Is my solenoid bad?

[Dstock]

2012 TXT freedom. I went lithium and just connected all positive to + and negatives to - on the new lithium battery. I installed ammeter/voltmeter shunt is inline on negative side, to watch Ah and now see that I have 0.5 Ah drain at all times even with the cart off! Tow switch doesn’t change the drain.

I put all negative cables directly to the battery negative post. Main BL(-) is from controller to shunt of ammeter and then shunt to negative battery post.

Cart works great except the battery is draining fast. Ammeter works correctly in use reading expected amps use and Ah remaining in real-time.

More weird stuff: (without the key in) if I disconnect the negative wire from the shut which was going to battery negative post, the stock state-of-charge meter turns on and also the Reverse buzzer does not work. When connected up, the reverse buzzer works.

Solenoid terminals have continuity across low voltage side and open across high side. And each high terminal has continuity to both lows but not high to high.

Pics below, Thanks.

[Dstock]

[Dstock]

[bronsonj]

I can't see the pictures. Picture hosting sites are blocked by my office. But the solenoid normally has a resistor across the small terminals. The effect of the resistor is to allow a small current across to charge the capacitors in the controller and therefore cause less arcing when the contacts in the solenoid close.

What size lithium battery did you go with? What other loads are on the system? Maybe a DC Voltage converter? SOC display on all the time?

If you charge up fully, what is the voltage? If you don't use the cart for a couple days what is the voltage? Just trying to quantify what "draining fast" means for you.

On my cart, I charge up to 57.6V when I really want some range. My cart is programmed to stop at 48.5V. I notice that the first 1.5v or so seems to drain much faster.

[ThreeCW]

Originally Posted by Dstock

I put all negative cables directly to the battery negative post. Main BL(-) is from controller to shunt of ammeter and then shunt to negative battery post.
Cart works great except the battery is draining fast. Ammeter works correctly in use reading expected amps use and Ah remaining in real-time.

Since you "put all negative cables directly to the battery negative post", the only load you are measuring through the shunt is in the blue cable running to your controller. The loads in the other 4 black wires to your battery negative are not being measured at the shunt.

Normally a shunt is wired to monitor the entire load from the battery with all negative wires routed through the shunt.

You mention you have a 0.5 Ah drain measured on your shunt at all times. Do you mean a 0.5 Amp drain if it is being measured on your ammeter?

I have a totally different cart so it may be comparing apples to blueberries, but with my key switch off, my solenoid is open, power is bypassing my solenoid through a 470 ohm resistor and my ammeter show 0.0 amps.

With my key switch turned on, the solenoid is closed, power is directly connected to my controller and my ammeter reads 0.4 amps.

Because you are continuously measuring 0.5 Amps (?), I suspect that your solenoid could be welded shut.

Check the solenoid with the key switch off. Set your meter to ohms and check the resistance across the two large posts of your solenoid. The solenoid should be open and the resistance should read only the value of the resistor connected across the two large posts (typically 250 or 470 ohms).

If you are reading zero ohms, it means your solenoid is closed instead of being open ... which most likely means a welded (failed) solenoid.

If that is the case, I would suggest removing the solenoid from the cart and bench testing it to confirm the resistance across the two large posts of the solenoid with the resistor removed. It should be infinite ohms (no continuity) if it is open or will be zero ohms if the contacts are closed - indicating a failed solenoid.

Note that most (some?) carts will still run with a failed solenoid but it will result in a continuous draw on the battery pack ... like you are experiencing. I understand that a welded shut solenoid may be hard on a controller, so it would be advised to disconnect a failed solenoid while waiting on a replacement.

Perform your trouble shooting and let us know your results.

[JohnnieB]

Unlike the controller in a series drive, the controller in a sepex drive (such as the one in the TXT48 in this thread) are fully powered up all the time except when Run/Tow is in Tow and when the charger is connected. Also, there appears to be a pre-charge resistor installed (typically a 470Ω resistor between the solenoid's large terminals for a 48V or similar battery packs), so there is an amp draw 100% of the time the high amp cables are connected.

However, 500mA (0.5A) does sound a bit high for the controller's electronic and filter capacitor bleeder networks to be drawing, so there may be additional items draining the battery pack.

To find out how many mA the filter capacitor bleeder network is drawing, disconnect the controllers 16-pin plug, wait several minutes (5 or so), then measure the voltage on the solenoid's battery side large terminal followed by measuring the voltage on the solenoid's controller side large terminal. Battery side ought to be about 5V, or so, higher than controller side and the exact difference between the two is the voltage drop across the 470Ω pre-charge resistor, so you can use Ohm's Law to calculate the amp draw.

The amps feeding the controller's electronic circuitry comes in on Pin-5, which is connected to the blue wire from the charge receptacle (Charge disable/interlock), so if you disconnect the blue wire from the red/orange wire and insert an ammeter (DMM) between the wire from the charge receptacle to the controller, you can measure the amps the controller's electronics draw.

Add the two together and you'll have the total mA the controller is drawing when it is not feed amps to the motor.

[ThreeCW]

Originally Posted by JohnnieB

Unlike the controller in a series drive, the controller in a sepex drive (such as the one in the TXT48 in this thread) are fully powered up all the time except when Run/Tow is in Tow and when the charger is connected.

Wow … I guess my apples to blueberries comparison was not valid.

Not sure if this is a 2 minute penalty or a game misconduct. Either way I’ll sit this one out.

Thanks for setting the record straight JohnnieB

[JohnnieB]

Originally Posted by ThreeCW

Wow … I guess my apples to blueberries comparison was not valid.

Not sure if this is a 2 minute penalty or a game misconduct. Either way I’ll sit this one out.

Thanks for setting the record straight JohnnieB

Even series drive controllers draw some mA through the pre-charge resistor.

Series, sepex and AC controllers all contain a huge amount of capacitance between the B- and B+ terminals, someplace from about 10,000µF (Curtis 1206AC) up to about 14,000µF (Curtis 1206) with the 1206SX and 1206MX having about 12,000µF.

They serve two purposes, filtering electrical noise and the power source for the motor (They provide peak instantaneous amps of the PWM to the motor while the battery recharges them at an average amp rate.)

For safety reasons, the capacitors have a bleeder network that discharges them in a few minutes since the energy stored on them makes a good arc welder as well as delivering a nasty shock. Problem is if they are discharged when the solenoid contacts close, the inrush of amps that charge them is huge and eats up the solenoid contacts. By keeping them charged to near the battery pack voltage via a pre-charge resistor, the arcing on the solenoid contacts is minimized and the solenoid lasts longer.

The amp draw is roughly the same as the discharge rate of the bleeder network. Measure voltage drop across the precharge resistor and divide that number by the resistor's Ohmic value and you get the amp draw of the controller when inactive. For example, if a 36V system has a 5V drop across the 250Ω pre-charge, then there is a 20mA draw all the time the battery is connected via the pre-charge resistor.

Attached are pictures of 1206, 1206SX, 1206MX and 1206AC controllers showing the capacitors.

[Dstock]

Thank you for your great info and time Johnnie, I was hoping you would respond. I haven’t had a chance to look into more yet but I will and I will report back.

Don’t want you to think your efforts/info/advice are no appreciated :).

In the mean time, I had bus bars delivered to get away from connecting everything to the battery….and to actually have the ammeter monitor all consumption. I was a little worried there might be some common grounds too which this might help me sort out but I’m not sure. I bought the cart use 5 years ago and have never had an issue. I did install an amp and I am getting keyed power from fuse panel and constant 12+ from the DC/DC converter pin 5.