Precharge resistor decomplicated

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Precharge resistor decomplicated

Mark Hanson-2

Hi,

 

The easiest way to precharge the cap bank inside the controller is with a 250-470 ohm 10W wirewound resistor (1.7 - 3 sec charge time) across the contactor that opens & closes each time you press the accelerator peddle (safety contactor).  The main contactor that is activated by the key switch does *not* have a pre-charge resistor across it.  I have a 470 ohm 10W in my E-Porsche www.evalbum.com/1273 and is how I've wired my EV's since the 1970's.

 

An NTC Inrush current limiter (not to be confused with a PTC-fuse) can also be used, like the jumbo types Ametherm makes.  The 220 start resistance of the MS22 22103 or Digi-Key stock 570-1008-ND would also work and precharge the cap bank 7kuf - 12kuf in less time than a resistor.  It's rated 75 joules (watt-seconds) and with a (CE^2/2) of 50 joules for a 120V 7kuf cap bank would work well. (I use them on cap banks at work on my UPS inverter magnetic bearing systems using LiFePO4 batts)

 

Also I use a CL-60 (now KC006L-ND Digi-Key) on my vacuum pump in series with the 12V so it starts much quieter.  

 

Have a renewable energy day,

Mark

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Re: Precharge resistor decomplicated

JS-20
Mark Hanson wrote:
> Hi,
>
>  
>
> The easiest way to precharge the cap bank inside the controller is with a 250-470 ohm 10W wirewound resistor. . .

I still prefer the light bulb.  I use two 40 watt bulbs in parallel to
protect against bulb failure.

40 watt bulbs for oven or refrigerator duty seem a bit more
rugged than standard bulbs.

John in Sylmar, CA
www.evalbum.com/1749

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Re: Precharge resistor decomplicated

Seth Rothenberg
> I still prefer the light bulb.  I use two 40 watt bulbs in parallel to
> protect against bulb failure.
>
> 40 watt bulbs for oven or refrigerator duty seem a bit more
> rugged than standard bulbs.

If I followed this correctly,
when you take your foot off the pedal,
the safety contactor drops out, and the lights
(Light Emitting Heaters) come on?

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Re: Precharge resistor decomplicated

JS-20
Seth Rothenberg wrote:

>> I still prefer the light bulb.  I use two 40 watt bulbs in parallel to
>> protect against bulb failure.
>>
>> 40 watt bulbs for oven or refrigerator duty seem a bit more
>> rugged than standard bulbs.
>
> If I followed this correctly,
> when you take your foot off the pedal,
> the safety contactor drops out, and the lights
> (Light Emitting Heaters) come on?
>

No.
The contactor puts full pack voltage on the controller capacitors.
The light bulbs are across the contactor, so connected to the pack.
There is very little difference between pack voltage and controller
capacitors, so little or no current flows.

Thank you for making me think.  (First person to do so today!)

John in Sylmar, CA
Light bulb collector since 1943!

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Re: Precharge resistor decomplicated

Seth Rothenberg
> Thank you for making me think.  (First person to do so today!)

Thanks for making me think - I
went looking for more on this topic,
and now I think I'm ready to start
drawing....

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Re: Precharge resistor decomplicated

Lee Hart
In reply to this post by Seth Rothenberg
Seth Rothenberg wrote:

>> I still prefer the light bulb.  I use two 40 watt bulbs in parallel to
>> protect against bulb failure.
>>
>> 40 watt bulbs for oven or refrigerator duty seem a bit more
>> rugged than standard bulbs.
>
> If I followed this correctly,
> when you take your foot off the pedal,
> the safety contactor drops out, and the lights
> (Light Emitting Heaters) come on?

No; when the pedal is released, the controller only draws some trivial
current. The main contactor may drop out, but the precharge resistor
keeps it precharged anyway.

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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