I want to fit a small fan to vent my battery box when the battery is
charging. I only want the fan to run during charging, so was thinking
of a relay that would only close when the voltage is above 28v or so.
Any ideas???

Is there a charge light on the charger? Or a a FULLY Charged light?

If so, measure the voltage of the light. It will either be 110VAC or
maybe 12 or 24 VDC.

Go to Radio shack and buy a relay with that voltage as the excitation
voltage and can handle the load of the fan. Make sure the fan you buy is
ignition protected. (ALSO BUY A SOCKET... EASIER TO SOLDER AND REPLACE)

Mount the relay somewhere where the sparking will not blow you up (Gas
boat I assume??)

Most relays will have a normally closed, Normally open and common.
Depending on which light you have, select the proper terminals and
connect to your fan.


One other option.... You may take your voltmeter and follow the battery
leads into the charger and past the final diodes... These should read
+13V (or 26V) only during charging. You should be able to connect the
proper voltage fan to this. Some chargers are different but this would
work on my old charger.

BE CAREFUL... 110V is all around when the charger is plugged in or the
breaker is on. Also, 110V may be around when the charger is unplugged
or the breaker is off. (Capacitors store power)

You may find a relay that turns on between 24V and 26 V but it may
flutter at 25V and burn up the contacts.




CS wrote:

I want to fit a small fan to vent my battery box when the battery is
charging. I only want the fan to run during charging, so was thinking
of a relay that would only close when the voltage is above 28v or so.
Any ideas???

On 27 Jan 2007 03:55:29 -0800, "CS" wrote:

I want to fit a small fan to vent my battery box when the battery is
charging. I only want the fan to run during charging, so was thinking
of a relay that would only close when the voltage is above 28v or so.
Any ideas???
Colin,
A Voltage Controlled Relay will do what you want. Kits are available
for 12v which could possibly be modified for 24v. Alternatively knock
one up with a bit of Vero board and an op-amp or comparitor.

I cannot remember what you are doing about Battery Condition
monitoring? Should you make a wise choice and fit a "Smartgauge", the
fan control becomes easy. Take a look at
http://www.smartgauge.co.uk/venting2.html and other pages. I am only
suggesting this as a spin off of using a Smartgauge for monitoring.
Its an unneccessary and expensive option for just fan control.

Any system hat you use should obviously work whether charging from a
mains source or from the alternator. If you consider a "Smartgauge"
then give me a call (my number in the "Where to buy" section.
(Richard)
Richard

Nb "Pound Eater" Parkend G+S

Richard,

Thanks - I already have a Smartbank Standard and had already bought a
Link 20 to monitor the batteries before the Smartgauge came out. The
Smartgauge solution is however elegant. I'll have a rethink!! Any
suggestions for 24v (or 2 x 12v) explosive safe fan(s)??

Colin

Yandina Ltd. makes just such a device. They are available here in 12v
or 24v versions:
http://www.backwoodssolar.com/Catalo...htm#VENT%20FAN



On 27 Jan 2007 03:55:29 -0800, "CS" wrote:

I want to fit a small fan to vent my battery box when the battery is
charging. I only want the fan to run during charging, so was thinking
of a relay that would only close when the voltage is above 28v or so.
Any ideas???

On 27 Jan 2007 23:35:47 -0800, "CS" wrote:

Richard,

Thanks - I already have a Smartbank Standard and had already bought a
Link 20 to monitor the batteries before the Smartgauge came out. The
Smartgauge solution is however elegant. I'll have a rethink!! Any
suggestions for 24v (or 2 x 12v) explosive safe fan(s)??

Colin
The Smartgauge is IMHO better for monitoring although the Link will
show current drain or charge as you know. Worth thing about a SG and
modifying the SB to SB advanced?

Brushless DC fans are a good option

Richard

Nb "Pound Eater" Parkend G+S

On 28 Jan, 08:49, Al Thomason wrote:
Yandina Ltd. makes just such a device. They are available here in 12v
or 24v versions:http://www.backwoodssolar.com/Catalo...htm#VENT%20FAN

Thanks - same site has an automatic vent fan control.

Yandina Ltd. makes just such a device. They are available here in 12v
or 24v versions:http://www.backwoodssolar.com/Catalo...NT%20FANThanks - same site has an automatic vent fan control.

Sorry - though you were referring to fan.

"CS" wrote in news:1169898929.753591.25280
@k78g2000cwa.googlegroups.com:

I want to fit a small fan to vent my battery box when the battery is
charging. I only want the fan to run during charging, so was thinking
of a relay that would only close when the voltage is above 28v or so.
Any ideas???



Don't put ANYTHING in the engine or battery compartment that has anything
to do with CONTACTS opening or closing! BOOOM! Hydrogen gas!



Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

Larry wrote:
"CS" wrote in news:1169898929.753591.25280
@k78g2000cwa.googlegroups.com:

I want to fit a small fan to vent my battery box when the battery is
charging. I only want the fan to run during charging, so was thinking
of a relay that would only close when the voltage is above 28v or so.
Any ideas???



Don't put ANYTHING in the engine or battery compartment that has anything
to do with CONTACTS opening or closing! BOOOM! Hydrogen gas!



Larry
You've never seen a sealed relay?