ideas to isolate a big power inverter...

[ash_on_mtb]

Hi all,

I'm onto my third solenoid now, and quickly getting the $hits, so I'm throwing it open to suggestions...

I run a 1500w inverter for all sorts of things, and have it hardlined to the battery. As its a long lead (located in the rear QP, so runs protected against chassis) I would prefer to be able to 'cut' it as close to the battery as possible. I've been trying 100amp cont. solenoids, but they keep warping.

So now I'm looking for new ideas.

One of those screw down terminals won't work as it will be undone during driving and make occasional contact. I'd like a dash switch on whatever I end up using. I was thinking about using the on'off switch on the unit itself and extending the wiring, but I'd still have a live run of cable...

Any ideas? Circuit breaker? A row of solenoid in parallel/series (whichever, I forget)? We're looking at say worst case 1200watts continuous, so whatever that is divided by 12 is the amps. More than a winch??

ta.

[drivesafe]

Mate, you could track down a 200 amp continuos rated solenoid or just fit a marine battery switch near the battery.

[chimpboy]

We're looking at say worst case 1200watts continuous, so whatever that is divided by 12 is the amps.

No offence, but

Anyway, how about something like this:

http://www.jmsonline.net/SOLENOID-200-AMP-12-VOLT.htm



Used in boats, not really sure what for. Not really all that expensive. You'll want to wire in an ordinary automotive relay as well as a dash switch probably.

[Moph]

Jaycar 120A circuit breaker near battery running to manual marine battery switch in cabin? Should be nice and reliable - only drama being running 2G cable through the dash to the switch...

Edit: Chimpboy's 200A solenoid looks like it should do the job too!

[ash_on_mtb]

so we're tipping that a quality 200amp will cover it?! What about running a couple of 100a in a row, like a winch?

Whats a marine battery switch?

And it was only the 3rd time I read what I wrote, that I got it..

And as an aside, I wonder why I'm killing 100amp solenoids then if thats the case?

[ausoops]

how are they 'warping'?
a solenoid has a contact resistance that creates a voltage drop across it. power losses develop across the contact face which manefest itself as heat. and power losses are the product of the square of the current (ie if you double the current you quadruple the power losses) if you are running the inverter at full capacity you would be pulling 100A+. if for example your contact resistance was 0.01ohms then at 100 amps you would be generating 100W of heat, (for example consider the heat a 100W lightbulb puts out. this is what the casing of the solenoid has to dissipate in order to not self-destruct.

[ozy1]

here ya go, no more issues,

http://www.jmsonline.net/SOLENOID-FOR-DIESEL.htm

[DamTriton]

Firstly, 2 x 100 amp CB's (or solenoid) in series does not equal 200 amps to blow. MAYBE in parallel if the currents through each were equalized you might get away with it.

Best bet as stated is a 200 amp CB or solenoid. This would give 1500 Watts with headroom for inverter efficiency (usually assumed to be 80% in the real world).

Real figures 1500 watts = 125 amps at 12 volts. With 80% efficiency this would be in the vicinity of 155-160 amps. You were blowing you 100 amp solenoids due to not factoring in the 80% efficiency, meaning in real terms you could only draw about 960 watts before the solenoid was overloaded (or at 100 amps continuous).

[money_killer]

Firstly, 2 x 100 amp CB's (or solenoid) in series does not equal 200 amps to blow. MAYBE in parallel if the currents through each were equalized you might get away with it.

Best bet as stated is a 200 amp CB or solenoid. This would give 1500 Watts with headroom for inverter efficiency (usually assumed to be 80% in the real world).

Real figures 1500 watts = 125 amps at 12 volts. With 80% efficiency this would be in the vicinity of 155-160 amps. You were blowing you 100 amp solenoids due to not factoring in the 80% efficiency, meaning in real terms you could only draw about 960 watts before the solenoid was overloaded (or at 100 amps continuous).

bout time some one replyed who knows wat there talking about. u bet me too it

[ash_on_mtb]

best bet, 200amp solenoid.

I need to source one before the long weekend, which is cutting into my US lead time... Anyone know of an aussie source (low $$, prob 'web based?) of 200amp cole hersee solenoids??

Thanks for the input, discovered today to add to the problem, the 100Ah supercharge battery has gone to god, or at least its maker... *sigh*... Never ends sometimes.

[DamTriton]

Firstly, 2 x 100 amp CB's (or solenoid) in series does not equal 200 amps to blow. MAYBE in parallel if the currents through each were equalized you might get away with it.

Best bet as stated is a 200 amp CB or solenoid. This would give 1500 Watts with headroom for inverter efficiency (usually assumed to be 80% in the real world).

Real figures 1500 watts = 125 amps at 12 volts. With 80% efficiency this would be in the vicinity of 155-160 amps. You were blowing you 100 amp solenoids due to not factoring in the 80% efficiency, meaning in real terms you could only draw about 960 watts before the solenoid was overloaded (or at 100 amps continuous).

bout time some one replyed who knows wat there talking about. u bet me too it

WTF do I know, I'm a Registered Nurse!!

(Electronics trademan early in my life )

[ash_on_mtb]

I've had a prowl around, and exhausted the places I know to look.

Anyone got a tip on where I could find a 200amp solenoid??

Cheers...

[chimpboy]

I've had a prowl around, and exhausted the places I know to look.

Anyone got a tip on where I could find a 200amp solenoid??

Cheers...

I have never bought anything from these guys but I found them on Google:

http://commerce1.cera.net/tacbusparts/s ... ?cat_id=70

Online store.

I thought it would be easier to find places that sell them... apparently not!

[ash_on_mtb]

http://www.alanco.com.au/view/pg?comman ... key=alanco

Found one from these guys in WA


200amp, 12v Cole Hersee, $135+

Lets see how that goes...?!

[BEAR 80]

Try a winch solenoid, approx 500amp, plenty big enough.