TinyRC.com - XMODS, XMOD, Micro Flight, ZipZaps, ZipZaps SE, Bit Char-G, MicroSizers, TTTT, Plantraco Desktop Rover, SuperSlicks, Digi Q, Forums, News, Pictures, Parts, and Shop
Forums, XMODS, XMOD, Micro Flight, ZipZaps, ZipZaps SE, Bit Char-G, MicroSizers, TTTT, Plantraco Desktop Rover, SuperSlicks, Digi Q
XMODS Hop-Ups, XMODS Parts, XMOD Hop-Ups, XMOD Parts, Bit Char-G Hop-Ups, Bit Char-G Parts, MicroSizers Hop-Ups, MicroSizers Parts
  #1  
Old 01-02-2003, 08:40 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
Lightbulb The Layman's Dual Cell Mod (tm)

If you can swap a battery, you can dual-cell mod your bit!

This mod is for all the people who don't like the idea of using a dremel on their bit to do a dual cell mod. This is the easiest dual cell mod you can do since it fits in the original battery space without modification or soldering required.

Other advantages include the fact that it does not adversely affect your weight distribution. Your car will not flip over, spin out, or wheelie because of extra battery weight; in fact it weighs less than the stock battery which is great for those interested in trimming off extra weight to increase speed and acceleration.

The one disadvantage is that the capacity is only 40mAh, less than the stock NiCd's 50mAh and much less than the 150mAh NIMH replacements. *BUT* if you've been following the Peak Charg'd thread over in the Bit Science discussion area, you know that even the stock NiCd is not charged fully with the rapid charge method. A fully charged STOCK battery will run for 45 minutes if fully charged! So this one would run for "only" 36 minutes fully charged. You probably won't fill up the capacity anyway with rapid charging from the controller or a custom built charger, so it should run just as well as any other battery. I charge my Layman's Dual Cell with a 3v 500mah adapter for a few minutes and it runs longer than my stock controller-charged bit. You should probably charge at a lower current (250mah for a few minutes longer maybe) since the batteries are so small, but even if you manage to burn one out, you have four more batteries left from that original pack, and each pack of 6 cells is only $1.50 anyway. Pics are attached below.

Installation:

First, I have to thank Ovgron for finding the batteries I used. Check out allelectronics.com for the listing of the multipack we'll be using, CAT# NMH-11. If you do order this item and are already paying shipping, you should also check out my Infinite Speed Potentiometer Mod (tm) for a potentiometer that this store also sells, CAT# SVP-20.

First, remove the heat shrink from the batteries, and you're left with a string of six (not seven like the catalog says) tiny button cells, all connected by strips of metal. Snip off the two closest to the end with wire cutters (setting aside the other four for extras). Break them apart in the center (superglued) and fold them in half. You've just finished most of this mod!

Grab a bit battery (preferably stock since the NIMH replacement batteries are actually a little shorter) to use as a measure; bend the center metal piece still connecting the two batteries until the total length is the same as the bit battery. Now test-fit the battery inside your bit (the narrow end goes where the positive "button" end of the stock battery went). The idea is for the metal piece connecting the two tiny cells to serve as a spring to tension-fit the cell in place. You may have to trim any little bits of metal left from the original attachment and use a razor to scrape off excess superglue, but leave the center piece of metal alone. It takes a little fiddling to get it to fit correctly, but I've found that the easiest way to fit it is to put it in place while it is stretched a little wider than necessary, angling the lowest part of the metal connector down and pushing down on it with a small flat screwdriver. Once it is in place, you can take two small screwdrivers and pry the batteries apart, pushing against the terminals as snugly as possible. Test it before you put the PCB back on to make sure it is charging. Shake it around a little and make sure it is still connected. If not, you may have to put a dot of solder on the terminals to hold it in place (but since I promised you wouldn't have to solder, you can wedge a thin piece of metal in there instead). If you can't get it after several tries, take it out and stretch it back to the original dimensions, then try again.

This is the dual cell mod of choice if you want to have room for other mods and stay inside the stock case, like the Infinite Speed Potentiometer Mod (tm) mentioned earlier.

Let me know if you find this post useful or have any questions. Happy modding!

Last edited by actofgod; 01-02-2003 at 08:56 PM.
Reply With Quote
  #2  
Old 01-02-2003, 08:41 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
various batteries. The pack used is in the lower right, with two cells already snipped off.
Attached Images
File Type: jpg bitbattmod1.jpg (49.6 KB, 5754 views)
Reply With Quote
  #3  
Old 01-02-2003, 08:42 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
an exact match
Attached Images
File Type: jpg bitbattmod2.jpg (41.8 KB, 5710 views)
Reply With Quote
  #4  
Old 01-02-2003, 08:43 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
a blurry closeup of the metal connector between the two tiny cells.
Attached Images
File Type: jpg bitbattmod3.jpg (36.5 KB, 5558 views)
Reply With Quote
  #5  
Old 01-04-2003, 02:03 PM
kwikbb's Avatar
kwikbb kwikbb is offline
smoove operator
 
Join Date: Sep 2002
Location: East Coast Reprezent'n
Posts: 1,049
Wow actofgod, another great post. Looks like it may be another candidate for Bit Science, Great stuff .
Reply With Quote
  #6  
Old 01-04-2003, 04:56 PM
SPEED's Avatar
SPEED SPEED is offline
SPEED IS GOOD
 
Join Date: Aug 2002
Posts: 257
WOW!!! You have some great ideas!! very interested in your other posts about the "adjustable" speed. Keep up the GREAT WORK!!
__________________

SPEED-The state of being in rapid motion
Reply With Quote
  #7  
Old 01-05-2003, 03:07 AM
sessiz10's Avatar
sessiz10 sessiz10 is offline
Told ya.
 
Join Date: Nov 2002
Location: NY, USA
Posts: 1,214
Send a message via AIM to sessiz10
Okay, 1st this is a great mod, I hate solder never liked it never will. 1 question though. The 150 mah bats are smaller than the stock ZIP bats leaving some room between contacts in the chassis. Here is my question. Would it be possible to stick just 1 of those buttons in between the 150 mah bat and the neg contact on the chassis?
I'm going to order some of those bats anyway to do this mod. Once again excellent mod.
__________________
____________________

Meh.
Reply With Quote
  #8  
Old 01-05-2003, 06:32 AM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
Quote:
Originally posted by sessiz10
Would it be possible to stick just 1 of those buttons in between the 150 mah bat and the neg contact on the chassis?
Unfortunately, no. They are around 5mm thick each while the difference between the two types of cells is barely 1mm.

Last edited by actofgod; 01-06-2003 at 11:21 AM.
Reply With Quote
  #9  
Old 01-06-2003, 12:26 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
Cool The Layman's Tri-Cell Mod (tm)

Ok, only a few people appear to be interested in my dual-cell no-solder mod? How about three cells? Anyone else doing a no-solder, no-dremel, all-in-stock-body tri cell sleeper? Didn't think so.

This is even easier than the last one, believe it or not. It's almost a perfect fit, except like the last one the PCB is a little tighter when snapping it back on. I got mine back on though.. and this beauty can FLY. It practically goes up on two wheels when you're turning, even in the lower speed. Boost it and bye-bye...

Luckily with the potentiometer mod in place, I just dial the voltage down a little until I can keep all four wheels on the ground, heh. STILL no wheelies though, since it doesn't have all that extra weight to make it unbalanced. You can actually race with this thing, unlike the ones using three 1/3aaa batteries, since the extra weight doesn't make the car flip as easily, and the little weight that's there is centered where the original stock battery was. This will outrun any other three cell 3.6v mod.

Pics to follow.
Reply With Quote
  #10  
Old 01-06-2003, 12:27 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
another exact match
Attached Images
File Type: jpg bitbattmod4.jpg (43.0 KB, 5149 views)
Reply With Quote
  #11  
Old 01-06-2003, 12:28 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
blurry closeup of installed cells
Attached Images
File Type: jpg jan06#09.jpg (36.9 KB, 1743 views)

Last edited by actofgod; 04-23-2003 at 08:59 AM.
Reply With Quote
  #12  
Old 01-06-2003, 01:11 PM
Namuna's Avatar
Namuna Namuna is offline
Hulk smash!
 
Join Date: Jul 2002
Posts: 2,193
Send a message via AIM to Namuna Send a message via Yahoo to Namuna
While you're doubling/trippling the voltage, you're also losing as much on the amperage...Those button batteries are actually LESS on the mAH rating than the stock NiCads!

It's all up to debate (good work actofgod), off you go
Attached Images
File Type: gif bitscience.gif (20.4 KB, 4997 views)
Reply With Quote
  #13  
Old 01-06-2003, 02:53 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
Quote:
Originally posted by Namuna
While you're doubling/trippling the voltage, you're also losing as much on the amperage...Those button batteries are actually LESS on the mAH rating than the stock NiCads!
That's the drawback to using this method, but if I'm understanding the Peak Charg'd thread right, it shouldn't matter much.

Until I read the peak charge thread, I figured that since a 50mah stock battery charges in 45 seconds, a 150mah NIMH should get charged three times. But it turns out that regular charging only fills up a stock battery a tiny bit.

FMZPLAYER1 calculated that a single charge on his z-car charger gave the car 11mah, much less than a stock battery holds. So in theory, a 50mAh NiCd could hold a triple charge just like a 150mAh NIMH. The longer run times after installing a 150mAh battery came from the fact that I charged it 3x and expected it to hold the charge. I had never tried charging the stock battery more than once.

Tinyrc found that a peak charged 50mah stock cell, just 10mah more than one of these, will run for about 45 minutes. If I can find a way to charge this 3-cell pack to its maximum capacity also, I could expect it to run for 4/5 of that, or 36 minutes, unless I'm misunderstanding something.

What I'm working on now is figuring out the easiest way to get the button cells charged to their max capacity of 40mAh each, or at least as close as I can safely get without detection circuitry. I'm already using an adjustable AC adapter @500mA, set to 3.0v for the dual cell and 4.5v for the tri cell. What I need to know is if this is enough voltage for each set of cells for them to get the full 500ma current. Then once I know the current for sure, I can figure out how long I need to charge at that current to get close to the max capacity. I imagine I will need to use a lower charging current to be safe, like 100mA or 300mA.

Any thoughts? I'm learning this as I go -- corrections welcome.
Reply With Quote
  #14  
Old 01-06-2003, 04:13 PM
Namuna's Avatar
Namuna Namuna is offline
Hulk smash!
 
Join Date: Jul 2002
Posts: 2,193
Send a message via AIM to Namuna Send a message via Yahoo to Namuna
When you're charging batteries, you SHOULD be sending through a voltage that is EQUAL to the pack (2.4v for dual, 3.6v for triple and so on) going higher than the rated is overkill and could be detrimental.

How much amperage you send through is really up to how confident you are that the batteries can take it. Considering the stock Bit Charger (on the remote) PUMPS out ~2.5A, that 500mA adapter isn't going to hurt anything...Then again, you're using an AC adapter and not a proper DC adapter (unless you're using something to convert) but that's a different story.

...Anyway, for some math: Divide the capacity of the battery by the charge rate of the charger, then increase the amount of time by about 20% to allow for a certain amount of inefficiency (batteries and charging them is not an exact science).

- At 500mA, it would take a little less than 6 minutes to charge the 3.6v/40mAH pack (40mAH/500mA X 20%= hours needed to full charge)


Considering these calculations we can look at how much juice a Bit battery gets from a 45second charge @2500mA (the stock charger).
2500mA = 41.66mA pr/minute = .6944mA pr/second.

.6944mA X 45 seconds = 31.25mAH - 20% inefficiency = ~25mAH (so, a single charge on a Bit Charger is really only providing 1/2 the capacity of the stock 50mAH battery)
Reply With Quote
  #15  
Old 01-06-2003, 06:46 PM
Chilledout Chilledout is offline
TinyRC Pro
 
Join Date: Jan 2003
Posts: 19
namuna please confirm you electronics experties as you clearly think you are right in your previous statement.

But i do believe you have learnt something about electronics since you posted this as in one of your other posts yuo stated that you had been measuring the curent the remote pumps into the battery by shorting the charging terminals with your dvm and then measuring the current.

doing this you were only measuring the curent the transmiter could generate when the terminals were shorted. there is only one way to monitor the charge rate of the transmiter and that is by puting the dvm in series with the charging circuit in the transmitter.

i used this method to determine that rechargeable batterys are more effective at charging than akalines as akalines would startoff about 950mah the dro to about 850mah but when i used rechargeable batterys the charge current started at 1.05Ah and finished at 1ah.

Your calculations however are corect but just have the wrong data.

it should be with rechargeable aa's

1000mah/60 = 16.6ma/60 = 0.277 ma/sec

0.277 x 45 = 12.5mah

this is why people with peak chargers are reporting runtimes of upto 40mins.

i should get my new peak charger tomorow will let everyone know whether i can reciprocate those figures.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
which dual cell should i do, laymans, external, internal etc eman1 Bit Char-G / MicroSizers 11 09-02-2003 08:42 PM
Laymans cell mod Calsonic_racer Bit Char-G / MicroSizers 2 04-10-2003 07:40 PM
Laymans dual cell vs. traditional dual cell Zephyranthes Bit Char-G Mods and Projects 6 02-18-2003 07:12 PM
Dual cell mod ( will 2 - 50 mah's achieve + speed?) Suntzu28 ZipZaps 7 01-11-2003 10:57 AM
Dual cell mod and discharge problem (cell reversal). kenny_dilger Bit Char-G / MicroSizers 1 12-17-2002 11:23 PM


All times are GMT -5. The time now is 04:16 PM.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Mini Inferno Sale - Up to $85 Instant Savings!
Micro-T Hop-Ups
RC18R, M18, Micro RS4, Mini-LST, TamTech-Gear, Minizilla, RC18T, RC18B, RC18MT
shop.tinyrc.com Products
Tiny RC Community News
[03/17/10] Kyosho Mini-Z F1 MF-010 SP2... : The Kyosho Mini-Z F1 MF-010 SP2 Carbon Limited ASF 2.4GHz Tx-Less Chassis Set - more»
[10/23/09] Kyosho Mini-Z MR-03 In Stock! : The Mini-Z MR-03 (http://mr-03.com) is now In Stock and Pre-Orders are shipping! - more»
[09/06/09] Labor Day Savings - $5 Off... : Labor Day traditionally marks the unofficial end of summer - but we're not ready to let go! So, we - more»
Mini-Z, Mini-Z Racer, MR-02, MA-010
M18, M18T, RC18T, Mini-LST, Mini-T, Micro RS4, XRay, 1/18, 18th scale
XMODS, XMOD, Micro Flight, ZipZaps, ZipZaps SE, Bit Char-G, MicroSizers, TTTT, Plantraco Desktop Rover, SuperSlicks, Digi Q
Mini Inferno, Mini Inferno ST, half EIGHT, 1/16, 16th scale
Epoch, Indoor Racer, 1/43, 43rd scale
E-Savage, eSavage, eZilla, e-Zilla, HPI
Robots, Bots, Bipeds, Wheeled, Manoi, Roomba, NXT, Lego, Hacking
Crawling, Crawlers, Micro, RC, Losi Mini-Rock Crawler, Duratrax Cliff Climber
Kyosho Minium, Caliber 120, Minium Forums
Mini-Z Hop-Ups, Mini-Z Parts, Mini Inferno Hop-Ups, Mini Inferno Parts, M18 Hop-Ups, M18 Parts