Regulator Designs? 40v Drop 18v And At Least 15 Amps


Hello All, I am thinking this may be a custom build but I will poke around for help. I need to drop the 40 volts from the main drive batteries to usable voltage for the Sabertooth 2x12a motor controller and also the EZB itself of course. Since these run power to the drive motors I need at least 15 amps of current and I would like to have a buffer up to 20 for the EZB V4, and other smaller electronics.

The main batteries are Lipo 40v

The drive motors are 18v

Then there is EZB v4

Any help is appreciated. So far I have come up with paralleling several low dropout regulators , maybe 15 or 20 together sharing a common load.


How about something like this

You will also need the programmer to set it up:


Never drop for motors. Provide the proper source current for motor. Only drop for solid state.

Why do you need 40v batteries?


Sweet that's a good idea. I knew the 10 amp ones were common ,but I did not know they had one with an output that high. Realistically I would like to have an 18v but perhaps 12 volt would work fine.

So they output 9 amps if are fed a 40v input based on that output chart. So if that is the case I would need two in parallel with diodes to control forward voltage right?

Do you think the 18v drill motors would still do ok at 12 volts? I am using hammer drill motors that have 600 oz in with 18v. I imagine it would still output at lease half of the 600 at 12 volts.


OK looks like we replied at the same time. Well the trimmer and main motor on the mower are 40v as well as the 5 lipo batteries I have to power it from ryobi. I was trying to run the 40v for the main motors and then drop it for the drill motors and of course I need a drop for control electronics too.


Do you think I should just have a couple 18 volt batteries on board and have two charging circuits. One 40 volt supply and one 18 volt supply? Then I can drop from the 18v for things like the ezb?


Why do you have to use 40v source? I don't advise dropping voltage to share with motors and solid state. The current will not be evenly distributed amongst the two. Also a high amount of heat will be generated. Can you not use a few 18v batteries in parallel to increase the amperage?

Using a regulator for motors is not a good idea. Check my response in this thread


Understood, I greatly appreciate the input. I will do a mixed battery voltage setup them. 18v for the drive motors and 40v for the big motors.

The electric mower I am using as the donor chassis for the robot mower runs on 40 volts DC as well as the filament trimmer heads I have. When I bought the mower I inherited 4 x 40v 2.4ah batteries and my brother bought me a new 40v 5 ah battery as well. I wouldn't want to run the drill motors on 40 volts as that might create excess heat. Anyways hopefully that explains in short.


I think the power supply combo you and DJ have come up with is a good solid one. If you want to buck the voltage down from the 18v batteries for the EZB and other devices that will accept anywhere from 4.8 to 9v then I'd suggest the Castle Creations CC Bec 10A 6S Switching Regulator. Here's the specs. The last line shows the programmer you need to set the voltage:

1.2" (30mm) x .6" (15mm) x .4" (10mm) , Weight: .4oz (11g)
Input voltage: 5V to 25.2V (2S to 6S LiPo)
Current output: 12 volts input = 7 amps continuous, 10 amp peak
Current output: 24 volts input = 5 amps* continuous, 7 amp peak
Selectable Output: 4.8 - 9.0V via the Castle Link (sold separately), Default voltage is 5.1V

I use two of these on each of my B9 arms to adjust voltage from 12v down to 7 and 6 volts for servos. Their small and pricey but really stand up and do the job. There are three wires for output. I just use the red and balck for voltage and snip off the third.

Here's an amazon link:
10 amp CC Bec

Here's the Castle Link: