If you fit a 40V battery to a 20V tool, you will likely destroy one or both, except they ought to have different connections to prevent this!
www.checkfire.co.uk
The mAh rating indicates the amount of charge the battery can store and deliver, ie typically related to how long it will give the necessary voltage before it needs recharging.
Thanks let me ponder what you have said. It would seem that there isn't a way of getting more oomph from the existing tool / hedge trimmer, under-powered as it is. It seems that it is all a matter of the voltage - and I can't experiment without risking overloading the tool. What I find confusing is where in the description of the replacement batter(ies) it implies dual 20 / 40 V.If you fit a 40V battery to a 20V tool, you will likely destroy one or both, except they ought to have different connections to prevent this!
Lithium batteries and the like store a lot of energy, are potentially dangerous.
They can have safety measures incorporated in them such as temperature sensing and sometimes digital communication between battery and tool. Different manufacturers can adopt different approaches, so circuits can vary, for which reason different brands are typically not interchangeable.
I urge you not to experiment by trying "incorrect" batteries in a product!
Lithium-Ion Battery Dangers: The Stats | Checkfire Ltd.
How dangerous are lithium-ion batteries? Here, we dive into the statistics and risks associated with lithium-ion batteries.
The mAh rating indicates the amount of charge the battery can store and deliver, ie typically related to how long it will give the necessary voltage before it needs recharging.
If you need more 'oomph' to do the job - drilling or cutting - you really need all of:
A more powerful motor in the tool, which may mean higher voltage
The higher voltage battery to operate the more powerful tool, and
The higher mAh rating for the battery that comes with that.
If the manufacturer is offering a 40V battery for your specific tool as a plug in alternative to the 20V, that's fine.
Just to pick up on this point, it's really a matter of current.
I found a video where 'Big Clive' reverse engineers the Ferrex 20/40V battery, and it's clear that the battery provides not just a simple electrical source, but that there's digital communication between the tool and battery (and between charger and battery when on charge).
The 20/40 battery has twice the number of cells in it compared with the 20V version, it's bigger, and will weigh almost twice as much!
I don't think you can.
bigclivedotcom on YouTube did a tear down of a lot of the Aldi Ferrex stuff. The 20/40v battery is two 20v batteries in one pack. The 20v tool when plugged into the 20/40v dual battery will use both 20v batteries in Parallel thus doubling the Ah available. This just means the tool will run effectively twice as long.Just to pick up on this point, it's really a matter of current.
Depending on the design of the motor, its power is related to the strength of permanent magnets designed into the motor, the winding(s) - (thickness of wire and number of turns etc), how any electronics driving it have been designed etc, and ultimately the amount of current you can put through the system before it starts overheating and destroying itself.
The only way you have to increase motor power "from the outside" is to increase the voltage, which seems what you are motivated to do. But it risks burning out the motor, and anything else in the tool that uses that voltage.
If the motor were to short circuit, the amount of energy in the lithium battery, liberated all at once, can cause a fire or explosion. That's my main concern - your safety!
If you want a more powerful hedge cutter, you need one with a more powerful motor.
Edit - just been looking at the Ferrex 20/40V battery. You can fit it to your hedge trimmer, but the trimmer will still run from the 20V connection, with the same result as at present. The battery may last a bit longer than the ordinary 20V one though.
You beat me to it!
Maybe consider this article on choosing a battery powered Hedge trimmer.
