The Spawn of the Beast - mini chopper project

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zogthegreat
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The Spawn of the Beast - mini chopper project

Post by zogthegreat » Fri Nov 10, 2017 2:24 pm

Hi everyone!

This will be my first real project on this forum. I'm already posting this project on another forum, but since I'm asking for advice/help on another thread, I thought that it would only be appropriate to contribute to this forum also.

Last year I did a Razor Dirt Quad build, where I rebuilt the rear swing arm to hold a 54lb 9.5hp industrial motor and 4 12v 18ah batteries:

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This is the motor next to a Unite 1000w 36v motor:

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The build was a lot of fun and I ended up calling the project "The Beast" because of the size of the motor. In reality, however, I should have called it "The Wild Pig". It had a high center of gravity that made it handle like a pig on straight roads! I never got to open up the throttle on it, so I was disappointed with it in the end. I was thinking about lowering it by rebuilding the front suspension, but ultimately, I decided that it would be to much work.

I decided to find a go kart frame to drop the motor on to and I went out last weekend to a 39 mile long yard sale down here in central Florida to look for a frame when I saw this:

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It had a 5hp gas motor on it that I told the owner I didn't want. After bargaining with the gentleman, I got the frame for $40.00! Since I'm putting most of the hardware from the The Beast on it, I decided to call it "The Spawn of the Beast".

My original plan was to set it up like this:

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(The red box on top of the batteries is a Kelly KDZ48200 controller.)

I was going to go for a "retro" look with analog gauges, however.....

I scored on eBay yesterday morning! On of the 12v 18ah SLA's that I was planning to use on this project somehow or other shorted out on my trip from Montreal to Florida, (I live full time in a 36' motorhome these days, I'm originally from California and -30 SUCKS!!!). So I went on eBay to peruse for new SLA's. I was looking at $120.00 with shipping for 4 new batteries and I thought that I would check and compare the price of lithium's when I found this:

https://www.ebay.com/itm/122752553886

:D :D :D :D :D :D

I couldn't afford it this month, (I just spent $1000.00 on gas!), but I really couldn't not afford it! A BMS isn't that hard to repair/replace and the entire pack only weighs 8 lbs! Each 12v 18ah SLA comes in at 12.5 lbs, so I'm losing 40 lbs of batteries!

Which means I have to change my design plans. As I said, I was going to go for a "retro" look, but now I'm thinking something sleeker and futuristic. I really have to wait for the battery to arrive next Monday and see what I'm dealing with. One thought that I'm having is to disassemble the pack and build a faux gas tank to hold the batteries, (although, since the batteries are my "fuel", is it really a faux tank?). I'm actually thinking strong angles like the F-117 fighter had.

For the speedometer/tachometer I'm going to build this:

http://www.instructables.com/id/Arduino ... aphics-LC/

With a matching volt/ammeter for my "fuel gauge".

Right now I'm just waiting for the new batteries to come in so that I can see what I have to work with. I'm also thinking of building a rear swing arm, I have to think it through to see how much work/rebuilding of the frame I would have to do. Another thought that I had is to find a used mountain bike front suspension and modify it onto my front forks.

Because of the size of the forks and frame, cable brakes wont do the job. So I will be adding hydraulic front and rear brakes from a motorcycle. I want to keep the front bike tire to try to keep the weight down, so I will have to get a new front hub to mount the front brake disc on.
1st computer I used - Tandy TRS-80, 1st computer I owned - IBM PC-XT, 1st computer I fried - IBM XT-286

Pulse Charger Revolution, current stock w/ lead-acid batteries, (soon to change......)
Razor E300, modded with YK41B, Unite 36v 1000w, disc brakes

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zogthegreat
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Re: The Spawn of the Beast - mini chopper project

Post by zogthegreat » Fri Nov 10, 2017 6:01 pm

I got some work done on the frame today. There are a lot of holes from what appears to be two different gas tanks, as well as several others that I can't figure out what they were for:

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I welded them up and cut off the fugly arsed repair job someone did on the foot pegs:

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OK, I'm not the worlds greatest welder, but seriously? Whoever did this didn't even clean up the left over mig wire! Then I went at the paint with a wire brush attached to my angle grinder and a flap disk:

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And then some black primer to keep it from rusting while I figure out my design plans:

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Purdy!

The axle was a PITA to get out. One of the worm screws is rusted in. I tried using a propane torch, but that didn't work, so I'm going to drill out the center of the screw and try to use an easy-out to get the rest. I'm hoping to save the mount to reuse.

Image
1st computer I used - Tandy TRS-80, 1st computer I owned - IBM PC-XT, 1st computer I fried - IBM XT-286

Pulse Charger Revolution, current stock w/ lead-acid batteries, (soon to change......)
Razor E300, modded with YK41B, Unite 36v 1000w, disc brakes

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zogthegreat
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Joined: Tue May 13, 2014 3:25 pm

Re: The Spawn of the Beast - mini chopper project

Post by zogthegreat » Sun Nov 12, 2017 2:07 pm

Well, it was a good news/bad news day today. The good news is that my battery pack came in!

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These are Lifepo4 cells, not the Li-Ion the seller had advertised, but that part doesn't really matter to me:

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They are also flat cells, not the 18650's that I was expecting, but once again, not a problem.

They problems is I was told on another thread that my motor will fry the batteries! Not good! So that leaves me the following choices:

1 - Install a 20a fuse to protect the batteries and hope for the best.

2 - Change the motor for something that will be large enough to move the chopper, but won't damage the batteries.

3 - Save the battery pack for another project and buy some SLA's.

Grrrr! I had a really cool design worked out that depended on these batteries! (sigh), Back to the drawing board again!
1st computer I used - Tandy TRS-80, 1st computer I owned - IBM PC-XT, 1st computer I fried - IBM XT-286

Pulse Charger Revolution, current stock w/ lead-acid batteries, (soon to change......)
Razor E300, modded with YK41B, Unite 36v 1000w, disc brakes

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zogthegreat
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Joined: Tue May 13, 2014 3:25 pm

Re: The Spawn of the Beast - mini chopper project

Post by zogthegreat » Tue Nov 21, 2017 8:20 pm

So, I managed to locate 4 x 12v, 35ah SLA batteries for $160.00 with shipping. Now I'm looking for a charger that is more than 3a, (12 hours to charge my batteries is a tad excessive!). Does anyone have any suggestions for a charger that's not too expensive?
1st computer I used - Tandy TRS-80, 1st computer I owned - IBM PC-XT, 1st computer I fried - IBM XT-286

Pulse Charger Revolution, current stock w/ lead-acid batteries, (soon to change......)
Razor E300, modded with YK41B, Unite 36v 1000w, disc brakes

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amberwolf
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Re: The Spawn of the Beast - mini chopper project

Post by amberwolf » Wed Nov 22, 2017 1:25 am

First you should check the charge rate listed on the side of the batteries. Exceeding that can cause them to turn their electrolyte into gas (and being sealed, it's difficult to fix that).

Next I'd recommend looking at chargers for powerchairs. 24v chargers are common on those, sometimes up to 5A or more. Use two chargers, one on each series set of 2 SLA. You may have to break the series connection between the "top" two and the "bottom" two SLA to charge like this, as teh chargers may not be isolated. (then remake the connection to discharge, assuming you're using four SLA in series for 48v).

BTW, 35Ah SLA are very heavy; I suspect these four batteries will weigh close to twice what your motor does. If so, just the electrical system on there will weigh as much as a person.

(my 2kWh battery pack plus my two MXUS3k hubmotor wheels on the trike is also not light--I expect it all weighs more than the heavy frame, wood panels, canopy, etc; and it affects the range when there's a lot of stops and starts, like my work commute).

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