95 C.C. rewired to 4ga

[gaminde]

found this on another site

I believe curtis recommends a precharge resistor of 750 ohms at 10 watts. However the specific resistance isn't terribly critical; anything anywhere near 1K ohms would do the job; as long as the wattage was in the range of 10.

Alternatively, a 15 watt, 110V light bulb apparently works well too.
__________________

[gaminde]

Another on line site


Precharge

A design guide to DC precharge circuits.

When initially connecting a battery to a load with capacitive input, there is an inrush of current as the load capacitance is charged up to the battery voltage. With large batteries (with a low source resistance) and powerful loads (with large capacitors across the input), the inrush current can easily peak 1000 A.
A precharge circuit limits that inrush current, without limiting the operating current.

A precharge circuit between a battery and its load is required if any of the following are issues:

The load has input capacitors will be damaged by the inrush current
The main fuse will blow if asked to carry the inrush current
The contactors, if present, will be damaged by the inrush current
The battery cells are not rated for the inrush current

[sonicj]

Originally Posted by gaminde

Ok same thing, if the caps are pre_charged then less arching at the relay and high ohm would be fine just to keep the caps loaded. No reason to use all your juice on a resistor doing no work.

do you know what the resistance and wattage of a stock resistor is ???

curtis shows a 250Ω 5W for the common 1204/1205 series of controllers.

changing the resistor value won't change the quiescent power consumption at rest. it will change the rate at which the caps are allowed to charge/recover.
-sj

[sonicj]

Originally Posted by gaminde

Another on line site


Precharge

A design guide to DC precharge circuits.

When initially connecting a battery to a load with capacitive input, there is an inrush of current as the load capacitance is charged up to the battery voltage. With large batteries (with a low source resistance) and powerful loads (with large capacitors across the input), the inrush current can easily peak 1000 A.
A precharge circuit limits that inrush current, without limiting the operating current.

A precharge circuit between a battery and its load is required if any of the following are issues:

The load has input capacitors will be damaged by the inrush current
The main fuse will blow if asked to carry the inrush current
The contactors, if present, will be damaged by the inrush current
The battery cells are not rated for the inrush current

good info!

fwiw, i do not have a pre-charge resistor on my cart. reason being, i have no in-rush current. my controller, stays hardwired to the batteries 24/7 and i use a reversing contactor for making/breaking the interlock system. the only time i use a pre-charge resistor is when re-connecting the batteries after they have been disconnected for maintenance.

the energy stored in the caps dissipates surprisingly quick! you have to immediately connect the batteries after pre-charging or else you get a big @$$ lightning bolt when the lug contacts the post!
-sj

[scottyb]

What is this!? Engineering students gone wild????

Since the beginning 36v systems have used a 250 ohm 5w resistor and 48v systems have used a 470 ohm 10w resistors. Period. ...... Is there a problem the rest of us are not aware of with this suddenly? .....

[jack condon]

no but I can count the color bands when i find a conversion chart.

[shadowman]

Originally Posted by scottyb

What is this!? Engineering students gone wild????

Since the beginning 36v systems have used a 250 ohm 5w resistor and 48v systems have used a 470 ohm 10w resistors. Period. ...... Is there a problem the rest of us are not aware of with this suddenly? .....

your reading my mind.....i should have stayed at camp.........................

[gaminde]

Originally Posted by sonicj

good info!

fwiw, i do not have a pre-charge resistor on my cart. reason being, i have no in-rush current. my controller,
-sj

Sonicj you have to be running more than 2 volts for a resistor