Need LRA of old well pump - unknown model

[sendicott]

I am planning an off-grid system for a cabin in Wyoming. There is no access in winter - it will be a summer cabin. The main load is a water well pump that is currently run by a generator. Almost no other loads. Client hates generators. Need to use pump 10 min/day, sometimes 30 min. We don't know the model of the pump.

What we know about the pump:
Installation doc says 1/2 HP Red Jacket
I have water depth etc if needed.

My measurements while running on generator:
117.5 V
61 Hz
11.4 Amps
1116 Watts

Controller box label:
Red Jacket no. 50NO-CBP
for 1/2 HP, 115V, 60Hz, 14.5A
Lists 9 possible pump models. Resistance measurements in box suggest 2 possible models. One has LRA 50, the other has LRA 58.

The generator:
Claims max start power it can supply is 4375 Watts. That is 36.5 Amps at 120V

So, here are my questions:
1. How to determine LRA? Typical calculation is 5 to 7 X continuous current. That would be 57 to 80 Amps. Other clues suggest 50A, 58A, 36.5A.
There are meters that claim to measure it. Can I trust the cheap ones? Is it worth buying an expensive Fluke for one time use?
2. The generator label is attractive because it suggests a low LRA of 36.5 A. Should I believe that? Are generators more forgiving of surge current than inverters?
3. 1/2 HP is nominally c. 375 Watts and I am measuring 1100 W continuous. I assume that is a red flag for the pump but we don't want to pull and replace the pump.
4. Is it possible something is wrong in the controller box? Bad capacitor?
5. Soft start devices?
6. The possible LRAs make a big difference in choice of inverters. Bigger inverters require higher battery voltage and higher battery V dictates more solar panels than we need for this cabin.

 

[ChrisG]

I just replaced a 1/2hp 240v red jacket pump that was set at 100ft deep. Using a Harbor Freight amp meter to measure inrush it pulled 34 amps (8160 watts). A Honda 7k generator couldn’t start it, a Duramax 10k generator grunted through painfully but did start it. The harbor freight meter was pretty accurate.

Running was about 1400W.

Instead of buying a massive $$ inverter or generator to run it, I replaced it with a Gundos SQ series pump which has a soft start built into it. Now anything can run it. Amazing pump.

Here is my post on it: https://diysolarforum.com/threads/grundfos-10-sq07-well-pump…just-awesome.60580/

 

[Horsefly]

We have an almost 60 year old 1/2 hp well pump. It pulls about 1400W when running, and the one time I measured the inrush / LRA (just before we bought an inverter) it was 32A. My guess is yours will be about the same. If you are only seeing 1100W running, be happy. ?