SR48400 and HD Solenoid Troubles

[JakeJones8]

Hey All! New to Ezgo's and ran into 2 issues please let me know if you can help!

1) Just installed a SR48400 from Alltrax as well as a HD Solenoid and HD F/R Switch. Drove it around the block a few times and noticed no difference in torque (from stock) and it took a good 100yards or so to get up to full speed which was only ~15mph. That can't be right for a cart that has 22" tires, Alltrax SR48400, brand new 36v batteries, and a plub quick motor right? (attached current alltrax software setup and have excel data logs if needed)

2) After driving off and on for 20min, the cart died in my driveway while driving it. One Green 6 Red flashes (pre-charge failure). Manual said stuck solenoid? Did the test from the forums and when I took off the resistor and cable from solenoid 2nd post to controller B+ the solenoid stopped clicking and I was getting 0v on the second terminal with the gas pressed. When everything is hooked up and you press the gas you get a click noise but no go. Did a brand new solenoid really break in the first 20min of driving it? Or is this related to question 1?

Got an email in to Scotty but since it is the weekend thought I would try here as well...Please let me know what you think!

[JohnnieB]

Mathematically, 22" tall tires can up the speed up to about 17MPH with the stock motor, but the 4" tire height increase also reduces torque by 18%, so the cart won't reach theoretical speed, and if the oversized tires are the low pressure type (<10PSI max inflation pressure) the cart might not reach the 14MPH stock speed for a 36V series drive. A Plum Quick motor may alter the equation, but PQ makes several different motors for series drive cart. Which one are you running?

The text prior to the "Stuck solenoid" possibility says the error is due to the voltage at the controller's B+ terminal differs from the voltage on the controller's KSI terminal (Red push-on connector) by more than 5V. In other words, there are several other possibilities.

The slow acceleration may be due to new batteries and cold temperatures. New batteries only have about 75% of their rated storage capacity and it takes a couple dozen charge cycle before the reach their rated capacity. Batteries are rated at 80°F and at 50°F they only have about 80% of the capacity the have at their rated temperature. You have US2000 batteries, which are 220AH, so newness can take them down to 165AH and Dallas's 50° weather can further reduce that to about 132AH, so the acceleration will likely be sluggish until the batteries are broken in and the weather warms up.

Also, US Battery brand batteries have a higher voltage then other brands and no all charger charge them fully. Attached is a SoC chart for US Battery brand golf cart batteries.

The images aren't clear enough to read the battery voltage on the monitor screen, but it ought to be 38.5V when the solenoid contacts first close if they are fully charged.

I use Quattro Pro rather than Excel, and I prefer to start with the raw .csv (comma separated values) file, but if you only have the data in the Excel format, please post it. In either format, you have to zip it and attach the .zip file.

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if the solenoid is not clicking, that problem will have to be fixed first. Attached is a schematic of a SR in an EZGO series drive with the solenoid activation circuit highlighted.

[JakeJones8]

Johnnie thanks for the reply! Answers to your questions are below:

I am running the plumb quick bandit (picture attached) with street tires over 10psi. Thanks for the info on 17mph, I am not sure how the speed is calculated but I trust you. Regarding the torque though, I would imagine the Bandit should have got me back some of that 18% loss and then the 400amp controller should have gotten me another 30ish% on top of that right? Theoretically, putting me ahead of where I should have been? The current takeoff doesn't jerk at all. It is a smooth slow takeoff with no "umph". I also noticed off of someone else’s setup my “throttle rate” is only at 12.5%. If I kick that up to 50% in the software will it make a big difference?

I am impressed with your research on which batteries I am using and my location’s current temperature! Haha. I will keep this in mind as the batteries are broken in. I have 3 logged runs using .csv format that I attached as a .zip file for your review if you don’t mind.

Lastly, the solenoid only clicks when all wires are connected as you have in your diagram and how I have it currently wired (but it won't move, just click). When I take off the resistor and cable from post two, it will not click at all. I will dig into this across the many other posts on this topic across the forums.

Thanks!

[scottyb]

When the small solenoid wire is connected to controller J1 black as shown in the installation manual the SR48400 has control over the negative side of the solenoid activation circuit. This way when the SR control senses that there is no precharge resistor it will not activate the minus side of the activation circuit. So the solenoid is acting normal.
Failure of the SW180 solenoid is very rare. Be sure all of your cables are in good condition and connections are clean and tight. Be sure all small wires are not touching where they should not.
Solenoid activation (click) will only happen when there is power at the small + and - terminals.

[JakeJones8]

Thanks Scotty. That explains why it wasn't clicking. So, assuming I hook everything up and it starts clicking again, the cart still won't move F or R and gives me precharge failure lights from the controller. How come it worked for about an hour then died mid-ride? That Green resistor you included doesn't have a + or - side right (the diode for small terminals did w/ the stripe)? I looked all over it and couldnt find either side marked... I guess I will check the voltage difference between B+ and KSI and post results here. Thanks!

[bronsonj]

After you get the cart running again....

It's hard to tell from your pictures, but it looks like your throttle response rate is set to 12.5%. I don't know how the Bandit likes to run, but on my stock TXT48 motor with alltrax controller I have my throttle rate set to 60% and turf mode on. Turf mode prevents too hard of an acceleration so that combo works well for me. My cart is lighter though so you may need higher throttle rate. FWIW, I have the 3 mode switch and initially set kiddie mode to 12.5% throttle rate but have since turned it up.

I don't think field maps apply to series carts, but if it does then you'll need the right map for that Bandit motor. Scotty/Johnnie, are field maps relevant to series motors?

[JohnnieB]

Originally Posted by bronsonj

I don't think field maps apply to series carts, but if it does then you'll need the right map for that Bandit motor. Scotty/Johnnie, are field maps relevant to series motors?

Series motors/controllers don't have field maps and I'm pretty sure they don't have the Street/Turf option either. They have a Peak Amp mode instead, but that isn't the same.

[JohnnieB]

Looks like I didn't attach the US Battery SoC chart to my earlier post, so here it is.

Took a look at the data logs and your batteries weren't fully charged. Don't know if the cart had been ran prior to the data logs being recorded, but the the battery voltage on the first entry with the relay column being true on the data log with the earliest time stamp was 37.2V, which is 70% SoC.

What charger are you using?

Despite what the throttle % column entries indicated, it took a whole second for the controllers output to reach 100% duty cycle (Throttle position vs throttle pointer columns), so the throttle rate slider should be upped to about 50% or so, then tweaked up or down as needed.

During the 1 second throttle up ramp, the controller throughput maxed at 400.9A, so the motor amp draw was pretty much in the ballpark. However the battery voltage had dropped top 27.1V by then and the subsequent motor were much lower than they would have been if the battery pack's voltage hadn't dropped so far, so acceleration was less than it ought to have been.

Looks like low battery capacity due to a combination of the batteries not being fully broken in yet, cold weather and batteries not fully charged, plus throttle rate needs to be cranked up some also.

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The change in speed is based on the tire's circumference, which determines how many times it revolves in a mile. The change in torque is based on the tire's radius, which is effectively a gear ratio and the tire's gear ratio combined with the ratio of the gears in the transaxle or differential determines how many times the motor's armature spins to rotate the tire once. I put together a spreadsheet that does the calculations.

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The solenoid is clicking but the cart isn't moving, so the problem is in the high current circuit, or throttle.

Connect your DVM between the controller's B- and M- terminals.
Press pedal just far enough to make solenoid click and you should read FULL battery pack voltage (38.5V if fully charged)

If you don't, use the red test lead to trace the heavy green cables back to the battery pack through the F/R switch assembly and solenoid contacts top the battery pack.

[JakeJones8]

Ok, took readings on everything that was asked. Please see data below. Is the error coming on because when the pedal is pressed all the way down my B+ is 28.3v and KSI is 37.6v (9.3v difference)? If so, how is this fixed? Thanks!

38.1v = Battery Pack Terminals at time of testing

Solenoid
38.1v = 1st Solenoid Terminal
37.2v = 2nd Solenoid Terminal w/ cart on no pedal
28.3v = 2nd Solenoid Terminal w/ pedal pressed all the way and solenoid clicked

B+ Terminal
37.1v = Cart on no pedal
28.3v = Pedal pressed all the way and solenoid clicked

KSI Terminal (I used the small peg on the solenoid where the positive diode connects as I didn’t want to pull the “red plug” out incase that messed something up. I assume this is ok as they are in the same “line” per the diagram?)
0v = Cart on no pedal
37.6v = Pedal pressed all the way and solenoid clicked

(-) on B- and (+) on M-
37.1v = Cart on no pedal
28.3v = Pedal pressed all the way and solenoid clicked

[JakeJones8]

Also, I attached better images (less glare) of the setup in Alltrax (I realize the cart is in reverse so ignore that on the last tab). Johnnie was right about all the tabs and options.