Author Topic: 3kw Non-hub Moped Conversion help  (Read 28740 times)

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #60 on: March 12, 2019, 06:59:31 PM »
The cables can be secured to the frame using black zip ties or even black insulation tape, but you need to make sure that the battery connections on the contactor are safely insulated.
I recommend using rubber/plastic boots to completely enclose the exposed metal terminals as shown below:



I would also rotate the lower terminal and place the locking washer between the terminal and the contactor so that it is spaced even further away from the frame, but don't position it too close to the contactor's ground connection, or that could result in a short circuit too.  :o

The contactor should not need to be mounted on rubber grommets as the mounting bracket should already be electrically isolated, and very little vibration (if any) will be produced by the electric motor.

Regarding the seat, good results can be achieved by constructing the basic shape from cardboard and then apply layers of fibreglass over the top to achieve the required strength.
After some body filler and a lot of sanding you end up with a surface that can then be painted to match the tank and side panels etc.

Here are the before and after pictures of my brother's first moped taken back in 1980:





The above image was scanned from some old slides which were developed nearly 39 years ago, hence the strange colours.
The slide showing a close up of the mural on the top of the petrol tank seems to have been relatively unaffected:



Exposed groups of cables can be bound together using black PVC loom tape, which is similar to black PVC insulation tape but without the adhesive backing.

Alan
 

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #61 on: April 09, 2019, 08:24:28 PM »
Those look awesome!
I will be putting the terminal boots when I get them in a few days. I will also get a few locking washers for a few things.

I really didn't want to do a fiberglass body for the seat. I was thinking about just making a longer seat out of pleather. I also just got the loom tape yesterday and started wrapping some wires that I knew where they would go. That might be a last resort if I can't get the seat to look the way I want.

I just realized that step-down converter is only rated to 72v. When I am fully charged I'll be running around 80v. Will that blow the converter?
Here's a link to the step-down converter. https://www.ebay.com/itm/Pro-Chaser-DC-DC-48V-60V-72V-Converter-Regulator-Step-Down-to-12V-240W-20A-/223130887152?hash=item33f3a323f0


Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #62 on: April 09, 2019, 10:29:23 PM »
I just realized that step-down converter is only rated to 72v. When I am fully charged I'll be running around 80v. Will that blow the converter?

The voltages stated on the converter are usually nominal voltages, not fully charged voltage. A 72V lead acid pack would typically be charged to ~87V, which should quickly drop to ~83V when the charger is switched off. The converter should work fine with a 72V lithium pack.

Alan
 

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #63 on: April 10, 2019, 12:50:39 PM »
You were right! It worked with the 72v step-down! Check out what came alive last night!

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #64 on: May 07, 2019, 08:24:09 PM »
So, I know this is weird, I was hoping to have 2-36v batteries running in series for 72v for space. The motor draws 94A max continuous. If I have a BMS on each of the batteries, would I need that BMS to have 100a protection or 50a protection? Does each battery pull the amps equally or are they both pulling 100amps?

I was looking at these BMS to see if I could use them, they are rather pricey.
http://www.batterysupports.com/36v-37v-42v-10s-100a-10x-36v-lithium-ion-lipolymer-battery-bms-p-390.html

Would it be easier to just build a 72v battery? (20s with 100a protection). I wanted it to be 2-36v 15a in series to build the batteries and have a few of them I could swap in and out?

Does that make sense?

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #65 on: May 07, 2019, 10:59:59 PM »
If two packs are connected in series, each pack supplies full current but only half of the total voltage, but if two packs are connected in parallel, each pack supplies full voltage but only half of the total current.

So in your case, each BMS must be able to supply >94A continuously.

A single 72V battery might be the simplest option, but you would also need a 72V charger (or 2 x 36V chargers with their outputs wired in series) with an accurately regulated 84V maximum output (20 cells @ 4.2V = 84V)

As it is not recommended to swap half a battery pack at a time, it should not really matter whether your spare packs are 2 x 36v or 1 x 72V.
Your 2 x 36V packs should always be charged and discharged evenly as a matched pair, so they are basically being treated as a single pack anyway. ;)

Alan
 

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #66 on: May 08, 2019, 12:24:22 AM »
Yeah, that's what I figured... not what I wanted to hear. But what I thought. I have to figure out how to wire them together in the space I have.

If I have two banks together, how would I put them together while keeping them stacked on top of each other? 2 stacks of 10s6p in series?

Thanks again Alan!

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #67 on: May 08, 2019, 08:56:39 AM »
If I have two banks together, how would I put them together while keeping them stacked on top of each other? 2 stacks of 10s6p in series?

You might want to try this battery shape configurator to find the best shape to suit your battery space.

If you have room for a single 20S6P pack like this:

it could be mounted flat on its side for a lower centre of gravity, or you could make two packs and stack one on top the other for double the range.  ;)

I would suggest placing a suitable piece of thick card between the two packs before taping them together using either Duct tape or reinforced filament tape.

Don't forget to allow additional room for your BMS unit.   ::)

Alan
 
EDIT: Battery diagram added
« Last Edit: May 08, 2019, 09:28:27 AM by Bikemad »

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #68 on: June 11, 2019, 02:57:59 PM »
Hey everyone, finishing up my final battery configuration. I figured out I needed higher thickness for nickel strips. I got .3mm thick by 8mm wide to handle the higher 13.9amps that each cell can use.

I also got a 20s7p 72v -100amp BMS. Below is what I am thinking of doing for my moped. I already have to have the specific size for the battery compartment. So I have to create the two 10s packs in series for 20s configuration. I have it separated by a 1/8inch foam sheet and then the BMS will be on top of it. My questions are:

  • What gauge wire should go between the positive and negative from one cell to the other to complete the other? It's about 7inches or 200mm from the front and back? The other wire that goes to the controller is only 10 gauge that came with the Golden motor. Would I be ok with 10 Gauge wire?
  • Will I be ok with the eva foam I bought to go around the pack to separate the two 10s packs from touching? Would you wrap each of them and then solder the BMS in?

Below is my image for what I'm thinking. The other image is my 30Q's together

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #69 on: June 26, 2019, 12:53:53 PM »
Ok! The battery is done! However...

I recycled the series connection from my old battery connection wires when I went to a single 72v battery. I didn't realize that the plug posts were switched. I plugged it into my system and then turned on the bike. A small spark and all the fuses blew. I tested my battery, and I replaced the 12v system fuse. I switched the plugs to be correct and now I have no movement from the motor. But the battery and the 12v systems are working now. I assume if I replace the "100 amp- 32v MIDI" fuse, everything will work again?

Image of the fuse. https://imgur.com/gallery/kdMJXm3

Do you think that my controller was saved by the fuse? The 12v system was, (10amp fuse). I feel like if the 12v system was the controller was? What happens when you reverse the polls?

Thanks, everyone!

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #70 on: June 26, 2019, 11:08:59 PM »
Try some 32A fuse wire in place of the blown fuse to temporarily test if the controller is OK, but don't apply too much throttle or you could blow the fuse wire.  :o

If the motor then turns, you will hopefully be OK with just a replacement 100A fuse.



Alan
 

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #71 on: July 03, 2019, 03:18:01 AM »
Thanks Bikemad!

I replaced the 100amp fuse and it turned over for a second then shuts off. The lights still work?

The pack is registering with the voltmeter @ 66.4v. So that’s 3.32v per cell. Is the pack too low? My 72v charger didn’t get here yet so I have to wait to charge. Could I test the Bms somehow? Or did I fry my controller?

Thanks!

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #72 on: July 03, 2019, 10:21:13 AM »
If your pack is only measuring 66.4V without any load on it, the pack is basically fully discharged, and the voltage will quickly drop even lower when you apply a load to it.

Here are the controller's default voltage settings for a 72V battery:



Current reducing would start at 66V and the controller would cut the power completely at 63V.

If it is not the the controller itself that is cutting out, then it is likely that the BMS is cutting the power to prevent damage to the low cells, because the lowest group of paralleled cells has reached their safe minimum voltage.

Here is an amended 7S chart which now shows the approximate battery state of charge for a lithium 20S battery pack:


(I multiplied the original 7S figures by 20/7 to obtain the 20S figures shown above.)

It might be worth setting your controller's Low voltage protection value (V) to 67V, and the  Low voltage triggering current reducing (V) to 70V as I suspect the default values are more suited to lead acid batteries than lithium.

I am hopeful that the controller will start working correctly again once the battery has been recharged.



Alan

 
« Last Edit: July 03, 2019, 01:56:13 PM by Bikemad »

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #73 on: October 10, 2019, 01:37:06 AM »
Thanks everyone for your help!

I just thought you would like to see it. It's not finished by any means but I thought you would like it.

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #74 on: July 01, 2020, 04:14:33 PM »
Hey everyone, I'm about finished. I added a new tank/cover for my components and added turn signals. The image is attached.

I had a question about wiring up brake lights.
Could I use the 3V power coming from the brake switches on the Goldenmotor brake cables that go to the controller? Is this possible? I can hook up a normally open relay to turn it on? I tried this before and got 3 blinking lights from the controller?

What have others done to trigger a brake light?

Thanks!