Chainsaw's Simple 12V DIY Backup System

chainsaw

After playing around with various designs of backup systems, I have concluded that this is the simplest (and less dangerous) for a DIY person to tackle.

1. The 240V power sensing device...........You have seen them, refer to photo. Just make sure will produce 9V (enough to operate) Where to get one. Ask F&F.

2. The Relay Sound a bit on the HD side (well its same price as normal headlight relay) You can really hear it snap in and out. No arcing of contacts etc, like some have reported. Where do I get it? Cost $14.95 I just soldered the wires onto the HD terminals, can use a spade fitting on the smaller ones.
http://www.jaycar.com.au/productView.as ... BCATID=754

3. The Air Supply Got one of these after seeing it on OBOs thread (thanks Colin). They are noisy, yes but then I suppose don't need a buzzer or light for a warning device. I used this one, permanent magnet model (like aquarium pumps) not much to wear out.
http://www.guppysaquariumproducts.com.a ... _1543.html

I am sure you can work out the rest from photos.

chainsaw

Limit of three photos.

Cut end off power supply and either solder or fit crimp spade connector. Doen't really matter about polarity. Just connect to the smaller spade terminals.

Solder the compressor wires onto the larger terminals, again polarity doesn't matter.

Ensure insulated well and put couple of small zip ties around the wires. Then wrap it all in insulation (or shrinkwrap)

chainsaw

Finished job. Ready for action. :support:

Outbackozzie

Exactly how I now do mine.

bonsaibelly

Good one! - How long does it pump for if the power go's out?

bonsaibelly

Good one! - How long does it pump for if the power go's out?

Zman

Hi chainsaw looks cool mate.

Just wondering how much the battery was, how much juice does it store and is it loud enough to piss off my neighbors pigions a few meters away? :think:

Also i dont understand the picture of how everything connects together. Can you explain that bit?

Cheers

Privatteer

Just one note. Using a 12vdc plugpack will be better.
At 9v the coil is going to have a higher current flow than its designed for and will probably burn out faster.

ivansng

Zman, I think that is as basic as a electrical circuit can be... Basically the 9VDC power pack (and yes 12VDC is better) that is plugged into the mains would energise the relay and make the relay contacts (COM - Common (not labelled), NO - Normally Open, NC - Normally Closed) switch from the NC position to the NO position.

So when 240VAC power is powering the 9VDC power pack, the battery + terminal is floating, not connected to the pump. On loss of 240VAC power, the relay will lose its pull and de-energised switching back to the NC position. In this position, the battery + terminal will be connected to the pump + terminal and hence run the pump.

chainsaw

Thanks everyone for extra input,

I should have put an explanation of operation at the start. :dontknow:

If you can't get the HD relay, a normal automotive headlight relay will work. But Burnsy had trouble with contacts I read in one of his posts.

At 25W air pump will draw 2 Amps current. So depends how large a battery you fit is to how long it will run. Batteries are rated in Amp/Hours So if you had a 50A/Hr would run for about 24 hours.

OBO. I realise thats how you have yours (running continuously) But there was never a thread devoted to this design.

chainsaw

ivansng wrote:

Zman, I think that is as basic as a electrical circuit can be... Basically the 9VDC power pack (and yes 12VDC is better) that is plugged into the mains would energise the relay and make the relay contacts (COM - Common (not labelled), NO - Normally Open, NC - Normally Closed) switch from the NC position to the NO position.

So when 240VAC power is powering the 9VDC power pack, the battery + terminal is floating, not connected to the pump. On loss of 240VAC power, the relay will lose its pull and de-energised switching back to the NC position. In this position, the battery + terminal will be connected to the pump + terminal and hence run the pump.

Agree 12V power pack would be more suitable (if got one) in my first design I used the power pack (12V) from a laptop PC.

The terminal 87 can be used to power another air pump and using a timer on the power would then operate like a throw over switch. Providing have a small smart charger on the battery.

Zman

ivansng wrote:

Zman, I think that is as basic as a electrical circuit can be... Basically the 9VDC power pack (and yes 12VDC is better) that is plugged into the mains would energise the relay and make the relay contacts (COM - Common (not labelled), NO - Normally Open, NC - Normally Closed) switch from the NC position to the NO position.

Its a circuit board or this on the relay? Any chance you can get a shot of this chainsaw?

Outbackozzie

chainsaw wrote:

OBO. I realise thats how you have yours (running continuously) But there was never a thread devoted to this design.

No, mine runs exactly the same as yours, except I use a 12v plugpack to hold the relay open.

This was brought up in the battery backup thread at one stage. Its as simple as it can get, if anything goes wrong it defaults to running.

The air pump is a 35w model, which draws around 3.2 Amps. A 100 AH battery will provide around 20 hours of runtime, after which the air supply will keep running, but at a pretty rapidly reducing rate. I'd say 25 hours would be about the max.

chainsaw

Zman

[/quote]
Its a circuit board or this on the relay? Any chance you can get a shot of this chainsaw?[/quote]

No circuit board at all. Just a couple of items wired together, all 12V no 240V stuff here to fry your hair. :upset:

The relay is the heart of the whole operation and I don't understand your question about circuit board. Everything is contained inside the relay. Look at the photo circuit............WYSIWYG. Just have to attach things to it to make it work, all 12V.

Dont try using the part number within the photo (FRC6BC-1), use the Jaycar one at the bottom. Jaycar SY4073.

Zman

Finally got it chainsaw.

The relay is where you attach everything :mrgreen:

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