Hi all. I stopped using my Edecoa 2500w pure sine wave inverter to charge my Oralb toothbrush after it blew the charger on two. Today I used the inverter on my 200w slow cooker regrettably coz it's blown the electronics board on that too. The element and fuse that's on the board test ok. Anyone know of an inverter that doesn't damage the electronics of such items?
Cheers Tony
dorian said
11:18 AM Jul 14, 2022
A pure sine wave inverter should be the ideal choice for electrical appliances. Are you sure you don't have a "modified sine wave" type?
It might help to see the damage on the PCBs. That might give us a clue as to what happened.
FreecamperTas said
12:29 PM Jul 14, 2022
Hi Dorian. Thanks for your reply. I've attached a screen shot of what I bought in 2017. Advertised as pure sine wave. There's no visible damage to the PCB. cheers Tony
When a Victron Phoenix Inverter 12/3000 costs $1700 to $1900 something has to give when one costs less than $300
Whenarewethere said
12:42 PM Jul 14, 2022
Sorry, double post
-- Edited by Whenarewethere on Thursday 14th of July 2022 12:42:32 PM
Mike Harding said
12:43 PM Jul 14, 2022
Agreed. You won't buy a 5kW sine wave for $290.
In another post you mentioned being an electronics technician so I suggest you measure its 240V output with your DMM set to AC. If it's sine wave it should read 240V give or take, if it's square wave it'll read something quite different, guessing, maybe 150V. As always, don't stick your pinkies in bad places.
dorian said
12:45 PM Jul 14, 2022
I was thinking that we could inspect the electronics on the damaged items, not the inverter.
FreecamperTas said
01:27 PM Jul 14, 2022
Thanks again guys. Yeah I did measure the 240v going into the slow cooker PCB. I'd need an oscilloscope to have a look at the inverter output. Also, there's no visible signs of damage to the slow cooker PCB so suspect something from silicon Valley has buggered up.
Mike Harding said
02:25 PM Jul 14, 2022
FreecamperTas wrote:
Yeah I did measure the 240v going into the slow cooker PCB.
Did you measure it on your DMM set to AC? If so what was the reading?
You don't need a 'scope to do this, and in any event be very cautious of connecting a scope to 240V most scopes are not speced for direct mains connection, your DMM expects a sine wave and performs RMS calculations so if you feed it a square wave the numbers will be incorrect and you'll get a reading way out from 240V.
Whenarewethere said
02:54 PM Jul 14, 2022
It doesn't actually solve the problem but at least you will not destroy another toothbrush.
Hi all. I stopped using my Edecoa 2500w pure sine wave inverter to charge my Oralb toothbrush after it blew the charger on two. Today I used the inverter on my 200w slow cooker regrettably coz it's blown the electronics board on that too. The element and fuse that's on the board test ok. Anyone know of an inverter that doesn't damage the electronics of such items?
Cheers Tony
I have a Giandel 3000/6000 inverter and have never had an issue except that they are not as expensive now as when I bought mine. I found some good reviews before i purchased.
It also has a remote switch so that you can turn it off remotely so that it doesnt use power in standby.
I have an old version of this UPS plus additional battery units. Ok I am comparing a UPS to an inverter without its only battery. But really 2700 watts of quality power costs a "touch" more the $300
Whenarewethere said
10:57 PM Jul 14, 2022
Sub $300 2500 watt inverter 4.6kg
Victron 1600 watt inverter 15.5kg
Victron 2400 watt inverter 19.0kg
My UPS 2700 watt without batteries 22kg
I wonder what is inside a cheap inverter?
dorian said
03:20 AM Jul 15, 2022
I would think that most inverters would have a surge rating to allow them to accommodate inductive loads such as electric motors. These draw substantial currents during starting.
As for the weights of the Victron inverters, my question would be, what is inside an expensive inverter?
I can see that this 2400W / 20kg unit has a large toroidal transformer:
I suspect that the cheaper inverters may step up the battery voltage via a high frequency ferrite transformer, and then produce a pseudo-sinusoidal output by pulse-width-modulating the output voltage via MOSFET choppers and a couple of series connected inductors.
-- Edited by dorian on Friday 15th of July 2022 06:02:55 AM
Whenarewethere said
07:00 AM Jul 15, 2022
I have pulled my one apart a few times to clean out the dust, disconnecting the battery first. It has a very big transformer in it plus quite a bit of other stuff & 3 80mm fans.
dorian said
07:10 AM Jul 15, 2022
Here are several high power car subwoofer audio amps, some as high as 4000W:
They most probably all use Class D topologies. That's probably how the cheaper inverters work.
FreecamperTas said
01:21 PM Jul 15, 2022
Mike Harding wrote:
FreecamperTas wrote:
Yeah I did measure the 240v going into the slow cooker PCB.
Did you measure it on your DMM set to AC? If so what was the reading?
, and in any event be very cautious of connecting a scope to 240V most scopes are not speced for direct mains connection,
Yep. 240v ac.
Haha...I connected an earthed scope to a live TV chassis a few times in my career as a TV engineer in UK. Well...engineer in UK but TV serviceman here in Oz. Always kept one arm behind my back and no rings on fingers (:
Mike Harding said
02:11 PM Jul 15, 2022
FreecamperTas wrote:
Did you measure it on your DMM set to AC? If so what was the reading?
Yep. 240v ac.
Interesting, Maybe under no load it is a square wave and fools the meter? These inverters are usually triangular waves.
As for oscilloscopes; I always remove the earth from oscilloscopes at the mains plug although nowadays most scopes are digital and powered from a plug pack so the issue doesn't arise however what I really meant is that the input spec of most scopes is not adequate for the 340V mains peak.
---
Dorian: I believe you are correct in your description of inverters.
My Victron 500W synthesizes a sine wave at low voltage and subsequently transforms it to 240V whereas the cheaper units use a high frequency chopper and wave shape afterwards.
The Victron approach is much better as it keeps semiconductors away from the higher voltage and ensures they are not subject to such things as mains level inductive spikes but it does make the inverter much more expensive and heaver but I suspect the cheaper approach will have a hard time meeting EMC emissions requirements which is why most of the cheap Chinese simply don't bother to even try.
kgarnett said
02:21 PM Jul 15, 2022
I have also removed the earth at the mains plug on my Tektronix scopes and also the try to remember that the scope frame is floating.
I can see that this 2400W / 20kg unit has a large toroidal transformer: 06:02:55 AM
In my UPS the 6 batteries are in series, so 72 volts DC. So even though the thing weights a tonne, I suppose it's easier starting at 72 volts rather than from 12 volts. At least the extra battery boxes wiring can be thinner, even though these cables are surprisingly heavy.
Mike Harding said
04:40 PM Jul 15, 2022
kgarnett wrote:
I have also removed the earth at the mains plug on my Tektronix scopes and also the try to remember that the scope frame is floating.
If you are doing general electronics development it's a sensible thing to do although occasionally, for noise purposes, I have reconnected it. On one scope I split the earth lead at the mains plug and affixed a male/female spade connector so I could easily earth it or not.
And yes, it's easy to forget the scope is floating and if your mind is on other things and to attach the line side to said scope with embarrassing results for your fingers or, perhaps, signal generators et al :)
I did quite a lot of work on HV testing systems and a qualified rubber mat brought some peace of mind nevertheless I have never forgotten what my tutor of 45 years past told me; "A competent electrical/electronics/HV engineer always works with one hand in his pocket... you never quite know what he's doing with it though...." :)
----
Dorian: Thanks for the info, I'll take a look.
jegog said
11:33 PM Jul 17, 2022
Mike Harding wrote:
kgarnett wrote:
I have also removed the earth at the mains plug on my Tektronix scopes and also the try to remember that the scope frame is floating.
If you are doing general electronics development it's a sensible thing to do although occasionally, for noise purposes, I have reconnected it. On one scope I split the earth lead at the mains plug and affixed a male/female spade connector so I could easily earth it or not.
And yes, it's easy to forget the scope is floating and if your mind is on other things and to attach the line side to said scope with embarrassing results for your fingers or, perhaps, signal generators et al :)
I did quite a lot of work on HV testing systems and a qualified rubber mat brought some peace of mind nevertheless I have never forgotten what my tutor of 45 years past told me; "A competent electrical/electronics/HV engineer always works with one hand in his pocket... you never quite know what he's doing with it though...." :)
----
Dorian: Thanks for the info, I'll take a look.
I have used the BWD 880 power oscilloscope. A 4 channel scope designed mains power analysis. Used it on theatre light controllers. Or use a 240 to 240 isolation transformer. Either plug the scope our the equipment into it. And nowadays with battery powered portable oscilloscopes there is no issue.
Deliberately removing the earth protection is a no-no.
Mike Harding said
07:11 AM Jul 18, 2022
jegog wrote:
Deliberately removing the earth protection is a no-no.
Hi all. I stopped using my Edecoa 2500w pure sine wave inverter to charge my Oralb toothbrush after it blew the charger on two. Today I used the inverter on my 200w slow cooker regrettably coz it's blown the electronics board on that too. The element and fuse that's on the board test ok. Anyone know of an inverter that doesn't damage the electronics of such items?
Cheers Tony
A pure sine wave inverter should be the ideal choice for electrical appliances. Are you sure you don't have a "modified sine wave" type?
https://www.edecoa.com/products
It might help to see the damage on the PCBs. That might give us a clue as to what happened.
Hi Dorian. Thanks for your reply. I've attached a screen shot of what I bought in 2017. Advertised as pure sine wave. There's no visible damage to the PCB.
cheers Tony
When a Victron Phoenix Inverter 12/3000 costs $1700 to $1900 something has to give when one costs less than $300
Sorry, double post
-- Edited by Whenarewethere on Thursday 14th of July 2022 12:42:32 PM
Agreed. You won't buy a 5kW sine wave for $290.
In another post you mentioned being an electronics technician so I suggest you measure its 240V output with your DMM set to AC. If it's sine wave it should read 240V give or take, if it's square wave it'll read something quite different, guessing, maybe 150V. As always, don't stick your pinkies in bad places.
Did you measure it on your DMM set to AC? If so what was the reading?
You don't need a 'scope to do this, and in any event be very cautious of connecting a scope to 240V most scopes are not speced for direct mains connection, your DMM expects a sine wave and performs RMS calculations so if you feed it a square wave the numbers will be incorrect and you'll get a reading way out from 240V.
It doesn't actually solve the problem but at least you will not destroy another toothbrush.
https://thegreynomads.activeboard.com/t65253740/oral-b-2-x-aa-battery-toothbrush/
I have a Giandel 3000/6000 inverter and have never had an issue except that they are not as expensive now as when I bought mine. I found some good reviews before i purchased.
It also has a remote switch so that you can turn it off remotely so that it doesnt use power in standby.
https://www.ebay.com.au/itm/231856179554?epid=25045298358&hash=item35fbb48962:g:QQoAAOSwzCFedJfl&amdata=enc%3AAQAHAAAA4Hnck82yqTwGXALFTQwumQPfFPOSeZuFDUATZjcSIQ7%2F4GXMoSkuGlWhPcedI6v4N2rR%2BeIZb2o9sajlMrIz09CtLBaU24DyDjaS8YYFuqifOdIRiKaMp9L6cTzYhjIxc8VCp2oV4WBDFYs7y%2Bmx2PQXwDLCvNhIiYJGlRGB260aWYT8ZNlME9duJUoRG2DIhbF2bwcqKanFvGmDiGxDHiho6h7ZjcTfH1EUf8caw1aT0bmmbLdKy%2FRR%2FNTCOP5QIeB994EnpK2mk%2FJZ%2BFFgqi%2BW8NUhp57wWauecjn12hFs%7Ctkp%3ABFBMzOqBx79g
Seems like you are having a bad run on electrics at the moment.
-- Edited by TimTim on Thursday 14th of July 2022 09:46:30 PM
I don't understand how a sub $300 inverter 2500 watts can also have a surge of 5000 watts.
As compared to a professional UPS 3.0kVA 2700 watts & no mention of a surge capacity.
https://www.techbuy.com.au/p/169038/UPS_RACKMOUNT/EATON/5PX3000IRT3UAU.asp
I have an old version of this UPS plus additional battery units. Ok I am comparing a UPS to an inverter without its only battery. But really 2700 watts of quality power costs a "touch" more the $300
Sub $300 2500 watt inverter 4.6kg
Victron 1600 watt inverter 15.5kg
Victron 2400 watt inverter 19.0kg
My UPS 2700 watt without batteries 22kg
I wonder what is inside a cheap inverter?
I would think that most inverters would have a surge rating to allow them to accommodate inductive loads such as electric motors. These draw substantial currents during starting.
As for the weights of the Victron inverters, my question would be, what is inside an expensive inverter?
I can see that this 2400W / 20kg unit has a large toroidal transformer:
http://www.scpowsolar.com/h-pd-41.html#_pp=0_336_8_-1
http://7498591.s21i.faiusr.com/2/ABUIABACGAAgn5DfsgUo0uuiogMw2AQ41wQ.jpg (inside view)
Here is a datasheet for a 3kVA / 25kg toroidal transformer:
https://www.farnell.com/datasheets/2279510.pdf
I suspect that the cheaper inverters may step up the battery voltage via a high frequency ferrite transformer, and then produce a pseudo-sinusoidal output by pulse-width-modulating the output voltage via MOSFET choppers and a couple of series connected inductors.
Something like a Class D audio amplifier ...
https://en.wikipedia.org/wiki/Class-D_amplifier
-- Edited by dorian on Friday 15th of July 2022 06:02:55 AM
I have pulled my one apart a few times to clean out the dust, disconnecting the battery first. It has a very big transformer in it plus quite a bit of other stuff & 3 80mm fans.
Here are several high power car subwoofer audio amps, some as high as 4000W:
https://www.forbes.com/wheels/accessories/best-car-subwoofer-amplifiers/
They most probably all use Class D topologies. That's probably how the cheaper inverters work.
Yep. 240v ac.
Haha...I connected an earthed scope to a live TV chassis a few times in my career as a TV engineer in UK. Well...engineer in UK but TV serviceman here in Oz. Always kept one arm behind my back and no rings on fingers (:
Interesting, Maybe under no load it is a square wave and fools the meter? These inverters are usually triangular waves.
As for oscilloscopes; I always remove the earth from oscilloscopes at the mains plug although nowadays most scopes are digital and powered from a plug pack so the issue doesn't arise however what I really meant is that the input spec of most scopes is not adequate for the 340V mains peak.
---
Dorian: I believe you are correct in your description of inverters.
My Victron 500W synthesizes a sine wave at low voltage and subsequently transforms it to 240V whereas the cheaper units use a high frequency chopper and wave shape afterwards.
The Victron approach is much better as it keeps semiconductors away from the higher voltage and ensures they are not subject to such things as mains level inductive spikes but it does make the inverter much more expensive and heaver but I suspect the cheaper approach will have a hard time meeting EMC emissions requirements which is why most of the cheap Chinese simply don't bother to even try.
I have also removed the earth at the mains plug on my Tektronix scopes and also the try to remember that the scope frame is floating.
There are several inverter circuits here:
https://elektrotanya.com/showresult?what=inverter&kategoria=All&kat2=All
You'll need to refine your search to exclude the inverter circuits in monitors, for example.
Here are 3 high power inverters and one 200VA.
https://elektrotanya.com/e-ast_12v_2000w_pure_sine_inverter_sch.pdf/download.html (E-AST 12V 2000W PURE SINE INVERTER)
https://elektrotanya.com/novopal_puresine_ps3000_-_48v-230v_3000w_inverter_schema.pdf/download.html (NOVOPAL PURESINE PS3000 - 48V-230V 3000W INVERTER SCHEMA)
https://elektrotanya.com/3000va_power_inverter_12vdc-230vac_modified_sinus.zip/download.html (3000VA POWER INVERTER 12VDC-230VAC MODIFIED SINUS)
https://elektrotanya.com/200va_power_inverter_for_cars.pdf/download.html (200VA POWER INVERTER FOR CARS)
In my UPS the 6 batteries are in series, so 72 volts DC. So even though the thing weights a tonne, I suppose it's easier starting at 72 volts rather than from 12 volts. At least the extra battery boxes wiring can be thinner, even though these cables are surprisingly heavy.
If you are doing general electronics development it's a sensible thing to do although occasionally, for noise purposes, I have reconnected it. On one scope I split the earth lead at the mains plug and affixed a male/female spade connector so I could easily earth it or not.
And yes, it's easy to forget the scope is floating and if your mind is on other things and to attach the line side to said scope with embarrassing results for your fingers or, perhaps, signal generators et al :)
I did quite a lot of work on HV testing systems and a qualified rubber mat brought some peace of mind nevertheless I have never forgotten what my tutor of 45 years past told me; "A competent electrical/electronics/HV engineer always works with one hand in his pocket... you never quite know what he's doing with it though...." :)
----
Dorian: Thanks for the info, I'll take a look.
I have used the BWD 880 power oscilloscope. A 4 channel scope designed mains power analysis. Used it on theatre light controllers. Or use a 240 to 240 isolation transformer. Either plug the scope our the equipment into it. And nowadays with battery powered portable oscilloscopes there is no issue.
Deliberately removing the earth protection is a no-no.
Only if you don't know what you're doing.