Safe 2 Cell mod

[rmyc]

this is my 2 cell mod.... it uses the second cell only when going forward( it could be change for revese or both)
the idea was not to hype up the bit-chip to 3v but only the motor
soo if some thing burn it would be the motor, and not the chip

E.E. , if there is any thing wrong with this , holla!!

thanks

[rmyc]

in froward

[rmyc]

in reverse

[john]

that's very interesting, and if it works would come in very handy. I have 2 questions:

Did you try it yet or is this just an idea you came up with?

Is there an easy way to charge the 2nd cell?

This could be a really sweet way to handle a 2 cell mod. I'll be watching this one intently! I don't see any reason why it wouldn't work, other than you're sending a different charge in series through the 2nd batt, but I'd think that it could take it.

[Bunta]

Hi rmyc!

I like your idea it is creative.

I have one question for ya,, how do you propose to charge the 2nd battery after it's discharged?

I think that the PCBs can handle a paltry 2.4 volts,, I've heard of some mad scientist who have used 9v and 12v!

good luck and keep coming up with them mods!

-Bunta out

[Dayfall]

Don't forget about the voltage drop across the diodes. I am not an EE mojor, but I have read that there is a 0.7v loss from the average diode. The transistors that run the motor loose about 0.2v each. I think a better way to do it is to find the power leads to the PNP transistors (and their pullup resistors), cut those leads, and run your 3v to them.

[rmyc]

Originally posted by john
Did you try it yet or is this just an idea you came up with?


well actually i havent tried it on my bit yet..
..i tried it on another motor and it work fine
i'll probably try it on my bit some time soon, but I DONT KNOW HOW TO SOLDER....lol
..as soon as i learn how to solder i'll do it, or i'll ask a friend.

[rmyc]

Charging

Charging hmmm....i haven't thought about it yet
...well cause they aren't really linked up. you could SOME HOW link them up paralell and double chage em with the stock charger

i'll figure it out sometime , someday

[Namuna]

..

[john]

What if both batteries where connected in parallel in addition to what you are talking about, but there was a switch to break the connection to the second cell for when it's running?

Wouldn't that effectively let you flip the switch to connect the positive terminals in parallel to charge it, and disconnect the positive terminals (with the switch) when you run it?

[NorCalCoug]

I've run 6 volts with no issues and flirted with a 12v garage door opener battery for a little bit. No motors burnt out yet, no bits burnt out yet. :)

[GT-ahh]

when you connect batteries in parallel it doubles the current not the voltage, so the motor would only be getting 1.5v or whatever.
and also you have to completely flatten both batteries in order to charge them or you get a memory effect, and as both batteries wont go flat at the same time this will be difficult.
btw, has anyone actually fried a circuit or motor from a dual cell mod?

[GT-ahh]

sorry to double post but just reviewing your schematic it does not look viable because the second battery has to be earthed to pump voltage into the motor and when you press forward the bit-chip pumps voltage out where youve got the 2nd battery should be earthed. you might even overload the circuit and then youve got one expensive fridge magnet....

[rmyc]

Originally posted by john
What if both batteries where connected in parallel in addition to what you are talking about, but there was a switch to break the connection to the second cell for when it's running?

Wouldn't that effectively let you flip the switch to connect the positive terminals in parallel to charge it, and disconnect the positive terminals (with the switch) when you run it?

yah that's what i thought about ...

[rmyc]

Originally posted by Namuna
..

Thanks y'all..it's a big honer for me to be moved to BIT Science.
*sob**sob*

Thanks

[xatu]

Rmyc, do you have some ACTUAL, real life pictures of it? I want to see some, because I want to make this, just because I want my car to go faster! :D

Thanx!

[Chilledout]

sorry lads this would work but there is one flaw tell me what you have when the bit is neither in forwad or reverse. the 2nd battery is being shorted through two diodes which for this to work would have had to be schotkey diodes as they have a forwad voltage drop of somthing like 0.1v

it is however possible to do it without having reverse ill post the diagram in a sec its very simple but you will need a schotkey diode as its the best type of diode for this sort of application.

i ahve just realised that even if you put this battery directly conected to the motor instead of the bit's circut board. the curent the extra 1.5 v will produce becuase I = v/r will still go through the transistors on the circuit board thus not really releaving the strain that an extra cell would add.

it would however only straign the motor controll transistors and not the steering circuity and the radio receiver like just adding another cell to the input of the bits pcb so it may still be worth it but then without reverse.

you could stop the short circuit of the 2nd battery by having enough diodes to drop the voltage to more than 1.5 volts but then this will slow down the car as well.

[Chilledout]

you can omit all the diodes if you are only planning to run two cells as when put in reverse all that happens is that 1.5v is put to the 1.5v of the other cell as there is not potential difference no curent will flow if there is one will charge up the other.

but if you want to run more than two extra cells then there will be a potential difference when the car is put in reverse and the.

the qustion is when the car is in idle does the cars controll circuitry leave the circuit closed or open as if it is closed the extra batter will cause the motor to continue to spin and not stop.

in the long run it may be worth just wireing the two batterys to the pcb board and replacing any burnt out components if they blow.

does anyone know what parts the fets are and if they can be replaced with heavier duty ones

[brandxman]

I was just wondering if anyone had thought of finding/useing relays to do this.

In my Full size daily driver jeep I just upgraded the head lights to much higher power units (95 watt low/140watt high beam, off road use only.) to keep from melting the stock wires will all of the extra juice being pulled I had to install a relay system. What the realy basically does is create 2 circuts...one running the stock power the other running the much higher power. the stock power is then used to drive a kind of switch that can handle the current flow of the high power side. Its hard to discribe with out some pics....soooo...follow this link to see how it was done for car head lights.

http://lighting.mbz.org/tech/relays/relays.html

Anyway with a Relay system the Bit's onboard curcits would think they are running the stock power, but in reality they would be running the Relay which in turn would do the actual switching on/off of the much higher powered batterys, keeping all of that extra juice far, far, far away from the important stuff.

Now for actually making it go.....you've got me there, I'm not even sure the parts exist small enough to make this happen, but i thought it might help point someone in the right direction.

--B

[mrcdemon]

this 2 cell mod is pretty cool. some pics and stuff of the real thing would be nice though... thanks

[rmyc]

hey ya'll

i finaly had gutts to try soldering .( note to all...i used a lighter.. way lazy to use my goot)
and i did my 2 cell safe circuit. it works great .
i did a 3 cel conv. , but it took up alot of space and it was wheel'n and flip'n alot.
any ways here's the pic of the finished diodes

**will post pics of the unwrapped diodes later

[hogjowlz]

this is smart but not needed i think. ive put together 5 or 6 dual cells so far and nothing has fried. an easier way to remedy would be to ad a fuse if you are that worried. then you risk blowing up nothing.

[CRUMB]

ummmmmm yeah im sorry but thats all confusing to me:confused: