# cordless chargers and inverters



## guest (Feb 21, 2009)

Modified sine wave inverters do not get along with ANY charger so you need to get a true sinewave inverter. Problems range from as little as the charger won't work all the way to burnouts of charger and/or inverter.

True sinewave inverters aren't that expensive anymore.


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## socalelect (Nov 14, 2011)

mxslick said:


> Modified sine wave inverters do not get along with ANY charger so you need to get a true sinewave inverter. Problems range from as little as the charger won't work all the way to burnouts of charger and/or inverter.
> 
> True sinewave inverters aren't that expensive anymore.


Im kind of ******** in the inverter sense. How does it burn them out?


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## MechanicalDVR (Dec 29, 2007)

I had a real cheap inverter that my wife bought at Bed Bath Beyond for like $7 that I had in my van for charging my 12v Bosch stuff and then my M12 stuff. It worked just fine, if anything it charged faster than in a normal 120v outlet. When I switched vans to one that had a larger Black & Decker 4 outlet inverter with built in fuse and reset button (not sure of model #) installed on the dash sometimes the DeWalt charger would give the bad battery indicator flash but on the second try it would charge the battery.


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## guest (Feb 21, 2009)

socalelect said:


> Im kind of ******** in the inverter sense. How does it burn them out?


It has something to do with the stepped nature of the modified wave, it basically steps a bunch of DC pulses (at increasing then decreasing voltage values) to mimic a sinewave and the voltage/time constant has a lot of sustained levels (the "DC component") as opposed to a true sinewave's smooth rise and fall of voltage over time. 

Picture a staircase going up and down as opposed to a straight line...

I wish I had my test bench set up, I could capture oscilloscope traces of both to show the difference.


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## BBQ (Nov 16, 2010)

My experiance is that it is a crap shoot, some cheap inverters and chargers get along, some don't.


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## Wireless (Jan 22, 2007)

Makita batteries do not work well with inverters (4 batteries gone rather quickly) Makita does not warranty batteries charged off inverters.


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## socalelect (Nov 14, 2011)

Wireless said:


> Makita batteries do not work well with inverters (4 batteries gone rather quickly) Makita does not warranty batteries charged off inverters.


How do they know there inverter charged


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## guest (Feb 21, 2009)

socalelect said:


> How do they know there inverter charged


Good question...I can't see how either unless the inverter charging process somehow causes "special" internal damage to the battery...:detective:


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## Semi-Ret Electrician (Nov 10, 2011)

I don't have any problem w/ MSW on Black & Decker or Dewalt or any other cheap chargers, but it will fry a Milwaukee.

I believe Milwaukee even warns about it in the manual. They have a digital charger that doesn't like the weird MSW.


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## Shockdoc (Mar 4, 2010)

I have a 2500 watt old school, works fine with ALL my chargers, Dewalt, Makita and Miliwauki . Been using it for 10 years now w/o failure.


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## retiredsparktech (Mar 8, 2011)

Semi-Ret Electrician said:


> I don't have any problem w/ MSW on Black & Decker or Dewalt or any other cheap chargers, but it will fry a Milwaukee.
> 
> I believe Milwaukee even warns about it in the manual. They have a digital charger that doesn't like the weird MSW.


The Milwaukee chargers use a capacitive reactance type of power supply instead of a transformer. IIRC, it's rated to be used on a pure sine wave supply. The other makes possibly use the old type power transformer or a switching type power supply. The switching supplies can even be used on 120 volt DC sources, because of the nature of their design.


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## Vintage Sounds (Oct 23, 2009)

I wouldn't chance it. I've seen a lot of fried chargers that died after being run on an MSW inverter, and not just Milwaukee either. Ridgid, Makita, Ryobi...maybe others, but definitely firsthand saw those three above. Even if it survives how do you know you didn't shorten the life?

When I was about 16 I took a renewable energy course at a local conservation area, and the instructor was discussing inverters. He said that back in the day all the old timer telecom techs who worked for Bell Canada rolled with a company-provided 50 watt _square_ _wave_ inverter in their trucks. Then, he brought one out to show us...it looked like not much more than a couple of TO-3 power transistors stuck on a generic heatsink. I wonder how their tools liked that.


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## Sparky J (May 17, 2011)

I believe it's like us and the storms we had last week, generator regular powers everything but sensitive electronics don't like it. Generator with inverter or power conditioner that provides "clean power" (low THD) that doesn't burn up electronics costs more but s better IMO.


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## Shockdoc (Mar 4, 2010)

I only fried a charger once off a portable generator. The on board truck inverter has never let me down and has kept freshly charged batteries ready for my arrival to a job.


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## The Motts (Sep 23, 2009)

Makita makes an in-vehicle charger for their Lithium ion batteries:










Milwaukee also makes one for the M12 batteries:


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