Wiring in LED voltage displays

[Shark]

OKay im getting a couple of these to keep a check on both my batteries BUT it got me thinking wether they would drain the battery if i left them connected all the time

http://www.virtual-village.com.au/green ... 001480-167

So i was wondering if number one i could leave them on all the time, not too keen on that one or if i can wire in a switch or even utilise the accesories power and run through some sort of relay, so they only come on when the ignition or car is running..

Any thoughts would be appreciated.

Marc

[Thylacine]

Their power consumption should be negligable, but without specs can't guarantee this.
Simple enough to put a relay in series with the +tive lead, switched by your ignition, and then you're 100% safe.



ed

[chimpboy]

Their power consumption should be negligable, but without specs can't guarantee this.
Simple enough to put a relay in series with the +tive lead, switched by your ignition, and then you're 100% safe.



ed

x2, better safe than sorry. I think you could just use a small dpst relay for this, not full size automotive relays eg http://jaycar.com.au/productView.asp?ID=SY4062

This is DPDT but it just means you don't use all the pins. Just an idea.

[PBBIZ2]

RS Components have a range of similiar 'green display' units and the rated consumption is inthe order of 150-350 milliamps. I use the 'red Datel' meter which draws around 3 milliamps, but its a different illumination to what you are using and a bit dearer.

[-Scott-]

You could put ignition switched relay in parallel with a simple momentary push-button. With ignition on, display is on; with ignition off, push the button to check your voltage.

[presto]

You could put ignition switched relay in parallel with a simple momentary push-button. With ignition on, display is on; with ignition off, push the button to check your voltage.

I've fitted a couple of these charge master charge monitors, they have the momentary read as well as accessory or ignition switching. Not as cheap but much prettier they also have low voltage alarms you can turn on or off. But with the other ones, if it was me I'd run them through a relay and momentary swtich like Scott said.

[-Scott-]

You could put ignition switched relay in parallel with a simple momentary push-button. With ignition on, display is on; with ignition off, push the button to check your voltage.

I've fitted a couple of these charge master charge monitors, they have the momentary read as well as accessory or ignition switching. Not as cheap but much prettier they also have low voltage alarms you can turn on or off. But with the other ones, if it was me I'd run them through a relay and momentary swtich like Scott said.

Approximate price?

[chimpboy]

Not as cheap but much prettier

Ewww, prettier? I vote that functional but hideously ugly. Matter of taste I guess

I would call the LED one at the top nicer but overall I'd rather have a gauge look that blended with the stock instruments better, 52mm gauge in a dash pod or something like that.

When you think about it the unit at the top is really quite good for $11.

[presto]

yeah I spose it's a matter of taste... Having said it was prettier, I still wouldnt put one in my car I usually sell them to caravaners and they're thoroughly impressed with them and their fancy lights

Cost between $100 and $150 from memory.

[Shark]

Yeah i like the idea on the ones i put up here, stoked with the feedback guys. I pretty much figured a relay setup from the ignition would be the best way. Am finally getting all the info i need..

Thanks very much

Marc

[DamTriton]

Yeah i like the idea on the ones i put up here, stoked with the feedback guys. I pretty much figured a relay setup from the ignition would be the best way. Am finally getting all the info i need..

Thanks very much

Marc

Add a push button across the relay contacts to the LED meter so you don't have to turn the ignition on to check the voltage.

Is there any real reason why you need the relay at all?????

If you want something that is a bit easier on the eyes and uses less current when on, use a LCD display and dim the backlight (easily organised through the ignition AND headlight switch).

[chimpboy]

Now you mention it Damkia they probably wire up with a power wire AND a voltage sense wire, so you are right there is no need for a relay at all.

The power wire can be an IGN or ACC sourced wire (plus pushbutton to battery if desired) and the sense wire can just go to the relevant battery.

It depends on how they wire up I guess.

[chimpboy]

Yes, it is probably the same as this ebay one:

http://cgi.ebay.com/3-12v-Digital-Red-L ... 56362e2d3a



No relay required, very easy, sorry for confusing things with any mention of a relay. I blame thylacine

All you'd do is (correct me if I'm wrong) have two displays, one for each battery. Three of the four wires are shared between the two displays - the +ve "working power" and both -ves. The +ve "measure input" wires go separately to each battery.

Wired this way they will be on with accessories or ignition (your choice).

Blue LCD looks good too:

http://cgi.ebay.com/NEW-3-Digital-Blue- ... 0471293548

[-Scott-]

Yes, it is probably the same as this ebay one:

http://cgi.ebay.com/3-12v-Digital-Red-L ... 56362e2d3a



No relay required, very easy, sorry for confusing things with any mention of a relay. I blame thylacine

All you'd do is (correct me if I'm wrong) have two displays, one for each battery. Three of the four wires are shared between the two displays - the +ve "working power" and both -ves. The +ve "measure input" wires go separately to each battery.

Wired this way they will be on with accessories or ignition (your choice).

Blue LCD looks good too:

http://cgi.ebay.com/NEW-3-Digital-Blue- ... 0471293548

With the device chimpboy has posted, the relay is less of an issue.

With the original device posted, there are only two wires in the pics, and only two pins on the back of the device.

[chimpboy]

Weird, the ad says "with 3 pin cables" but the pic shows two.

Anyway, I would use the 4-wire type in preference. If you do that you can wire up as follows:



Otherwise for the two-pin one you should use a relay if you don't want them running and (very slowly) draining your batteries all the time.

The two-wire type would be better in some applications but not this one I think.