capacitor keeps going poof

Discuss all the facets of R/C electronics here.
Post Reply
wolfden57
Regular Member
Posts: 11
Joined: Sun Dec 20, 2015 11:53 pm

capacitor keeps going poof

Post by wolfden57 » Wed Dec 30, 2015 8:22 pm

Just put together a terminator chassis with 2 B and D 18 turn modified brushed motors with a spectrum sr201 and traxxas 16.8v EVX-2 esc. While bench testing initially one of the capacitors :explosion: but the other one on the other motor didn't. The writing on the one was 47mf and 16v. So I replaced both with 47mf and 25v. Then second bench test one of those :explosion: but not the other.
I have been in this hobby for over 20 yrs and only had the 3 capacitors that were recommended on motors, but not messed with clods until this past year. This is my first with dual batteries. Any help would be greatly appreciated.

When it was at full throttle it looked pretty good even with no tires on it.

wolfden57
Regular Member
Posts: 11
Joined: Sun Dec 20, 2015 11:53 pm

Re: capacitor keeps going poof

Post by wolfden57 » Wed Dec 30, 2015 8:26 pm

I forgot to mention it's with one 5000nimh and 5100nimh batteries both connected. So pretty much too much juice possibility.

Chumley54
Regular Member
Posts: 21
Joined: Fri Nov 27, 2015 11:06 pm
Location: Northern NJ

Re: capacitor keeps going poof

Post by Chumley54 » Wed Dec 30, 2015 8:44 pm

Some capacitors do not have polarity, some do. Electrolytic capacitors are polarized. If you run them reversed polarity, they will poof. Electrolytic are not good run motors that run in reverse. Stick to non-polarized capacitors for motors that run forward and reverse. Check the case of the cap for a + or - sign. If it has one, them you are using the wrong style capaicotr or hooking it up reversed.

As long as polarity is right, and the voltage rating correct (Yours seem to be the right voltage), there is no easy way to blow up a capacitor.

A pic of the capacitor would be helpful.
1989 Clod Buster - Work in Progress
1989 Black Foot - Heavily Modded
1990 Midnight Pumpkin - Stock
1990 Monster Beetle - Stock - for Now
2016 Unimog 406 CC-01 Chassis

FlySky GT-3B - Hacked
Flysky GT-3C - Still Stock

User avatar
SFC K
Administrator
Posts: 7412
Joined: Wed Sep 30, 2009 1:42 am
Location: Oakdale, MN

Re: capacitor keeps going poof

Post by SFC K » Wed Dec 30, 2015 8:54 pm

Chumley54 wrote:Some capacitors do not have polarity, some do. Electrolytic capacitors are polarized. If you run them reversed polarity, they will poof. Electrolytic are not good run motors that run in reverse. Stick to non-polarized capacitors for motors that run forward and reverse. Check the case of the cap for a + or - sign. If it has one, them you are using the wrong style capaicotr or hooking it up reversed.

As long as polarity is right, and the voltage rating correct (Yours seem to be the right voltage), there is no easy way to blow up a capacitor.

A pic of the capacitor would be helpful.

That is some good info. I never knew their was a difference. Thanks for sharing!
Jeff

mavrick0
Approved Member
Posts: 287
Joined: Wed Feb 18, 2004 10:15 pm
Location: Ontario Canada
Contact:

Re: capacitor keeps going poof

Post by mavrick0 » Wed Dec 30, 2015 9:40 pm

And really with 2.4ghz technology you don't really need capacitor's anymore on motors. They were to reduce the "noise" made by the brushes arching and could cause interference with the old crystal radios.
A off roader may be able to jump and run around a track. A on roader may be able to run circles around the road but a monster truck will run over anything and everyone.

wolfden57
Regular Member
Posts: 11
Joined: Sun Dec 20, 2015 11:53 pm

Re: capacitor keeps going poof

Post by wolfden57 » Wed Dec 30, 2015 10:09 pm

These are some pics of the motor with the one capacitor that didn't pop yet lol
Attachments
IMG_3315.JPG
IMG_3315.JPG (83.11 KiB) Viewed 1171 times
IMG_3314.JPG
IMG_3314.JPG (95.74 KiB) Viewed 1171 times

wolfden57
Regular Member
Posts: 11
Joined: Sun Dec 20, 2015 11:53 pm

Re: capacitor keeps going poof

Post by wolfden57 » Wed Dec 30, 2015 10:11 pm

And really with 2.4ghz technology you don't really need capacitor's anymore on motors. They were to reduce the "noise" made by the brushes arching and could cause interference with the old crystal radios.

So that's good news as I didn't know the capacitors are not needed as well.

Chumley54
Regular Member
Posts: 21
Joined: Fri Nov 27, 2015 11:06 pm
Location: Northern NJ

Re: capacitor keeps going poof

Post by Chumley54 » Sat Jan 02, 2016 3:17 am

wolfden57 wrote:These are some pics of the motor with the one capacitor that didn't pop yet lol
That blue one is electrolytic and if you look at the black stripe it has (-) on it, indicating polarity.

Some caps...Ceramic ones in general :
9873-caps_ceramic.jpg
9873-caps_ceramic.jpg (15.38 KiB) Viewed 1146 times
like these are non polarized.

Anything with a mark, like this:
images.jpg
images.jpg (7.64 KiB) Viewed 1146 times
Are marked and have polarity. Using reverse polarity on any like that will kill them quickly.

On new caps, like LED's, sometimes the longer lead shows polarity:
tantalum_capacitor_polarity_markings_longer_lead.jpg
tantalum_capacitor_polarity_markings_longer_lead.jpg (11.56 KiB) Viewed 1146 times
Electrolytics look like this:
Polarity-wet-Al-Elcaps.jpg
Polarity-wet-Al-Elcaps.jpg (241.49 KiB) Viewed 1146 times
1989 Clod Buster - Work in Progress
1989 Black Foot - Heavily Modded
1990 Midnight Pumpkin - Stock
1990 Monster Beetle - Stock - for Now
2016 Unimog 406 CC-01 Chassis

FlySky GT-3B - Hacked
Flysky GT-3C - Still Stock

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests