DIY simple lipoly charger - Page 11 - RC Groups
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Apr 07, 2003, 06:36 AM
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billystiltner's Avatar
I just use a 145mah and 45mah so far.
I have shorted the 145mah out a few times.
I fixed the problem by adding some epoxy to where I soldered the wires to the plug. I used female plugs on the battery and male on the rx and charger. Shorting the 145mah didnt vaporize anything but once it shorted while measuring voltage with one of my voltmeters. It(the voltmeter) has the low battery indicator on constantly now, even with a fresh battery installed. The lipoly still works fine. Each time it shorted it was only for a split second except for the short while measuring voltage which was maybe a little longer than a split second. I dont use a glass container but I am always in the same room with the battery when charging. I would probably use a glass container though if I had larger cells or charged multiple cells. .
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Apr 07, 2003, 06:56 AM
Thats NOT indestructible
j8m8l's Avatar
Hey Guys

Is it just me or has the SH Designs site gone down?

If so can somone email me the schematic, and thet thing that says how to change the voltages and currents



My email addy is
Apr 10, 2003, 01:43 AM
Registered User
billystiltner's Avatar

I missed this when you posted.
The site seems to be working now and Scott has a new schematic up with lots of options.

I went ahead and sent you the files all zipped up.
Apr 15, 2003, 11:03 PM
Alfredo Rubio's Avatar
Hi guys.

Andy, I maked my own charger from your diagram, but when I take the numbers, the out voltage is 12 volts.. the multiturn had 3 pins, I only soldered the 2 than are closer, do you can post some pics, as I do not know about electronic I understand better with your diagram and pics, when I turn the screw in the multiturn, the voltage down to 11.20 V. and the R3 I found is 3.3 ohms to 2 Watts. Thanks for the help.
Apr 16, 2003, 01:35 PM
Alfredo Rubio's Avatar
Andy, forget my last post... It works, and works great, even I installed an std. resistence in R3, works great.... this little gems, the 145 mah Lipoly cell is great...

Thanks Andy.

Ohhh!!! before I forget, the total cost of my charger is $ 4.20 Dlls!!! Not bad...
Apr 17, 2003, 04:05 PM
Oxford Panic
AndyOne's Avatar

I'm glad you got your charger to work, I share your sense of satisfaction, espesially as you managed it at such a low price.

If you are using Kokam cells these are charged at 4.2 volts for each one in series to be correct. If you are using 3 in series you will need to set the output voltage to 12.6Volts to charge corectly.
Please post a comment on this or send me a private message as I may be able to help.

Apr 17, 2003, 10:21 PM
Alfredo Rubio's Avatar
When I conect the battery to the charger, the voltage grow from 3.8 in the start, and 1 hour letter the voltage is 4.5... If I remember well.

How many batterys can I charge? I only have 1 cell, but I want to get more... thanks.
Apr 18, 2003, 06:27 AM
Oxford Panic
AndyOne's Avatar

I guessed incorrectly that you wanted to charge a 3 cell battery.

To charge a single cell, the voltage should be set to 4.20 volts as close as you can get ie. between 4.15V and 4.25V. The output voltage of the charger will be held down at the begining of the charge and it is the cell that will control the voltage. Towards the end of the charge, the charger must control the voltage and limit it to prevent overcharging of the cell.

4.5V is too high and will damage the internal working of the cell. It is also unsafe to charge to a voltage higher than recommended. You may have seen further up this thread about the dangers of overcharging.

With the circuit as shown you can certainly charge a 2 cell battery but you would need more than 12V at the input, at least 16V for a 3 cell battery.

When charging multiple cell batteries please read the comments on safety further up this thread.

Apr 20, 2003, 02:13 PM
Alfredo Rubio's Avatar
I was wrong... the voltage in the end is 4.25

but as the charger is inexpensive, I will to make more chargers to each cell...

Apr 20, 2003, 05:11 PM
Propellers are cool.
propfan's Avatar
I've nearly finished an SHDesigns charger - just needs a connector and an LED. The voltage isn't right but it just needs a little adjustment.
I had trouble finding a combination of resistors to get 0.65 ohms (1 amp for 1020s). I ended up buying 3 packages of 10 ohm 1/2 watt resistors and wiring them all together (15 total for 0.67 ohms). Not pretty but it seems to work. (I'll find out when my batteries arrive! )
Apr 20, 2003, 05:31 PM
-plancks only-
Franck's Avatar
propfan, your solution should do.

I cant express how very pleased I am with the design, It charges my 3s1p Etechs 1200 perfectly, no hazards, and fully automatic (dont discharge the cells below 3Volt each though, in this condition cells need to be tricklecharged)
Last edited by Franck; Apr 22, 2003 at 12:58 PM.
Apr 22, 2003, 11:30 AM
Registered User
how done you one to know if the KOKAM is charged?
Apr 22, 2003, 11:13 PM
Registered User

i need schematic

can some one send me the led schematic? ill also need the resistor values.
is there any way this charger can charge bigger or smaller cells? such as the 148's and 48's? how about 1700's?

i might make a couple chargers for each of the different cells

my mail is
Apr 23, 2003, 10:54 AM
Registered User
billystiltner's Avatar
The charge is complete when voltage reaches 4.2V or current drops to .1 C

If the charger is working correctly and the charge started with .7C.

for which charger?
Apr 23, 2003, 11:15 AM
Registered User
Goodychrischild's Avatar
Has anyone worked out an LED circuit for the Andyone charger?
I can't find a small panel meter for less than 4GBP (like $6!) so an LED circuit would be better. I have built 2 of these chargers and they are working great but I am constantly monitoring with my meter at present as there is no fixed indication. I don't mind if there are several components involved, after all it shouldn't put people off building a charger without it if the want the lowest component count but it would be nice to have the option to add this feature if required.