How to calculate what current SHOULD be going to my flasher

Message

old git · #1 Post by **old git** » Mon Aug 23, 2010 8:38 pm

Anyhwo Have measured with the meter & am getting 2.93amps at the relay, seem to think someone had said that I should be getting 3.5-3.7 amps?
Anyone give me a formula so I can check this please.?
This is now with all new relay (rated 18-23w) all new front & back indicators inc. new bulbs (all rated 23w) bulbs have been checked & resistance from bulb holder upto plastic connectors on the rear are 0.05 & 0.06 ohms.

Also couple of guys have suggested my non-flashing indicators my be due to high resistance in the circuit somewhere, hence I guess the low amps above ???
So have also started to measure resistance in some of the spagetti & seem to have found the blue wires coming upto the connectors to both rear indicators tie-up with the blue/black wire in the middle of the switch on the left handlebar, but it is showing 103.5 ohms on both left & right wires when everthing else I have tested only shows 0.05 or 0.06 ohms (e.g these readings for the wire upto the plastic connctors before you then plug the last 12" or so which come from the indicators themselves.
So not finished yet, but seems like i might have found something, just not sure what yet.

Hishy · #2 Post by **Hishy** » Mon Aug 23, 2010 10:33 pm

the formula you are after is I=P/V with I being current, P being power (watts) and V for voltage (apologies if i'm being a little to basic :) )

so 2 lamps @ 23W will be I=46/12 roughly giving you a load of 3.8 Amps. (Based on 23w lamps, 10w would draw around 1.7 Amps)

What flasher unit did you get in the end?

As for the 100 odd ohm reading your getting, by what i can make from your post you have 103.5 ohms across either side of the indicator switch when the indicator switch is in the off position, with the rear indicators disconnected and the front lamps still connected??

if so you may be reading through the lamps themselves and picking up the internal resistance of the lamps.

Try disconnecting all your indicator lamps you should have continuity from one side of the indicator switch (ie turn left) to one of the terminals on each left indicator, the other terminal of the indicator should go to earth, check front and rear and then repeat on the other side you should be getting around 0.1-0.5 ohms on each wire.

The common wire on your indicator switch should go directly to one side of the flasher unit, the otherside of the flasher unit should be fed directly from your ignition switch and should be permamently fed with 12v as soon as the ignition is turned on.

If you need a hand i can pop over at the weekend

old git · #3 Post by **old git** » Tue Aug 24, 2010 4:54 am

Thanks for that, so me thinks not getting enough current to switch the dialectric relay over, enough to get the bulbs to light but not to flash.
Relay is a generic one i got from Bikers world in drakes broughton.
Went there sunday & asked the guy on the counter, for one to go with the indi's I got.

kiwi_rsvr · #4 Post by **kiwi_rsvr** » Tue Aug 24, 2010 4:34 pm

I have 10 watt bulbs in my aftermarket indicators, I purchased a "wideband" (commonly known as an LED flasher relay) for around 15 quid. problem solved.

Aladinsaneuk · #5 Post by **Aladinsaneuk** » Tue Aug 24, 2010 5:00 pm

erm kiwi

10 watt bulbs are standard.....

kiwi_rsvr · #6 Post by **kiwi_rsvr** » Tue Aug 24, 2010 5:51 pm

Yer your right .........I'll check mine tonight

, I do know that they would flash at all when first installed, maybe I meant 23 watt

, my excuse is that I'm aged and been at work for 14 hours without a break (well at least I feel sorry for myself)

Aladinsaneuk wrote:erm kiwi

10 watt bulbs are standard.....