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Thread: MSW inverter and cordless drill battery chargers

  1. #1

    Default MSW inverter and cordless drill battery chargers

    While only partially related to a solar theme, I think there are more electrical gurus here than anyplace else I could think of to pose such a question.

    A while back I had to replace the charger that came with my 19.2 volt Porter Cable cordless drill. I'd left it plugged in constantly, and it quit after 3 months.

    I posted the following question to Porter Cable but never recieved acknowledgement or a response.

    Is it okay to use a MSW inverter to charge PC batteries with a PC charger? I know Dewalt chargers self destruct on a MSW inverter.

    I have no other need of a true sine wave inverter and will not buy one just to run this charger.

    PC no longer makes the charger model which gave up, and I had to buy a different, newer model from them which doesn't weigh nearly as much, and doesn't seem to get as hot while operating. Unfortunatly this replaccement charger cost nearly as much as the drill kit did, and If I destroy this charger, the drill will become a paperweight. No way will I buy PC anything again.

    Thanks

  2. #2
    Join Date
    Mar 2006
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    SF Bay Area (California)
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    Default Re: MSW inverter and cordless drill battery chargers

    Unfortunately, MSQ inverters have the chance of destroying equipment. The newer power supplies and electronics are typically now power factor corrected--and should work much better on MSQ--in general. But without knowing (and experimenting) it is probably still impossible to guess before hand which will work or fail.

    If you have a scope, you can check the current profile for large peaks. Or, possibly a Kill-A-Watt meter and monitor power factor and see if it is near 1 or not (problem is, from what I have read, is that the older Kill-A-Watt meters can die on MSQW inverters (hmmm... such is life).

    In the end, if you are going to need a pure sine wave inverter, you can do worst (from what I have read around here) than purchasing a Exeltech Sine Wave inverter of some sort (still cost 10x the price of the cheap MSQ's though).

    Sorry, not a whole lot of extra information that I can provide...

    -Bill

  3. #3

    Default Re: MSW inverter and cordless drill battery chargers

    I ran a DR2424E MSW inverter when I just started off grid living, yes it fried my first DW bat charger + a couple of mobile phone chargers and every PIR light fitting and whilst it didnt fry my Compaq laptop it never ever shoowed the battery at 100 % . We learned and managed to charge the mobiles and other items only when my Kipor Inverter based (Honda EU copy) suitcase generator was running. A couple of hundred bucks and change could get you the small Morningstar 300w Sinewave inverter and you can expand your product use the choice is yours See http://cgi.ebay.com/Morningstar-Sure...QQcmdZViewItem

    The other cheaper option is a mains drill
    Outback FlexpowerOne FP1-6 , with Mate 3, Solar 2400W 12 x 200wp Isophoton mono Fixed Array, Tracked Single axis 972wp from 6 x 162wp Sharp Poly. Midnite Classic 150 CC. The Battery bank 12 yrs old and counting ! 700ah Exide 24 x 2v Cells, Zepher Power Vent, Midnite PV Combiner and SPD. To fit Lakota Longbow 48v Windturbine. Gesan 4.5kw 1500rpm Deutz Engined Autostart Diesel Generator.

  4. #4

    Default Re: MSW inverter and cordless drill battery chargers

    Do the electronic devices that self destruct on a MSW inverter do so by overheating?

    Or is it a case of instant failure?

    My 4 year old laptop will charge fully and run normally on my coleman 800, but the second the battery reaches 100 percent, the computer starts to brainfart. I never noticed more heat than normal from the ac/dc converter. I do notice that when the battery is charged by a wall outlet, it lasts longer than when charged by the msw. Also when bringing up the battery info capacity page , I notice over time that the full charge capacity falls much faster from the design capacity when recharging with the coleman as opposed to grid power.

    Are Nicad batteries succeptible to sulfating when left fully discharged?

    I don't have a scope, and for all I know the coleman 800 is a square wave rather than a modified sine wave inverter.

  5. #5
    Join Date
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    Default Re: MSW inverter and cordless drill battery chargers

    I will take a shot at your questions...

    One cannot tell for sure when and how any particular device will work or fail... The problem is MSQW inverters have very sharp on and off edges (rounded square wave)... Many small (and sometimes cheap) devices use the fact that utility power is a pure sine wave which have relatively soft leading and trailing edges. (the math turns out that square waves are a sum of a bunch of sine waves, each higher in frequency--I forgot it is something like all of the odd harmonics or something like that). When using inductors and capacitors on the front end of electronic devices (and electric motors)--these front ends behave differently at different frequencies... Capacitors tend to pass more current (and over heat the various devices) and inductors tend to block the higher frequencies.

    Electric induction motors (non-brushed motors) are, more or less, a spinning interior field tied to the 50/60 Hz line frequency (which is, in turn, driving their rotational speed by "dragging" the shaft rotor around with the 60 Hz electric field). When you have higher frequencies, these "rotational" fields are not turning with the shaft speed, but faster--and the only place for that excess energy to go is in heat (so these motors tend to overheat easier).

    Transformers also tend to create "eddy currents" from the higher frequency components and this currents are turned into waste heat (in the transformer).

    So, in the end, it is usually heat that causes some devices to fail when exposed to MSQW inverters. The problem is detecting an overheating condition before significant damage is done. Some items you can hold in your had and feel them get too warm, or you may smell something getting hot, etc...

    Over the years, I have had a few MSQW inverters and nothing has ever failed for me (1970's color TV, drills, electric shaver, some specialized meters that required AC to operate, etc.). And I have never really worried much about it before...

    But with the expense and "fragility" of some of these new electronics (computers and expensive audio gear)--I have avoided using MSQW inverters for anything I really care about (or in non-emergency situations).

    I should someday break down and purchase my own sine wave inverter--right now though, I purchased a backup Honda eu2000i generator as my "backup device" (as opposed to running my car battery in an emergency).

    Regarding NiCads... What kills them is constant overcharging (overheat), or discharging them in series where one (or more) cells discharge below 0 volts DC and actually reverse polarity and charge "backwards" (example, 4 fully charged NiCad cells and one 1/2 charged cell--the half charged cell will go to zero volts and reverse while the other 3 cells continue normal discharging). Storing them at Room Temperature and recharging them once per year is probably fine... Check out this neat Battery Storage FAQ for a one place stop to lookup how to store various chemistry/brands of batteries.

    Sulfate is "Lead Sulfate", so technically, sulfating is a term only for Lead Acid batteries and it is when the normal "fluffy/soft" Lead Sulfate that forms (as a battery is normally discharged) is left for day (or several days) before the battery is recharged back to 100% capacity. Lead Sulfate hardens (changes state?) after a day or few, and does not get changed back to Lead as the battery is charged--slowly reducing the overall capacity of the storage battery (hence the recommendations of not leaving a Lead Acid battery sit for months with less than full charge--or at least >80% charge).

    One other warning if your Lead Acid batteries are exposed to freezing temperatures--a fully charged battery will withstand very low temperatures before freezing (and splitting the battery case). A fully discharged one will freeze very near 32F/0C.

    Some Manufacturers of AGM batteries claim not to be affected by hardening sulfates.

    -Bill

  6. #6

    Default Re: MSW inverter and cordless drill battery chargers

    Thank you BB for the knowledge, and the effort required to type such a detailed response!

    The reasons I ask about the PC battery charger is that soon I will be Boondocking in Baja and will try to complete some woodworking projects in and around my Van.

    Now that I know the most my dc refer will use in a day is 28 amps@ 95 degree plus ambient temps, I actually have an energy surplus, at least on the sunny days.

    I was worried that if I ran my NICads nearly all the way down and didn't recharge them promptly, they would fail prematurely.

    If I absolutely needed to recharge the batteries and didn't feel like driving the 45 minutes to the nearest grid, I'm gonna try it on the MSW. I have one of those laser thermometers and a couple of small 12 volt muffin fans, so if worse comes to worse, I'll try it, ventilate and monitor the charger for too much heat.

    One thing about the PC charger that failed on me while left plugged into grid power, is inside the charger there was a 2 inch brass colored heavy metal cube with 2 wires running to it. I'd opened it up an hour after unplugging it, hoping I could just replace a fuse. This brass cube, after an hour unplugged was still too hot to touch.

    The replacement charger does not have this brass cube 'transformer?' in it. Would this make the new charger more or less succeptable to death from overheating?

    I read something about it being a switched source but that's another thing I'm clueless about.

  7. #7
    Join Date
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    Default Re: MSW inverter and cordless drill battery chargers

    I have no clue what will happen (or not) on a MSQW inverter.

    One problem that you may have is that a fan cannot cool the components enough to prevent failure.

    If you are going to use the MSQW inverter--you might as well try it now at home rather than in Mexico miles from no-where and have something fail.

    -Bill

  8. #8

    Default Re: MSW inverter and cordless drill battery chargers

    On second thought, I think I'm just gonna buy a harborfreight corded drill. It's cheaper than a true sine wave, and I can keep my PC drill's charger healthy. Since Ni cads don't get destroyed by being left discharged for a little while(thanks for that link), I'm not gonna risk destroying the charger when the nearest true sine wave is a 45 minute drive away.

    Thanks again for the knowledge and effort.

  9. #9

    Default Re: MSW inverter and cordless drill battery chargers

    You say that your new cordless charger is a lot lighter than the original model, be warned then as the dewalt chargers are also very light with no standard copper coiled transformer inside if your drill manufacturer has gone the dewalt design route it wont last long, 10/20 hours on MSW
    Outback FlexpowerOne FP1-6 , with Mate 3, Solar 2400W 12 x 200wp Isophoton mono Fixed Array, Tracked Single axis 972wp from 6 x 162wp Sharp Poly. Midnite Classic 150 CC. The Battery bank 12 yrs old and counting ! 700ah Exide 24 x 2v Cells, Zepher Power Vent, Midnite PV Combiner and SPD. To fit Lakota Longbow 48v Windturbine. Gesan 4.5kw 1500rpm Deutz Engined Autostart Diesel Generator.

  10. #10

    Default Re: MSW inverter and cordless drill battery chargers

    Today my uncle stopped by, and I told him of the topics of this thread. Long story short he gave me a cheap SKIL corded drill, and an old 9.6 volt craftsman cordless drill, battery and charger! The battery seems to take and hold a pretty good charge.

    The 9.6 I can just charge off my 12 volt system as long as I monitor it for overcharging.

    Now I don't have to risk the PC drill's charger.

    Thanks again for the input.

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