How about something like this

https://www.amazon.com/gp/aw/d/B002ITEL42/

You will also need the programmer to set it up:

www.amazon.com/gp/aw/d/B000BOG8V0/ Alan

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 https://synthiam.com/Community/Questions/8803

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.

http://www.homedepot.com/p/Ryobi-20-in-40-Volt-Brushless-Lithium-Ion-Cordless-Electric-Lawn-Mower-with-5-0-Ah-Battery-RY40180/206481611

this is the donor

40v Lipo brushless mower by ryobi I scored for $149

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: Link