chris-p-duck
|
| posted on 3/5/10 at 07:49 PM |
|
|
Bizarre fuel guage question
Hi all!
I have just got back in from the garage after finally finishing the rear lights and I have been sitting here contemplating the fuel guage.
What I have been pondering is as follows - I want the dash as simple as possible and was thinking of just having a fuel warning lamp instead of a
guage. Is that ok for IVA? Also is it possible to get 2 colour LEDs? I would like something that would be green for a certain range of resistance
and when a given resistance level is reached it turns red. Is that do-able and if so how??
All help gratefully received......
Cheers
Chris
|
|
|
|
|
mistergrumpy
|
| posted on 3/5/10 at 07:51 PM |
|
|
Pretty sure you don't need any gauge at all for IVA. I have one but it doesn't work properly at all.
As for the electrickery bits. I can't answer that sorry. I'm useless at that stuff.
|
|
|
blakep82
|
| posted on 3/5/10 at 08:01 PM |
|
|
RS should have everything you need.
can't remember if this is the correct one, there's a few that all look the same, but my plan would be 2 of
these fitted in the fuel tank at different
levels.
then something like this LED wise.
might be a good idea to have some way of accounting for a blown LED though.
don't know about those LEDs, but if they have 3 connections (common ground) on them, it should be dead easy.
thats my plan anyway. fuel gauge isn't needed for IVA either
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
|
|
|
55ant
|
| posted on 3/5/10 at 08:10 PM |
|
|
sounds like a good idea, my fuel gueage is more of a bump guage, just wiggles all over the show all the time.
away from cars, now cycling and building TT bikes
|
|
|
norfolkluego
|
| posted on 3/5/10 at 09:37 PM |
|
|
I aready have a similar setup with a sender and fuel gauge that registers empty or 'a lot' 
|
|
|
RK
|
| posted on 3/5/10 at 10:21 PM |
|
|
My gauge reads backwards, because the clown who put my sender in the tank, and then installed the tank, put it on backwards. Can't remove the
tank without taking the whole back end off the car. It is now therefore considered an anti theft device. Just as soon as a thief realises he has a
full tank, he runs out!
|
|
|
BenB
|
| posted on 4/5/10 at 07:17 AM |
|
|
Rigging up something like that would be very easy. You could do it nice and simply with some comparator ICs and voltage dividers using a swing-arm
potentiometer type fuel level sensor. It would be a good idea to design in some hysteresis on the triggering otherwise when you get near the switching
level the light will pulse on and off as you go over bumps which would be annoying.
The parts for said design will cost about a quid (not including the level sensor).
|
|
|
BenB
|
| posted on 4/5/10 at 07:20 AM |
|
|
http://www.ee.ttu.edu/lab/robot/hyster.htm gives a bit of detail on the hysteresis.
some single rail 12v op-amps and job's a good'un. You'ld just need to measure the resistance of the fuel level sensor (assuming a
swing arm jobby) so you can work out the resistances of the other bits in the potential dividers.
|
|
|
mangogrooveworkshop
|
| posted on 4/5/10 at 11:06 AM |
|
|
Its very simple lads ..
.My wife thinks its E for Enough and F for Finnished when its fuel related
As for no gauge...mmmm not sure you would like to tour the north of Scotland with that arrangement.....petrol supplies are very scarce in some
parts.....
[Edited on 4-5-10 by mangogrooveworkshop]
|
|
|
chris-p-duck
|
| posted on 5/5/10 at 05:10 PM |
|
|
I don't think touring north scotland is going to be a big issue - I'll be lucky to squeeze 100 miles out of a tank if I drive like a
granny!! And lets be honest how likely is that going to be?!?!?
Thanks for you help guys
Chris
|
|
|
02GF74
|
| posted on 7/5/10 at 07:16 PM |
|
|
^^^ wot they say.
one comparator or more to switch your LEDs.
what you have is variable resitor in your tank and its resistance varies as fule level changes. you compare the voltage from it against a referecce -
the comparator - when it is over or under you turn on or off a LED.
... but as mentioned, you want some damping since you don't want your LEDs flashing wildly as the fuel sloshes around.
fuel gauges get round this by having a bi-mettalic strip (I'd need to look up the detials) but it may be possible to put a large value capacitor
to slow the the voltage change from the sender.
you could use a PIC too, a single chip, damping via software - if you really get stuck, I could look into this for you.
something like this, but no damping; 8 level and each level can be calibrated - bit of an over kill using preset - you cold work out each value and
then use fixed value resistor - be cheaper and smaller too.
read about it here
|
|
|
02GF74
|
| posted on 7/5/10 at 07:23 PM |
|
|
... and bottom of the article descibes and shows circuit how to slap on a capacitor to slow down the signal, wot ^^^ I said 
|
|
|
chris-p-duck
|
| posted on 10/5/10 at 05:37 AM |
|
|
Thanks Guys!
I sawa that circuit diagrams at various laces on the web whilst searching for the solution to my problem and I have to say it scares me to death. I
dont understand what it is telling me and have even less clue as to how to physically make it!!
It was that line of thought that drove me to the single LED changing from green to red as I thought it would be simpler. Then after pondering it I
decided I actually prefered the single LED idea!!
Are there any good sites on t'internet that describe how to physically go about making these circuit boards? I need to do some learning at a
basic level......
Cheers
Chris
|
|
|
Guinness
|
| posted on 10/5/10 at 07:04 AM |
|
|
I went through SVA with no fuel gauge.
The ZZR1100 C had a fuel level sensor rather than a gauge (by the time they got to the D model they'd fitted a gauge!)
So as my original plan was to use the loom and clocks, I fitted one of the sensors into the bottom of the tank. It's about 2" high and
when it is submerged you have "enough" when it becomes partially exposed to the air / vapour a light flashes on the dash. When it is
fully exposed, the light comes on steady.
I didn't end up using it, as I fitted the Vaypor dash which has a virtual fuel gauge instead!
I can send you the ZZR wiring diagram if you want. You'd be able to get the sensor from a breakers (if I take mine out, all the fuel will
escape from my tank!).
As for driving round Scotland with no fuel gauge, I'm about to do it again in a couple of weeks. Touch wood my virtual fuel gauge has never let
me down yet! (You tell it the fuel tank size, calibrate it a couple of times, then it works out some complicated fuel consumption / revs / distance
calcs)
HTH
Mike
|
|
|
chris-p-duck
|
| posted on 10/5/10 at 11:53 AM |
|
|
I like the 'virtual' gauge idea, and I have a vaypor but didn't think it had that function. Will check when I get home.
I am moving more and more towards the 'do nothing' option for now and if I get some time/skill etc post IVA Ill have another go at
something. I have more pressing issues like making the rest of the car work at the moment! I used to ride a bike and a lack of fuel guage was never
a problem then!!
Cheers
Chris
|
|
|
MikeRJ
|
| posted on 10/5/10 at 03:09 PM |
|
|
This isn't a difficult circuit at all, but the "green" state seems a bit redundant since you are only indicating two states which
could be done with a red LED either on or off which would make the circuit even simpler.
That said, I'm not sure how useful it would be; surely some idea of fuel remaining would be essential for planning any trips?
If you add a bit of intelligence with a small micro, you could use a simple two-wire bi-colour LED and have several states e.g.
Green - full to half full
Yellow - half full to quarter full
Red - quarter full to reserve capacity
Blinking red - Fill up now you fool
You also get to use digital filtering to adjust the response to the fuel sloshing around
Quite happy to help you with something like this if you want.
|
|
|
chris-p-duck
|
| posted on 10/5/10 at 07:42 PM |
|
|
Hi,
Something like that would suit me down to the ground. I only went for the two state version as the tank is a 'T' shape so there is not a
lot of resolution from the sender in the full position - i.e. you could use probably a third of a tank plus and it would still show full. But as it
approaches the bottom of its travel the fluid in the tank is just in the leg of the 'T' so it will drop really quickly. If that makes
sense?!?!?
However if its do-able then any help you can give will be gratefully received
Thanks
Chris
|
|
|
MikeRJ
|
| posted on 11/5/10 at 04:09 PM |
|
|
I've written some code to implement this in a small PIC and included a "dim" function to reduce the brightness when you switch the
lights on at night.
The bit I haven't finalised yet is calibration. I'm envisaging a button for each transition point, you fill the tank to this point and
hold the button down for a couple of seconds to set the threshold which will then be stored to non-volatile memory within the PIC. If anyone has a
better idea then I'll be glad to hear it.
I need to knock up a schematic as well, but it will be fairly simple, definitely something you could make on stripboard if you want. Most of the
components will be for making the circuit robust enough to survive the electrical environment in a car.
|
|
|
chris-p-duck
|
| posted on 11/5/10 at 05:47 PM |
|
|
That sounds absolutely spot on!! Far far better than I could possibly have achieved!
Thanks very much
Chris
|
|
|
