RC India

My Esky LiPo charger adaptor blasted (bang+smoke) last night at around 12 pm. And this is the second time it has happened.  :banghead:
Has anyone experienced this too? Could there be a problem with the Esky charger? The LiPo voltage before I plugged it for charging was 12V.
Both the times all that blew up was a capacitor. I'm guessing it could be because of overloading.
Can I safely use a transformer based adaptor instead?   :help:

Hi Swapnil, I would suggest to buy a PC SMPS @ 300W and make 12V Power supply out of it. You will get 12V 15Amp stable and relaible output. I bout old 450W SMPC for Rs.250 which I am using for my Icharger 106B+

Hello Netsecrets..

Where do you fly ?

So no one has ever faced this problem before???

My adapter didnt blow, but if i dont connect it to anything the light stay, and when i connect it to the charger i106B the adapter flickers and the charger shuts down.
it was an 18V 1Amp adapter and i was charging a NiCd at 1A. so im guessing it blew.

I was hoping for more response from seniors to see if this is a general problem. I guess it's an overloading problem. Hope someone clears this up...

What current was being drawn by the charger ?  In other words, at how many amps were you charging the 3s lipo ?  If the power supply is not rated for those many amps, it would get overloaded.

Swapnil,

Your house is near to the power supply transformer (Actually cable from Transformer length to your house )is less and you got some overvoltage I think. Generally Transformer based adapters are designed to operate upto 250 volt (RMS).

The voltage is higher during off peak hour specially in night. So, next time buy an 12 volt adapter that can operate from 300 Volts (Marked 270 volt) and having more current capacity.

And I recommend you to avoid charging specially at night.

1 A for a 1000 mAH LiPo, similar to the 1st one bought from Sai sir. I think that I should have gone for a higher amp rating. I do have a spare PC SMPS, will try it.

Yes, indeed! My house is just beside the power supply transformer! I guess that's the real problem. It blew my refridgerator PCB too last month! Should I use a stabilizer for my LiPo charger?

And, charging at night was foolish but I wanted to maiden my plane in the morning. Will avoid doing that from now on.
Thanks sir!

high voltage can b a cause of ur smoking supply..
in past , my 2 smps supplies wasted by  high voltage..
here , normally voltage can reach sometimes 270v+.

Yeah, I guess the nearby transformer's the devil!

should we also use a spike strip or a stabilizer?

Excess voltage on your mains was certainly the cause. A stabiliser MAY help if the voltage changes are not very sudden and will also depend on the type of stabiliser. Stay away from "spikebusters".

O.K. Looks like a stabilizer is the way to go then!
Mr. wallet's gonna have to be rid of another bunch of hundie sticks!  :'( 

whats wrong with spikebusters?

A spike-buster is nothing but a power distribution box with a small circuit and a fuse in it. It blocks the spikes (sudden high-voltage changes) which occur while running big motors or any other heavy electric equipment. It cannot regulate or stabilize the incoming voltage. Its output voltage is always equal to input voltage.

A stabilizer stabilizes the output voltage (i.e always gives a constant voltage output if the input voltage is within the range) and ensures maximum life period for the equipments. It also protects from the high voltage spikes like spike buster.

But spikebuster wont do any harm? Added protection?
all said and done i just got my new adapter and i have connected it through my UPS. :)

UPS... COOL!

I use a SMPS to supply voltage both to the charger as well to the hotwire foam cutter.

Are you referring to a PC SMPS?

It will not do harm but will not help much either. It can only absorb, momentary spikes, not surges.

UPS will not help at all unless it is an "online" type.. And these are expensive.

Yes Swapnil, a standard PC SMPS. Normally, these would not function unless they are attached to mother boards, however there are well documented materials on the net that tell you how to bypass this sensor. Any smps works on a wide voltage range and beyond that has some protection features as well.

All stabilisers do not give a constant output voltage. Most of the ones commonly used for appliances just reduce/increase the supply by about 20V as the supply goes out of limits. These also do not protect against spikes.

Servo controlled stabilisers and CVT transformers will give a constant voltage but at a significantly higher cost. A laptop type of supply is a practical option for most of our applications. It will give a regulated output for an input range from about 100 - 270V.

Okay then, will a 12V, 5A 'laptop type of supply' be good enough?

Yes, just check that It's operating voltage range is 270+ volt. And prefer if it's lower voltage range is as high as 100.

An interesting internal design detail for you.

 If you purchase a 70-270 volt charger, it will operate at 70 volt and make 16 volt AC at HF Transformer, so that after rectification and regulation, it will generate 12 volt by using opto-coupler based duty cycle control. So, at 270 volt, HF transformers generate =16x270/70 volt = 61.71 volt peak. But most adapters use 40 volt/36 volt high speed diode I have seen like MOSPEC 40C25, 1N5408. Only samsung based adapter found with 100V HF Diode. But LG, HP & Others are defective in design (Commonly available laptop charges available in market).

I recommend if you get Samsung brand charger purchase it though it cost's a little bit higher and 3A is sufficient. Internally it uses much higher voltage safety factor for low voltage side high speed diode rectifier that makes it mostly undestructive throughout it's operating range as it is that culprit mostly fails.

An simple low cost solution

Just purchase a 24-0-24 volt step down transformer (300mA is sufficient). Make it as auto-transformer in series addition. Apply supply voltage n higher side and take output from lower voltage side. You can useany adapter and then that wont damage for overvoltage. It's a poor mans stabilizer (Actually optimized for use).

Wow, that's some good info Kalyan sir! I'll get a  samsung (70-270) 3A adaptor ASAP!

The PC SMPS mods look simple. But getting a 10ohm 10Watt resistor is gonna be difficult.

Kalyan sir, I just noticed the edit and couldn't fully understand it. Could you please elaborate it a bit?
I do have a spare 24-0-24 SD Xmer and could try your idea. How to 'make it as auto-transformer in series addition'?

Let your high voltage terminal have marked with 1 and 2 and Low voltage terminal is with 3 and 4 (Neglect center tap).
24-0-24 means a 48 volt coil with center tap.
The basic trick is that you increase the turn by adding two coil and so, volt/turn reduces and kept under control.

Now, let connect 2 and 3 (One primary and one secondary.).
Put Low voltage AC in Low voltage coil(between 3 & 4) or HV AC in HV Coil (between 1 & 2).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Case1:

Measure voltage of 1-2 and 1-4.
If V 1-4 > V 1-2,
===================> Your connection is right. (Voltage adding)
So, a continuous coil with tap -230 0 24 48
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Case 2
Measure voltage of 1-2 and 1-4.
If V 1-4 < V 1-2,
===================> Your connection is wrong. (Voltage subtracting).
Disconnect 2&3 and connect 2 & 4.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Now you get an transformer which can make 230+48 volt to 230 volt or vice versa.
Insted of using 48 volt, you may use 24 volt only (A single part)

Give input supply to
1 & 4 (for Case-1) or 1 & 3 (for case 2)
and get output from
1 & 2.

As 1 is common, connect Neutral to 1.
You get reduced voltage by

Vout = 230 x Vin / (230+48)

And you can safely apply input voltage upto 230+48 volt = 278 volt.
Or you may say your voltage will be 230 or less for input voltage 278 or less.

Read http://en.wikipedia.org/wiki/Autotransformer for more information.

Got it! Thanks Kalyan sir!

Finally I tapped a 12 V line from my CPU SMPS and attached a connector for the balancer-charger. And it works! (And in the end my wallet is as happy as me!  ;D  ;) ;D )
Gonna add a 'charge complete' alarm soon.
Now I can listen to songs while my PC charges LiPos and downloads RC videos at the same time!  ;D
 

Cool! :)
My adapter is again giving the same problem. Gotta replace it again. Thank god this one is just a substitute and my proper adapter is still working. But is in college.

I can't buy to your above investigation and also your advice not using  Charger on SMPS at mid night:

1. I have been using Dell/HP laptop for the past 6+ years, and usually work(not official) during night , 11PM till 3-4AM in the morning. This I have done almost every 365 day of the past 6 years. I have not lost any of my Adapter/Laptop

2. My Office always has constant 220+ volt. Adding to it, I hardly have any voltage fluctuation at my apartment which has dedicated 3-phase 11KV-220v transformers.

3. Leave apart Laptops, ALL TV/DVD Player/Set Top boxes of today use SMPS (My EC TV of Circa 1980's had Transformer). I would be surprised to know late night  TV watchers suddenly found thier TV bursting up at midnight!!

Your technical drill down into Duty cycle, Transient voltage of Diode etc are fine, but claiming the power electronics engineers at esteemed companies like LG, HP & others ignored such an important design aspect of crucial module like SMPS is unbelievable. Do you have any idea how much  Design-Protoype-Testing effort these company spends on product they launch, and kind of qualified Professional (and not Paper Chemists) they hire?

So my adaptors blasted because of overload after all?

I have found a much easier solution which bodes well for me. I use a 12V battery to power my charger.
When it dies i get it recharged.

I used to do that too. But charging a battery with a battery seemed weird...so I switched back to SMPS!

Its only for 9days so I dont mind it.
After 9 days i'll be back in college with my good trusted adapter. Until lady luck smiles.