# DIY Electric BirchMeier Backpack Sprayer



## AZChemist (Nov 7, 2018)

After years of spraying hundreds of gallons of insecticides and herbicides I'm throwing in the towel. In the summers months of AZ I religiously spray insecticides every 2 weeks. Alternating from the block wall perimeter to the house. 
The 2 main work horses were a echo and Birchmeier backpack sprayer. The birchmeier when it works is awesome! Not the most comfortable unit to wear, but the wand is great and pumped smooth.

After searching around for a while there were a few electric backpacks that peaked my interest but felt I could build one that catered my needs better for under $40.

I started off by buying a $4 1/2" female thread to 3/8 pex barb fitting just to find out 3/8 pex is not actually 3/8" so that idea was a wash. The swivel angle fitting I wanted is the same one on my sprayer mate but ended up being $20 shipped. Unfortunately the oem pump housing was collateral damage and I just removed the birchmeier fitting that was injection molded in. All that is left to do now is solder in a 3/8 barb fitting and then the pump can be plumbed in.

There is plenty of room on the bottom side of the sprayer for the pump or battery. Which I am unsure of at this point in time. I will be using Makita 18V batteries with wired in voltage reducer since I have quite the collection already. If I don't get around to that a 10ah SLA is a easy runner up.

The pump is ~$20 on Amazon, 100psi, and fully adjustable. Additionally shoulder pads, gauge, and a back pad will be installed as well.

If this one works out my diaphragm echo will follow.


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## Gilley11 (Nov 3, 2019)

Looking forward to see this build progress along.


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## Francoix (May 16, 2019)

Following


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## AZChemist (Nov 7, 2018)

Thanks to @Sunday I now have a elbow to attach the pump. He turned down the 1/4" npt x 3/8 barb fitting to a press fit and I soldered it in place.


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## AZChemist (Nov 7, 2018)

Before fabbing the bottom tray I sprayed 9 gallons this weekend. The purpose was to see if this pack was even going to function properly and it did not disappoint. With the pressure on the lowest setting of 40 psi it was plenty of pressure. The wand has a purple ceramic teejet (110025). The 8ah battery had plenty of power remaining as well. 
All the stainless is 316 and unfortunately didn't have the right rod but still trucked through it. The donor was some trays that went to a laboratory dishwasher for glassware.


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## Ware (Jan 28, 2017)

Nice work!


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## Gilley11 (Nov 3, 2019)

Great work. I'm thinking about turning an older 4gal pump sprayer that I have into a push unit, this writeup is just what I needed for motivation.


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## Gilley11 (Nov 3, 2019)

What are you using to regulate the pressure?


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## AZChemist (Nov 7, 2018)

The adjustable pump is on demand and only runs when the wand trigger is pulled.


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## AZChemist (Nov 7, 2018)

I will add a switch and back pad this weekend. Very impressed with how well the pump works. It is very responsive with zero pressure lag. While the Pump is just zip tied to the stainless I honestly don't think it needs anything more. The 8aH battery has now sprayed 15 gallons and shows no signs of getting low.
The 316 stainless I probally still weighs less than the factory pump setup. The most weight comes from the massive battery which I am working on replacing with a makita 18v. 
I'm in love! Wish I had done this sooner.


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