Had to get towed today. :(

[Gale Hawkins]

At least now we know when to get the cart to the charger.

It it 75 today which is the first really warm day since the got the 2007 EZGO PDS cart in Jan.

We had done 20 miles before so today I decided to push it a little more. We have a 10 mile run we we can do from the house that is on very small roads and only passes about 10 houses.

When I unhooked the battery minder the readout was 39.9 volts. After about 5 miles it was reading 35v running on the level and holding about 33v on the hills. After about 15 miles it was 34v/31.5v.

When we started the third 10 leg after resting for 20 minutes that pack was getting low reading 36.8v parked and dropping to 29v on hills. We pushed on because at 28v on the hills it was still moving but slower. At 27v it would stall to the hills.

The three of us added 400 pounds of weight.

We lacked one hill getting back home and were tired so when the neighbor offered to give us a tow we said yes.

Well we know our limits now. When we see 29v on the hills know the fuel light is ON. When we see 28v we know we are about to be pushing. When we see 27v we are pushing.

We never plan to run the battery that low again for sure but it did answer some charger questions. It peaked at 18 amps and started tapering. I did notice the scale is to 30 amps so even in max output (21 amps) it is not going to look like it is 'full' charging like my other battery chargers.

Glad to have these unknowns behind up. I expect 30 minutes on the charger between each run would have let us finish the last 10 mile leg today. The first 20 miles was put on it non stop which would not be the case on a golf course.

The PDS cart does not loose a lot of speed on the hills as long as under heavy load the battery pack does not drop below 30v I noticed today.

 

[dougmcp]

Nothing like doing some fun experimenting.

Hope you placed the cart in the tow mode, if not, you may be in for trouble.

 

[Gale Hawkins]

I am getting too old and fat for that much fun.

Actually I am glad we know the limits of the battery bank and how fast they fail after dropping below the 50% SOC (state of charge). I had already told the kids that when the readout reported 31.5 volts up hill that would be a safe point to stop and recharge but since this was a ride until you drop test we pushed on.\

Today my hip knows about the pushing before the neighbor showed up.

Yes my son flipped the tow swithch for the tow. The driver went very slow but it could have been an expensive tow to have burned out the motor or more.

As a note the EZGO charger was still running at 7 am today which was 15 hours later but was totally off when I returned at 3 PM so I started the BatteryMINDer 36271. It just started raining and it will be a few days before it will be good riding.

In the gas vs. electric debate I would say GAS for sure if range/speed demands are high. For our use I am glad we got electric but for many rural based folks they may be happier with gas.

 

[rcpd34]

Good info. What happens if you forget to put it in tow mode and tow it?

 

[Pimp Daddy]

You could TOAST the motor or the controller...

 

[Gale Hawkins]

He did tow us to the top of the last hill before you get to our house. by coasting without the tow mode on we did get the batteries hot enough to make it home OK and to the charging shed.

 

[Pimp Daddy]

Gale... From what i understand about the PDS/DCS controllers. When in the run mode the controllers try to stop a runaway cart when the accelerator is not activated...Towing a cart in the RUN mode builds up heat.... Not good for the controller/motor

 

[dougmcp]

When you leave the run/tow switch in the run position and try to tow it, the controller applies the anti-rollaway plug brake and effectively shorts the motor, towing will usually take out the motor first and when it sends the short back to the controller in the form of generated power, the controller goes out too.

 

[Gale Hawkins]

PD that makes sense. The charge coming from the 'motor/generator' has to pass through the controller to get to the battery. With the steep hill chip that we have the regen starting at 13 MPH with the pedal on the floor and at 10 MPH with it released. I have recorded briefly 45 volts being produced by the motor when going down a steep hill at 13 MPH and suddenly releasing the pedal.

With the battery bank down to 28 volts when pulling the most regen voltage we saw was 39 volts and it make the cart much faster when back on the level for a minute or two.

While the cart does not know where it is coasting down a steep hill or being towed I expect I am sure it would start frying parts even at 10 MPH very far. The manual clearly states to use the Tow switch to prevent destroying the cart. While the regen is a neat feature that motor is not designed to be used as a full-time generator I am sure.

The speed chip (jumper plug) keeps regen from happening until about 20 MPH so the PDS carts will go faster down hill.

The shunt motor is new to me so I a lot of learning to do.

 

[Gale Hawkins]

Thanks for that chearing that up in my head.

 

[Pimp Daddy]

Gale... Don't think towing a cart is an approved means of recharging the batteries...

No mater what you do with the accelerator pedal.

The switch was labeled RUN/TOW...What part of that is unclear...

Sounds like either it's running or being towed....

 

[Gale Hawkins]

I totally agree with the manual instructions too.

The battery charger is for charging the cart batteries and the regen braking is only to slow the cart. Even the manual states regen braking is not to be used in place of the cart brakes.

 

[dougmcp]

I agree that regen is not the way to charge the cart but it's a fun thinking process anyway.

There is a big difference between regen and roll away protection and are 2 separate functions in a sepex motor:

Regen Speed Control:
Polarity control of the field which is used for forward and reverse, but then when you want to go into REGEN, you fix the field current and then as the speed of the vehicle comes up the back EMF (Electro Motive Force) of the armature is resisted by the field. So the over speed control comes very simple in a separately excited system. You have to sense the speed with a sensor which all of these vehicles have. Once you sense the over speed condition you just elevate the field up and you get REGEN braking.

Roll away protection:
It's not Regen, it's called "plugging", where you short the armature out and you apply a field current, so you operate the motor into a short. There is no regenerative action and all that energy is going into heat of the armature but does, in fact, brake the car.

 

[Gale Hawkins]

Thanks Doug. This is good info for all us PDS EZGO owners.

I have read about this in the manuals but did not know enough to sort it out. It said the anti roll feature did not lock it so the motor could keep turning so not to build up heat in one spot. Now that makes sense.

Regen is just plain cool. With the steep hill plug installed we can be sure we do not go over 10 MPH by taking foot off the pedal even if the brakes failed.

I am glad you posted this because it is great content to add to the site. I had never read about shunt motors until last month when we got the cart.