Dewalt Flexvolt for projects?

[electromateria]

What do you guys think about using multiple Dewalt Flexvolt batteries (20v/60v - 6ah) to power DC motor projects? I need to buy 4 of them for work and figure they'd have a second use and save some $$$. I plan to 3d print adapters and mount them onto projects.

Can I accurately adjust the max voltage output on them with a cheap or simple circuit? Example lets say I have a 36vdc motor I need to run how would I do that? I have a 24vdc hub motor, 36vdc motor from a lawmower, a 2.5hp 90v 20 amp treadmill motor, plus a bunch of other ones I want to play around with.

[coppercone2]

AVE was working on a real power supply that connects to a power tool battery motor, not sure where it went, other people might offer a DC power supply that is compatible with your battery.

I am sure you have seen the USB chargers and portable inverters (yes, for a corded object) that those power tool companies are selling in home depot. They have a tiny inverter for a single battery and the new 'generators' that run on 6+ batteries from dewalt/milwakee marketed as small jobsite generator replacements or backups or noise sensitive work.. so naturally your idea is very sound

the absolutely most simple but heavy and expenisve option is to get one of those miniature inverters and couple it to a variac and a rectifier/capacitor to make a unregulated motor test power supply, that might work. For a small source that is LV you can use the new ones that are meant to be USB chargers, I believe with USBc, so you can run a USB power supply off of them. If you can get one that does USBC the output will be a nice high figure.

https://hackaday.com/2021/07/18/its-super-easy-to-build-yourself-a-usb-c-variable-power-supply-these-days/

[electromateria]

AVE was working on a real power supply that connects to a power tool battery motor, not sure where it went, other people might offer a DC power supply that is compatible with your battery.

I am sure you have seen the USB chargers and portable inverters (yes, for a corded object) that those power tool companies are selling in home depot. They have a tiny inverter for a single battery and the new 'generators' that run on 6+ batteries from dewalt/milwakee marketed as small jobsite generator replacements or backups or noise sensitive work.. so naturally your idea is very sound

the absolutely most simple but heavy and expenisve option is to get one of those miniature inverters and couple it to a variac and a rectifier/capacitor to make a unregulated motor test power supply, that might work. For a small source that is LV you can use the new ones that are meant to be USB chargers, I believe with USBc, so you can run a USB power supply off of them. If you can get one that does USBC the output will be a nice high figure.

https://hackaday.com/2021/07/18/its-super-easy-to-build-yourself-a-usb-c-variable-power-supply-these-days/

I appreciate the reply! Thanks for the info

So what I want to make is a "variable DC power supply"? 99% of results for that are: AC -> DC power supply. Is there anything specific I can search for to get what I need?

I think I found the AVE vidjayo in question:

https://youtu.be/ezLOAwF3rl8?t=146

Also found this one:



Is there any pre-made circuit I can buy or does it need to be custom made?

Like this thing but with variable DC output, I don't need any AC output:

https://www.homedepot.ca/product/dewalt-20v-60v-max-lithium-ion-battery-charger-and-1800-watt-portable-power-station/1001014509

[electromateria]

I found some interesting videos. I'm slowly learning I think, maybe I'm not looking into the right things though

• buck converter
• switching dc regulator
• linear power supply
• switching power adapter
• transformer
• MC34063A

^ This video shows a basic dc-dc step up votage booster. The basics seem easy enough, but for my application I'd need efficiency features, it would need to handle powerful batteries and generally it seems making a custom circuit is FAR out of my depth.

DCB606 Battery:

    6AH at 20V
    2AH at 60V
    120Wh on all voltages



I'm unsure which specific booster circuit can handle 4 of these batteries in parallel. 6ah x 4 = 24ah @ 20v, how much amperage gets released from the batteries?

This circuit looks interesting and well made and dirt cheap ($20 shipped): LTC3780 Buck/Boost DC/DC Converter 10A 130W -  https://www.ebay.ca/itm/294332088817



If I bought a more powerful one like this it should work right? Any help on what specs I need would be appreciated.

Or maybe I'll buy 4 of those circuits so I can modify each battery voltage and combine the output?

I feel information overload ahhh 

[wizard69]

Have you considered making your own battery(s) with fixed voltages?   You didn't state what these motor powered projects are but it might be easier to come up with your own battery tailored to the application.   

The other thing you need to watch out for is the potential for  voltage generation from whatever the project is.  This could be significant depending upon the project and I'm not sure a DeWalt battery pack can handle that well.   

[electromateria]

Have you considered making your own battery(s) with fixed voltages?   You didn't state what these motor powered projects are but it might be easier to come up with your own battery tailored to the application.   

The other thing you need to watch out for is the potential for  voltage generation from whatever the project is.  This could be significant depending upon the project and I'm not sure a DeWalt battery pack can handle that well.   

Yeah definitely considered it but I don't want to spend too much money on batteries. Those 4 dewalt batteries are already $700 CAD and I need them for work. I don't really want a custom built battery pack for every project I make. Say I have an electric scooter on 32v, then a very small electric vehicle on 120v, then a custom made tool that runs off 40v.. it seems I should try to get the battery packs to be as variable as possible to run everything. They already are easy to charge, come neatly packaged, have built in circuit for either 20v/60v.

You mean if the batteries are powering a motor and it acts as a generator to send voltage backwards? Yea that definitely maybe an issue. No idea how to work around that yet or what happens once that current hits the booster circuit / batteries. Maybe I could direct it into a super-capacitor bank or discharge it or something its possible the batteries have protection they have a circuit on them

It seems (please correct me if I'm wrong) that LTC3780 can handle all 4 batteries in parallel since they discharge at 10 amps. The problem is that it could only modify the voltage in a limited range. I'd need to buy multiple converters then hook batteries to them individually depending what output I need.

Ideally I need a 10 amp dc-dc converter that goes from 12v-120v - what do you think of this one? https://www.amazon.ca/Regulator-DROK-Numerical-Converter-Adjustable/dp/B08G4S8QQ8/

Parameters
Input voltage: DC 8V-60V
Input current: 0-15A
Output voltage: DC 10V-120V
Output current: 0-15A
Output ways : 1
Conversion efficiency: 85%
Working frequency: 150KHz
Short circuit protection: 20A fuse
Operating temperature :﹣40℃~+85℃

[ledtester]

...
Ideally I need a 10 amp dc-dc converter that goes from 12v-120v - what do you think of this one? https://www.amazon.ca/Regulator-DROK-Numerical-Converter-Adjustable/dp/B08G4S8QQ8/

Parameters
Input voltage: DC 8V-60V
Input current: 0-15A
Output voltage: DC 10V-120V
Output current: 0-15A
Output ways : 1
Conversion efficiency: 85%
Working frequency: 150KHz
Short circuit protection: 20A fuse
Operating temperature :﹣40℃~+85℃

I'd watch this video first:

[electromateria]

^ Thanks for that information! Very much appreciated 

So are most of the booster circuits a scam or just that particular one?

This guy seems happy with the circuit (drok brand), it's very similar to the aliexpress circuits but costs a bit more:



I'm not sure if it's just the knockoffs which are a scam or if all these circuits fail to push amps. Most of these testing video are charging batteries at low amp output..

I guess it might make sense to just run the batteries at their output voltage (20 or 60v) and avoid the converter.. even if that means slightly under or overvolting a motor?

What do you guys think about using an MPPT Solar charge controller to modify the output voltage? https://www.ebay.ca/itm/265259797856

[ledtester]

Once you've been around the aliexpress/ebay/amazon scene for a while you begin to realize the following...

- "DROK" is just a reseller - they don't manufacture their products
- any of these modules that you find on amazon you pretty much can also find on aliexpress/ebay (and they'll generally be priced cheaper)
- most power supply modules sold on aliexpress/ebay/amazon don't meet their stated specifications; that doesn't mean they are totally worthless, it just means you can't rely on what sellers say about them
- case in point: there are a lot of "LM2596" buck converter modules available on these sites but it's been proven they don't use real LM2596 chips

One notable exception to this are the products from Riden (aka Ruideng).  Their power supply modules perform well and are very popular. There's a ongoing thread on the RD60xx series of buck converters here:

https://www.eevblog.com/forum/testgear/ruideng-riden-rd6006-dc-power-supply/

[wizard69]

Yeah definitely considered it but I don't want to spend too much money on batteries. Those 4 dewalt batteries are already $700 CAD and I need them for work. I don't really want a custom built battery pack for every project I make. Say I have an electric scooter on 32v, then a very small electric vehicle on 120v, then a custom made tool that runs off 40v.. it seems I should try to get the battery packs to be as variable as possible to run everything. They already are easy to charge, come neatly packaged, have built in circuit for either 20v/60v.

A DIY battery should be cheaper than a DeWalt battery.   That is if Tesla doesn't corner the entire lithium battery market next year.   

My biggest concern would be using tools and batteries with which my bread is made.   If you blow one up you could go hungry, hopefully in a metaphoric way.

You mean if the batteries are powering a motor and it acts as a generator to send voltage backwards? Yea that definitely maybe an issue. No idea how to work around that yet or what happens once that current hits the booster circuit / batteries. Maybe I could direct it into a super-capacitor bank or discharge it or something its possible the batteries have protection they have a circuit on them

yes exactly!   I'm almost certain that DeWalt has some protection in their batteries but that would be relative to what a hand tool could develop.    You are talking about vehicles of some sort which could potentially generate for long periods of time.    I'm not sure I'd want to expose my work batteries to this, simply due to not understanding what the pack can do with that excess voltage.

Beyond all of that a vehicle controller should be more sophisticated vs a batter tool controller.   Regenerative braking would be ideal but electronic braking for sure.  I just look at control for a vehicle as being more advanced and should have some integration with the pack protection and charging circuits.   Beyond all of that there are a lot of controls out there right now for electric bicycle conversions that might be more suitable out of the box for vehicle control.

It seems (please correct me if I'm wrong) that LTC3780 can handle all 4 batteries in parallel since they discharge at 10 amps. The problem is that it could only modify the voltage in a limited range. I'd need to buy multiple converters then hook batteries to them individually depending what output I need.

I'm not sure where the LTC3780 came from but it has been my impression that DeWalt is getting the different voltage outputs by switching the series/parallel configuration of the batteries.   If you want variable voltage for motor control wouldn't it make sense to build with motor control hardware?   If we are talking DC motors this could be a simple H-bridge type control.

Ideally I need a 10 amp dc-dc converter that goes from 12v-120v - what do you think of this one? https://www.amazon.ca/Regulator-DROK-Numerical-Converter-Adjustable/dp/B08G4S8QQ8/

Parameters
Input voltage: DC 8V-60V
Input current: 0-15A
Output voltage: DC 10V-120V
Output current: 0-15A
Output ways : 1
Conversion efficiency: 85%
Working frequency: 150KHz
Short circuit protection: 20A fuse
Operating temperature :﹣40℃~+85℃

I seem to be off the rails here because I don't see any rational need for a DC to DC converter to change bus voltage.   Again if the goal is to drive a vehicle, the batteries should be at the nominal bus voltage you want to design around.   Using a boost converter makes no sense at all in my mind.

This is why I come back to the idea that you really want to design your own battery solution or buy one at the voltage you want to run at.   There are more options than ever for the DIYer.  It is probably better to pick up one of the pre engineered battery solutions simply to avoid the hazards of a poorly designed lithium pack.   It seems like every hobby niche has its own battery solution these days, model trains for instance have just about every voltage up to 28 VDC if I remember right.   I'm just not convinced that expensive DeWalt batteries are the best nor the cheapest avenue here.