Maxwell Ultracaps 3000 farad 2.7V

[jeffreythe00]

Hey guys,

I was looking to buy some of those super caps that someone else posted a while ago from electronicgoldmine but I didn't have any money and they sold out.

So... Ive been searching ebay and found these

These are lots of 12! Its a really good deal for these caps. I bought myself a set. These cost about $18.50/Ea

Maxwell 3000 Farad Ultracapacitor Supercapacitor Super,Ultra Capacitor USED (12) | eBay

After a bit more searching... I found these. About $15.50/Ea with shipping to your house. 2.5V @ 2600 Farad

http://www.ebay.com/itm/Maxwell-260...pt=PCA_UPS&hash=item45fdc7cd6c#ht_2122wt_1397

 

[Jacob32123]

Who wants to run a GB?

 

[jeffreythe00]

^ depending on how many people want to join... I could do a gb. Who knows, maybe I will want some more!

 

[Cyparagon]

I like the simplicity, but 6mA when over-volted doesn't sound like enough when considering you'd be charging them at several amps. Would charging an array to 2.4V instead be a better protective measure?

a word of caution about connecting more than 3 of these Boostcaps in series as you will need a voltage balancing network to prevent any one capacitor from going over the 2.5 VDC... This is due to each capacitor having a different internal resistance.

Resistance or not, KCL ensures they all get the same current. Maybe you mean different capacitance?

 

[LaZeRz]

Heh, I think these are the ones Fiddy bought! I have one sitting next to me now.

 

[bobhaha]

These are really cool! I have a bank of 5 in series.



I only charge them to 10V to be safe... There is a 0.45V difference in charge from the first cap in the series and the last one. It will over charge if not properly protected. You could undercharge the caps like I do.... or you can buy connectors that have built in over load protection circuitry. PM Fiddy for more info on those.

I went with undercharing them because the protection circuitry is current limiting and I want as much power as I can get!

 

[jeffreythe00]

^ How are you charging yours? I am trying to find a DIY way to charge mine when I get them and so far I haven't really found a good way. I was thinking about using a 12v battery charger and a 100W 5 ohm resisted but I really don't know... Please let me know

 

[bobhaha]

I have this power supply...

Linear Adjustable Variable DC Power Supply 30V 5A Digital Power Supply PS305D | eBay

It's 5A current limited. Just place the max voltage to 10V (in my case) making sure the current is at its max range, then hook up the leads across the terminals. The voltage will drop to ~0.8V @5A and as the caps charge they will accept more and more voltage. Once they hit 10V the current will start dropping. I usually disconnect them when the current hits 1A (from 5A max) at 10V.

 

[Cyparagon]

You may want to try charging them up to 10V, then topping off each cell individually.

 

[jimdt7]

Thats a CAPACITOR :drool:

But these scare me a lot !

 

[jeffreythe00]

Jimdt7 these caps are only 2.7 volts each. They are absolutely harmless. It takes about 50V to break the skins resistance and become unsafe.

 

[bennett326]

i *MIGHT* be in for 1-2 in a GB i could charge these with a adjustable computer psu i made right?

the psu uses a lm338 voltage regulator...btw

 

[Cyparagon]

^Yes, but only if you keep an eye on the current so you don't damage the regulator.

They are absolutely harmless.

By themselves, perhaps, but the arcing and sparks/shrapnel from shorting them through things is dangerous.

 

[jeffreythe00]

By themselves, perhaps, but the arcing and sparks/shrapnel from shorting them through things is dangerous.

Do they really? :thinking:

Yeah, I suppose I forgot to mention that sparks and shrapnel can be pretty dangerous too..

 

[Cyparagon]

My instructor was skeptical about such high capacitance devices since he was used to the common ~100µF electrolytics, so I brought in a pair and started poking at a penny with a small steel rod. At one point, the current welded the two together, so the steel melted and fell onto the floor. Oops. :yabbem: Could have gone worse.

 

[jeffreythe00]

Thats pretty awesome! Im sure he was kind of surprised!

However, Are you sure steel fell on the floor? Because most newer pennies are made of copper plated zinc which melts pretty easy. You can melt a newer penny with a regular bic lighter and a pair of pliers. Though I have seen steel nails melt on YT with these caps so I wouldn't be surprised.

Just thought i'd ask