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cordless tool alternatives
Simon - 25/4/22 at 06:57 PM

ok, just thinking aloud.....

...but if I wanted to use my 300w/240v strimmer with a decent 12v battery (say 80amps) and an inverter, would I get hours and hours of useage? I don't give two hoots about carrying a battery etc (can put on a trolley).

My calcs are 300/240 = 1.25amps so theoretically 64 hours! To be honest, I'd be happy with 7 or 8 hours.

Cheers

gremlin1234 - 25/4/22 at 07:59 PM

300W for 8hours is 2.4KWh
a 12V battery would need a 200Ah rating. (ignoring other losses etc)

daviep - 26/4/22 at 08:07 AM

quote:
Originally posted by Simon
ok, just thinking aloud.....

...but if I wanted to use my 300w/240v strimmer with a decent 12v battery (say 80amps) and an inverter, would I get hours and hours of useage? I don't give two hoots about carrying a battery etc (can put on a trolley).

My calcs are 300/240 = 1.25amps so theoretically 64 hours! To be honest, I'd be happy with 7 or 8 hours.

Cheers


Your maths are not quite correct, power, current & voltage are all related. 300w@240v does equal 1.25amp, but 300w@12v equals 25 amps.

So 80Ah battery in theory would last over 3 hours but I would guess the inefficiency of the inverter would mean you wouldn't get near this.

As Gremlin said your battery would need to be 200ah to even theoretically get 8 hours run time.

nick205 - 26/4/22 at 10:49 AM

How much "strimming" exactly have you got to do?

My garden's not big by any means, so nut much strimming. A Ryobi cordless strimmer that came with 2 batteries + charger did the job just fine.

Rather than messing about trying to convert what you've got (I'm all in for make and mend BTW) it may be more cost effective to get a cordless strimmer with 4-5 batteries and a couple of chargers.

The other consideration is cordless strimmer grunt.

If you've got a lot of thick/heavy duty strimming to get done cordless ones will take longer and struggle. My parents have a 2 stroke one called a "weed eater". Granted it's noisey, but it slays the work without even thinking about it.

russbost - 26/4/22 at 12:19 PM

I would also add that any cheap 12V inverters won't do the job, the Chinese ones are advertised with vastly inflated estimates of prowess, I have a supposedly 2kW 12V inverter which was given to me, it's capable of genuinely supplying about 3-400W continuously, but is dreadfully inefficient, it draws around 0.9A when just sitting doing nothing, connected to 12V with no load!

For the sort of money you'd pay for a sufficiently powerful battery & inverter you could easily buy professional quality cordless equipment

gremlin1234 - 26/4/22 at 01:00 PM

if I wanted that much portable power, I would look for a small generator
https://cpc.farnell.com/sip/03920/compact-petrol-generator-750w/dp/SI17878
~£156

and you could probably get away with a smaller one than this

russbost - 26/4/22 at 01:13 PM

quote:
Originally posted by gremlin1234
if I wanted that much portable power, I would look for a small generator
https://cpc.farnell.com/sip/03920/compact-petrol-generator-750w/dp/SI17878
~£156

and you could probably get away with a smaller one than this


But if you're going to buy a genny, you might just as well buy a petrol strimmer, with all the pain with fuel, bioethanol dissolving various bits of it, fouling plugs, non starting etc etc, surely the whole point of electric tools is that they just work & you don't need to "add" anything to make them work - they are also much quieter & not smelly!

nick205 - 26/4/22 at 01:32 PM

quote:
Originally posted by russbost
quote:
Originally posted by gremlin1234
if I wanted that much portable power, I would look for a small generator
https://cpc.farnell.com/sip/03920/compact-petrol-generator-750w/dp/SI17878
~£156

and you could probably get away with a smaller one than this


But if you're going to buy a genny, you might just as well buy a petrol strimmer, with all the pain with fuel, bioethanol dissolving various bits of it, fouling plugs, non starting etc etc, surely the whole point of electric tools is that they just work & you don't need to "add" anything to make them work - they are also much quieter & not smelly!



Cordless tools of this nature are certainly quieter and less smelly. As per my post above (and if you speak to working contractors) they're usually not much cop though and struggle to cope with anything to demanding or long run times.

Neighbour is a gardening contractor domestic and commercial) and has a mixture of cordless and petrol/2 stroke kit. For work that needs doing with minimum fuss he defaults to his petrol/2 stroke kit.

I also go back to the question of how much strimming is it the OP needs to get done?

To be considering 8 hrs run time that's a massive amount of strimming!

Simon - 26/4/22 at 07:39 PM

Cheers everyone - it was after Gremlin's comment that I realised my maths was wrong - bizarre as electric cars give the kwh battery capacity and kw power of motors so should have figured that out.

I've started a small grass cutting business for the summer (for those that like gardening but find pushing a lawnmower a bit of a struggle) and only have an electric strimmer. It'll probably be better to buy a petrol strimmer - watching one on fb marketplace for £40!

jjams82 - 4/5/22 at 08:46 AM

If you can I'd advise an older 2 stroke model... While noisier and has all the faff of adding oil to jerry cans etc it's more fun going BRAAAMMMPP BRAAAAAPPP BARRRAAAAAAAAAAARRPPPPPPPP then the MUHHHHHHHHHHH of the modern 4 stroke oh hang on, £40 on FB marketplace - Ignore.

Got the morning yammerings and couldn't help thinking of it as a S2k vs diesel Polo comparison.

As you were.

(ps good luck, finding something that's got some kind of daft head you can't wind cord onto without a physics degree and can get bits for sounds like a fun job for someone else)

[Edited on 4/5/22 by jjams82]

[Edited on 4/5/22 by jjams82]