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!

various batteries. The pack used is in the lower right, with two cells already snipped off.

an exact match

a blurry closeup of the metal connector between the two tiny cells.

Wow actofgod, another great post. Looks like it may be another candidate for Bit Science, Great stuff :D.

WOW!!! You have some great ideas!! very interested in your other posts about the "adjustable" speed. Keep up the GREAT WORK!!

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.

Unfortunately, no. They are around 5mm thick each while the difference between the two types of cells is barely 1mm.

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.

another exact match

blurry closeup of installed cells

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

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. :)

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)

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.

HEY! I like this dual and triple cell mod. The run time would be pretty decent if peak charging. Although the motor you use and how you drive will determine run times (notice Tiny used 1.0 motor for his test). A faster motor will eat the juice faster. I have a dual 150 mah Zip Zap with clone pcb, NOS motor and I rarely charge it to full capacity or run it dead just because I don't have enough time to run it forever. I use a high end peak charger from my 1/10th scale RC cars to charge (I been watching Peak Char-g'd thread). I also have a couple of booster cars, which seem to eat the juice a little faster too. Even the stock 50 mah battery provides excellent runtime of 20 to 30 minutes depending on motor used. I guess I will try your battery mod in a booster to see how it works with peak charging. I also like the no solder/ no destroy for this mod. I was going to take a pcb from a booster and put it in a Zip Zap because it is easier to fit two 1/3aaa batteries in the chassis, but now I may hold off on destroying a booster car. Although I do like the longer wheelbase on the Zip Zaps, which handle real well at the high speed of dual cells (hmm, may try this mod on a Zip Zap too). Higher charge currents will kill a battery quicker. I been running 300 to 500 ma charge rate, just depends how long you want to wait for the battery to charge.

Went to radioshack.com and found these!

http://www.radioshack.com/product.as...Fid=960%2D0485

http://www.radioshack.com/product.as...Fid=960%2D0481

DOn't know if they would fit, but they sure do look like they would.

[EDIT] these aren't Nmih's and cost more :rolleyes:

That'd be nice if it worked. Usually though, NiCd's have a lower capacity for the same given size as a NIMH. I don't think these could be 150% the capacity and be the same size, but maybe someone can run by a RS and double check. I'll do it next time I'm there. Thanks for the links!

2 Battery packs on the way. I hope to make a 5-6 cell zip too.
Thanks for the idea.
JAredR420

act of god m8 cool mod! i just had a few quesions.

1) could this be charged from your controller? 3 cell or 2 cell?
2) what about a custom made 4aa battery charger?
3) how long would i need to charge?
4) could u please send me one of your 2cells and 3cell batteries please? id pay u of coarse.

thankyou very much

Originally posted by tarnjit
act of god m8 cool mod! i just had a few quesions.

1) could this be charged from your controller? 3 cell or 2 cell?

1) Just like any other dual cell setup, you'll need more voltage than the stock controller supplies. Use any methods that work on a normal dual cell setup, like wiring the controller's batteries straight to the charging posts or building a separate charger using multiple batteries or an AC-to-DC adapter. I'm using the adapter b/c I can then charge at a lower current -- that's safer on those tiny batteries.


2) what about a custom made 4aa battery charger?

2) Yes, that's enough voltage to charge either the dual-cell or tri-cell just fine, but I'd still prefer an adapter setup. The voltage and current stay constant and somewhat predictable with an adapter, unlike a battery-based charger.

3) how long would i need to charge?

3) No clue; I've never used a battery setup to charge dual or tri- cell bits. You'd need to know the current that those batteries put out so you could calculate it. Another reason to go with the adapter. If you're still interested in a battery-based charger, search the forum for others who have made one of these.

4) could u please send me one of your 2cells and 3cell batteries please? id pay u of coarse.

4) If you mean the battery packs, it'd be just as cheap to order from allelectronics.com as from me. $1.50 plus $6 flat rate shipping (get some other things while you're there). It is super-easy to go from a shrink-wrapped pack to usable batteries with just a pair of wire cutters.

Well i got done reading a charger adapter set that uses the TX itself instead of a seperate Project box. Basically what he did was he did the adpater mod, but did it to his remote. He got and adpater plug and put it on his TX. When the wall adapter is plugged into the remote the power from the batteries of the TX are cut off then the power from the wall adapter powers the Controller. I was wondering if this set up is able to charge these kinds of batteries??? I'm pretty sure it's possible but i want to make sure.


the credit goes to kameraguy from Micro Rc Center for the great idea.

Hi guys, I just mod my LXX nissan skyline castro with the layman tri cell mod and its awesome. Although it still can't wheelies with a 3.0 motor :(. I wanted to know how long should I charge for all 3 cell to get their full capacity with a standard lone charger I made. I can change voltage from the charger from 1.5v - 12v at 300ma. Any help would be greatly appreciate. Thanks

well i tried doing the layman's mod but i can't seem to get the batteries to charge? anyone got any clues how to fix this?

me neither, well i kinda get it to charge. I charge for like 5 min at 3v (300ma), it would only last about 5 min run time with a 3.0 motor. SOme one help us please. thanks

Charging FAQ
 

For those wondering about the charging voltage and charge time, see Namuna's post on the first page. I'll recap here:

1) Try to charge at the same voltage as the battery pack, but since they don't sell AC-to-DC adapters (that I've seen) at those voltages, go to the next step up. Ex: 2.4v dual cell = 3.0v charger; 3.6v tri cell = 4.5v charger. If you want to charge both types, get an adjustable charger.

2) Each adapter has a different current that it delivers, in mA. To figure out how long (in hours) you need to charge with a given current, divide the capacity of the batteries (40mAh) by the charge rate in mA. (ChilledOut says that rechargeable AA's put out about 1000mA if you're using them for a custom AA charger instead of using an AC-to-DC adapter.) Multiply by 1.2 to account for inefficiencies in the charging process, then multiply by 60 to convert to minutes. Finally, multiply whatever follows the decimal point by 60 to get the seconds.

Ex: using 300mAh charger, 40mAh / 300 = 0.13333
0.13333 * 1.2 = 0.16
0.16 * 60 = 9.6 minutes
0.6 (the part after the decimal in 9.6) * 60 = 36
final answer: 9 minutes, 36 seconds

Ex: using a 600mAh charger, 40mAh / 600 = 0.06667
0.06667 * 1.2 = 0.08
0.08 * 60 = 4.8 minutes
0.8 (the part after the decimal in 4.8) * 60 = 48
final answer: 4 minutes, 48 seconds

3) Once you have figured out how long you need to charge to reach *peak* capacity, keep in mind that that is the theoretically absolute MAX time you could charge. I recommend playing it safe and cutting it off a little before. It will decrease the lifespan of your batteries if you overcharge them. Each time they are overcharged, they lose some of their max capacity. Don't overcharge! Go back and do the calculations above again, and this time don't multiply by 1.2 in the second step. That's a guideline "safe" charge time limit that I use, but you'll have to decide for yourself how close to the limit you want to get.

Why does charging take so long? I did a little research on NIMH battery charging; normal, "overnight" charging is charged at "C/10", or the capacity of the battery in mAh ("C") divided by 10. Rapid, 1-hr charging is done at a charge rate of "C". For a 1500mAh AA battery, you'd charge at 150mAh for overnight charge and 1500mAh for rapid charge. They recommend charging at the high rate only until the battery is about 80% full and then "topping off" at a lower charge rate.

These tiny button batteries are 40mAh, so they'd be slow-charged at 4mA (!) and rapid charged (1-hr) at 40mA. We're super-rapid charging here, well beyond the recommendations. A 500mA charger charges at 12.5 times the recommended maximum charge rate.

Maybe they will handle this high rate, but the higher the rate you use, the harder it is on them. If you're willing to wait longer at a lower charge rate, you might be better off in terms of battery life. On the other hand, these batteries are pretty cheap if you buy several packs at a time when you order. It's up to you to decide what charge rate you will use. I'm going to use 300mA for now.

Your runtimes will vary depending on which motor you use. Tinyrc used a 1.0 motor to get the 45 minute results with a stock battery, and I'm not sure if that was driving around with steering or just running the motor while sitting in its back.

Troubleshooting:

1) Make sure the batteries are oriented correctly. The positive end is clearly marked with a + sign. That narrow end should face where the button tip of the old battery went, towards the side with the red wire. All batteries should face the same direction.

2) Make sure the batteries aren't contacting something on the PCB. If you have snipped the batteries apart and have a little space where the metal is exposed through the shrink wrap, turn it so that the metal faces sideways, away from the PCB. You can also try using clear tape on the bottom side of the PCB as an insulator. This may be your problem if it works with the PCB lifted up but does not work, or works sporadically, with everything put back together.

3) Charge at a voltage higher than or equal to the combined battery pack. If using AA's (not recommended), you'll probably need one more battery than the number of cells in the car, since they lose some voltage over time. I've had the most luck charging at 3.0v for dual cell and 4.5v for tri cell.

4) Test the car while on the charger to make sure it is getting a good connection. If it is not working while on the charger, it may or may not be charging the batteries, or your car may have a loose wire. Check the battery contact points to make sure they are all touching. Revert to an uncharged stock battery and test.

5) That's about all I can think of at the moment. If you're still having trouble, post details about what you're doing and what you've tried and maybe someone can help.

I have done all said and I too am having a problem charging. I can't even get a 10 sec run time. I have a 3v, 500ma ac->dc adapter. Measured output is 3.8v. Will not charge the tri cell mod I have done. Can anyone help?
JaredR420

Try a dual cell first.. if it charges that fine but won't charge the tri cell then you need more voltage. I use 3v for dual cell and 4.5v for tri cell. How long are you charging? What motor are you using?

I am using a bitmod 3.5. The car is slower than it ever was and lasts about 10 sec. I will try more voltage.
JaredR420

Looks goooood to me haha
 

ive never been too successful with any of the other dual batter mods , looks liek theres some hope now ! i hope?:rolleyes:

Whats the deal with charging these !@#$ things?
 

Ive been hearin a bunch of what-not about charging times and i have a few questions !
1) Do i have to buy a different charger for this mod ?Cant I use my stock charger

2) how does this dual mod compare to the other dual and even triple battery mods (speed wise)

Thanx for the cool mod act of god ! :D

I suggest taking the charging plate off the controller and wiring it to a 3-4 battery holder of your choice. I use 4 AAAs for my ZipZap, works great.

Originally posted by MadMicroDoc
1) Do I have to buy a different charger for this mod? Can't I use my stock charger?

The stock controller charger will not charge a dual or tri cell mod. Check out http://www.questformadness.com/ for some guides to making a custom charger. I wired an AC-to-DC adapter straight to an old charging base. There is a lot of information about regular dual cell mods in this forum; all of that applies equally to this mod.

2) How does this dual mod compare to the other dual and even triple battery mods (speed wise)

The voltage is the same; the weight is less. It may be a little faster. The tradeoff for the easy installation is less capacity though. As with the "standard" extra-cell mods, there is a more noticeable improvement going from one cell to two than from two cells to three.

wow what a great mod , it seemed easy at first and than u hit me witht he hard part charging it do those batteries come precharged cuz i think it would be easier just to buy new ones after every run lol

Actually, mine did come with a little juice in them (kinda unusual.. maybe they did a partial charge to verify the pack was wired correctly?) but it certainly wouldn't be worth buying new ones each time :)

It's really not very hard to make your own charger. Buy an AC-to-DC adapter rated between 300mA and 800mA, depending on how fast you want to charge (safety vs. speed) and get one rated between 3.0v (for two cells) and 4.5v (for three cells). I got a Radioshack Adapta-Plug so I could change the voltage. I also got a Hobby Leads adapter for it and soldered the two free wires directly to a charging base from an old clone charging pad, leaving the adapta-plug end sticking out a few inches. Now I plug the two ends together and charge away. Otherwise, you could just strip the wires on your adapter and wire it that way.

If you don't have a spare charging base from an old controller or something, I've also done it where I left the charging base in the controller and drilled a hole in the case to run the wire through to the base, then snipped the existing charging wires from the controller. You can connect the adapter directly to the controller then disconnect when the car is done charging. You'll have to time it yourself instead of watching the controller LED, of course.

that doesnt sound too too bad as soon as i scrounge up 20 bucks ill give it a try and than complain about it when i cant execute lol

maybe some pictures ?
 

hey do u think you could put some pics of makin that chrger ? Thanx, i already am hyped about this mod, i ordered two packs of those bats and a 2 AA holder ha then i almost sh!t myself when i found out you need a 4 AA holder !! haa well ill think of sumthing
which brings me to another point what the hell was i thinkign ??
haha cool mod actofgod

im curious can u use all of these batteries and do the same thing http://www.allelectronics.com/cgi-bi...-12&type=store :confused:

hmmm
 

Im not sure about those batts, looks like they might be a little too big :confused: Just finished the layman's tri and dual mods on a couple of my cars, check it out :)

another pic
 

another pic