Re: (ET) Elec-Trak E20 fixing up and modifications (including Curtis conversion)

["David Roden" <etpost drmm net>]

Ben, that is mighty impressive work.  Well done.

> this allowed me to rewire all battery connections and the motor
> armature with 2 gauge wire to avoid power loss at higher amperage
> draws. This benefit could be debated but as I was starting from a clean
> slate, I felt it was worthwhile. 

I don't know who would debate the benefit.  

The original wiring was probably deliberately designed a bit undersize, to 
limit current to some extent.  That would give the motor some protection.  
 
Since you have a controller that (we hope; see my previous posts on this 
topic) properly limits motor current, you can probably use larger wire 
safely.

One thing I didn't see you mention is a main breaker or fuse between the 
battery and the controller.  Do you have one?  If not, you really should.  
A good DC rated breaker could replace the original disconnect, though not 
in the same location, I don't think.

> For the new throttle control, I bought a genuine Curtis FP-6D 

When I was planning to install the 4QD in my R36 rider, I looked at a 
couple of Happ controls, intended for arcade games.  They aren't cheap, 
but 
they seem pretty darn sturdy, even more so than the Curtis potboxes.

As part of installing the Alltrax in the E15, after also looking at a Happ 
arcade pedal, I almost used a homebrew pedal and a GE forklift potbox.  

In the end, I decided I wanted to stay with a hand control, and used a 
Solectria potbox that I had on hand.  

BTW, I still have that GE potbox, if anyone is interested.  It's a beast.

> These throttle controls always have a microswitch to detect when the
> throttle is closed or has been opened. This is useful for designing a
> "high pedal disable" circuit meaning if a safety switch is opened or
> the tractor is flipped from FWD to REV, you must let off the throttle
> first before power will be applied to the field and the armature. 

I think of high pedal disable as requiring a return to zero after powering 
up the controller with the accelerator potentiometer set high, but that's 
a 
good use for it too. 

The Curtis controllers don't have HPD built in?  It seems like basic 
safety.  A couple of on-road EV Curtis-precursor series motor controllers 
I 
had 30-35 years ago (PMC DCC-96 and PMC-25) certainly had it.

> I didn't bother to fill or patch any dents or holes so while it looks
> pretty good, I'm not afraid to use it. 

Very sensible.  Not that I'm opposed to making an ET a showpiece!  It's 
just that to me a work tractor shouldn't be too handsome or you won't want 
to use if for real work.  

I think of the guy who delivered hay to us years ago, and griped because 
his shiny new pickup truck got a few mild surface scratches from the brush 
along the path to our barn.  I'm an old guy.  In my world, pickups aren't 
daily drivers unless you're using them for actual WORK.  Who delivers hay 
with a pretty truck?  And who mows and pulls stumps with a pretty tractor? 
 
End of sermon.

> The rear wheels are fine but the fronts leak air and go flat over
> several weeks, so at some point I'll add tubes or replace the rims. 

Not uncommon with these old wheels.  My R36's rims are pretty leaky, 
especially the used one I got recently to replace a stripped original.  
Tubes will be going in soon.

> FRONT LIFT TO WINCH CONVERSION

I'll be keen to hear how this works out with the mower deck and other 
front 
accessories.  We've discussed replacements for the front lift many times 
on 
this list.

> I went with a Minn-Kota MK-345PC 12v 3-bank, 15A per bank smart
> charger. 

I hope that works ouit for you.

One thing to watch out for with modular charging - before starting the 
tractor, make sure all the battery blocks are actually charged!  

If one charger bank fails and you don't notice, you'll be left with a pair 
of battery blocks that didn't charge fully, it at all.  Once you start 
using the tractor, they'll go flat in a hurry.  You can easily end up 
reversing and ruining those uncharged blocks - or worse, get what a friend 
of mine used to call a "Trojan Teakettle."

I use individual 12v chargers, and have almost had this happen a couple of 
times.  It's easy to forget to check.

> add a 12v fan + transformer 

Why not just use a 120 volt AC muffin fan?  Parallel it with the charger 
input.

> 12v LED vehicle and work lights 

Sounds like a huge improvement over the dim stock incandescent lights.  

A couple of years ago I looked at small LED light bars for mounting on top 
of the hood, or maybe on the grille, but I never followed through.  
Fitting 
them to the stock headlight buckets is much more elegant.

> I got panel mount LEDs to use as FWD (green) and REV (red) indicators. 

Good idea.  

When I converted to the Alltrax, I added a forward/reverse toggle switch/ 
For a while, I'd forget to put it back into forward after backing up, and 
get a suprise.  

Eventually I added a reverse beeper.  The Alltrax had an output for one.  
I 
don't forget any more. :-\

> I'm probably overdriving the LEDs to some degree. 

If you put a milliammeter in series, and add enough resistance to limit 
the 
forward current to 20ma, they should last for many years.

> I made all the jumpers with 2 gauge wire and bolt on ends purchased at
> an auto parts store. 

Those work, but they're actually meant for temporary use.  Crimp on 
connectors are a better choice for the long term, especially with flooded 
batteries. 

A really good hydraulic hex crimper and a few dies will empty out your 
wallet, but you'll be able to hand it down to your grandkids.  

Hammer crimpers work OK but don't do a true hex crimp, so they're a bit 
controversial in the road EV conversion world, what's left of it.

A manual hex crimper is fine, if you have the chest and arm muscles 
required to work it.

If you do, here are instructions for making a low cost manual crimper from 
a pair of cheapo-tool-store bolt cutters:

http://evdl.org/pages/dubecrimper.html

Or you can buy a cheap and cheerful Chinese hydraulic hex crimper online.  
Mine leaks a bit, but is still hanging in there.  The dies are metric 
sizes, but they're usually close enough.


David Roden - Akron, Ohio, USA

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