Reply
 
Thread Tools Search this Thread
 
Old 01 April 2005, 09:17   #1
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Secret question, so mum’s the work

Question for any electronics experts on the forum, would it be possible to use a capacitor to trickle charge a small battery Ideally, what would happen is that a supply would turn on for a moment (5 sec), the capacitor would be able to store sufficient power to slowly charge a battery over a longer period (30 min) Don’t ask why cos it’s a secret but if it is successful free ones to all that help Des
__________________
Scary Des is offline   Reply With Quote
Old 01 April 2005, 09:39   #2
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Capacitors discharge over a very brief period as a rule - ie in a flashgun for example.

Capacitors also have to be really huge to store a worthwhile charge.

To store the equivalant power of ONE AA battery you would need about 10,000 farads.

A 1 Farad capacitor is about the size of a 1 litre pop bottle and costs about £40.
__________________
codprawn is offline   Reply With Quote
Old 01 April 2005, 11:29   #3
Member
 
benc's Avatar
 
Country: UK - England
Town: Southampton
Boat name: Aquaholic
Make: Ribeye
Length: 7m +
Engine: 250 V8
Join Date: Mar 2005
Posts: 1,323
Send a message via Skype™ to benc
How about something like this?

http://www.elektor-electronics.co.uk...Power%20Supply

(Showed a work colleague and he suggested this might help - Thanks Chris)
__________________
benc is offline   Reply With Quote
Old 01 April 2005, 12:20   #4
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Quote:
Originally Posted by benc
How about something like this?

http://www.elektor-electronics.co.uk...Power%20Supply

(Showed a work colleague and he suggested this might help - Thanks Chris)
Thanks Interesting I take it that this is something you build yourself Des
__________________
Scary Des is offline   Reply With Quote
Old 01 April 2005, 12:28   #5
Member
 
benc's Avatar
 
Country: UK - England
Town: Southampton
Boat name: Aquaholic
Make: Ribeye
Length: 7m +
Engine: 250 V8
Join Date: Mar 2005
Posts: 1,323
Send a message via Skype™ to benc
Yeah it is, might be able to get someone to help build it for a fee if required
__________________
benc is offline   Reply With Quote
Old 05 April 2005, 01:45   #6
Member
 
gtflash's Avatar
 
Country: UK - England
Town: southampton
Boat name: TOP CAT 2
Make: Scorpion 8.1
Length: 8m +
Engine: 250hp HO
Join Date: Aug 2003
Posts: 1,804
Quote:
Originally Posted by codprawn
Capacitors discharge over a very brief period as a rule - ie in a flashgun for example.

Capacitors also have to be really huge to store a worthwhile charge.

To store the equivalant power of ONE AA battery you would need about 10,000 farads.

A 1 Farad capacitor is about the size of a 1 litre pop bottle and costs about £40.
thats dead right, caps are typically used for smoothing in power supplys as they can reduce a ripple or dip for a momentary lapse... almost the opposite of what ur asking of them
__________________
gtflash is offline   Reply With Quote
Old 05 April 2005, 11:20   #7
Member
 
Country: France
Town: Brittany
Length: no boat
Join Date: Nov 2004
Posts: 119
Quote:
Originally Posted by codprawn
A 1 Farad capacitor is about the size of a 1 litre pop bottle and costs about £40.
The 7.5Kv one we had wasn't & cost a bit more than 40 quid
__________________
Nick Thompson is offline   Reply With Quote
Old 06 April 2005, 01:35   #8
Member
 
gtflash's Avatar
 
Country: UK - England
Town: southampton
Boat name: TOP CAT 2
Make: Scorpion 8.1
Length: 8m +
Engine: 250hp HO
Join Date: Aug 2003
Posts: 1,804
Quote:
Originally Posted by Nick Thompson
The 7.5Kv one we had wasn't & cost a bit more than 40 quid
in general 12v ones are a lot more money than HV ones, our three phase big buggers we use at work cost pennies in comparison to the one on my car stereo.

remember ohms law. v = i.r so less voltage = more current = more money!! its a bit like sayin the word boat during a purchase, the shop attendant just presses the x3 button on the total!!
__________________
gtflash is offline   Reply With Quote
Old 07 April 2005, 19:57   #9
Member
 
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
Quote:
Originally Posted by Scary Des
Question for any electronics experts on the forum, would it be possible to use a capacitor to trickle charge a small battery Ideally, what would happen is that a supply would turn on for a moment (5 sec), the capacitor would be able to store sufficient power to slowly charge a battery over a longer period (30 min) Don’t ask why cos it’s a secret but if it is successful free ones to all that help Des
Hardly an expert, though I used to build avionics.

Two problems with your idea: First is leakage. Capacitors all have some inherent leakage. To charge one to a voltage suitable for charging a battery (i.e. about 20% more than the battery's rated voltage) would yield that voltage for a relatively short period of time.

Second is that as you draw off that current, the voltage will drop (giving you the same problem as in the first scenario.)

To overcome those effects, you'd need a really large capacitor array, and a pretty good size power supply to charge them quickly.

You'd probably be better off looking for a longer lasting battery in the first place.

My opinion only;

jky
__________________
jyasaki is offline   Reply With Quote
Old 07 April 2005, 21:19   #10
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Once built some very big caps using some plastic dustbins and sheets of polythene - filled the whole lot up with oil - fortunately got caught by my parents before I could do any REAL harm!!!
__________________
codprawn is offline   Reply With Quote
Old 08 April 2005, 15:42   #11
Member
 
gtflash's Avatar
 
Country: UK - England
Town: southampton
Boat name: TOP CAT 2
Make: Scorpion 8.1
Length: 8m +
Engine: 250hp HO
Join Date: Aug 2003
Posts: 1,804
cool sounds like one of my sorta experiments

Quote:
Originally Posted by codprawn
Once built some very big caps using some plastic dustbins and sheets of polythene - filled the whole lot up with oil - fortunately got caught by my parents before I could do any REAL harm!!!
__________________
gtflash is offline   Reply With Quote
Old 08 April 2005, 16:01   #12
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Quote:
Originally Posted by gtflash
cool sounds like one of my sorta experiments
Yeah in my very misspent youth I used to muck around with Tesla coils and all sorts - didn't realise they also make very good transmitters until my whole street could no longer receive tv!!!

Then i made the fatal mistake of discovering girls - should have stuck to blowing things up instead - less hassle!!!
__________________
codprawn is offline   Reply With Quote
Old 08 April 2005, 16:10   #13
Member
 
benc's Avatar
 
Country: UK - England
Town: Southampton
Boat name: Aquaholic
Make: Ribeye
Length: 7m +
Engine: 250 V8
Join Date: Mar 2005
Posts: 1,323
Send a message via Skype™ to benc
You could have gone with the inflatable type - you could have then stuck to blowing things up
__________________
benc is offline   Reply With Quote
Old 08 April 2005, 17:12   #14
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Quote:
Originally Posted by benc
You could have gone with the inflatable type - you could have then stuck to blowing things up
Like it.................
__________________
codprawn is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT. The time now is 14:58.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.