# Gravel and Dirt roads in an EV



## RKM (Jun 9, 2008)

Joe,

Welcome!

I'm new to this as well but have done quite a bit of reading. I have gravel to travel, so share your concern. My understanding is that water isn't really the problem you would intuitively think it would be. Stones and road grit are to be avoided.

As I understand it, most DC motors are open while most AC motors are TEFC (totally enclosed fan cooled). The AC would seem to be the better choice for this reason. Unfortunately, an AC motor and controller combination is very much more expensive than DC (maybe AC for the second conversion!).

I have seen a Warp 9 wrapped with a finer mesh screen over the opening. This may adversely affect cooling (?). 

My intention is to install a full belly pan on the car. This should serve to shield the motor from road debris as well as improve aerodynamics and range. Victor at Metric Mind has an excellent demonstration of installing a belly pan. See the "aerodynamics" section of the Wiki (top right corner).

This forum is a great resource for your conversion! Good Luck.

Rob


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## madderscience (Jun 28, 2008)

Assuming you can't or won't afford a fully enclosed AC motor....

A DC system would do fine on gravel/dirt roads but I would go to more pains to ensure that no debris enters the motor. A fine (screen-door-pitch) screen mesh over the brush end and a coarser (1/4" pitch maybe) screen on the fan end should not interfere too much with cooling (and an appropriately sized motor shouldn't get too hot anyway) and a full or partial belly pan to prevent spray from hitting the motor, controller and other electronics would be a good idea. 

Furthermore pay attention to placement of batteries, cables and EV components to reduce the likelihood of dust or water contamination and accessibility for cleaning.

Another issue with an EV is due to the added weight (and stress on the chassis) the additional vibration of regular dirt road driving will require you to find a good, solid chassis, probably a compact pickup truck like an S-10 or ford ranger. the S-10 has kits available.

As for your round trip (20 miles) it shouldn't be a problem unless it is a big climb in one direction, in which case you might want to do some math to see how much extra energy is used vs. a flat and level round trip. Insulate your battery pack if you live in a climate that gets cold if you intend to use the EV year round and size the battery pack appropriately, taking into consideration your farthest needed range and any hills you need to climb.

Good Luck.


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## Joe_L (Sep 17, 2008)

Thanks for the quick replies,

I work as a process engineer for a mining company. The AC motors in a plant setting are something to see. They run with inches of caked on slurry, damp environments and still no problems. Truly impressive. I was concerned about the DC application, so good guess on that.

Since golf carts travel over all sorts of terrain, I figured that a gravel road would just require some extra fabrication to ensure motor longevity. Spring would be the most difficult time due to the road being in vary states of disrepair. We will probably encase the bottom of the engine bay with some aluminum similar to a skid pan. 

The S-10 is a good point, we were thinking an early 90's Saturn because they are light, more aerodynamic, smaller (less weight) battery pack to achieve range and economical (should be able to find one with a bad head gasket and a 5 speed for a few hundred dollars). However, the added weight would probably still be 150-200 kg. This could prove hard on the already light frame.

I will start another thread shortly. I am still doing some calculations from the NuWiki and trying to determine which path to head down.


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## Cornelius (Sep 15, 2007)

EV America supplies a small piece of window screen sized to fit the metal guard cover when you purchase an Advanced DC motor from them. According to Bob Batson, the owner of EV America, there have been some issues of small stones getting into a motor and causing damage, so now they supply customers with the extra screen.


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## TelnetManta (Jun 5, 2008)

I also came across this during a google search:

http://www.wacparts.com/index.php?main_page=product_info&products_id=25

Kind of pricey but it might give you a few ideas.......


Ben in SC


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## TX_Dj (Jul 25, 2008)

Belly pan is a good thing, because it keeps stuff from coming up into the engine bay that you don't want. It's also a good thing to have on the whole underbelly, because it increases aerodynamics for the air that's moving under the vehicle, which is a big source of drag.

It's been many years, but I once saw pics of a guy who was using an old DC generator for a traction motor, one that is designed to have a positive-displacement blower external to the device for cooling. He rigged his blower up with an air filter similar to what you'd use on a car's intake- something that screens tiny particulates, but can flow hundreds of CFM (more than his blower was capable, I'm sure). Since it was a positive airflow, there was no reason to worry much about the air outlet, because nothing could get in there while the blower was running.

It would be more difficult to implement something like this on an ADC or WarP motor, because they typically use an impeller or centrifugal type fan with a large series of openings around the outside of the motor frame... but not impossible.

Key thing to keep in mind is that the bearings are sealed (I think that's right) and so all you really have to worry about would be dust caking up around the armature and along the commutator and brushes.

I bet though, if you contact Jim Husted of Hi-Torque Electric, he could help answer some of those questions in an expert fashion, as he is truly a motor expert.


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## atzi (Jun 26, 2008)

Is the screen to go under the factory guard or over it?


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## AlterPower (Sep 5, 2008)

There are solid coverbands made for Warp 9 motors. Covers the screen and has a mount for forced air ducting.

http://www.go-ev.com/

Best!

JK


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## Guest (Dec 9, 2008)

We have had good success with this ducted band from EV parts. We simply mounted it around the commutator end of the Warp 9, ran some flexible aluminum ducting from that to a dayton 12v blower, and put an air filter over the blower intake. 

This helps the motor run cooler, and it prevents dust and sand from entering the motor.

Dust and sand could potentially wreck this motor in a couple of hours of operation. You are definitely on the right track that it could be a problem.

Electric motors are a bit different from ICE motors. Voltage and current aren't really a problem at any value. But the windings do have resistance, and so the HEAT caused by current IS a problem. 

If you have overpowered your car with a larger motor than you need - good job. 

If its close, cooling is one way to remove that heat, and well worth the current draw for an aux fan ducted into the air intake end of the motor.

Jack Rickard


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