Ben Nelson's Electro-Metro Build thread

[Daox]

If you would have left those wonderful side decals on it would have matched the polystyrene.

[MetroMPG]

Congrats on the anniversary and meeting your goals.

And THANKS for reminding me about the same pots on the side of the FS controller. I'd sort of forgotten about those. Maybe there's more performance inside waiting to be let out. Spring is coming. Couple more months I'll be back in Ontario and the car will be back on the road.

[bennelson]

It was as warm as one could hope for in Wisconsin winter this weekend.

Which of course meant that I would have the spring urge to tinker.

For a while, I have had an idea about a controller bypass for the car. ( This is discussed in more detail in another thread

While PWM (Pulse-Width-Modulation) electronic motor controllers are great, they do get expensive fast at higher voltages. I bought the highest voltage I could afford, which was a Curtis 72V controller.

The car performs reasonably well for a "grocery-getter", but simply doesn't have the speed for the larger country roads, including the 45 mph road right outside my house. My house is also just on the other side of a hill, with a 55 mph speed limit on the other side of it, so guess how fast people drive past my place.

Well, they drive faster than I want to pull out in front of with my little 72v eco-beater.

I really don't need a lot of control, just higher speed for one little section of road. too bad buying the next controller up would be so much money. If only there was a way to use my controller at low and medium speed, and just get some higher voltage straight into the motor for selected stretches of road.

Off to my box of miscellaneous forklift parts.
A common electro-mechanical part is a "contactor". Contactors are basically very beefy mechanical on/off switches. A specialized type, a reversing contactor, completes one circuit a split second after disconnecting the first one. It's a simple way to switch high-amperage circuits.

I put together two reversing contactors, screwed them to a hunk o' plywood, and started cabling them up. The idea is that normally the contactors keep the original controller in the circuit, but when powered up, they disconnect that and connect the batteries, plus two ADDITIONAL BATTERIES directly to the motor - TURBO MODE!



In case you didn't know, the more voltage, the faster the motor spins.

Once I got everything cabled up, I tested it in the driveway with the car's front drive wheels jacked off the ground. Everything seemed to work fine, so it was off to road testing.

I got out on the road, and drove along, going through a couple of gears to get it up to about 40 mph. Then I let off the go pedal, and hit the TURBO.

It's like there was a whole 'nuther gear - but amazingly, it had lots of power, like a lower gear, but at the same time, more speed, like a higher gear! This is only possible through the power of higher voltage.

The car briskly accelerated to 55 and then crept up to just past 60. My ammeter was pegged out. It's only a 300 amp, and the PWM controller is rated at 400. I really have no idea how many amps I was pulling, but it was plenty!

The Turbo Bypass really opens up a lot of possibilities. I could now drive a short hop on the freeway. I can power up that last stretch of road, just before my house, where the speed limit hops up. Maybe I will even try that one really big hill.

Still, before doing much more of anything, I need to properly rig up some diodes and other little bits that will make the system work better. (And not FRY the controller!) Trying to hand-hold a momentary-on switch while driving and then hitting the main contactor isn't exactly elegant.

What I do love about this is that I was able to go beyond the voltage limitation of the PWM controller, just by using a little imagination, and some parts I already had around.

Without spending a cent, I was able to experience how my car could perform as a 96V system. Not bad for "try before you buy".

I can now only imagine what the car would be like at 108, 120, or 144 volts.

Of course I am now bitten and hunger for more voltage. It really is hard to describe the feeling of flying down the road propelled by nothing more than electro-magnetism.

Ok, I guess there is a standard line to describe it.

It's electrifying.


EV grins,

-Ben

[MPaulHolmes]

Ben, that is amazing! Over 60 mph! 96v! It's amazing how much of a difference 24v makes. I can't wait for 144v.

[bennelson]

I was feeling a bit destructive today and was wondering what it would take to fit some more batteries in the car in place of the back seat.

So, I removed the back seat.



And the back seatbelts.


Leaving Sharpie® notes to myself in case I ever want to re-install them.

To remove the shoulder harness, I needed to remove the car's interior panels.


And to get those out, I really needed to take out the piece of plexiglass over the batteries that the charger was mounted to.

Oh heck, all this stuff is coming out!!!!


I pulled a whole pile of stuff out of the car. I did a little recabling to make everything reach, and shoved the main contactor and relays down below the batteries.

I could now move the batteries over just enough to slide the charger down beside them as well.

Since I needed a new cable to reach the repositioned contactor, I thought it was a good opportunity to add an Anderson connector as a main battery disconnect. This will make it MUCH easier to disconnect power for working on the car. Before, I always had to unbolt the fuse and it was under the plexiglass and hard to get at - a pain in the butt!

Here's the Anderson connector right on top. Just grab it and pull the two halves to disconnect all power.


Here's what the car now looks like with the entire rear seat removed and all the back body interior panels gone.


Boy, that carpet looks pretty dirty too. Anyone ever replace carpet in a car before? How tough is it? Astroturf might be pretty funny in there.

Anyways, with the back seat gone, it's pretty easy to visualize how I could cut a rectangular hole and build a box that drops down into that to hold more batteries.

In the wayback, there is the spare tire well directly below the batteries. It is an odd shape and not wide enough for four batteries. I think when I first experimented with how to put the batteries in the back, I found the two batteries would fit down into the well, but the other two couldn't, so I just put all four straight across on scrap bed frame metal.

If I cut a box down into the spare wheel well. I could fit all the batteries below the car.

I then might be able to put the back seat and cargo area floor carpet back in and actually have cargo space! (although not weight-carrying capability!)

This geo metro is using the same batteries I am (although a lot more of them!) and nicely displays how they can be sunk in the trunk.



I also liked the design of this Geo Metro.

Here, you can see the Yellow Tops in a box where the back seat was.


Can't tell how that's the back seat? How about if we put the seat back in?


That's right, it's so nice you can even put the baby's seat back there.

So anyways, I am thinking that I can put 12 batteries in the car. I can parallel them and stick with my measely 72V system, without having to upgrade my controller or charger.

BUT, if I can "road-test" somebody else's homebuilt 144V controller (hint hint) I could rig the batteries up as a 12 batt series!

Now we would be talking serious transportation!!!

How many inches of road clearance do I need? I wouldn't want a speed-bump to smash my battery box...

I still need to figure out how to boost my suspension.



PS: If I have 4 batteries in the way-back, 4 under the rear seat, and 2 in front, that only gets me 10 batteries - 120v if series or 60v in parallel!

Where would I cram 2 more batteries? Under the hood. For the life of me, I can't find it, but I have seen a photograph of a Geo Metro with my exact same batteries under the hood.

All four batteries are in the radiator position, but they run the length of the car. That makes a block of batteries 13 inches deep and 28 inches wide, just like in the back of my car right now.

I measures between the headlights in front, and it's just a hair over 28 inches! Measuring between the transmission and the grill is about 14 inches! I may have to trim a little bit off the motor adapter plate (it sticks out further than it needs to) but I should be able to fit 4 batteries in radiator position.

I knew there was a reason we so overbuilt that front battery tray....

[RarestAce]

i was looking and i found a few items that might help with your suspension issues RIDE CONTROL HELPERS : JC Whitney: Auto Parts & Accessories Automan LEAF SPRING ADJUSTABLE HELPERS : JC Whitney: Auto Parts & Accessories
Gabriel HIJACKERS® AIR-ADJUSTABLE SHOCKS : JC Whitney: Auto Parts & Accessories i hope this will help

[MPaulHolmes]

Originally Posted by bennelson

So anyways, I am thinking that I can put 12 batteries in the car. I can parallel them and stick with my measely 72V system, without having to upgrade my controller or charger.

That's what Dr. Larry Tillman did.
Dr. Larry's EV

There aren't any really good pictures of how the batteries are arranged, but you get to see some of Darin's comments from like 2 or 3 years ago!

Originally Posted by bennelson

BUT, if I can "road-test" somebody else's homebuilt 144V controller (hint hint) I could rig the batteries up as a 12 batt series!

Who's? I want one too! haha!

Originally Posted by bennelson

Now we would be talking serious transportation!!!

oh ya! It sound like the 12 batteries are going to make it nicely! This is very exciting.

[TheSGC]

Definitely do the two strings of 72 volts. Your range would be sweet, and upgrading to 144 volts would be as simple as a quick rewire.

I thought about doing a parallel setup for 96 volts, but the batteries I am using are just too big to have 16 of them!

So how many batteries do you have to play with?

[bennelson]

I think I have 18 total batteries?

I remember buying 12, and then going back and getting whatever was left in another trip.

I think I have a total of 13 between my Metro and garage and 5 more in the Citicar (in storage)

I may have had up to two dozen, but sold 6 to another guy who is trying to get a Citicar on the road (haven't seen him since then.)

When I actually go to the full dozen batteries, I will have to load test them all and pick out the best ones and try to match them all up as best I can.

[Daox]

Sounds like a great idea Ben. You'll have some pretty nice range with 12 batteries. I'd be all too happy to help out too.