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Old Mar 11, 2003, 07:16 PM
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Upstate New York-- Rochester, NY USA
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Radio Shack Li-Ion charger $.97

After reading the thread here on the $1.99 Li-Ions at Best Buy, Went a bought a several packs. It is a Flashing Battery for a NOKIA phone, says High Capacity Lithium-Ion Cells. Took apart one of the batteries and removed the curcuit boards ended up with a nice cell, about 16 grams.
Well needed a charger for the batteries, to build one as indicated on this forum, went to Radio Shack to get some parts, talked with the guy behind the counter about needing a LI-Ion charger and he had a discontinued Plug in the cigar lighter RS charger for Qualcom Q cell phones. Well for $.97. Thought I would take a chance and try a couple out...
Well, the charger puts out 4.2v and charged a single cell just fine, no heat, nor major problem... Current started out about 500mAh and dropped steadly over the couple of hours of charging down to about 50mAh, when the led on the unit was dimmer but not out, but the output voltage was 4.3v Not sure if the 4.3 is a Killer or with in the error of my measurement...
The charger is Cat. #273-1229A Cigarette Lightr Adapter/Charger, for use with Qualcomm Q phones.


PS> There are some nice surface mount Blue LEDs on the circuit board, will only turn on at about 2.3-2.5v, AS IS, with no additional parts. have added one to my bitcharger conversion for low voltage detection.

Any thoughts??? on the 4.3v is this a killer???

Carl
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Old Mar 12, 2003, 10:02 PM
RIP "Long Shadow Flyer"
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Upstate New York-- Rochester, NY USA
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These chargers seem to be working great with the Nokia Batteries. Removed the circuit boards from the plastic case and mounted them in a case I had for an Computer External drive. The case has a nice 12v power supply and fan built in. Will be adding 2 more boards tomarrow to charge 4 cells at a time...
Will post a picture when complete.
Seems like my concern on the 4.3v appears not to be a problem, (may be error in my meter), that is where these batteries seem to peak, the current draw drops to near 0 and the Led goes almost out.
Have charged 6 cells and am impressed with how well these chargers work... Cycled one of the cells 2X and seems to work fine.... hehe!! Yipeeeeeeeee!

Went back to the Radio Shack store and bought the rest of what they had... ( I now have 6 in All)

Now I will have a 4 cell charger for $4.00 plus the $1.00 I paid for the external drive case at an electronics flea market...

Carl
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Old Mar 13, 2003, 05:44 AM
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crvogt,

Can you measure the amperage the charger is putting out?

With that info, the time it would take to charge various sized LiPos can be calculated - thanks ...

- Jube
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Old Mar 13, 2003, 10:42 AM
RIP "Long Shadow Flyer"
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The chargers are "constant voltage" so the current changes as the battery charges.... It starts out about 500-600mA and drops constently as the battery charges...

Attached is the picture of the 4 charger boards mounted in the external drive case...

Carl
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Old Mar 13, 2003, 05:57 PM
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Very creative, Carl. Nice work.
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Old Mar 13, 2003, 07:51 PM
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Can you charge a 2-Cell Qualcomm 830 Lion pack with this Radio Shack Cigarette plug Charger? or just 1 cell?

-Mike-
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Old Mar 13, 2003, 08:27 PM
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Guys,
The unit you describe is a voltage reg, i.e., it puts out constant voltage only. It depends on the PCM you removed from the Li Ion cells to protect the cell from overvoltage. The caution is to be very careful and not to leave the charger unattended since you have no PCM on the cell any more and Li Ions are explosive if overcharged.
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Old Mar 14, 2003, 06:06 AM
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Way back when (seems like a thousand years ago - actually, about 5 or 6 months, I think), asperkins described his method for charging Qualcom LiIon cells.

He simply put the PCM he removed from the Qualcom pack in series with the charger, for charging only. That protected the cell from overcharging.

- Jube
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Old Mar 14, 2003, 08:11 AM
RIP "Long Shadow Flyer"
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Upstate New York-- Rochester, NY USA
Joined Oct 2001
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So far the only Lithium batteries I have are the Li-ion cells from the Nokia "Blue Products" Flashing batteries purchased from Best Buy. The PCM circuit boards have been removed. They are single cells 3.7v at about 750mAh as indicated on another thread....

http://www.rcgroups.com/forums/showt...threadid=95468

I only charge single cells on my charger.... since the output of the charger is only 4.2 volts....

Note:
Saftey,
1. I wear Saftey Glasses
2. Charge only while the charger is attended
3. Batteries are placed on a Metal kitchen counter top protector while charging.
4. Have Ammeter and Voltmeter connected to one of the cells to monitor progress...

So far there has been no heat produced by the batteries, stay cool and no indication of a problem. As the voltage approaches the 4.2v level the current goes to <50mA..

I will try to add one of the PCM boards (removed from teh batteries) to the output wire from each of the charger boards. Sounds like a good idea, will see what happens...

Thanks for the input
Carl
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Old May 31, 2003, 05:50 AM
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Upstate New York-- Rochester, NY USA
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Update

Went to Radio Shack the other day, they are "blowing out" another Cigarette Lighter Charger for only $.97. Cat No. 17-616 (for use with Nokia Wireless Phones).
These have a 10v output after checking the circuit board vs the last ones, found that it appeared that only the value of R7 was different. I put a 50K pot in place of R7 and can vary the output from 4.6-12.47v. I can set the output to charge 6 or 7 cell packs.

The circuit board is a Unitec charger board (seems common on these RS chargers) and uses a MC34063 Monolithic switching regulator.
http://www.intusoft.com/onsemipdfs/AN920-D.pdf
http://www.unisonic.com.tw/products/icpdf3/MC34063.pdf

So far the only problem I have had with these charges is with connecting a battery backwards. DO NOT connect a battery backwards, I blew out one of the boards. Use polarized plugs to prevent reverse hook up.

My plan is to make up another 6 pack Nimh charger, switchable for 6 and 7 cell packs, current limited to 500mA.

Will keep you posted..
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Old May 31, 2003, 06:50 AM
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Here is a picture of the Charger
Carl
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Old Aug 28, 2003, 05:22 PM
MX
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Carl,

Is the 17-616 good for LiPoly? Can't tell from your description.

Thanks,

MX
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Old Aug 29, 2003, 10:15 AM
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When set to the proper voltage, any constant voltage source can be used to charge LiPoly cells. However, GREAT CARE MUST BE USED because these constant-voltage sources lack the intelligence of the automatic LiPoly chargers.

As the battery charges, the current will automatically taper off as the voltage of the battery gets closer and closer to the voltage of the charger. That's physics, but it can also bite you on the petard. If the voltage difference between charger and cell is too great, the charge current will be very high, too high in many cases.

Charge current is determined by the difference between the voltage of the battery, and the voltage of the charger. Again, physics, nothing magical about it.

To keep the charge current down, you need to charge the batteries in stages, as the automatic chargers do. You'd really need an ammeter inline between the charger and battery, as well as a voltmeter across the battery terminals. Watch the ammeter to make sure the current isn't exceeding 1C, or the battery's capacity, and adjust the voltage from the charger to keep it that way, making sure you don't exceed 4.2 Volts per cell. Once you hit 4.2 Volts per cell, the charge current will slowly taper off to zero.

Frankly, it's much easier to do it with an automatic purpose-built charger...
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Old Aug 29, 2003, 10:21 AM
MX
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I have one automatic charger, which I built from the design at
www.shdesigns.org. Problem is, I now have several LiPolys
and at 2 hours each, it's getting difficult to get them all charged
by the time I need them. I have some of the radio shack 17-616
chargers and was hoping to modify them so I can charge several
packs at a time. I'll probably modify one and monitor voltage
and current and see how it does.

Thanks,

MX
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Old Aug 30, 2003, 08:51 AM
RIP "Long Shadow Flyer"
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Upstate New York-- Rochester, NY USA
Joined Oct 2001
732 Posts
I have built 2 charging units now, one unit has 4 of the RS chargers (originally designed for Li-Ion phone batteries) set at 4.2V. I used it last winter to charge single cell Li-ion batterys for indoor planes. The second unit has 6 of the RS chargers each charger has a toggle switch to select 8.4v or 9.8v.
I have been using it to charge 6 and 7 cell NiMh and Ni-Cad packs. I have been very pleased with the results, none of the batteries charged by these units have gotten warm or had any problems...

The Circuit boards in these chargers can be modified with a potentiometer to provide various voltages for charging. For example if you adjust the onboard Regulator to give 8.4v it will not output anything above 8.4. When the charger is set to 8.4V they will start charging at about 800-1000mA untill the voltage begins to rise in the battery, then the current drops constantly till the battery is charged to 8.4v. The Leds show the current, bright at first when the current flow is high, then go very dim when the battery is charged.

Hope this helps,
Carl
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