$10 3S A123 charger. - RC Groups
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Sep 25, 2007, 03:19 PM
Southern Pride
everydayflyer's Avatar

$10 3S A123 charger.

This Tread startred out as a Zip (speed ) charge for the 2300 mAh cells before the 1100 mAh cells were available.
One person todate has reported Zip charging the 1100 mAh VPV 3S pack.


The MUS 3S A123 2300 mAh battery now has 269 flight
and 246 Zip charges on it

First let me say that if you are not an avid DIY type and do not understand such then do not try this.
This is only suitable for charging 3S A123 (M1) packs and must not even be considered for any other type of battery!

There are several or more using this type of charging setup and it is safe in the hands of knowledgeable / experienced users.

I feel that this is indeed safer than most attempts at saving damaged / over discharged LiPoly.

Photo shows A DVM being used with a current shunt in line measuring amps. and there is also an Eagle Tree Micro Loger being used to log the charge.

Link to my shunt post.


See post # 5 for follow up data.

Note: It turns out that this zip cord is close to 17 gauge as per being masured and compared to deminsion from wire gauge chart.

Added CBA graph to track pack life.

10-2-07 Added another graph and supporting data .

10-10-07 Graph of Dsch # 140 added.

10-14-07 Logged flight # 162 today on Ultra Mini stick and this 3S pack. pack now has 142 Zip charges total of 165 cycles and there is no noticeable decline in performance or flight times.

11-06-07 CBA graph Dsch #194 added

11-18-07 Flight # 200 today

12-09-07 228 flights / 205 Zip charges . No noticeable drop in performance or capacity. Run right before last flight 325 watts @ 32A and after 8 min. flights still takes 1800 to 2000 mAh to recharge.

12-03-07 Added 6S split pack here:


Update :12-16-07 Dsch # 250 and 251 here:


Latest improvement and it is a great one ,IMO.


and the DIY Thread is


My latest BD Terminator in its' new house.

Last edited by everydayflyer; Feb 25, 2008 at 10:17 PM.
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Sep 25, 2007, 04:05 PM
rroback's Avatar
How many cycles have you had on direct, 12v charging of your a123 packs? I'm thinking of wiring up a 12s2p pack as four, 3s2p packs so I can charge direct. I'd be doing that at the field, and then balancing/slower charging at home.

Sep 25, 2007, 04:58 PM
Southern Pride
everydayflyer's Avatar
Approx. 30 cycles on the pack I run in my RC Truck but only three on this new(?) pack which I am using in my Ultra Mini Stick.


I do not believe that such fast charging will be very conducive to long battery life but then these cells are cheap enough that I really do not care if they do not last hundreds of cycles.
This battery was charged at 10A for the first 20 cycles and it was monitored and balanced as necessary during those cycles. Cycle 15-20 required no balancing and imbalance was always less than 0.03
v during those 5 charges.

Stopping charge at 1A resulted in .

Cells are right at 4.0 v ea. after a few minutes. I plan on stopping the charge at 2A the next time I go flying and check pack voltage there.

Edited as from memory was off a bit!

Flew 3 flights this evening and monitored each charge .

All three flights 8 minutes.

First charge stoped charge at 2A. / 5:30

Next two charges monitored with TP 101C /210V combo.

Start cells at 3.25
28 amps. / 5A rate at 4 min charged stoped / cells @ 3.9V imbalance 0.010

Start cell@ 3.27 / 26A at start / stoped at 4A / 5:41 / cells at 3.84 / imbalance 0.010.

Cells reach approx. 125F at the hottest point(s) I can find with my RAYTEK IR gun near the end of charge. Zip cord reaches approx. 120F.

Last edited by everydayflyer; Sep 25, 2007 at 08:21 PM.
Sep 25, 2007, 05:11 PM
Registered User
BEC's Avatar
My goodness - everything old is new again. This is one of the original charging concepts form the dawn of electric powered flight (say the mid to late 1970s) where one could charge an 8 cell NiCd directly from a 12V car battery, or a 12 cell NiCd from a series arrangement of three 6V motorcycle batteries, etc. There as well a length of ordinary lamp cord was used as a current-limiter......
Sep 26, 2007, 11:47 AM
Southern Pride
everydayflyer's Avatar

3S A123 Zip charge update

See post #1 for charging set data / photo.

I now have a total of 11 Zip charges on this pack.
I flew and data logged a 8min. flight and the charge following it.

Data for these on graphs.

Prior to first flight pac was zip charged last evening with a 1A stop point used. This morning cells were at 3.766 - 3.775 - 3.780

Second charge 27A @ start / 2:30 20A / stopped @5A

End of third flight cells 3.230 - 3.244 - 3.230
Start 26A
@ 1:30 21A cells 3.54 imbalance 0.005
@3:00 20.2A cells 3.56 imbalance 0.010
@ 4:30 19A cells 3.6 imbalance 0.010

@6:10 5A charge stopped cells 3.848 - 3.853 - 3.829 imbalance 0.014

Fourth charge

EOF cells @ 3.254 - 3.273 - 3.254 imbalance 0.019

Stopped charge at 13.5A 5:10

As a check used TP 1010C to top off.

1010C added 46 mAh in 1:18 cells 3.605 - 3.600 - 3.600 imbalance 0.005

My dual deep cycles were holding 12.42 under load and were at 12.71v 3 min. after last charge.

8 min. flights and 5 min. charges.

The fact that this pack is very difficult to remove for a pack change for additional flights make no difference now. I can live with a 5 min. wait between flights.


A balanced pack stays balanced if not discharge to deeply. Charging at extreme rates does not effect balance to any measurable degree.
When charge rate drops to 15A it drops like a Hawk in a dive and from all indications pack is fully charged. This also happens to be the point were cells start to increase in temperature noticeable.

I just happen to have an old Astro Flight Nicad charger with a 0-15 min. spring powered timer. Now if I can find it ( darn this move) I will use the timer and set for 5 min. after a normal flight just incase I get distracted. I can always restart it to check amps. and perhaps I will add another DVM to read pack voltage.

Last edited by everydayflyer; Sep 26, 2007 at 12:10 PM.
Sep 26, 2007, 03:18 PM
Permanently Banned
a VOLTAGE CLAMP is much easier
Sep 26, 2007, 03:35 PM
Registered User
Dan Baldwin's Avatar
Originally Posted by hall woo
a VOLTAGE CLAMP is much easier

A "VOLTAGE CLAMP" is much easier than a piece of wire?!?!?!?!?
Sep 26, 2007, 04:04 PM
Permanently Banned
YEP, don't need any extra wires just plug n play after SETUP
Sep 26, 2007, 05:15 PM
"Each Day Is A Lesson"
diver don's Avatar

Without a doubt, that is the ugliest 3 cell pack I have ever seen.

You love your goop, don't you.

I'm sure it functions a lot better than it looks.

Sep 26, 2007, 06:04 PM
Southern Pride
everydayflyer's Avatar
Originally Posted by diver don

Without a doubt, that is the ugliest 3 cell pack I have ever seen.

You love your goop, don't you.

I'm sure it functions a lot better than it looks.

Well if I took one of your packs and ran it in my Mamba Max Powered Traxxas Rustler in the rain , mud etc. for around two hundred runs it most likely would look kinda ruff also.

Yes I love my Goop fact is my sweet wife picked up two more tubes of it for me yesterday.

I have had club members kid me about my ugly planes and my standard reply is at 50 feet and 50 MPH they look just fine.

Sep 26, 2007, 06:24 PM
"Each Day Is A Lesson"
diver don's Avatar
Good point.

Sep 26, 2007, 08:03 PM
Fly Backwards
hcopter's Avatar

I'm surprised to see such high amps from your zip charger. Are you sure that is 20 gauge cord and not 16 ? I am using 10 ft of 18 gauge and never see over about 15 amps at the start of a charge. I usually pull mine off when they hit 4 amps as voltage is over 11 and climbing fast by then.

Sep 26, 2007, 08:29 PM
Southern Pride
everydayflyer's Avatar
Are you sure that is 20 gauge cord and not 16 ?
Well it is marked 20 gauge but being it was a cheap extension cord who knows.

Wire chart here:

list 18 ga. as 6.385 Ohms per K and
20 ga. as 10.15 Ohms per K

You are using 10 ft. and I am using 8 ft. if you are interested enough I guess you could do the math. Higher amps just means a faster charge and amps are down to 20A in approx. 2 to 2 1/2 min. and the battery barely gets warm.
I have charged the old ugly Truck pack at over 40A in something like 4 minutes in the past and it is still alive and well.

11th attachment here:


A blip (mis connection) at over 100 amps. and the upon reconnect initial inrush 78 amps. average over 30A.
Last edited by everydayflyer; Sep 26, 2007 at 09:10 PM.
Sep 26, 2007, 09:03 PM
Fly Backwards
hcopter's Avatar
Fun to play around with the voltage drop calculator on that page. 10 ft of 18ga with 12v source (not 12.6) and 15 amp load puts the voltage at the load at 10.03v which is pretty close to what I see at the beginning of a charge.
Sep 27, 2007, 11:52 AM
Southern Pride
everydayflyer's Avatar
Originally Posted by hcopter
Fun to play around with the voltage drop calculator on that page. 10 ft of 18ga with 12v source (not 12.6) and 15 amp load puts the voltage at the load at 10.03v which is pretty close to what I see at the beginning of a charge.

How good are your connections?

I am using very good gater clips, all connections are soldered ,my Deep Cyles have stainless steel screws and wing nuts and with 250Ah on tap I do not have much of a voltage drop.

As a test this morning I hooked my Zip Charger up to my field charging extension line which puts 13 feet of 10gauge between it and the deep Cyles.
At start of charge 17A and quickly dropped to 15A. (11.8V at charger input) I then connected Zip charger dirrect to Deep Cycle as per standard useage and charge rate was 22A.(12.4V at charger input )

For those keeping score pack now has a total of 41 cycles on it.
40Flights 1 CBA test, 19 TP1010C charges at 10 and 22 Zip charges.

First flight was last Sat. evening , 4 1/2 days ago.

Added: I stripped and measured an end I had left over and fact is size of wire is close to 17 gauge. Guess this is an above specification run of zip cord.

Last edited by everydayflyer; Sep 27, 2007 at 01:28 PM.

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