Author Topic: Will This Transformer Do For Tool Purchased In USA?  (Read 16442 times)

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Offline Boris_yo

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Will This Transformer Do For Tool Purchased In USA?
« on: March 06, 2012, 07:46:09 am »
Hello, i have this cordless screwdriver/drill that i bought from USA and want to use it with 220V-50Hz electricity in Israel with this kind of wall socket (adapter from US plug to Israeli plug i already have). This is what i see on sticker under the bottom of its charger:



There is no mention of wattage on sticker, but is there a way to find out/calculate? Will the following charger be a good fit for tool? I heard that it is better to get transformer with 20% more wattage than tool requires just in case.



Thank you.
« Last Edit: March 06, 2012, 08:12:40 am by Boris_yo »
 

Offline Pentium100

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #1 on: March 06, 2012, 07:53:52 am »
Also find out how much an autotransfomer costs. Maybe it is cheaper than a new charger.

It seems to me that this charger has some intelligence built in, not just a DC power supply, so it may be expensive.
 

Offline Boris_yo

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #2 on: March 06, 2012, 08:11:50 am »
Also find out how much an autotransfomer costs. Maybe it is cheaper than a new charger.

It seems to me that this charger has some intelligence built in, not just a DC power supply, so it may be expensive.

It's not, only over $10.

However this one is over $88:

« Last Edit: March 06, 2012, 08:35:42 am by Boris_yo »
 

Offline sonicj

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #3 on: March 06, 2012, 08:50:58 am »
There is no mention of wattage on sticker, but is there a way to find out/calculate? Will the following charger be a good fit for tool? I heard that it is better to get transformer with 20% more wattage than tool requires just in case.
amps x volts = watts
2A x 120V = 240W
20% of 240W is 48W so... around 300 Watts would be appropriate.
 

Offline Pentium100

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #4 on: March 06, 2012, 08:51:43 am »
Wow, a 300W autotransformer in my local electronics store only costs ~30EUR.

Now that I read your post one more time, it turns out that you are asking about an autotransfomer too (for whatever reason at first I believed it was an AC/DC adapter).

No, you need the autotransformer to be at least 240VA, because the charger needs 120V and 2A (it probably uses a series capacitor to reduce the voltage resulting in a very low power factor).
 

Offline IanB

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #5 on: March 06, 2012, 08:56:08 am »
Unless it is very inefficient I can't believe that battery charger draws more than about 100 W from the mains, in spite of the 2.0 A written on the label. Perhaps the 2.0 A is the peak surge current for breaker/fuse rating purposes?

I would try a 100 W transformer and see what happens. Also make sure it is a proper transformer and not an electronic one. The electronic ones are only for resistive loads like hair dryers and are only rated for short periods of operation.
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Offline Boris_yo

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #6 on: March 06, 2012, 09:44:07 am »
People tell me they to buy adapter for around $10 for tool from US to work. They say i don't need converter and only adapter. One told me he bought such adapter with input 230v 26VA fore his 20v tool and all works well for him.

I need to know what electrician experts on this forum think about this. Thanks.
 

Offline Pentium100

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #7 on: March 06, 2012, 10:10:07 am »
Unless it is very inefficient I can't believe that battery charger draws more than about 100 W from the mains, in spite of the 2.0 A written on the label. Perhaps the 2.0 A is the peak surge current for breaker/fuse rating purposes?

Judging from the warning that the terminals are live and the 2A current rating I think the charger uses a series capacitor to reduce the voltage instead of a transformer. A series capacitor does not dissipate power, but the power factor becomes really low. I attached an example circuit diagram.

Because transformers are actually rated in VA (apparent power), you need a transformer that can supply the current even though it does not do any useful work.
 

Offline IanB

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #8 on: March 06, 2012, 10:16:48 am »
People tell me they to buy adapter for around $10 for tool from US to work. They say i don't need converter and only adapter. One told me he bought such adapter with input 230v 26VA fore his 20v tool and all works well for him.

I need to know what electrician experts on this forum think about this. Thanks.

Your DeWalt battery charger has 120 V AC 60 Hz 2.0 A written on it.

If you take that at face value you need a voltage converter that can output 120 V at 2.0 A at least, which would be a 300 W voltage converter transformer allowing for a safety margin. You won't buy one of those for $10.

You can't simply use a plug adapter with that battery charger as it requires 120 V.

The moral of the story is to buy things in Israel designed for use in Israel. Don't buy things from America and try to use them where they were not designed to be used.
« Last Edit: March 06, 2012, 10:22:34 am by IanB »
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Offline IanB

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #9 on: March 06, 2012, 10:21:47 am »
Judging from the warning that the terminals are live and the 2A current rating I think the charger uses a series capacitor to reduce the voltage instead of a transformer. A series capacitor does not dissipate power, but the power factor becomes really low. I attached an example circuit diagram.

I see that. But it seems like incredibly poor design for something that needs 2-3 A, which is why I had my doubts. But since I don't have it in my hands to take apart, who knows? With the information printed on the label we have to take it at face value.
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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #10 on: March 06, 2012, 10:25:48 am »
If you take the printed information at face value, you would also have to convert the 50 Hz power to 60 Hz, which is going to be much more complex than a simple transformer. Most devices rectify it anyway and don't care, but it would result in a decrease in charging current of 15% in Pentium100's proposed circuit, and an increase in ripple. I wouldn't expect such a big cap to be cheaper than a transformer either, but who knows.
 

Offline Pentium100

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #11 on: March 06, 2012, 10:39:57 am »
Don't buy things from America and try to use them where they were not designed to be used.
Or figure out a way how to make them work where you live.
I wouldn't expect such a big cap to be cheaper than a transformer either, but who knows.
Motor run capacitors are not very expensive.

On the other hand, it could be just a switching power supply (without a transformer). That also can have a low power factor, but probably not THAT low (~0.2).

I would take it apart (if possible) and figure out how to modify it to work with 240V. If it really has a CR dropper, then reducing the capacitance could work.
« Last Edit: March 06, 2012, 10:43:01 am by Pentium100 »
 

Offline Boris_yo

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #12 on: March 06, 2012, 10:40:59 am »
Quote from: IanB

You can't simply use a plug adapter with that battery charger as it requires 120 V.


What i meant adapter which is 230V - 110V, but not converter. At least that is what i was told in local forum. People said i don't need converter, but i need 230V - 110V adapter. I always assumed that adapter is unit that simply adapts abroad power plugs tpo local power plugs and vise versa, but they say it is 230V - 110V which i can only assume it is converter, but it is not, according to their statement.

Just want to remind that tool is cordless and works only on Ni-CAD battery so it is battery that needs to be charged through charger.
« Last Edit: March 06, 2012, 10:45:36 am by Boris_yo »
 

Offline Pentium100

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #13 on: March 06, 2012, 10:45:01 am »
What i meant adapter which is 230V - 110V, but not converter.
It is an autotransformer, which is like a regular transformer but it only has one winding with taps. It can step up/down the voltage just like a regular transformer and is cheaper, but does not provide isolation, so the "secondary" is live.
 

Offline G7PSK

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #14 on: March 06, 2012, 10:54:11 am »
If the charger contains a transformer it may burn out on 50HZ as it is rated for 60HZ and at 50 it will draw more current if its a switch mode unit it may be quite happy at 240 volts as these things tend to be made for use anywhere and the only make the pins for the socket different for the various markets.
 

Offline Pentium100

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #15 on: March 06, 2012, 11:05:44 am »
if its a switch mode unit it may be quite happy at 240 volts as these things tend to be made for use anywhere and the only make the pins for the socket different for the various markets.
If it were OK at 240V that would be written on the sticker. It can use input capacitors rated for 200V for example and they wuld blow up if connected to 240V.

I have two low power devices that are 120V/60Hz and they both work OK on 50Hz. Though you should find out if the device gets too hot when connected to 50Hz.
 

Offline T4P

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #16 on: March 06, 2012, 05:36:52 pm »
Hmm , i wonder what's inside the charger , how does a charger draw more then 240W is beyond me .
 

Offline Pentium100

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #17 on: March 06, 2012, 11:43:49 pm »
Hmm , i wonder what's inside the charger , how does a charger draw more then 240W is beyond me .
I don;t think it draws 240W. It can draw a lot of current if it has a really low power factor. After all, if I plug a 20uF capacitor to 240V it will draw a lot of current, but use almost no power.
 

Offline T4P

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #18 on: March 07, 2012, 12:29:07 pm »
Hmm , i wonder what's inside the charger , how does a charger draw more then 240W is beyond me .
I don;t think it draws 240W. It can draw a lot of current if it has a really low power factor. After all, if I plug a 20uF capacitor to 240V it will draw a lot of current, but use almost no power.
Maybe on startup . SMPS can do such shit to energize the caps , it draws a massive amount to energize those low ESR caps.
 

Offline Boris_yo

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #19 on: March 20, 2012, 10:06:06 pm »
Here is what DeWalt support told me:

Quote
All of the products that are sold and marketed in the US are designed for 120v current, we do not offer any that include a 220v charger. You can use this charger on 230v current with a minimum 400 watt step down transformer or inverter.

Are these step down transformer and inverters the ones that cost a lot?
 

Offline T4P

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #20 on: March 21, 2012, 01:46:52 am »
Here is what DeWalt support told me:

Quote
All of the products that are sold and marketed in the US are designed for 120v current, we do not offer any that include a 220v charger. You can use this charger on 230v current with a minimum 400 watt step down transformer or inverter.

Are these step down transformer and inverters the ones that cost a lot?
No .
 

Offline Monkeh

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #21 on: March 21, 2012, 01:52:27 am »
A transformer for that is liable to cost more than a suitable replacement charger. I highly doubt the batteries are any different (except their hilarious '20V' ones) to ones from Europe.
 

Offline sonicj

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #22 on: March 21, 2012, 06:24:00 am »
except their hilarious '20V' ones
the management dickheads who came up with the 20V Max lineup need to be punched in the face and fired!

the success and longevity of the 18V XRP line is their clear competitive advantage over the competition. 

"hey, lets jump on the flatpack bandwagon and f*** over all of long time customers by investing all of our battery advancements in this new incompatible "20V' format and raise the price on all of the old s**t so maintaining old tools no longer looks cost effective."  ******bags!
-sj
 

Offline siliconmix

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #23 on: March 21, 2012, 08:55:01 am »
There is no mention of wattage on sticker, but is there a way to find out/calculate? Will the following charger be a good fit for tool? I heard that it is better to get transformer with 20% more wattage than tool requires just in case.
amps x volts = watts
2A x 120V = 240W
20% of 240W is 48W so... around 300 Watts would be appropriate.
isn't there a power factor in ohm's law for ac or something ?
 

Offline PetrosA

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Re: Will This Transformer Do For Tool Purchased In USA?
« Reply #24 on: March 21, 2012, 11:32:08 am »
Your cheapest option may be to buy just the charger in Israel. You will need at least a 300W transformer for the charger to work. I have a 375W inverter in my truck and you can hear it bog down when a charger goes into charge mode (I have chargers from Hilti, Metabo, Fein and Milwaukee and they all draw a lot of current when charging). Some cycle on and off, putting a heavy draw on the inverter each time. Another option may be to replace the transformer inside the charger.
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