The Spawn of the Beast - mini chopper project

[zogthegreat]

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:

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

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:

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:

(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



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-Bike-Speedometer-With-128-X-64-Graphics-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.

 

[zogthegreat]

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:

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

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:

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

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.

 

[zogthegreat]

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

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

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!

 

[zogthegreat]

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?

 

[amberwolf]

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).

 

[zogthegreat]

Hi amberwolf , thanks for the response.

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).

I've been trying to dig up the actual charge rate, but all I'm finding thus far is this:

Nominal Voltage: 12V
Nominal Capacity: 35Ah
Terminal Type: NB
Weight: 24.68 Lbs
Length: 7.72" (196 mm)
Width: 5.16" (131 mm)
Height: 6.42" (163 mm)

I will do some more research tomorrow to see if I can't find more information.

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).

I was looking for powerchair chargers today after you suggested them, but I can't find anything 5a or higher at a reasonable price. I did find this though:

https://www.ebay.com/itm/172350367249?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

Do you think that it will do the job?

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).

LOL, yeah, I hear you. I used to have the same motor with 4 x 12v 18ah SLA's, those came in at about 12.5 lbs each. Maybe the weight will act as an anti-theft?

Thanks again

zog

 

[amberwolf]

I've been trying to dig up the actual charge rate, but all I'm finding thus far is this:

I thought I'd try to be helpful and find a couple of manufacturers that list this data, but I can't seem to find ones that do. :/

I know I've seen it printed on the side of the batteries on some of them (check your old ones to see if they have it), but not all. They do usually have the charge *voltage* listed there (depending on whetehr it's a cyclic charge or a float), and sometimes even the discharge rates.

I checked MK power for one example
http://www.mkbattery.com/images/MU-1%20SLD%20G.pdf
a similar battery size to what you're getting, and one I've used before (I think there are two of them in the powerchair in my shed, both dead though). But it doesn't say

It's been so long since I worked iwth SLA I don't recall the rule of thumb for charge rates vs battery size/capactiy/etc., but there is a fairly safe level you can default ot if you don't know what the rate is. I'm just not sure of a good trustworthy place to find the info. :/

I do know from experience too high a rate will damage the batteries. IIRC I toasted a set of 12Ah SLA with a 5A charger (maybe it was an 8A, cant' remember right now).

I was looking for powerchair chargers today after you suggested them, but I can't find anything 5a or higher at a reasonable price.

Actually I was thinking about used ones, which you might find at goodwill or other thrift stores, or at powerchair repair places, etc. Or you can ask on Freecycle (or craigslist) if anyone in your area happens to have an old powerchair they don't need the charger from anymore.

https://www.ebay.com/itm/172350367249?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

Do you think that it will do the job?

As long as the golf cart batteries it's meant for are SLA / AGM / etc., and not FLA, then yes. But in the "similar items" on that page is a 5A version for 2 bucks more.



FWIW, the powerchair chargers are often potted fanless units, like the Cycle Satiator, and the Meanwell LED PSUs, etc., so they are basiclaly weatherproof and vibration proof, making them safe and easy to mount to the bike so you can charge wherever you are just by plugging in the AC cord. (and breaking the center series connection, if the chargers are not isolated internally).

Most of the other chargers are neither weather nor vibration resistant (much less proof) so carrying them around risks breaking them.

 

[zogthegreat]

As long as the golf cart batteries it's meant for are SLA / AGM / etc., and not FLA, then yes. But in the "similar items" on that page is a 5A version for 2 bucks more.

Doh! Thanks for the correction, I have the 5a in my bookmarks, forgot to delete the 4a. I will check about the FLA part, most golf carts that I've helped repair use SLA/AGM's

FWIW, the powerchair chargers are often potted fanless units, like the Cycle Satiator, and the Meanwell LED PSUs, etc., so they are basiclaly weatherproof and vibration proof, making them safe and easy to mount to the bike so you can charge wherever you are just by plugging in the AC cord. (and breaking the center series connection, if the chargers are not isolated internally).

Most of the other chargers are neither weather nor vibration resistant (much less proof) so carrying them around risks breaking them.

Something like this?

https://www.ebay.com/itm/Merits-sc1150a-30v-battery-charger-for-scooter-wheelchair/162747127582?hash=item25e47c171e:g:2acAAOSwYwJaBc18

I actually found two on offerup.com, I might be able to get them at around $20,00 ea.

(EDIT), I reread the page for the 5a charger.

"Only for LEAD-ACID BATTERY"

So it kind of looks good, but if the power chair chargers will work, I would prefer them. Then I can build them into the bike frame, have a cutout switch to disconnect them for charging but linking both chargers to to a single 110v plug.

Sorry, 2:00 am here, zoggy needs to get some sleep to be more coherent!

(EDIT 2) I noticed that the golf cart charger was for the same type of golf cart that my neighbor has and I checked the batteries. They are FLA's (Trojan t105's), so no go on that charger!

 

[amberwolf]

Something like this?

https://www.ebay.com/itm/Merits-sc1150a-30v-battery-charger-for-scooter-wheelchair/162747127582?hash=item25e47c171e:g:2acAAOSwYwJaBc18

I actually found two on offerup.com, I might be able to get them at around $20,00 ea.

Those are definitely NOT potted/sealed; you can clearly see vents on the end.

Many of the low-current sealed ones have a plastic case. Most of the higher current sealed ones have an aluminum case, but there won't be any vent holes in it. Only rarely do they have a plug hole--the cords are mostly wired straight in.

"Only for LEAD-ACID BATTERY"

SLA are also lead-acid (sealed lead-acid), as are AGM. But so are FLA, which have a different charge methodology than the SLA/AGM types. (they can take more abuse in charging than SLA/AGM, because you can refill the electrolyte when it boils off).

 

[zogthegreat]

How about this one?

https://www.ebay.com/itm/Mean-Well-CLG-100-24-DLU-LED-Driver-Power-Supply-AC-DC-Dimmable-PSU-96W-24V-4A/272921614277?epid=665378040&hash=item3f8b6557c5:g:CLsAAOSwcrFZg2Ku

 

[zogthegreat]

Another thought that I just had would be to buy laptop batteries in eBay like this:

https://www.ebay.com/itm/lot-9c-battery-for-HP-EliteBook-6930p-8440p-8440w-6730b-6535b-KU531AA-482962-001/322868637071?hash=item4b2c786d8f:m:m6ui4tU7YnzvTgFxwvT1i8g

A lot of 10 would be $160.00, the same price as the SLA's. I admit that 90 cells wouldn't give a huge amount of run time, but I'm only planning to use the chopper in the RV park.

 

[izeman]

how are you doing this while you live in a motor home? do you have a workshop on a trailer or something?
taking all the welding stuff and tools with you must take away a lot of storing room.

 

[zogthegreat]

how are you doing this while you live in a motor home? do you have a workshop on a trailer or something?
taking all the welding stuff and tools with you must take away a lot of storing room.

LOL, I have a very tolerant landlord who I make sure to help whenever he needs a hand! He did shoot down my plan to drop a 6.5 gas motor on it, didn't want the extra noise in the park, but allows me to grind and weld on the picnic table outside of my RV.

My tools and welding machine take up 2 1/2 bays on my motorhome, although I have to move them around when I'm traveling to balance the weight. One of the reasons I went with a coach and not a trailer is the storage space underneath.

When I get out to Arizona next year, I'll start looking for a place to buy. A LARGE garage or space to build a workshop will be among my priorities, along with some space between myself and my neighbors. I'm an insomniac, so I like to work late sometimes. And no fraking HMO's!

 

[izeman]

...I'm an insomniac, so I like to work late sometimes. And no fraking HMO's!

so it may be good that you live in a motor home, away from crowded places. using the angle grinder at night in my neighborhood and we'd have a BIG problem *lol*.

 

[zogthegreat]

I try to be respectful of my neighbors, so I usually stop with the power tools around 6:00 pm. My neighbors probably wouldn't care or can't hear, (at 52, I'm one of the "youngsters" in the park! ).

 

[amberwolf]

Another thought that I just had would be to buy laptop batteries in eBay like this:

https://www.ebay.com/itm/lot-9c-battery-for-HP-EliteBook-6930p-8440p-8440w-6730b-6535b-KU531AA-482962-001/322868637071?hash=item4b2c786d8f:m:m6ui4tU7YnzvTgFxwvT1i8g

A lot of 10 would be $160.00, the same price as the SLA's. I admit that 90 cells wouldn't give a huge amount of run time, but I'm only planning to use the chopper in the RV park.

Before you go down that path, you should read the many threads about 18650 cells, sorting, testing, pack design and building, because you have to pick the right cells to support the load you put on them, and parallel enough of htem to both handle that plus give you the Ah you need, and you ahve to sort which are good and whihc aren't so the bad ones don't take out the good ones in parallel with them, etc.

At a guess, with the currents you'll pull, you'll need several hundred cells to get enough in parallel and series, of the type that are probably in those packs. More if they're not all good cells and/or not all the same.

 

[amberwolf]

How about this one?

https://www.ebay.com/itm/Mean-Well-CLG-100-24-DLU-LED-Driver-Power-Supply-AC-DC-Dimmable-PSU-96W-24V-4A/272921614277?epid=665378040&hash=item3f8b6557c5:g:CLsAAOSwcrFZg2Ku

That's the right idea; I don't know if that specific one would work, but it's the basic sealed type.

I'm using the HLG-600H-54A, IIRC, as a charger for 14s (58.something V) at 12A. I parallel two of them for 24A if I need a fast charge. This particular model/type is adjustable both in current and voltage--but theyre a few times the price of the one you link (because they're 600w rather than 100w). If you search the forum for HLG you'll find a number of discussions about them (and other adjustable chargers), and there's info on other models in some of them, that would cost less.

 

[zogthegreat]

I was digging for something in my storage bays this morning when I came across a 12v power supply that I use for bench work like this:

https://www.ebay.com/itm/Kasonic-Universal-12V-24V-DC-Power-Supply-Driver-Adapter-For-LED-Strip/152483355211?hash=item2380b75a4b:m:mDKqU0vUZYlGXq_huYIZqpA

They have a 24v 10a 250w. Keeping in cooled and waterproofing it wouldn't be a problem for me. Do you think something like this would work?

 

[amberwolf]

That's basically the same as the open-frame MeanWell PSUs discussed over the years here on ES; you can search on those to see results and modifications.

Like any other non-potted PSU, it's not vibration resistant, so parts can break off inside, or heavy parts (transformers) can crack the PCB/traces over time. It might never happen to any particular unit, but it does happen sometimes--it tends to lead to intermittent or "wierd" problems rather than complete failures. This happens to ebike controllers, too, usually with big parts like electrolytic caps if they're not glued down securely, or if it has PCB's hanging out unsupported inside the casing (few do, but there have been some). Even happens to batteries that aren't built solidly, especially ones made of lots of little cells when they're not held together at the ends by something other than just the electrical connections.

Side note that cooling and waterproofing are usually contradictory things for open-frame units. If water cant' get into it, then neither can air, and heat can't get out like it's supposed to. If not run near their ilmits that may not be a problem, but when they are, it can be. There's always ways to do it, but some get complex, and/or aren't as efficient (so you can't run them as hard), and/or are bulkier or heavier, etc.



As to whether that specific one would work, then like the sealed Meanwell previously linked (and any other non-charging-specific PSU, you'd need to find it's specs and compare them with what's needed to charge batteries (whcih is different than what is needed to power things, especially in current-limiting: if it current limits by simply dropping the voltage smoothly, it could charge a battery. If it limits by shutting off under over-limit loads (hiccup), it won't charge a battery (or work as a current-limited PSU for things expected to exceed the load).

Many LED PSUs will do this, but there's plenty of sellers out there that have stock to sell of random PSUs, that see that PSUs with "LED" in the title sell better so they put it in theirs, even though they don't actually qualify, cuz they don't work the same. So you have to find the specs (not from the seller, but from the manufacturer) and see how it actually works.