A look inside my Pila IBC charger

verge · Feb 10, 2013

I have been wondering about what's inside of Pila IBC charger. Last night, I opened my Pila charger and took pictures of its inside.

The case doesn't look like some easy to break brittle plastic material, it feels and looks tough plastic material. It has four self-tapping screws, so I have to be careful taking them out and specially when putting them back in.

The components that stand out are the two pieces of small 8-pin IC VM7205 (pic Pila002), two pieces of what looks like High Current Voltage Regulator (pics Pila009 & Pila010) that are covered by aluminum heat sink, two pieces of large white ceramic resistor and an assortment of other resistors and diodes.

Everything is soldered to the circuit board and it is fitted into the case through four holes which also served as the screw holes and covered by round rubber foot covers.

There are no dangling wires to worry about nor circuit connections that might get broken as you take the circuit board out after opening the case. All of the electronic components are soldered to the circuit board. The pieces that you might lose are the four screws.

According to http://www.vimicro.com/products/analog_ic/index.html

VM7205 series advanced Lithium-Ion (Li-Ion) and Lithium-Polymer (Li-Pol) Linear Charger ICs are designed for cost-sensitive and compact portable electronics. They combine high-accuracy current and voltage regulation, battery condition monitoring, temperature monitoring, charge termination, charge-status indication, and internal impedance compensation in a single 8-pin IC. It is the best suitable device to be used in the PDA, mobile phones, and other portable devices.

Here are the pictures;

Pila001

Pila002 (with 2 pcs. VM7205 ic)

Pila003

Pila004 (with 2 pcs. big white ceramic resistor 2WR22J)

Pila005

Pila006

Pila007

Pila008

Pila009 (with 2 pcs. High Current Voltage Regulator covered by aluminum heat-sink)

Pila010 (with 2 pcs. High Current Voltage Regulator covered by aluminum heat-sink)

verge · Feb 10, 2013

More information on the IC used in Pila IBC charger;

https://docs.google.com/gview?url=h...LiPo%20charger%20controller.pdf&embedded=true

VIMICRO
VM7205
July 2003 REV 3.0

_________________________________________
ADVANCED LINEAR CHARGER IC for
LITHIUM-ION AND LITHIUM-POLYMER Battery
_________________________________________

FEATURES

• Ideal for Single (4.2V) Li-ion or Li-Polymer Packs

• Better Than ±1% Voltage Regulation Accuracy With Preset Voltage

• Adjustable precharge current with an external resistor

• Adjustable Charging Current During Constant Current Charging Stage

• Constant Voltage Charging

• Automatic Battery-Recharge Feature

• Cell-Tempered Monitoring Before and During Charge

• Dynamic compensation of Battery Pack's Internal Impedance to Reduce Charge Time

• Charge Status Output for Dual Led

• Cell Condition Monitoring

• Automatic Low-Power Sleed Mode When Vcc is Removed or When Voltage Supply is Lower than battery voltage

• Requires Small Number of External Components

• Packaging: 8-Pin SOP or MSOP

-------------------------------------------

DESCRIPTION

The VM7205 series advanced Lithium-Ion (Li-Ion) and Lithium-Polymer (Li-Pol) Linear Charger ICs are designed for cost-sensitive and compact portable electronics. They combine high-accuracy current and voltage regulation, battery condition monitoring, temperature monitoring, charge termination, charge-status indication, and internal impedance compensation in a single 8-pin IC. It is the best suitable device to be used in the PDA, mobile phones, and other portable devices.

The VM7205 monitors the battery charging status by detecting the battery voltage level. The VM7205 charges the battery in three phases: conditioning, constant current, and constant voltage. If the battery voltage is below the low-voltage threshold, Vmin (normally at 3V), the VM7205 precharges using a low current to condition the battery. The conditioning charge rate can be adjusted with an external resistor. After the battery is precharged to Vmin, the VM7205 applies a constant current to the battery. An external sense-resistor sets the current. The constant-current phase continues until the battery reaches the charge-regulation voltage (normally at 4.2V) and then the VM7205 begins the constant-voltage phase. The accuracy of the voltage regulation is better than ±1% over the operating-temperature and supply-voltage ranges. Under this stage the charging current will gradually decrease. Charge stops when the current tapers to the charge termination threshold, ITERM. The VM7205 will continue monitoring the battery voltage level and entering a new cycle of charging if the battery's voltage level has fell below VRECHG (normally at VREG - 125mV).

During the charging process, for the safety concern, the VM7205 continuously measures battery temperature using the battery's internal heat sensitive resistor and an external resistors. If the temperature of the battery exceeds the pre-set temperature range, the charging process will come to a halt after 0.5 seconds; After the temperature fell back into the pre-set temperature range, the charging will continue again after 0.5 seconds. The VM7205 can also dynamically compensate the battery pack's internal impedance to reduce the charge time.

-------------------------------------------

__philippe · Feb 10, 2013

Thanks for your Pila IBC "insider" pictures.

Definitely looks like quality construction with solid material and premium components.
Pila good reputation stands on firm foundation...;-)

Cheers,

__philippe

LEDAdd1ct · Feb 10, 2013

Awesome breakdown!

Paloa · Feb 10, 2013

Thank you for that detailed inside look. Glad the internals match the reputation.

The_Driver · Feb 10, 2013

The problem with the Pila is that it "cooks" (i.e. warms them up) the batteries, because those 2 heatsinks are directy below the battery bays. If the heatsinks were somewhere else the batteries wouldn't get warm at all. The Pila is also rather slow if you want to charge newer, high-capacity batteries like the ones with 3400mAh Panasonic cells inside.
Newer chargers like the Xtar SP2 are imho much better and cheaper.
That does not mean though, that the Pila isn't nicely made

.

Norm · Feb 10, 2013

The_Driver said:
The problem with the Pila is that it "cooks" (i.e. warms them up) the batteries, because those 2 heatsinks are directy below the battery bays. If the heatsinks were somewhere else the batteries wouldn't get warm at all. The Pila is also rather slow if you want to charge newer, high-capacity batteries like the ones with 3400mAh Panasonic cells inside.

Had my Pila for a number of years, I've never had a battery more than lukewarm, the photos to me just confirm the quality.

Norm

The_Driver · Feb 10, 2013

Norm said:
Had my Pila for a number of years, I've never had a battery more than lukewarm, the photos to me just confirm the quality.

Norm

Any warming of the cells is bad since the li-ion charging process is like 99% efficient. There should be no heat at all, especially at these low currents.
Any I never said that isn't of high quality. I just think the design is a bit flawed and I think it's a bit too expensive for what to you get these days.

You have to agree though that putting heatsinks, which are in a plastic enclosure (the case), directly under the charging cells is not the smartest thing one can do...

Norm · Feb 10, 2013

The_Driver said:
The problem with the Pila is that it "cooks" (i.e. warms them up) the batteries, because those 2 heatsinks are directy below the battery bays. If the heatsinks were somewhere else the batteries wouldn't get warm at all

The_Driver said:
Any warming of the cells is bad since the li-ion charging process is like 99% efficient.

You said "cooks" most people would read cooks and think hot cells, that simply isn't the case, my cells come of the charger just barley noticeable warmer than room temperature, which isn't going to damage cells. I haven't ever seen or heard of heat being a problem with the Pila, links to back up your statement please.

The cells would be subject to far more heat on a hot summers day here 40c +, much higher than they would experience during charging using the Pila.

Norm

Let's not take this thread further off topic.

Thanks for the excellent pics verge.

verge · Feb 11, 2013

The Pila IBC charged my AW 18650 2900mAh protected batteries for more than a year now and continue to do so. The way I see it, this Pila IBC charger was built to last for a long time. The selection of case material and electronic components just shows that saving on parts cost is probably not big concern to its manufacturer. They just wanted to build the best Li-ion charger at that time. The placement of components is not helter-skelter and I really like that everything is soldered and bolted to the circuit board. The circuit board is slide fit and guided to the case.

I wished I was able to take an up-close and clear photo of its VM7205 ic, but the letters on the ic are almost the same color of the body I had to use a jewelers 10x loupe to read the letters and numbers printed on the ic. This charger is top notch.

I hope somebody attempts to hack this charger and add charging currents of 1A and 2A like the Xtar SP2.

AnAppleSnail · Feb 11, 2013

verge said:
I hope somebody attempts to hack this charger and add charging currents of 1A and 2A like the Xtar SP2.

You may need to add a small case fan at those currents. The build quality shown in there amazes me -- My charger is an Ultrafire with the chemistry options I need. Pila seems to have right-sized their components to last a long time as used. Running at higher current -- Assuming that the parts have the electrical capacity -- will likely require added cooling. How small do they make little fans?

Again, thank you for the pictures showing this well-built machine!

HKJ · Feb 11, 2013

Interesting to see the inside of the Pila.
I am surprised by the power resistors and the heatsinks, it does have higher input voltage than normal for linear chargers (normal 5volt, Pila 6 volt), i.e. it need to get rid of more heat, but not that much more. Many modern chargers uses 12 volt input and a switching regulator, this also keeps the heat low.
Except for the switch on the minus terminal (I assume it is meant as a switch), it looks like a very robust construction.

verge · Feb 11, 2013

https://docs.google.com/gview?url=h...LiPo%20charger%20controller.pdf&embedded=true

2. Current Regulation Phase

After the battery voltage level reaches VMIN, the
VM7205 enters the Current Regulation Phase.
The charging current is set as: Ireg＝Vcsreg/R1.
Therefore, the charging current can be set to a
desired level by adjusting the external resistor
(R1).

Is this as simple as replacing one resistor (R1) to raise the CC of Pila IBC from 600mA to 1A?

Norm · Feb 11, 2013

verge said:
Is this as simple as replacing one resistor (R1) to raise the CC of Pila IBC from 600mA to 1A?

Providing the existing PSU can handle the extra current.

Norm

verge · Feb 11, 2013

Norm said:
Providing the existing PSU can handle the extra current.

Norm

Do you think VM7205 can also handle output current of 1A to 2A?

tobrien · Feb 11, 2013

thanks for those photos. It'd be cool to see if Pila updated the charger at all some way or another. I can't really think of much else it needs though

madecov · Feb 12, 2013

I've had my PILA since 2008 or 2009
Still going strong and no indications that there are any problems.

verge · Feb 12, 2013

Looking at Figure 5 of VM7205 datasheet, and comparing it with Pila IBC circuit board, I figured that replacing the 2W 0.22 ohm ceramic resistor (R1) with a 0.15 ohm ceramic resistor would change the charging current to 1 ampere. Do I also need to raise the power rating of the R1 resistor?

The psu that came with the Pila IBC is already rated 6V and 2A, so replacing it is already sufficient for the job.

Any other thoughts or suggestions?

Norm · Feb 12, 2013

verge said:
The psu that came with the Pila IBC is already rated 6V and 2A, so replacing it is already sufficient for the job.

IMHO The power supply is rated at 2A so a certain safety margin can be maintained, you want to charge two cells @ 1A, right on the maximum rating of the PSU without any overhead to run the charger itself.

Norm

verge · Feb 13, 2013

Will it hurt the charger and battery if I used a 12V with higher amp (4A?) rating psu instead of its supplied 6V 2A psu?

A look inside my Pila IBC charger

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