[Aroy]

Originally Posted by Sutripta

Hi,
Can you help us source a ~100mV FSD centre zero movement rugged enough for a Jeep.

Regards
Sutripta

You can surf the net for rugged centre zero voltmeters. Most of the rugged ones are moving iron, rather than the normal moving coil types.

Here are some links for you
Automotive Voltmeter Manufacturer,Automotive Voltmeter India,Voltmeter For Automobiles,Voltmeter For Vehicles,Voltmeter For Cars,Voltmeter For Jeeps,India
Automotive Voltage Meter - Automotive Voltmeter, Automotive Voltage Meter Manufacturer, Automotive Voltmeter Exporter

[Sutripta]

^^^
Hi,
These don't seem to be 100 mV FSD centre zero type.

Regards
Sutripta

[Aroy]

Originally Posted by Sutripta

^^^
Hi,
These don't seem to be 100 mV FSD centre zero type.

Regards
Sutripta

100mV meters are normally instrumentation grade, so will not be rugged enough for automotive use. What is done, is that you put an inexpensive DC Operational amplifier with a driver to boost the voltage, so that an automotive meter of 0-15V works as a 100mV meter.

Similarly you can use a shunt in series with the main power cable and use the voltage drop across it as an ammeter.

Actually I was tinkering with the idea of using a Digital Multimeter Module, suitably mounted, for vehicle display.

[Sudarshan]

^^ Sirs ( Roy Sir & Da Sir ) . gone through your above posts , half of the things went over head

Cant it be made little simpler ? like fit it, forget it & just read it ?? ,
I am not that much technically equipped, for this meter job .

Sudarshan

[Aroy]

Originally Posted by Sudarshan

^^ Sirs ( Roy Sir & Da Sir ) . gone through your above posts , half of the things went over head

Cant it be made little simpler ? like fit it, forget it & just read it ?? ,
I am not that much technically equipped, for this meter job .

Sudarshan

Here is an explanation
For ammeter
. Buy a shunt (it is just a precision resistance), with a matching meter
. Insert it at a suitable place in the main cable, preferably where the main cable connects to the battery.
. Now mount the ammeter on the dashboard, and connect the wires to both sides of the shunt. Use an inline fuse to ensure safety in case of a short circuit. As the main current passes through the shunt, the wiring to the meter will carry low current (depending on the meter any where from 1/100 to 1/1000 of the main current).

For Voltmeter
. Buy a Voltmeter
. Mount the meter on the dashboard
. Connect the voltmeter - one end to a suitable wire nearest to the battery terminal, and earth the other end. Again use an inline fuse to isolate the circuit in case of short.

NOTES
. It is best to mount the fuses inside the engine bay. The location in Ambassadors is best - on the metal panel between the engine and the cabin.
. If possible use moving iron/magnet meters rather than the normal moving coil meters. These are more rugged and less prone to vibration induced damage.
. Instead of Analog meters you can use a digital meter. The rest of the circuit is same, except that the meters will need a separate power connection.

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Amazon.com: Vector VEC008 Digital LCD Voltmeter, 12 Volt: Automotive
Amazon.com: Equus 3721 Battery and Charging System Monitor: Automotive

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[shekaran]

hi guys,
some fuel for thoughts from my side :
1. oil pressure gauge - which is best ? mechanical or electrical ? (our jeeps seem to have the old mechanical type, oil pipe running till the meter (accurate but old tech)- electrical also has oil line but near the oil filter itself, only sensor send signals to meter (latest tech so accuracy can also be expected))
2. temperature gauge - why always sensor type ? any latest improvements ?
3. voltmeter or ammeter - which is best in jeep ? how to infer the readings on jeep useage ?

i am in the process of altering the full electrical system in my jeep, independent of common connections - for ease of simplicity, long life, easy fault rectification, etc.,. only problem, electrician taking his own time to make independent looms, lol.
am thinking of replacing the oil pressure gauge into an electrical one (to minimise the risk of oil tube rupture), have a digital voltmeter included etc.,. (already have a voltmeter connected across the battery terminals to show battery volt state).
so, jeep gurus, electrical gurus, pls throw some light.
best regards.

[Sudarshan]

Originally Posted by Aroy

and here is one more tool just for you
Buy Professional Digital Laser Photo Tachometer Non Contact RPM Tach and accessories from India's largest online store for international products and accessories

Thanks Sir , I think I already have it check my post # 43 here

http://www.team-bhp.com/forum/4x4-te...-thread-3.html

Sudarshan

[Sutripta]

Originally Posted by Aroy

In case an ammeter is needed, you can use the type used in DC power electric distribution systems - it has a small shunt which is inserted in the circuit, and a voltmeter is connected across the shunt. Of course the meter is calibrated in amperes!

Reading this, I thought we had a ready made, off the shelf, bolt on automotive solution.
But then going through posts like the one below, am I correct in assuming that that is not the case.

Originally Posted by Aroy

100mV meters are normally instrumentation grade, so will not be rugged enough for automotive use.
Precisely.
What is done, is that you put an inexpensive DC Operational amplifier with a driver to boost the voltage, so that an automotive meter of 0-15V works as a 100mV meter.
Similarly you can use a shunt in series with the main power cable and use the voltage drop across it as an ammeter.
What will the meter show in switched off condition. Does one need an OpAmp with rail to rail swing? Are such OpAmps cheap and rugged? What will be the ground reference for this OpAmp?

Once again, do we have a ready made automotive solution using this concept.

Originally Posted by Aroy

. Buy a shunt (it is just a precision resistance), with a matching meter
What should be the specifications for the shunt?


Buy Equus 3721 Battery and Charging System Monitor and accessories from India's largest online store for international products and accessories
Seems to be a voltmeter (with a bit of added intelligence), not ammeter.

Amazon.com: Vector VEC008 Digital LCD Voltmeter, 12 Volt: Automotive
Seems to be a voltmeter, not ammeter.

Amazon.com: Equus 3721 Battery and Charging System Monitor: Automotive
Same product as first link.

Originally Posted by Aroy

You can surf the net for rugged centre zero voltmeters.

You are far better at trawling the net than I'll ever be. That's why the request to you.

Regards
Sutripta

[Samurai]

Starting problem is back. Some times it starts at first crank, sometimes it clicks a few times. Yesterday, Sachin and I had a small offroad session to test his new DI engine.





Sachin is quite a Jeep whisperer, a fairly unknown one. That is because he hardly posts anything on the forum. But he is an automobile engineer by qualification, and had worked in a car garage for a year hoping to start his own some day. Then he took over the family business, and had to give up that dream. But he didn't give up completely, he has restored countless Jeeps until now as a hobby. He currently owns three 4WD vehicles he himself restored. He is as good as any mechanic.

After one look at the starting problem, Sachin concluded that it is the starter motor that is at fault. So, tomorrow I have to take it to the garage for full service and get the start motor overhauled.



At the end of session, my Jeep simply refused to start. It kept clicking forever. So we decided to push start. It first I forgot I was in 4L, so Jeep refused move at all.

When I push start any vehicle, I engage second gear and let go the clutch once the vehicle is moving at 10kmph. However, Sachin taught me a new trick yesterday. He asked me to crank the ignition as I let go the clutch. That way the vehicle can be push started at much lower speed. I mean, it makes sense. Moving vehicle makes the starter motor's job much easier. So I was able to push start the Jeep at very slow speed thanks to simultaneous cranking.

[Aroy]

Originally Posted by Sutripta

Reading this, I thought we had a ready made, off the shelf, bolt on automotive solution.
But then going through posts like the one below, am I correct in assuming that that is not the case.

Once again, do we have a ready made automotive solution using this concept.

You are far better at trawling the net than I'll ever be. That's why the request to you.

Regards
Sutripta

1. The bolt on solution was always there, at least in the Jeeps, Ambassadors and Fiats of yore. You inserted the ammeter in the power circuit. If I am not wrong one of the wires entering the "Ignition Key" is main power from battery and a corresponding wire goes to power the various functions. You insert the ammeter after the switch.

2. Depending on where you put the voltmeter - before or after the ignition switch. If before it will always show the battery voltage, if after then it will show only when the switch is on. In my college days we used a simple op-amp, I think 701 as a DC amplifier. It requires only a few resistances, an input, output and two power supplies + and -. Now a days the amplifier is integrated within the voltmeter/ammeter modules.

3. The shunt specifications
- Stable at the maximum rated current - no over heating
- the voltage drop at maximum current is matched to the voltmeter.

4. After some introspection, I think that the old style meters are best suited for Jeeps, as they are field proven rugged analog technology. Though for an SUV I would not mind a digital module.

As far as trawling the net is concerned, all you need is a connection, and then "Google" Zindabad!

[Sutripta]

^^^
My comments inline in bold.

Originally Posted by Aroy

1. The bolt on solution was always there, at least in the Jeeps, Ambassadors and Fiats of yore. You inserted the ammeter in the power circuit.
Was talking of a bolt on implementation of your suggestion. Namely using a shunt and a voltmeter to mimic an ammeter, without using the long heavy wire runs. The original solution has always been there.

2. Depending on where you put the voltmeter - before or after the ignition switch. If before it will always show the battery voltage, if after then it will show only when the switch is on.
Discussion is actually on ammeters, not voltmeters.

In my college days we used a simple op-amp, I think 701 as a DC amplifier. It requires only a few resistances, an input, output and two power supplies + and -.
Likely to be a 741.
You actually implemented it in a car? Lots of questions, starting with how did you manage the symmetric power supply?

3. The shunt specifications
- Stable at the maximum rated current - no over heating
- the voltage drop at maximum current is matched to the voltmeter.
Engineering details rather than literature please.

4. After some introspection, I think that the old style meters are best suited for Jeeps, as they are field proven rugged analog technology. Though for an SUV I would not mind a digital module.
Introspection is good!

As far as trawling the net is concerned, all you need is a connection, and then "Google" Zindabad!
Thanks for the words of encouragement, but we know that that is not a fact!

Regards
Sutripta

[ramkya1]

My jeep also has starting problems, lots of useful information here, has been a very informative thread.

Will post some more in the 550 thread somewhere. The fuel gauge is also faulty, will try changing float, the temp problem was investigated thoroughly, turned out to be a faulty temp gauge.

-----

[headers]

Originally Posted by Samurai

When I push start any vehicle, I engage second gear and let go the clutch once the vehicle is moving at 10kmph. However, Sachin taught me a new trick yesterday. He asked me to crank the ignition as I let go the clutch. That way the vehicle can be push started at much lower speed. I mean, it makes sense. Moving vehicle makes the starter motor's job much easier. So I was able to push start the Jeep at very slow speed thanks to simultaneous cranking.

Infact, 3rd gear works better in such low speed engines - 2nd is ok for petrol engines.

[svsantosh]

Originally Posted by Samurai

However, Sachin taught me a new trick yesterday. He asked me to crank the ignition as I let go the clutch

IIRC, Arka wrote about this in Tbhp quite some time ago... I practise it whenever needed and it is lot helpful than just push start.

[Samurai]

I also considered replacing the starter motor with a brand new one. It is one of the rare parts in my Jeep that is still not replaced. But Sachin tells me that is not a good idea. Apparently older starter motors are more reliable than the new stuff. So I am only getting the starter motor serviced.

Originally Posted by svsantosh

IIRC, Arka wrote about this in Tbhp quite some time ago... I practise it whenever needed and it is lot helpful than just push start.

I must have missed it. I wasn't aware of this until this weekend.