Can I modify cordless trimmer to get more power?


Old 10-14-19, 10:43 PM
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Can I modify cordless trimmer to get more power?

I want to increase the power (speed and torque if possible) of my 20 volt black and decker weed eater. I have four batteries for it and wondered if I wired two of them together if that would help or would I need to do something else with the motor? Iím fine if this shortens the life of the trimmer or batteries. Iíd like to make it have more power and Iíll buy a new one once this one doesnít work. It does ok so even if I got just a little bit more power that would help out a lot. Thanks!
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Old 10-15-19, 03:47 AM
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A 20 vdc motor should only be operated from a 20 vdc source. You could tie two batteries in parallel to maintain 20 vdc but now the trimmer is no longer portable unless you find a way to attach the second battery. I would first try sharpening the trimmer. Do you lubricate the cutting blades while in use? If that doesn't work, take a sample of the material you are trying to cut to a power equipment dealer and have them recommend a tool. Good luck.
Old 10-15-19, 04:40 AM
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If you want more power... buy a trimmer with more power.

Yes, you could increase it's power but it would be more work than your trimmer is worth. Doubling the voltage by running two packs in series is way too much and would quickly let out the magic smoke. If you really wanted a project you could build your own battery packs and increase the voltage slightly. Lithium batteries are the best as they can dump huge amounts of power without their voltage sagging but you are in for a lot of work making the packs and making them convenient to use.
Old 10-15-19, 04:53 AM
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As far as I know there is nothing you can do to increase speed and torque.

Did this thin ever have speed and torque that was satisfactory for you.

Paralleling batteries will give you a longer run time at it's max power but not increase the speed and torque.

You have 4 batteries so either you have a large area to weed eat or they are dying quickly.

If dying quickly is the problem then perhaps new batteries are in order.
B&D usually use nicads which are not great.
Take a look on Amazon etc. for compatible NI-MH batteries.
Used to take 2 batteries to do my place then I found a compatible 3Ah NI-MH battery on Amazon.
I bought 2 as I thought I would need 2 but one does my yard with plenty of zip left.
Old 10-15-19, 06:35 AM
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This is the great divide with battery tools, if you have small compact yard battery tools might work, if your yard is big and expansive then gas is best.

You always have to buy the tool to fit the need!
joecaption voted this post useful.
Old 10-30-19, 02:14 PM
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Thanks. I bought the trimmer at our previous house and now itís just a little bit under powered. I have four batteries because I used all black and decker tools at first. Iíve moved on from them as they have died. They held up well and the batteries all still measure around 17 volts quite a few years later. Iíll probably keep an eye out for a more powerful battery trimmer.
Old 10-31-19, 12:04 PM
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Slightly OT since it's not directly relevant to the OP's problem but I have replaced the NiCad batteries in my older Ryobi power tools with (newer) Li-Ions (that are backwards-compatible). My sense is that those tools don't just have better battery life but that they also have better power, particularly the very torque-dependent tools like the circular and reciprocating saws.

None of the old NiCads will hold enough of a charge to test them head-to-head now but even when the NiCads were fresh-out-of-the-box new, I could never bear down on them like an A/C-powered tool. Either the blade would bog down or the battery would discharge alarmingly quickly, so the charge life would be much better if I moderated how much pressure I was using. And they never delivered power even for more than a few seconds like an A/C tool. But the Li-Ions ask no quarter. I use them exactly like they were A/C-powered, and to my way of thinking they perform like they were A/C-powered. The harder I push, the faster they cut.

The new batteries are essentially the same size as the old but they're twice the capacity, 3ah vs 1.5 or 1.6ah. I don't know if that has any effect on it but I used to think of the battery-powered Ryobis as 'wimpy' tools that didn't have enough duration enough even for a coupe of high-speed trips through a 2x4. So unless it was something really small-scale, my first option always used to be the plug-in A/C tool. Now unless it's a job I'm likely to spend more than a couple of hours at, the Li-Ion tools are my first choice. Because they preform as capably as A/C-powered but there's no cord to get in the way.

I've got no means to determine empirically but my subjective observation is that they're more powerful. I'm thinking maybe the tools had more power engineered into them than the old NiCad batteries could drive, even when new. And the new Li-Ion batteries get more power out of them because there's greater instantaneous delivery.

Just a guess, and probably not relevant to the OP.
Old 10-31-19, 12:22 PM
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Just make sure you charge lithium batteries properly. They are rather fussy compared to older chemistries and have a bad habit of catching fire if charged incorrectly.
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