Sounds like maybe the current is class 4 rapids (too much amperage for your application)?

Can you adjust this?

If so, maybe bring the controller down to class 1-2 (less than half its max rating) and see run time?

 

So, yesterday after work i was able to mow for nearly 30 minutes before my observed voltage dropped into the 30's. I was also able to use my clamping ammeter to measure amperage on the primary positive lead from the battery pack to the fuse (and then to controller).

The amps measured were in the 2.x to 3.x range with very brief surges up to the 6's.

This leads me back to my non-uniform battery pack as the main source of my issues.

Anyone want to offer their analysis?

---Devin

 

It's only drawing a peak of 6 amps? Sounds very low to me. The ME-1004 performance graph shows 20 amp just to get it running. Battery amps doesn't always equal motor amps, but I would think they would be close in a DC motor.

Definitely get a 4th deep cycle battery. Regular batteries are designed for a short burst of power to start an engine and then moderate use to, say, power the lights while being continuously recharged by an alternator. I bet most of the voltage sag you're seeing is coming from that one battery because it isn't deigned for 100+ amp continuous draw.

 

During pack discharge from 51-40v, you are seeing current use ranging 2-6 amps?
That is a power range of 100-300w.
What are the ratings of the SLA batteries your using?

 

Hello ddorminey,

For the record, the specs for a ME1004 motor are:

The ME1004 (ME1910) is a Permanent Magnet, Brush Type, DC Motor with Neodymium Iron Boron Magnets. Capable of 200 amps continuous, and 400 amps for 1 minute. Efficiency is 90%. The 1" diameter shaft is similar to that on most Lawn and Garden Tractor engines. At 2.5" is also longer than other models to facilitate coupling. This motor is perfect for an engine replacement on a Lawn and Garden tractor when converting internal combustion engine tractors to electric propulsion. A motor control is necessary to control speed and prevent damage over time to the collector, due to inrush current. This is a link to a kit including this motor. ME1004 Drive Kit


Features

Double brush-set
Sturdy 1" x 2.5" Drive Shaft

• Brush-type Permanent Magnet DC motor.
• Light weight, high efficiency design.
• Designed for 48 VDC battery operated equipment.
• 200 A continuous at 48 V (400 A for 1 minute)
• Capable of 9.6 KW continuous and 20 KW for 1 minute.
• Totally open, fan cooled motor.
• Runs in either direction

Specifications

Power: 11 Hp cont. -- 23 pk Hp
Voltage: 48 Volt rated
Speed: 3700 rpm @ 48V unloaded
Size: 8" OD, 6.4 " long (w/o shaft)
Shaft: 1 "x 2.5 ", 1/4" keyway
Weight: 32 lbs

So, the "math" for a ~10,000W (10kw) motor
...running at 48V
...would be: 10,000(W)/48(V)=208.33(A)
&
1.) Yes, I agree, the "odd" battery is most likely causing your issues

2.) "Lead is dead" is the current consensus
...because lead batteries are considerably heavier
...& as such the mower has to expend a lot of energy, just to "carry" them batteries around

Many Lithium battery packs can just "hold" much more energy
...& have much less maintenance that's required
...& last longer/many, many more dis-charge & re-charge "cycles" than Lead chemistry

The prices are starting to "level off" too

 

Oh...almost forgot
...welcome to the forum

FYI:
I have a similar set up on my ElMoto (~10kW motor running @48V)

When I first converted it (back ~2017) I used (4) 12V 35AH (deep cell) Lead Acid batteries
...they weighed ~40 lbs. ea. (so ~160 lbs. just in batteries)
...my "range" was only ~9 miles
...& they cost ~$60.00 ea. (so ~$250.00 total)

The next summer, I installed a 48V Lithium module (from a Chevy Volt)
...it only weighed ~50 lbs.
...& my "range" went up to ~25 miles
...& it cost me ~$250.00

Summary:
...~100lb. weight reduction
...& ~3X the range
...for about the same cost

* Please educate yourself
...&/or ask questions
Because most any "thing" that contains energy (gas cans, battery packs etc.)
...can be dangerous (if not treated properly)
&
Many folks use a BMS with their Lithium battery packs
...to help them monitor the cells (& cell groups)
...& "keep an eye on, what's going on inside"

Here is a 1,000mi. update video, I did about my Elmoto ~3 yrs. ago
* A PZEM-051 "power meter" (like seen in the video)
...may be a good addition to your mower

 

Sooo, my inexperience is showing.

After y'alls comments yesterday, i went back home, dug out the manual, and set my ammeter up correctly for DC.

For the record, my lawn mower is a Cub Cadet XT1 LT50 with hydrostatic drive and a 50" mowing deck. It comes with a 22HP Kohler ICE that has given up the ghost at just over 400 hours.

The mowing deck is currently set as high as it goes. I sharpened the blades and greased the deck spindles to minimize drag.

Now, I am reading a draw of 100+ amps to drive the machine around and 150 to 165 amps to drive machine and run the mower deck at the same time.

This seems to line up pretty well with my run time, y'alls expectations and reality. It also kills this project since I'd have to have 300 to 500 Ah of battery to run the mower as long as I need it to. (We have nearly 5 acres to mow.) This would require a battery pack that (including existing costs) exceeds my budget.

On the gripping hand, the ME-1004 has the ability to run the mower without strain, nor without exceeding its contiuous power rating of 200 amps. The Altrax controller didnt even get warm.

TLDR - Good kit, not enough budget. I can replace the mower with an identical unit for $2700. The deal with the finance committee was to be able to do the conversion cheaper. I'm already at $2500 and another $1000 is way over tolerance levels.

Thanks for everyone's input and advice. I'll likely be back in the near future with a different project.

Thanks!

---Devin

 

On the gripping hand

Great series of books, but I'm a fan of Niven anyway.

 

Pournelle was my favorite but you are right, Niven was a legend.