Harbor Freight EarthquakeXT battery charger - 110 to 220V

[chema.rb]

Hi!

I just returned from the US. I bought there a battery powered impact wrench:

https://www.harborfreight.com/20v-max-lithium-38-in-cordless-xtreme-torque-impact-wrench-kit-63536.html

I have opened the battery charger and I can't figure out an easy way to convert it to 220V. The big capacitor is rated for 400V.



Any ideas?

[deflicted]

Is it really worth trying to convert the device directly? Everyone I know who has traveled abroad has taken with them a cheap travel electric adapter for their electric shavers, hair dryers, etc. Wouldn't one of those work for your purposes? Unless you just want to do it for the fun of tinkering, in which case, carry on. 

[chema.rb]

It's just for the sake of it, you always learn something in the process.

[Armadillo]

It had been hardwired for 170vdc full wave rectified [US market]
Line balun and filters are omitted? 
If you use a adapter, man it's a big adapter.
There is no simple way doubler action except to reverse engineered it or get the schematic for the 230vac version.   

[chema.rb]

Yeah, I also noticed the missing choke(s) in the input side

I don't think Harbor Freight design their own tools, probably is just a generic design from one of the chinese tool manufacturers.

Charger is rated 80W, I will try to run in in a 100w step down converter.

[dtuned]

Some if their new tools are made by tti.

[capt bullshot]

If the big capacitor is rated 400V, chances are good that this thing has an universal input like most of the power bricks used for laptops etc. Looks like a flyback converter, these do not need any primary voltage selector to be universal input.

It's up to you to just try it out - either it goes bang or it works.

[chema.rb]

I managed to identify the varistor and it's a 7N561K, and it's rated for 350V AC. Do you think I should try to identify any other components?

[capt bullshot]

Yes, the primary side switching transistor would give a good hint.
If it is rated for at least about 600V, IMO this is an universal input power supply.

[Jacek_Paw]

Could you post a photos of the charger's case?

[chema.rb]

Sure!

[chema.rb]

Yes, the primary side switching transistor would give a good hint.
If it is rated for at least about 600V, IMO this is an universal input power supply.

CS10N60F A9HD, rated for 600V

[boffin]

One of the differences I see between 120 and 240v switchers is simply using 1/2 wave vs full wave rectification on the primary side to only get 1/2 the power in to start with.

If you really want to run it on 240V, I'd pull 2 of the big power diodes out.

[capt bullshot]

Yes, the primary side switching transistor would give a good hint.
If it is rated for at least about 600V, IMO this is an universal input power supply.

CS10N60F A9HD, rated for 600V

OK, next step would introduce real testing:
Run it from a variac, starting at 110V, with nominal load applied.
Watch the waveforms at the drain of the primary transitor and at the secondary rectifier diodes.
Ramp up slowly the voltage - peak reverse voltage on the rectifier will rise, also peak voltage at the drain.
Watch for anomalies like clipping, oscillation or voltages execeeding the ratings (of the MOSFET and the rectifier)
Try the same at no load condition.

If you don't have the tools, either be brave and just turn it on on 240V and watch what happens or run it off 120V.

Removing half of the primary rectifier wouldn't reduce the peak voltage, just puts more ripple current on the input capacitor and undesirable DC on the AC input.

[drussell]

Removing half of the primary rectifier wouldn't reduce the peak voltage, just puts more ripple current on the input capacitor and undesirable DC on the AC input.

Indeed!  This is often forgotten!

Remember that on a half-wave rectifier the output Epeak is still 1.4Erms (the RMS of the AC input voltage.)  The average is only 0.45Erms vs. 0.9Erms for a bridge rectifier circuit with four diodes but the peak is the same. 

The "old-school way" for full wave rectification, often used in tube gear, where you use two diodes and a center-tapped transformer gives you 0.7Erms peak and 0.45Erms vs. the 1.4x and 0.9x of the bridge circuit.

Of course, this also changes the way the current is drawn from the source, be it through a transformer (where you need to consider peak vs. average current for assessing your power handling) or directly off the AC line.

[Armadillo]

Removing half of the primary rectifier wouldn't reduce the peak voltage, just puts more ripple current on the input capacitor and undesirable DC on the AC input.

Indeed!  This is often forgotten!

Remember that on a half-wave rectifier the output Epeak is still 1.4Erms (the RMS of the AC input voltage.)  The average is only 0.45Erms vs. 0.9Erms for a bridge rectifier circuit with four diodes but the peak is the same. 

The "old-school way" for full wave rectification, often used in tube gear, where you use two diodes and a center-tapped transformer gives you 0.7Erms peak and 0.45Erms vs. the 1.4x and 0.9x of the bridge circuit.

Of course, this also changes the way the current is drawn from the source, be it through a transformer (where you need to consider peak vs. average current for assessing your power handling) or directly off the AC line.

Yeap!, you forgotten the smoothing electrolytic capacitor also.
Its already converted from AC to DC. So, what's up peak from old school?

[chema.rb]

Yes, the primary side switching transistor would give a good hint.
If it is rated for at least about 600V, IMO this is an universal input power supply.

CS10N60F A9HD, rated for 600V

OK, next step would introduce real testing:
Run it from a variac, starting at 110V, with nominal load applied.
Watch the waveforms at the drain of the primary transitor and at the secondary rectifier diodes.
Ramp up slowly the voltage - peak reverse voltage on the rectifier will rise, also peak voltage at the drain.
Watch for anomalies like clipping, oscillation or voltages execeeding the ratings (of the MOSFET and the rectifier)
Try the same at no load condition.

If you don't have the tools, either be brave and just turn it on on 240V and watch what happens or run it off 120V.

Removing half of the primary rectifier wouldn't reduce the peak voltage, just puts more ripple current on the input capacitor and undesirable DC on the AC input.

I think this is a bit over my posibilities right now. I have a couple of multimeters, and a broken oscilloscope I am trying to get back to life (LeCroy 9310A). I will try to source a variac, and I'll need an isolation transformer too!

Thanks for the help.

[IanB]

All the indications so far suggest this charger is not designed to run on 230 V. Even if you spend lots of time and effort your chances of success are very low.

Considering the source and the unpopulated components on the board you can assume with some justification that it was designed and built down to a price. Adding unnecessary support for 230 V on a 120 V appliance merely adds to the cost. Therefore, why would they do that? It's only going to happen if the unit were going to be sold in 230 V markets (e.g. big brands with world wide markets like Ryobi). This one doesn't look like it fits into that category. It is a Harbor Freight special.

[Armadillo]

I think this is a bit over my posibilities right now. I have a couple of multimeters, and a broken oscilloscope I am trying to get back to life (LeCroy 9310A). I will try to source a variac, and I'll need an isolation transformer too!

And just maybe double check on property insurance too, as this is a "Lithium Battery Charger" not a regular power supply even though the front end *LOOKS* universal.
Even if it can, the PWM will be so limited that the overall efficiency becomes questionable, yeah!.
Is it worth the time and efforts to go against the label notice, in terms of the safety aspect and the law in the UK or US?
I don't know, but I am sure some would be brave enough to go for it.
Cheers, 

[chema.rb]

All the indications so far suggest this charger is not designed to run on 230 V. Even if you spend lots of time and effort your chances of success are very low.

Why you say that? Just for the missing filters?

As far as I have been able to identify, everithing is rated high enough for 220V, I need to have a look on the PWM IC, but it's too tiny, I need a microscope.

[Zucca]

https://www.eevblog.com/forum/chat/need-a-russian-speacker-to-translate-a-you-tube-hack-video/msg376102/#msg376102

I did a 110V to 220V conversion  like this video on a Makita battery charger, and I enjoyed it... the tricky part was to connect another pin in the secondary side of the transformer, there was a R to move in order to  select 110Vac...

My experience: if in the primary side all the components are rated for 400V you should not burn anything there. Secondary download the IC501 and IC409 (or IC403?) datasheet, this will help you to understand  how the secondary works.

Next use a variac or a variable trafo to increase slowly the voltage from 110V to something bigger... take your measurement.

AFAIR the russian guy in the video stated at some point:"just plug the 220V in it,  if you burn something you have just to replace it..."

[chema.rb]

https://www.eevblog.com/forum/chat/need-a-russian-speacker-to-translate-a-you-tube-hack-video/msg376102/#msg376102

I did a 110V to 220V conversion  like this video on a Makita battery charger, and I enjoyed it... the tricky part was to connect another pin in the secondary side of the transformer, there was a R to move in order to  select 110Vac...

My experience: if in the primary side all the components are rated for 400V you should not burn anything there. Secondary download the IC501 and IC409 (or IC403?) datasheet, this will help you to understand  how the secondary works.

Next use a variac or a variable trafo to increase slowly the voltage from 110V to something bigger... take your measurement.

AFAIR the russian guy in the video stated at some point:"just plug the 220V in it,  if you burn something you have just to replace it..."

I'll check them.

What about the PWM IC (IC401)?  I was trying to identify it to know if it designed for universal voltage. Does it matter?

[chema.rb]

The SMPS control IC is marked 281H18 150 and there is a symbol like a "p". I can't locate the datasheet, anyone can help?

[texaspyro]

BOLTR on youtube (the Canadian "skookum" guy) did a teardown on this tool.  He was expecting a typical piece of Chinese / HF crap and was rather shocked at it's rather superb quality, build, and capabilities.   It's not your typical HF crap-tool.

[chema.rb]

The SMPS control IC is marked 281H18 150 and there is a symbol like a "p". I can't locate the datasheet, anyone can help?

It seems the "18" part in the iC marking is some type of datecode. I have found chinese seller selling from 281H01 to 281H56.