Building Cordless Electric Backpack Leaf Blower

nitid

Joined Dec 17, 2012
1
I am working out the logistics for turning a corded leaf blower into a battery powered backpack blower to use at work with a hopper for spreading sand. We have gas powered ones, but the CO fumes are dangerous inside. As well, the high power blows the sand out too fine, I am looking for a swath of sand so as to seed the coating it covers to rejection quickly. The method we use now is shoveling it out of a wheel barrow.

So what I have uncovered thus far, is that perhaps I have a chance to take a 12 amp 120 volt blower and power it with one or two 12 v batteries. I am hitting a wall with the calculations involved. I found a nifty online DC to AC calculator that tells me what amperage I will need with what battery voltage rating to get the desired AC through an inverter. (http://www.batterystuff.com/kb/tools/ac-to-dc-amperage-conversion-run-through-an-inverter.html)

So I here is my thinking as I have rudimentary knowledge cuz I took a low voltage tech program recently:

Hook a couple or few 12 v batteries in parallel. invert power to 220 volts AC. apply step-down transformer to get 120 v and more amperage. perhaps i do not need more than one battery. Mayhaps a 24 volt. It all depends on the calculations; I have no idea where to start to find out what amperages I will get and need. plus - can I get transformers with any amount of coils ? I am assuming the amount of coils effect amperage? Or are there standard sizes to work with?

My main worry is after all is said and done, the damn thing will only run for ten minutes. I was looking at lithium Ion deep cycle marine batteries. (http://www.lithiumion-batteries.com/12VoltLithiumBattery.php) I figure I could possibly get away with 6 amps at 120v to run an electric blower at it's low setting. I need it to run for 3 - 4 hours and would not mind switching the battery half way through.

Any thoughts?

wayneh

Joined Sep 9, 2010
17,153
12A at 120V is 1,440 watts, or roughly 2HP. That's going to take some serious battery! Basically, to get the same power, you need 120A at 12V, plus a bit more to cover the inevitable losses in conversion. That's comparable to the cranking current you need to start your car. 3-4 hours of cranking is a LOT.

BTW, there's no gain in going to 220V first - that just adds another conversion step.

#12

Joined Nov 30, 2010
18,222
How about closing off part of the air intake hole? Giving the fan less air to work with will cause it to use less power and blow with less velocity.

shortbus

Joined Sep 30, 2009
8,696
How about closing off part of the air intake hole? Giving the fan less air to work with will cause it to use less power and blow with less velocity.
And possibly over-speeding the motor, throwing off the rotor windings or commutator strips.

John P

Joined Oct 14, 2008
1,899
I'm having a hard time imagining what happens when you "seed the coating it covers to rejection quickly".

Is the trailing cable really a huge problem with an AC powered blower? It seems like way too much power to come from a portable battery.

mcgyvr

Joined Oct 15, 2009
5,394
yep..just use a corded AC blower and move on.