Pre charge resistor for 24s A123 84v.

999zip999

100 TW
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Jan 10, 2010
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Dana Point So. Cal
I use two 100 Ohm 10 watt resistor's from radio shack. My pic needs resize I try later with the pic. I started this thread for Briogio.
 
http://liionbms.com/php/precharge.php Calculation for precharge resistor.
Just make sure its bigger than enough watts and no worries.
 
I've used 150 ohm 10W for 44.4-88.8V nominal (12s-24s rc lipo) and it works perfect at those voltages with all my controllers.
 
Ive been testing 47ohm, 5W@ 96V into 4470microfarad for 2sec+ no probs, on my circuit breaker setup.
Most setups the resistor watts seems well overated for the I2t, just up the resistor and the joules can be dissipated over more time.
A lot of resistors can be like 1/10 of the 1sec calculated power rating say 20 to 50J, not the instananeous power rating, that's wrong to base it on, as there's not heating effect from power at 300W only energy can create heat.
 
999zip999 said:
I use two 100 Ohm 10 watt resistor's from radio shack. My pic needs resize I try later with the pic. I started this thread for Briogio.

Thanks a lot! :mrgreen:
As a bona fide "representative" of the Ebike clueless club , I would be wanting the simplest, smallest, cheapest battery switch possible.
As "Supreme Ruler" of this club, I feel that I can speak for all my members, and if I can't I will!! :!:
 
I don't use a switch. Just seemed not needed and something else to screw up. This has worked perfect for me.precharge.JPG
 
Wesnewell do you leave the resistor in line the whoe time ?
And as Tresurer you are behind on your dues 3 months paypal or a cedit card is fine.
I'm having trouble resizing the pic.
So what batteries did you get from Ilia ? What is your end charge voltage ?
 
999zip999 said:
Wesnewell do you leave the resistor in line the whoe time ?
And as Tresurer you are behind on your dues 3 months paypal or a cedit card is fine.
I'm having trouble resizing the pic.
So what batteries did you get from Ilia ? What is your end charge voltage ?

If your talking about my battery from Ilia, originally was 48 volt, kinda f*cked it up last winter, sent it back to get upgraded to 72 volt. Haven't used it yet, still winter in the great white North!
 
999zip999 said:
Wesnewell do you leave the resistor in line the whole time ?
Yes, there's no need to remove it or put a switch on it.
 
999zip999 said:
Wesnewell do you leave the resistor in line the whoe time ?
And as Tresurer you are behind on your dues 3 months paypal or a cedit card is fine.
I'm having trouble resizing the pic.
So what batteries did you get from Ilia ? What is your end charge voltage ?

The resistor there should be fine. Once the switch is connected, essentially there is a short and this almost 0V across the reisitor hence almost 0 current through it.
 
wesnewell said:
I don't use a switch. Just seemed not needed and something else to screw up. This has worked perfect for me.

I love the simplicity of this set up, what amps is the fuse? what kind of switches do you use? what is the 150 ohms thing? Did I mention my Clueless Club? Any pictures of this on a bike?
 
Connecting the precharge resistor takes the spark out the conection. No spark when connecting the precharge resistor and no spark when connecting the main battery connection. With 4mm H.K. bullets.
The 150 ohm thing is a resistor I use two 100ohm resistor's side by side with the two wires solder togethere at both ends and in or to a wire. Go look up a 10watt 100 ohm resistor to see what one looks like. A small block with wires coming out both ends.GEDC0293.JPG
I got the pic yea. Just plug in before plugging in the main battery. That's all the hand holding I can do.
 
Plus you should answer the question what battery from Ilia do you have the lipo or The allcell ? And what is your final charge voltage ? So two questions.
 
999zip999 said:
Plus you should answer the question what battery from Ilia do you have the lipo or The allcell ? And what is your final charge voltage ? So two questions.

Thanks for the patience to hold the hand of the President of the Clueless Club, all my fellow members appreciate it too.


Hi John, your battery is lipo. AllCell is the company that builds battery using chemistry that falls under LiPO category.

Each cell can be charged up to 4.2V level, but under load will quickly fell to its is 3.7V , times 20 cells (in series) that's 84V and 74V respectively.

Best

ilia
 
wesnewell said:
I don't use a switch. Just seemed not needed and something else to screw up. This has worked perfect for me.
I have the same exact setup - I wired 6mm gold RC type connectors for #2 and use a Home Depot sourced extension cord plug and outlet as my main battery disconnect - works like a charm with no sparking. I disconnect #2 when parking the bike and the nice thing is the pre-charge circuit keeps my Wattmeter powered so AH used on the ride to that point stays recorded...
 
Yes he's been building lipo batteries for a while and a lot stronger then the allcell he also sells. I saw he's old store behind the rat trap liquor store in the arm pit of So. San fransico the twenty other people in that place where all building for Burning Man. He has anew shop now. That's a hi power battery I beleave.
 
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