# Caps



## Tesseract (Sep 27, 2008)

The label indicates they are 85C electrolytics, have a 4.8A ripple current rating, and were made in 1996. Probably not really up to the task for a controller, then, both because of their age and relatively low ripple current rating. CDE type 944 in that same size would be good for 70-110A of ripple.


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## Guest (Nov 8, 2010)

So pretty much just scrap them! Bummer. I still have a few things to use. Thanks.


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## CaptConan (Jul 12, 2010)

While we're on the subject... can't find a datasheet for this guy.
ALS34H312L5C450... I'm guessing the 40/085/56 means it's rating for 85C, not sure what the other numbers mean.


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## Tesseract (Sep 27, 2008)

CaptConan said:


> While we're on the subject... can't find a datasheet for this guy.
> ALS34H312L5C450...



Found it... Click on the ALS34 series PDF here:

http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/FEBG - Electrolytic Capacitors


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## CaptConan (Jul 12, 2010)

Awesome, thank you.


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## zwmaster (Nov 23, 2009)

Are theese any good?


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## steven4601 (Nov 11, 2010)

Tesseract said:


> The label indicates they are 85C electrolytics, have a 4.8A ripple current rating, and were made in 1996. Probably not really up to the task for a controller, then, both because of their age and relatively low ripple current rating. CDE type 944 in that same size would be good for 70-110A of ripple.



Thank you for informing me about the 944/947 capacitors. They where exactly what I as looking for. (planning on building a 300A 500-700V inverter)


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## Tesseract (Sep 27, 2008)

steven4601 said:


> Thank you for informing me about the 944/947 capacitors. They where exactly what I as looking for. (planning on building a 300A 500-700V inverter)


Inverters need much less ripple current rating since the switches draw current in overlapping pulses. Worst case ripple is usually estimated at 8-10% of the maximum phase current, so 30A for your project.

That said, it is not practical to grow the aluminum oxide film thick enough to withstand more than 450VDC in an electrolytic capacitor while much higher voltages are trivial with polypropylene film, so...

zwmaster - good find on the SBE Power Ring. If you can make your own laminated bus structure to take advantage of its ultra-low ESR and ESL then more power to you; if not then your wasting your money.


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## steven4601 (Nov 11, 2010)

Well Im not certain about what you mean with ripple currents & inverters. 

I have tried to perform some very crude simulations regarding regenerative braking, which showed that adding a 600 - 1200uF capacitor over the IGBT's reduced the ripple current to the battery from ~ 90A to sub 20A.

Do you happen to have some sort of crude values (or a page) for BLDC motor leakage inductance? Im assuming something between 200 an 900uH, maybe im trying to calculate myself rich.


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