48v Ebike battery powering cordless 40v chainsaw or trimmer?

Any thoughts on powering cordless chainsaw/trimmer with a 48v ebike battery (13s lithium) packs? Unfortunately it looks virtually nobody makes a tools that run on a 48v system with the exception of Snapper who has a wimpy looking trimmer. I'm thinking of trying a Greenworks 40v tool, probably the trimmer since it's cheaper than a chainsaw for experimentation. I would think that the slightly higher voltage would be fine for the motor but the controller may not allow it depending on programming. Then there's the question if the tool and battery have to talk to each other like the Echo system apparently does. Anyone have any thoughts before I invest? I've skimmed through the thread where people talk about challenges with running "58v" Echo tools with ebike batteries but can't find anything about using Greenworks tools.

Thanks in advance for any advice!

Jesse

https://www.amazon.com/Greenworks-Cordless-Attachment-Included-2100202/dp/B00IPA15DS/ref=sr_1_3?crid=1G2TW1YYMLBLC&keywords=greenworks+40v+trimmer&qid=1569058676&smid=ATVPDKIKX0DER&sprefix=greenworks+40v+trimmer%2Caps%2C221&sr=8-3

Why not use the tools with the battery they're designed to use?

john61ct said:

Why not use the tools with the battery they're designed to use?

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They come with relatively small batteries. I can buy the tool without a stock battery at a significant savings and then I'm hoping to use my high capacity ebike batteries with them.

Well then, I guess it's a cheap science experiment even if the tool gets fried.

Note, just because one tool is OK, doesn't mean another will be.

Really best to keep to the spec'd voltage, like a switch in your pack to downgrade from 13S to 11S, or using a DCDC buck converter.

48 vs 40V is not that small a difference.

If you go for it, we look forward to your posting the results.

I bought a 40v greenworks 2.5 ah battery on clearance at walmart for $40. I now have 3 batteries .

Hi, I've hacked a number of battery powered tools. A lot of older ones which used nicad/nimh. I've gone over voltage on a number tools without problem. A DeWalt screwdriver originally used 7.2V. Never ran better than now with 12V Lithium. I think my vacuum sweeper was like 16V nicad, now 19.2V Lithium. Little carpet cleaner; 4.8V nicad to 6.6V LiFePO4. Many others. Most, if not all, are stupid tools. Newer tools may "talk with battery" and not allow hack. If you can, try it out on an adjustable power supply first.

Good luck,

major

john61ct said:

48 vs 40V is not that small a difference.

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except that so-called "40V tools" are really 36V. Ditto for so-called 80V tools -- they are 72V. And so on.

MJSfoto1956 said:

john61ct said:

48 vs 40V is not that small a difference.

Click to expand...

except that so-called "40V tools" are really 36V. Ditto for so-called 80V tools -- they are 72V. And so on.

Click to expand...

Yes, exactly, reinforces my statement.

But if the tool you're testing is that cheap, who cares if it burns out after 400 hours instead of lasting 1000?

Then again it may fry the first try. . .

I usually look for good bundle deals on sale, figure I'm paying for the excellent battery packs, and the tool ends up being almost free.

i would not put higher voltage packs on these things, the motor -might- handle it for a while but the trigger will not survive that for long. tried this with a matika.

and modern/new home player tools dont last 400h even when babied.

i made a couple belt-packs and even a small backpack for dewalt, the backpack is 50Ah so it has some proper endurance. it only needs a resistor in the handle to trick the dewalt electronics to thinking there is a battery connected and it will run with whatever is connected so you only need a XT90 or something more durable to hook it up. if you put the cable out the handle in the right place you can still keep the battery connector and use it as intended.

main advantage is that voltage sag is almost gone and tools have a lot more oomph.

Read the label on the tool, and use a battery of the same voltage on the label.

If it states 12V for a drill, you'd be safe to probably use Lithium at a full stage charge of 13.20V, or even 14V or whatever else you have. You state a chainsaw or trimmer, whatever the voltage states, get close to it. So as mentioned, say the marketing sticker states 40V, you can go ahead and use 36V nominal which is 42V charged 10S battery pack with no problems. Could probably even get away with 11S or 46.20V "probably" but who knows.

Otherwise you need a step down or a step up converter. Using a 48V will be needing a step down converter. More shithanging off the tool though. Heck you could use a 12V on a 48V with a step up converter, but your efficacy/efficiency wouldnt be that great.

Alright, got myself a greenworks 40v "digipro" trimmer for $100 USD off ebay. Model number 2100202. Says on the label to use only with battery 29472. But hey, following labels is for boring people...

I read up on this thread https://endless-sphere.com/forums/viewtopic.php?f=14&t=55790&start=75 which has some info about greenworks batteries, mostly older generation ones I think, and some descriptions of battery internals which seem to include a somewhat complex circuit board as well as a BMS and temp sensor. This thread is mostly focused on people re purposing the greenworks batteries to run ebikes. I'm hoping to do the opposite...

I took my aliexpress 13s6p 48v (46.6v at the time according to my cycleanalyst) and hooked it up to the outermost of the 4 connectors on the trimmer labeled + and -. I pushed the power on switch on the trimmer and to my surprise it powered up and the power indicator light came on. Unfortunately about 5 seconds later a red light came on and it started beeping. Apparently there's an Elon sensor that detects open source components In the first 5 seconds after power up I can actually run the motor at low or high power but it always shuts off and starts beeping at 5 seconds. More success than I expected but not quite what I want yet. I even read the paper manual for info but it mentions nothing about red light and beeping.

I plan to take the trimmer apart next and look at internal components. Basically to get it to run I think I'll need to imitate a Greenworks battery, or maybe I can bypass an internal computer and run battery voltage directly to the BLDC motor controller to get it to run.

So my questions for the forum are: does anyone know what the tool is looking for to run... battery temp sensor signal?... or special resister voltage that tells the tool that the oem battery is attached? I don't have a battery to play with yet but if I do get one and set up a harness that allows me to test what signals/voltages are going back and forth between all 4 of the terminals, what device is the cheapest to try to record and make sense of those signals. I don't really understand CANBUS and hopefully I don't have to learn for this project but I do want to make this configuration work. If I get it apart I'll try to post pictures and maybe someone can help me identify what I might be able to bypass on the internal side to get rid of the anti hacker fault.

Thanks in advance for any help!

the dewalt "protection" can be "fixed" with a simple resistor to fake the battery temp sensor.

measure the T and negative resistance port of a working battery and grab a regular resistor and put that in the matching side of the tool.

i just put a resistor in the handle of my tools so it always works no matter the power source.

I just found this thread which has the most info I've seen yet.

https://endless-sphere.com/forums/viewtopic.php?f=1&t=79384

Unfortunately it appears veloman and metallover haven't been active for a while. Looks like the greenworks tools actually require a communication signal from the battery pack in order to operate without tripping an error fault. As far as I can tell the to methods described in this thread for tricking the tool into running with a non-greenworks battery are using an Arduino to generate a fake communication signal as metallover apparently did and using BMS/controller from an actual greenworks battery as veloman did.

Also interesting to see a 3rd party battery from a company called Powerup widely available that is supposed to be compatible with Greenworks tools.

I recently took my new trimmer apart, I'm having trouble getting the pics onto imgur but hopefully can share soon. It's pretty simple inside: motor, thoroughly poted controller, battery voltace runs through the mechanical trigger switch, controller connects to power on/off/power-level switch. On the inside of the tool the 2 outside battery terminals are + and -. One middle terminal isn't connected to anything and the other (apparently the communication line) is a thin black wire running to the controller baord.

I have done this with the 80V tools - https://endless-sphere.com/forums/viewtopic.php?f=1&t=79384&p=1508164#p1508164

I used an oscilloscope to measure the battery signal then replicated it with a $5 Arduino.

I kind of doubt this code will work directly with the 40V tools, but there is a chance. The protocol/algorithm is probably just a little different.

If someone owns or has access to an oscilloscope, and has a Greenworks tool all torn apart, they should be able to figure out the pulses required to operate the tool. Then it is just plugging those into the Arduino code I posted!

Come to think of it, you should be able to download the Saleae logic software and use this logic analyzer to find the signals. This would probably work even better than the oscilloscope. I have used this setup before to measure signals.
https://www.amazon.com/HiLetgo-Analyzer-Ferrite-Channel-Arduino/dp/B077LSG5P2/ref=sr_1_3?dchild=1&keywords=logic+analyzer&psc=1&qid=1572875093&sr=8-3
https://www.saleae.com/downloads/

if you hack a cheap rigol scope you can decode serial and all that good stuff. so a scoope would be fine.

Metallover said:

I have done this with the 80V tools - https://endless-sphere.com/forums/viewtopic.php?f=1&t=79384&p=1508164#p1508164

I used an oscilloscope to measure the battery signal then replicated it with a $5 Arduino.

I kind of doubt this code will work directly with the 40V tools, but there is a chance. The protocol/algorithm is probably just a little different.

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Hi Metallover - did you figure out or know what the 4th connector is on the battery? +/-/Omega (that you've documented) and the 4th?

Thanks