50v Caps 49.9v pack

[mxer]

Is this tooooo close, or will I pop em ?...Is there any give ? ie tested at 55v fine etc....

Havn't looked at the fet's yet till i know the Caps will handle it

Btw, there are a couple more caps in there rated at 25v....

 

[Drunkskunk]

You're pushing it, but it should hold up fine. On one of my bikes I have been pushing the 63V capacitors to 63volts for a few years with no ill effects. There are others who go over the rating by a few volts often.

the 25v caps are on the low voltage side, and don't see full battery voltage.

 

[mxer]

This one is a spare so i'm not losing anything, Would like to use it though as it's rated at 25amps (saves me a shunt mod) and my 48v controller is rated at 16 amps (due a shunt mod) would be nice for a plug and play 25amp controller......

Nice one cheers....

I'll let you know how it goes....

 

[lostrack]

The extra capacitor pack castle creations sell for their ESCs are all 50V, with a 50.4V system. You'd hope that would be spec'd correctly. The on-board ones are 50V rated too.

 

[neptronix]

My philosophy, other than motors.. run everything a little below spec to give you some headroom.. as many components aren't specced with headroom included..

So i'd say no.. the controller could be worth a few $ on here and could be used for someone's budget build.

 

[cell_man]

IMO it is pretty ok to run a pack with the charged voltage very close to the cap rating. Something I do not think is ok but lots of people seem to get away with (most of the time...) is to run a pack with a charged voltage very close to the fet rating. Fets should be run with packs no more than about 75-80% of their rating (nominal pack voltage) and no more than about 90% of their rating for a charged pack. You might get away with it with some motors, but on another motor that is less forgiving, it can blow a fet.

 

[fechter]

I haven't seen many caps fail from excessive voltage and I think they have a lot of headroom built into the voltage rating. What the don't like is excessive ripple current or getting reversed.
FETs are another story. You need to over-rate the voltage quite a bit to accomodate voltage spikes from inductance in the wiring, etc. With really good caps and proper layout, you can run them pretty close to the rating.

 

[johnrobholmes]

The extra capacitor pack castle creations sell for their ESCs are all 50V, with a 50.4V system. You'd hope that would be spec'd correctly. The on-board ones are 50V rated too.

The reasoning I heard for this was that 63v caps didn't perform as well.

 

[dogman dan]

It's a question of do you feel lucky?

They should go past their spec voltage for at least a few v no problem. But given the way QC is done these days, they could be just as likely to fail at 40v. I'd call it 50-50 even run a bit under spec, so why not try and see?

Nevertheless, the advice to sell for half what you paid, and put that towards a controller with 100v caps is sound advice.

 

[The Mighty Volt]

+/- 10% is the rule I follow for FET's but as Fechter says, thats a different story.

 

[dnmun]

"Btw, there are a couple more caps in there rated at 25v...."

your controller has different voltages in different sections of the circuitry. the 25V caps are on the 12V regulator output and the small ones on each phase are for pumping charge to the high side of the phase wire so the mosfets can switch at that higher voltage.

the input caps are on the power section that is switched by the mosfets. if you wanna run this controller at higher voltage then these are the ones to swap out for higher voltage caps, along with the electrolytic that goes between the source/drain buss which also is high voltage like the input.

also if you raise the voltage the controller is designed to work at, you need to change the input power resistors to drop more voltage at the input to the 12V regulator.

 

[mxer]

It's a brushed controller, so no one is going to want it anyway, Basicly i have a load of brushed controllers 24v 36v (one we are talking about) and a 48v and motors that i plan to kill off and go brushless for the future.....

So it's gonna get it and Dogman, yeah i'm feeling lucky ......