Possible solution to battery connect spark??

[sailr]

Great idea. How about some of you electrical genuises out there drawing something up!

I dont get why they havent made a switch to handle this yet..

[domwilson]

A switches contacts would corrode. Perhaps something like this might help.
Use a 8mm plug on the positive ESC wire. Take a 8mm Male plug and solder a 5.5mm female plug to the wire end. Solder a resistor of your choice between the two 8mm plugs. When you connect your 5.5mm plug batteries into the connector, the resistor will charge the caps. Then you just connect the 8mm plugs together. See the pic.
It's just one idea.

[graill]

Here is a couple pics of the setup i have used on the Princess for nearly 2 years now. Note the 6.5 mm connectors, nearly 50 disc cycles (hundreds of connect/disc) , still looking brand new. I know my cap banks and esc have appreciated it also. I use a 72 volt 63ohm resistor, one each side, bit bigger than i need for a 52 volt system.

For those unfamiliar with the use of the resistor, place the resistor on the negative side of the circuit (last to be hooked up) *direction of the resistor does not matter in this particular type of circuit*. When you are ready to make your final connection, connect the resistor wire and then connect your main wiring, once your main wiring is connected, disconnect your resistor circuit and place your plug cap on or tape it up so the ends do not flop around or contact anything.

there is no need to wait any length of time as once you have connected the resistor the cap banks have been fed. Performing this procedure will take you less than a second or two.

While the resistor circuit ends will only show a low with a multimeter .5v or less, there still is the potential to make an unwanted circuit if the ends arent taped, plugged and secured properly.

[Doug Smock]

Personally I like the "Crack" when I apply voltage to my ESCs. Especially when my IC buds are within a ear shot.

Doug

[AndyKunz]

*direction of the resistor does not matter in this particular type of circuit*

It never does - resistors aren't polarized.

You can put it in either positive or negative side so long as it's the next-to-last connection you make (the last is the one that bypasses the resistor). I recommend that you connect the positive last, as this will ensure that your system is grounded properly. This can be important if you are using a BEC.



Andy

[domwilson]

Here is a couple pics of the setup i have used on the Princess for nearly 2 years now. Note the 6.5 mm connectors, nearly 50 disc cycles (hundreds of connect/disc) , still looking brand new. I know my cap banks and esc have appreciated it also. I use a 72 volt 63ohm resistor, one each side, bit bigger than i need for a 52 volt system.

For those unfamiliar with the use of the resistor, place the resistor on the negative side of the circuit (last to be hooked up) *direction of the resistor does not matter in this particular type of circuit*. When you are ready to make your final connection, connect the resistor wire and then connect your main wiring, once your main wiring is connected, disconnect your resistor circuit and place your plug cap on or tape it up so the ends do not flop around or contact anything.

there is no need to wait any length of time as once you have connected the resistor the cap banks have been fed. Performing this procedure will take you less than a second or two.

While the resistor circuit ends will only show a low with a multimeter .5v or less, there still is the potential to make an unwanted circuit if the ends arent taped, plugged and secured properly.

You can leave the resistor connected if you want (as long as it is not the wire wound type) as there is very little current (insignificant amount) flowing thru it when the mains are connected.

[Gary]

Personally I like the "Crack" when I apply voltage to my ESCs. Especially when my IC buds are within a ear shot.

Doug

Me To !!!! But i have found that connecting the leads to my tungue like a 9 volt battery will also get rid of the Crack!!LOL WooooHooooo!!!!!!!

[FloatDaBoat]

Resistance in a circuit is dissipated as heat. The wattage value of a resistor determines how much heat (Power) it’s able to withstand during constant circuit operation.

Attaching a 33 Ohm or 1 Ohm resistor straight across a 14.4 volt battery’s positive & negative terminals (and leaving it connected) would have the following results as per Ohm’s Law:

E / R = I
E X I = P

14.4 Volts X 33 Ohms = 0.4363 Amps
14.4 Volts X 0.4363 Amps = 6.28 Watts

14.4 Volts X 1 Ohm = 14.4 Amps
14.4 Volts X 14.4 Amps = 207 Watts

Neither a 33 Ohm (1/2 watt), nor a 1 Ohm (5 watt) resistor, would last for long under the loads in the examples. !!!Smoke Test !!!

However, this is not the case when charging the capacitors used in an ESC, as the maximum current flow is only momentary.

If all the variables were known, this could also be calculated, but it only gets more complicated Another way to determine the actual current drawn by the caps, would be to connect a digital multimeter (set to measure current, using a peak hold function) into the circuit at initial battery hook-up.

Warning: most digital multimeters will only safely measure 10 AMPS; my wild haired guess is that a 1 ohm resistor would still produce a noticeable arc, anyway.

This would be helpful in determining what the wattage value of the resistor should be. Consider this - - a 5 watt resistor is a BIG Honker, while a 1/2 watt is of reasonable size (if you‘d want to leave the resistor in the circuit in parallel with the battery). Once the caps are charged & the battery is connected, the resistor can be considered to be essentially out of the picture, as almost all the current follows the path of least resistance.

My 1 Ohms worth as a “Used-to-be Electronics Tech”.

[AndyKunz]

An easy way to get a ballpark is the look up the ESR on the caps. At the time you connect the cells, they will essentially be the only thing drawing power (everything else will pale in comparison).

Do the math. I = V/R (where V is your pack voltage and R is the ESR of the caps) to get an idea of the inrush current, scale it to what you want to remove your spark (even 10K will work, we're not talking rocket science here).

It doesn't matter if you caps charge in 1/2 second or 3 seconds, it will take you that long to get the connectors ready to mate. By then, most of the cap will be charged (the difference in voltage between the cap and battery will now cause the current to be minimal) and you won't get the spark.

Hey, this is a great way to play around and learn some basic electronics. Don't think you need the answer up front - play around to figure out how the answer really works!

Andy

[Chilli]

Somebody posted on OSE that they made up a temporary inline resistor. They use it for the initial plugin...charge the caps...and then take it out and plug in the normal connectors. Little or no spark. Sounds like a plan! I'm still cornfused about the right size resistor to get though!

Here is the thread on the temporary jumper I made. It's working great. I just have to figure out how not to loose it....

http://forums.offshoreelectrics.com/...light=arrestor

[sailr]

Thanks Nautiboyz. I really prefer your idea to the need to modify every battery and every esc with the jumpers! THANKS.

I know what you mean about losing it! Shrink wrap it in yellow!

[Raydee]

Here is the thread on the temporary jumper I made. It's working great. I just have to figure out how not to loose it....

http://forums.offshoreelectrics.com/...light=arrestor

I do like that idea the best. How long do the caps stay charged after you unplug the resistor jumper?

[sailr]

They should stay charged long enough to plug in your battery.

[AndyKunz]

Done correctly, it stays plugged in. Use a small connector such as ones on Deans antennas (remember those?). The contacts are actually male and female RS-232 connector pins that you can still find at Radio Shack, believe it or not. Use thin heat shrink over them to keep them from shorting against anything.

Put the female side and the resistor on the battery + wire. Put the male side on the ESC. Plug the - sides (black) together. Connect the small connection with the resistor on it together. As you fiddle with grabbing the big red connections, the caps are charging up. Plug the red ones together.

No sparks, nothing to lose.

Andy

[Chilli]

I do like that idea the best. How long do the caps stay charged after you unplug the resistor jumper?

I did a little reseach on the net on how long caps hold their charge and got answers anywhere from milliseconds to infinity to "it just depends on the circuit".

So I did a totaly unscientific experiment by connecting and disconnecting a 4S pack, waiting for a specified time and then turning on the reciever and listening to see if the caps had enough energy for for the ESC to arm. A Etti 150 with no cap bank would lose it's abitily to arm the ESC after about 2-3 minutes. A Etti 150 with a Etti cap bank would go at least 10 minues.

I guess it's all a matter of personal preference whether you use a spark arrestor and what type. It's all good.