Normal Battery Loads

It depends upon the state of charge of the battery, the alternator speed and whatever electrical loads are turned on at any moment.

The time-weighted average load on the battery is zero, disregarding battery deterioration over time.

The battery provides energy to start the car and from then on the electrical power should be coming from the alternator, including the power to re-charge the battery for what it "gave up" in starting he car. If the battery is providing power, then there is an issue that needs to be solved.

Have a look at your owners manual anyhow. The fuse ratings will be about 3x the expected loading on the system.

Just figure out what you want to be "on".

Thanks a lot to 'PWSlack' & 'Just an Engineer'. Let me clear my problem first. We are manufacturing Ignition Switch. My query is after starting up the car when it is in running condition how much normal current passes thru this ignition switch?

Condition1: In the day time when AC is on?

Condition2: In the night time when only Head lamp is on?

Bijoy Santra

Ah! So it's got nothing to do with the battery.

The answer is that it depends upon the design of the electrical system, which cannot be seen from here. Some systems wire directly through the switch to the various loads. Some wire through a relay contact that is maintained in the closed position by a contact on the switch, the relay contact withstanding the loads instead of the switch.

Whichever way, allow for sufficient extra capacity to run the number-plate-, tail- and turn-lights of a trailer attached to the tow-hook.

Hello again, Bijoy.

While I certainly have not seen every configuration of auto ignition switch, all I have seen do not run any current directly thru the keyswitch. The turning of the key to the selected operation (START, RUN, OFF, or ACC) will that transfer the rotary motion to a series of relays or contactors... these relays actually enable the varied electrical functions as selected. PWSlack said pretty much the same thing in #4, though I have not seen one with an electric contact within the switch assembly.

Is your ignition switch not for an automobile? Thread title tells me yes, please confirm. As well, are these for aftermarket replacement, or are these for new autos?

If they are for new ones, then the original poster needs to be working to the manufacturer's specification and not to something we can conjure-up at CR4.

If they are aftermarket replacements then I do have to ask, "where's the market" and "why"? _{Actually, the original poster needs to ask that question, just in case I become disinterested.}

"If they are for new ones, then the original poster needs to be working to the manufacturer's specification and not to something we can conjure-up at CR4."

I agree 100% with this. To be quite candid. this thread (and others by Bijoy) are starting to sound like homework. The questions being asked indicate (to my suspicious nature) that the manufacture of these components is never going to take place, this is information for a classroom project. Add to this the wording of the questions, the reluctance of Bijoy to answer some of my other questions and to register, my sonar goes 'ping'.

Bijoy, if this is truly not the case, I do apologize. Please help me to believe this is a venture you are active in, and I will offer more information that (I hope) will prove more helpful. If this is a class project, please come clean and tell us... we will not do your homework, but we can help you to get on the right track.

Thanks everybodies who all are interacting in my pretty question specially to Mr. Doorman who have already cleared my other abiguities also. But I want to clear one thing that this query is not related to a classroom project. We are working on TML (Tata Motors Ltd.) project. This switch is meant for automobile only. The name of the part is Ignition Switch Cum Steering Lock. The function of which is both lock the Steering as well as swiching to supply the current to Accesories, Spark Plug & Cranking during starting.

So waiting for help.

I retract my previous statement. I now do believe that someone who knows absolutely nothing about them, "are manufacturing Ignition Switch".

Hello again, Bijoy. Fair enough.

Well, let's see... I have a belief that (today, anyway) the typical TATA ignition/wheel lock subassembly looks like this:

We can see that there is no key cylinder installed, this is a sub-assembly that includes switches, interconnects, and the steering wheel lock. This looks very much like my previous description, and is pretty typical of most autos today (in the price range of TATA cars).

So, are you asking about the current passing through the individual switches within this subassembly? If yes, there are still many things unanswered. Here is a simple wire diagram of an auto electrical system... the ignition switch is near the top right-hand corner:

In this example, we see that the only thing isolated from the ignition switch is the starter motor (isolated from switch by starter solenoid). This arrangement is not very sophisticated, nor is it common today; as shown here, even the headlights are not driven by an isolator relay, but through the ignition switch. Is this similar to your NANO?

Will you tell us honestly... Bijoy... are you looking for help on the NANO? If yes, are you working directly for TATA, or some third party?

I will wait for an answer to this.

Hello again, Bijoy.

As an afterthought to my previous post, if you are looking for help with the NANO (or a similar TATA car), I would caution you against posting the correct wire diagram for the car here. If you wish for more assistance, register as a member, and then Internal Message me with the information.

It should also be stated that the diagram posted in #14 is not for the NANO, nor for any specific make or model of car. The ignition switch SA shown is a TATA part.

Should anyone wish an explanation for these unusual posts, im me, and I will reveal.

^{Yes, I know TML is more correct, not TATA. I just like typing 'TATA'.}

Thanks a lot for sharing all these things. But it is not for NANO. Bcz. NANO is not the only one model TML is developing. It is for some other Model.

During Testing we observe the Cable leading to Batery terminal of Switch is getting heated up at 50A (At Ign. & Accessories), 12VDC very quickly. That's why I raised this question. If I get the normal current in running condition I will do modify the terminal as well as wiring harness according to that.

Waiting for reply,

Bijoy Santra

Hmnmmmm... Well,

Is it one of the trunk cables? Does not matter...

If I read you correctly, you are running starter motor current THROUGH the column switch? There must be a language barrier... I find that very hard to believe. Please confirm this is so, or clarify further.

It is not unusual to see trunk cables generate some heat during starter motor operation. How hot? How fast?

I cannot size cables or relay arrays for you. This is the function of your registered and insured engineers.

Without a lot more information, there is not much that I can do for you here. Confirm with any cable sizing chart the sizes of cables (DO NOT forget about the grounding cable/strap... this is often overlooked), relay and switch contact data sheets, and information for equipment being energized.

I refuse to believe that someone who,"are manufacturing Ignition Switch" knows so little about it.

What is the true purpose of your question?

Exactly how I feel about this... to manufacture such switches, be it the low-power thing on the steering wheel or the heavy current relay down in the bowels, one will be bound by precise and rigid plans and specifications. The whole venture will be one of serious, heavy investment and involve competent engineers, technicians etc. Hardly anyone to mail infantile questions to CR4. So I consider this post a load of hot air and what surprises me most that so many good guys do not catch on to this right away.

Maybe he works for Toyota and they have came up with a theoretical concept to actually have a switch that switches off the stuff that will actually stop a car but as of yet don't yet understand how to do it without using a computer and code?

Get hold of sample cars, Insert an amp meter in line with ignition feed.

look at wiring diagrams and what load is on switch.