Split from Begode DC Output Inverter Project

[woke rider]

I want to make that for my ks14d. If I plug in a y adapter to my batter packs and then combine the 2 new battery outlets into 1 output and make a hole in the shell then that would be a 67 volt terminal, right? Then what kind of inverter would I plug it into?

[woke rider]

would it be safe to connect the batteries to this: and then connect the output on the converter to a ciggerette lighter plug, then install the plug as an output in the shell and the converter inside of the shell?

[RagingGrandpa]

3 hours ago, earthtwin said:

would it be safe to connect the batteries to  < a buck converter with 12VDC output >

Practical, yes.

Safety depends on the small details about how you install it. 
 

5 hours ago, earthtwin said:

If I plug in a y adapter to my batter packs

Beware: wiring devices directly to the packs creates the following new failure modes:

• Overcurrent (short-circuit) can damage the packs, making them unsafe to use. Be sure to add some sort of overcurrent protection (e.g.: a 10 amp melting fuse very close to your Y-splitter.)
• Your converter could over-discharge your packs (draining cells below 2V/cell), making them unsafe to use. Be sure any such converter is configured to turn itself off if its input voltage falls too low.
• Your converter could create electrical noise that interferes with the EUC controller and could cause a crash while riding.
   

3 hours ago, earthtwin said:

then install the converter inside of the shell

This is more risky, because the buck converter is fragile, and gets hot. Better that it be a removable external device. 

Also, it's electrically noisy during operation... but I don't think you'd activate it while riding?
 

3 hours ago, earthtwin said:

connect a ciggerette lighter plug  < and power a 12VDC automotive AC inverter with it >

90VDC -> 12VDC -> 120VAC is a rather wasteful process, with regard to cost, mass, and efficiency.
I think this is why eWheels is considering a more integrated solution for 90VDC -> 120VAC with no middle step. 

[atdlzpae]

@earthtwin Connecting batteries to a solar panel may not be the best idea.

Seriously though, you're correct - you use an XT60 2-way connector (or whatever internal connector to your ks14d) to get an additional endpoint. You make a new output of the unicycle (67V outside the case). Then you convert it to 12V or whatever voltage you need.

However, having actually done this (to charge my KS16s during riding) I strongly advice against it.

You need to poke a hole through the shell. You need to be extremely careful not to destroy anything. You need to be careful not to short the battery by accident. And you need to be very careful once your connector is out - after all, it's 67V outside of the case.
Oh... And EUC's use Li-ion batteries, they can burn if mistreated.
The chance you'll destroy your wheel is pretty big.

 

 

I do believe it's way better to just buy one of the LiFePo4 12V batteries.
It has protections built-in, you just charge it and use it. A little on an expensive side (1280Wh for $342 = $0.26 per Wh), but you don't risk opening your wheel and destroying or blowing it up.
LiFePo4 can handle like 10000 cycles, it will serve you for decades probably.

I made myself an external 2kWh 24V 5 years ago and I just carry it in my backpack if I ever need power on the go. Definitely worth not poking inside the wheel.

Edited November 15, 2023 by atdlzpae

[woke rider]

Thanks @RagingGrandpa

how do I protect the batteries from over discharge? Also should I use a switch to activate the 67v output and block the controller output? Or is the on/off button sufficient?

 

Edited November 15, 2023 by earthtwin
Another q

[atdlzpae]

54 minutes ago, earthtwin said:

how do I protect the batteries from over discharge?

E̵v̵e̵r̵y̵ ̵w̵h̵e̵e̵l̵ ̵b̵a̵t̵t̵e̵r̵y̵ ̵h̵a̵s̵ ̵a̵ ̵B̵M̵S̵ ̵i̵n̵s̵i̵d̵e̵ ̵o̵f̵ ̵i̵t̵,̵ ̵i̵t̵ ̵w̵i̵l̵l̵ ̵s̵h̵u̵t̵ ̵d̵o̵w̵n̵ ̵i̵f̵ ̵i̵t̵'̵s̵ ̵d̵i̵s̵c̵h̵a̵r̵g̵e̵d̵ ̵t̵o̵o̵ ̵m̵u̵c̵h̵.̵ ̵H̵o̵w̵e̵v̵e̵r̵,̵ ̵B̵M̵S̵ ̵d̵i̵s̵c̵o̵n̵n̵e̵c̵t̵s̵ ̵o̵n̵l̵y̵ ̵w̵h̵e̵n̵ ̵a̵ ̵v̵o̵l̵t̵a̵g̵e̵ ̵r̵e̵a̵c̵h̵e̵s̵ ̵l̵i̵k̵e̵ ̵3̵V̵ ̵a̵n̵d̵ ̵i̵t̵'̵s̵ ̵n̵o̵t̵ ̵h̵e̵a̵l̵t̵h̵y̵ ̵t̵o̵ ̵d̵i̵s̵c̵h̵a̵r̵g̵e̵ ̵i̵t̵ ̵s̵o̵ ̵m̵u̵c̵h̵.̵

Supposedly EUC batteries don't have overdischarge protection to lower the chance of overleans.

54 minutes ago, earthtwin said:

Also should I use a switch to activate the 67v output and block the controller output?

You just use a 2-way cable to connect the battery. Zero reason to disconnect the board.

Edited November 15, 2023 by atdlzpae

[woke rider]

Wow, that’s a lot easier than I thought! Thanks for the tips.

[Chriull]

10 minutes ago, atdlzpae said:

15 minutes ago, earthtwin said:

how do I protect the batteries from over discharge?

Every wheel battery has a BMS inside of it, it will shut down if it's discharged too much

This was long time ago once eucs (re)used ebike like bms - after too much faceplanting (remember @hobby16's shunting mods) there is no bms undervoltage shutoff anymore. Just the firmware prevents further euc usage.

11 minutes ago, earthtwin said:

Wow, that’s a lot easier than I thought! Thanks for the tips.

I wouldn't count on that

[woke rider]

Now I’m scared. If I want to upgrade to graphene batteries, how many of these would I have to install, and how?

[atdlzpae]

8 minutes ago, earthtwin said:

Now I’m scared. If I want to upgrade to graphene batteries, how many of these would I have to install, and how?

You don't. It's a "simple project" in theory, engineering is extremely difficult in practice.
Since you're asking basic questions about electronics, this is not a project for you. It will end with whoever is riding your wheel faceplanting.

First play with basic electronics - Arduinos, transistors and such. Only then transition to stuff like modifying a 0.5kWh battery.

31 minutes ago, Chriull said:

This was long time ago once eucs (re)used ebike like bms - after too much faceplanting (remember @hobby16's shunting mods) there is no bms undervoltage shutoff anymore. Just the firmware prevents further euc usage.

It makes complete sense. On the other hand it's interesting that battery voltages can sag so much during use.

[RagingGrandpa]

8 hours ago, earthtwin said:

I want to make that for my ks14d.

What AC device do you want to power with your EUC?

p.s. 

[atdlzpae]

1 hour ago, Arbolest said:

I've been holding on to a bunch of my old 84v wheels for nostalgia's sake, and I would love to be able to find a use for them since they never get ridden any more. With one of these I'd be able to use them like emergency generators for vital appliances (refrigerator/freezer, lamps/lighting) in a power outage!

Not really, just sell one of them and build a proper power wall for the money.

The issue is that almost all charger inverters (basically a UPS - charges while the power is on, discharges when power is gone) use 12/24/48V. 84V would be viable, but is very exotic, and thus non-standard. So an 84V solution would be very HIGH effort and high cost - custom components cost more.

Google "power wall" to see how people are doing it. There is zero reason to reinvent the wheel.

Yes, you can take your home "UPS" and put it in a truck for travel. Just design it so it's not bolted to a wall. Pretty much all camper vans nowadays have proper 110V/230V inverters.

[xiiijojjo]

10 hours ago, atdlzpae said:

It would be quite terrible actually. Flexible solar panels are like 10% efficient. So with 1000W of sun per square meter, you get around 100W.
So to charge a 2kWh wheel in like 10 hours (one full day, from dawn till dusk) in summer you'll need 2 sq. meters of solar panels to deploy.

So yes, it's viable if you're nocturnal.
If you're not, then going from home to home saying "I'd like to charge a wheel, I'll pay you $10" is way more viable.

The ones I'm looking at are 16% efficient and with a 3kwh+ wheel and 2-3 of these https://www.bougerv.com/products/200w-flexible-solar-panel paired with limited daily travel It would be ideal for my dream scenario of living on a euc and traveling the world. 

Edited November 16, 2023 by xiiijojjo

[atdlzpae]

@xiiijojjo What's your plan? How do you imagine your day?

[Arbolest]

20 hours ago, atdlzpae said:

Not really, just sell one of them and build a proper power wall for the money.

I think you're missing the point here. The reason I still have them is because I DON'T want to sell them.

 

20 hours ago, atdlzpae said:

The issue is that almost all charger inverters (basically a UPS - charges while the power is on, discharges when power is gone) use 12/24/48V. 84V would be viable, but is very exotic, and thus non-standard. So an 84V solution would be very HIGH effort and high cost - custom components cost more.

Perhaps I didn't explain my plan thoroughly enough... It would be extremely low effort for me to take all of my 84v packs and tie them all together in parallel with what basically amounts to some large Y-cables. All I would have to do then is simply plug in an inverter similar to the one in the above video (already specced/designed for wheel-level voltages) which would theoretically give me a 110v outlet that I could use just like any other (within whatever wattage limit it's designed for, of course). I don't need the box of batteries to constantly be charging like an actual UPS, so after I use it I just plug it in with any of the chargers I already have from the same wheels the packs came from and raise it back up to whatever working voltage I want it at, and it's ready to use again. As a plus, if I ever wanted to for any reason I could take one or more of the packs and put them back in their original wheels, no-harm-no-foul.

Simple. Low-effort. Low-cost. No custom components required aside from maybe the Y-cable which I would happily make myself. Like I said, it would be great for the DIY crowd. 

 

20 hours ago, atdlzpae said:

There is zero reason to reinvent the wheel.

Also this. Whether there is reason behind it or not, the act of reinventing the wheel is where I get much of the joy in my life.  

There's nothing quite like envisioning an idea or the solution to a problem and then bringing it into being through sheer force of will. Whether or not the idea has already occurred to someone else is irrelevant and doesn't change the satisfaction and fulfillment that the act of manifesting it brings you. 

[RagingGrandpa]

10 minutes ago, Arbolest said:

It would be extremely low effort for me to take all of my 84v packs and tie them all together in parallel

BTW, for most switching power supplies that power home electronics, it makes no difference if you feed them AC or DC. People have been successful in connecting two 84V EUC packs in series to result in ~160VDC, and then using it to power standard AC devices. (Not motors! Not heaters!) Extra care is needed, since the small on/off switches intended for AC in your devices will absolutely be damaged if you force them to interrupt a substantial DC current. Even a residential light switch will not survive long. 

But if you're brave, no inverter needed.

Edited November 17, 2023 by RagingGrandpa

[woke rider]

On 11/15/2023 at 3:34 PM, atdlzpae said:

Since you're asking basic questions about electronics, this is not a project for you.

I'll be the judge of that, but I want to make sure I have a proper procedure in place before I begin.

On 11/15/2023 at 3:53 PM, RagingGrandpa said:

What AC device do you want to power with your EUC?

At first I thought that I would like to be able to run and charge my laptop, but then I thought maybe I would stick with 12 volt DC appliances for camping. 12 volt appliances are actually quite common. I might want to buy an inexpensive ac inverter to at least charge my laptop.

So far, I understand that I will need to install a fuse, not sure how many amps, not sure where.

Will the power just stop draining on it's own after the voltage gets below 6 volts or so?

[RagingGrandpa]

32 minutes ago, earthtwin said:

I would like to be able to run and charge my laptop

https://www.amazon.com/s?k=12V+laptop+charger 

[woke rider]

@RagingGrandpa, right. How could I improve my procedure given the following.

Buy 3 Y connectors, a buck converter, a fuse, and a 12V accessory outlet.

Remove the outer shells.

Connect the Y connectors to the batteries and connect the dc outputs back together to produce one output 67v and the 2 normal outputs going back into the wheels normal circuits.

Install an exterior mount with quick release of the buck converter 12v accessory outlet that I fabricate.

Take the wheel outside and plug in a 12v appliance for a couple hours paying special attention to heat and smells.

[RagingGrandpa]

I think you mean for each pack to provide no more than 5 amps. So, buy three 5-amp fuses with holders and install them at the output of each of the packs, before any Y-connector. 

Then, if you melt a fuse, you'll know you did something wrong. Measure and retry.

[woke rider]

Will this wiring job actually be a new 67v dc output? How do I set the output to stop discharging at a certain level? Where should I put the fuses? Does this look safe?

Edited November 20, 2023 by RagingGrandpa
(bugfix img)

[Elliott Reitz]

On 11/15/2023 at 2:57 PM, RagingGrandpa said:

Practical, yes.

Safety depends on the small details about how you install it. 
 

Beware: wiring devices directly to the packs creates the following new failure modes:

• Overcurrent (short-circuit) can damage the packs, making them unsafe to use. Be sure to add some sort of overcurrent protection (e.g.: a 10 amp melting fuse very close to your Y-splitter.)
• Your converter could over-discharge your packs (draining cells below 2V/cell), making them unsafe to use. Be sure any such converter is configured to turn itself off if its input voltage falls too low.
• Your converter could create electrical noise that interferes with the EUC controller and could cause a crash while riding.
   

This is more risky, because the buck converter is fragile, and gets hot. Better that it be a removable external device. 

Also, it's electrically noisy during operation... but I don't think you'd activate it while riding?
 

90VDC -> 12VDC -> 120VAC is a rather wasteful process, with regard to cost, mass, and efficiency.
I think this is why eWheels is considering a more integrated solution for 90VDC -> 120VAC with no middle step. 

All I needed was an 8 pack of AA cells to run a pair of motorcycle horns. 

 

[RagingGrandpa]

On 11/18/2023 at 5:30 AM, iwantmymtv said:

[Kingsong 14D]
Will this wiring job actually be a new 67v dc output?

I'm not familiar with 14D... if there were two 67V battery packs, then yes, that looks fine.
 

On 11/18/2023 at 5:30 AM, iwantmymtv said:

How do I set the output to stop discharging at a certain level?

The battery packs do not have any such logic, so the "stop" function needs to come from your new voltage converter. 
You need to ensure whatever device you connect (e.g.: 12V buck converter) has an automatic low-voltage shutoff feature. Most do. Be sure to adjust it properly and test to confirm it shuts off automatically at 40V. 
 

On 11/18/2023 at 5:30 AM, iwantmymtv said:

Where should I put the fuses?

At the positions circled below: 

 

On 11/18/2023 at 5:30 AM, iwantmymtv said:

Does this look safe?

Not yet. 
Your new 'splitters' directly connect the two pack outputs together. I think the Kingsong controller only connected them after a protection FET, which it uses to isolate one pack if there is a problem. You're bypassing that function. 
It might be safer to split off only one of the two packs, and avoid joining them. I think they will both be active as long as the Kingsong controller does not detect a fault. 

If you're not sure and aren't willing to track down these details yourself, please consider: how much do you think it will cost you to replace the interior of your home, if it were destroyed by smoke damage? Next: how much does it cost to buy a standalone portable battery bank?