The Layman's Dual Cell Mod (tm)

[chelboed]

I'm gonna have to disagree witcha there xatu. I use high torque 2.8-3.0'ish motors in my 3cell cars with high gears. I usually use the highest gears possible. This way, I can still somewhat pull wheelies, but I don't get too much wheelspin off the line. That's what I used in my 1.9 second scale 1/4 mile car.

[xatu]

Hmm, well, to each is own I say! I would rather use my 2.2 motor dual celled over my 3.0 ish motor dual celled.

[chelboed]

dat's Koo, yo.

Ya know actually I don't use my torquer 3.0's much anymore on my 3cell car. I have been racing on road courses lately and I need a 1.0 or less, believe it or not.

[xatu]

A 1.0 single celled? Dam, a single cell 2.2 car makes me cry.... It goes too slow!

[deoblehc]

Here ya go...I said 3 cell. Three sell. III CELL.

See? Road course is pretty tight. 3cell is rediculous with a fast motor on such a small tight course.

I agree though on the single cell car with a 2.2. SUX.

[xatu]

Nice course ya got there! It's a pair of glasses

[deoblehc]

Ho HO HO haha lol.

I just thought I'd give you a better chance at reading my previous posts a lil better.

[e_lm_70]

Originally posted by chelboed
I'm gonna have to disagree witcha there xatu. I use high torque 2.8-3.0'ish motors in my 3cell cars with high gears. I usually use the highest gears possible. This way, I can still somewhat pull wheelies, but I don't get too much wheelspin off the line. That's what I used in my 1.9 second scale 1/4 mile car.

Mumble Mumble ...

Made some test with the crappy 3x1.2V 40mAh cells !

As result the best motor was the 2.2 (I tested the 1.6,2.2,2.6,3.0).

The reason for this result was quite clear to me.

If you take a multimeter and you mesure the Volt around the 3cells while full power, you can see that this Volt drop a lot.

The reason of Volt drop it is becouse these crappy cells can effort to provide more then 150mA.

As consequence a more efficient motor with higer impendence will provide a better performance.

Very fast motor need lot of Amp and has lower Impedence ...

BTW At best I was able to run up to 45sec with these 3 cells ... to few and to booring to charge with an external device !

Using a 1.2V 200mA with a 3.8 motor I just lose 20% in performance but my car run over 10minutes and no problem using a standard charger !

e_lm_70

P.S: With some soldering skills is possible to fit up to 6 of these micro cells (1.2Vx40mAh) 5 below the PCB and one over. In this case having 3.6Vx80mAh the performance in speed and duration could be acceptable .... but I'm till not bored enough for spend time on try this out !

[e_lm_70]

Originally posted by e_lm_70

The reason of Volt drop it is becouse these crappy cells can effort to provide more then 150mA.

Sorry:

The reason of Volt drop it is becouse these crappy cells can't effort to provide more then 150mA.

[actofgod]

It's true that smaller cells provide less current than larger cells. When adding a second button cell, you're increasing the voltage and therefore increasing the ability of the battery's current to overcome resistance and reach the PCB/motor. As you add more cells, you reach a point where virtually all of the current that the tiny cells are able to provide is being used; at that point, adding voltage doesn't have any effect, and you only increase weight (though runtime may be slightly better). Three button cells is about the best performance you can get with this mod. It's also the easiest one to install.

Yes, using a more efficient motor really helps runtime. I use a motor from a cannonball clone, roughly a 2.2-2.6 I believe, and it has nice torque and good power usage. If you are only getting a 45-sec runtime, then you are not fully charging the cells. I regularly get 5-8 minutes of runtime before it starts to slow down, using a ac-dc charger and the formula found earlier in this thread to compute charge time needed. The voltage does drop off quickly as the cells lose charge, but if you charge them fully you'll get a lot more runtime before that happens.

That being said, the runtime will never compare to a fully charged 150mah battery, and you shouldn't expect it to. It is meant to be an easy replacement for the stock battery (50mah), with comparable runtimes. (You may have forgotten, but a stock car using a stock charger runs only a few minutes at a time.) If you want better runtimes for an endurance track, you can always swap out the button cells with a regular batt easily, since there is no soldering required. And a tri-button-cell car will *always* beat out a single cell car in a drag or short track by a wide margin.. just make sure you are getting it charged completely. Slower chargerate= safer, with best "topping off" ability. Faster charger= more likely to blow a battery, less likely to be able to top off the charge without going over or under.

You just have to keep in mind what this mod is for. Don't expect miracles, and you won't be disappointed.

Is it bad to "overcharge" your batteries? ie. if they are fully charged after 3 minutes but you left it on 4, is there any negative effect on performance?

[chelboed]

e_lm_70,


While you're mumbling there...

I was talking to Xatu about 3x standard nimh cells. I don't use the Layman's anymore. I hate the run time.

And yes, I actually fit 6x of the Layman's under the PCB, but performance was crap compared to 3x standard nimh cells. And yes, they were fully charged.

I don't understand your post. Do I bore you? Your 'gripping' little piece of literature isn't anything new either.

[Spongebob]

I thought the PCB could only handle 6 volts.

[chelboed]

Like I said, it ran terribly. The PCB got warm, but didn't fry. It ran okay, but I think it was a little too much for it.

[JackD]

Couple of questions.

Is a 4 AA Batt charger sufficient to charge a 3 150 nimh cell BIT ? I'm getting really short run times on my 3 cell BIT and I am not sure why. Should I make a charger with more batts ? RS sells an 8 AA batt holder for a charger, however, would an 8 AA batt charger be too much charge for a 2 or 3 cell batt ?