EC12 #899

[greerdr]

And mirrows.

R.C.Greer

[Rob Guyatt]

Hi Al (and ALL),
Yes certainly 1.4 Amps for stall is not correct. Bottom line for any test is constant current power supply with enough current capacity for the demands of the load. It's the only way to get consistant results that can be compared. In your case I suspect the power supply is not able to give constant current and the result is voltage drop. In this case the voltage is dropping below 3.8 V causing the winch to shut down. When it does shut down the load is removed from battery and so voltage recovers and the winch restarts. This is what you describe in Note 2. This is not the stall protection system or low battery shutdown system. It is minimum operating voltage reset. This cycling of reset and restart while the physical load is still present can eventually cause damage to motor or transistors due to over heating.

Wiring size I specify is 20 awg. While rated at 3 or 4 Amps it will only give a very small voltage drop even at 20 Amps as long as it is kept short and the current is not for long. There's no need to go larger.

Anyway, your current measurement even if double what you specify indicates a large voltage drop. It would be best to measure voltage as close to the winch as possible at the same time to see what's happening. Trouble with digital voltage meters is they are very slow and difficult to get accurate readings in this application. The RMG Flash voltage meter has a feature where it stores and displays the lowest sampled reading per cycle. This is much more accurate than a DMM.

Your 6V battery, assuming it is charged, should be around 7 V. Regardless of what the actual current reading is the important factor here is that the voltage is going below 3.8 when you load the winch. A good wiring and battery system even if NimH (which are not good at supplying high current) should be able to sustain a winch stall at the full rated current without more than a volt or two of drop so that the stall protection system can work.

Scott, you mentioned "The running current for the EL is 550 ma versus 450 for the DL." The difference is actually the motor. We've been using that motor for some time now including for DL's. I suspect you read the DL spec from an older booklet.

Rob

Rob

[Albert Stall]

As you can tell, I contacted Rob Guyatt of RMG and he was kind enough to respond and give us the correct info.

A couple of my assumptions may have been wrong but the point is that the wiring does not have to be any larger than 20 awg which is what Futaba & Hobbico supply as their "Heavy Duty" extensions. The one thing I don't understand is how you can stall the winch, achieve a 12 amp draw and not have a huge voltage drop.

At least it peaked some interest and I can see that you gentlemen do look at the discussion page once in a while.

Al Stall