FXR Cap size for 4S

[Mini]

So upgraded my truck to 4S dual ESC and noticed the other day was just a little too hot for my liking was thinking of going to radio shack and picking up one of these http://www.radioshack.com/product/in...ductId=2102511
Looking at the specs it looks like it will do the job, I have done looked at other post were they say not to buy RS caps but saw others that said it would be ok, from the specs I saw and read of the one I wanna get would it be something that will last or would it be something that will blow up?

Any and all suggestions are welcome only wanna tear and resoder my truck one more time lololol. Thank you in advance.

[killswitch]

Nova's Ark sells an upgrade cap specifically for using 4 cells on a FXR. I think they're only like $3... I've been running mine that way for over a year now with no issues.

[Mini]

Thank you, just trying to see if I can use one that I dont have to wait for shipping.

[JohnRobHolmes]

It will work, just not as well as a low ESR cap. I have been looking for some and haven't really found anything to meet my specs.

[LostCrawler]

Whats Nova's ark web page can't find it on Google. Searched for Nova's Ark.

[EGRESSor]

surge voltage of the stock fxr caps is 18V
i think it´s not the voltage , it´s more the heat that kills the caps
some are heatshrinked

the most other caps have 5x higher ESR
and 5x less ripple current ability

there are some new low esr /high ripple current caps
http://www.edc.sanyo.com/pdf/e052.pdf

[greenlion]

I'm using the radio shack 35v 1000uf cap without any problems. I usually run 3s but have run several packs through on 4s. There may be a better cap out there but no complaints so far on this one.

[Mini]

Originally Posted by JohnRobHolmes

It will work, just not as well as a low ESR cap. I have been looking for some and haven't really found anything to meet my specs.

So your saying this: 470µF 35V 20% Radial-lead Electrolytic Capacitor
wil work better than this: 1000µF 35V 20% Radial-lead Electrolytic Capacitor


I'll order a cap from Tekin but if I don't have to I'll buy it from Radio Shack just want to make sure it won't catch my rig on fire

[Mini]

Originally Posted by LostCrawler

Whats Nova's ark web page can't find it on Google. Searched for Nova's Ark.

it's under Crawler Innovations

[JohnRobHolmes]

Originally Posted by Mini

So your saying this: 470µF 35V 20% Radial-lead Electrolytic Capacitor
wil work better than this: 1000µF 35V 20% Radial-lead Electrolytic Capacitor


I'll order a cap from Tekin but if I don't have to I'll buy it from Radio Shack just want to make sure it won't catch my rig on fire

The rig won't catch on fire immediately, but the FETS will be working harder against higher ripple voltage. In time that could lead to a failure. The big problem is when ripple voltage starts exceeding the components ratings. That leads to quick death.

What you don't see is the ESR of the cap, or the equivalent series resistance. Going to a higher capacitance doesn't matter much at the frequencies the controllers switch, but the ESR determines how fast the cap reacts. High ESR, higher ripple elsewhere in the system.

I haven't put a scope on Nova's caps to know if they snub as good as stock caps so I can't comment on them. Going with manufacturers parts is always safe.

[Mini]

Originally Posted by JohnRobHolmes

The rig won't catch on fire immediately, but the FETS will be working harder against higher ripple voltage. In time that could lead to a failure. The big problem is when ripple voltage starts exceeding the components ratings. That leads to quick death.

What you don't see is the ESR of the cap, or the equivalent series resistance. Going to a higher capacitance doesn't matter much at the frequencies the controllers switch, but the ESR determines how fast the cap reacts. High ESR, higher ripple elsewhere in the system.

I haven't put a scope on Nova's caps to know if they snub as good as stock caps so I can't comment on them. Going with manufacturers parts is always safe.

Thanks John yup that looks like the safe route just got some inside from Jimmy and Art and they suggested going with TT3543 25v 1800uf from Tekin, guess no driving for me this weekend lol

Just wanna say thank you to everyone for there suggestions and help in this matter.

[Mini]

Here is a pic

[greenlion]

Found this one at amain
http://www.amainhobbies.com/product_...ule-4S-6S-LiPo
Novak cap, 35v, 1800uf. Black and gold wrap looks similar to the tekin cap above; a little pricey for a cap though.

[JohnRobHolmes]

Being on those long thin wires defeats the purpose of a cap too. They should be as close to the power section of a controller as possible, if not directly mounted to the main power bus traces.

[Mini]

Originally Posted by JohnRobHolmes

Being on those long thin wires defeats the purpose of a cap too. They should be as close to the power section of a controller as possible, if not directly mounted to the main power bus traces.

X2

So how soon will we see the HH Cap?