Printer Friendly Forum Posts - greatest invention i am tyrying to build

Guys as you know i am highly skilled in the art of madness for electronics.I have build remote starting kits to building light and rain sensors(proof of concept and beta/alpha testing)build circuits that make cars talk to you via negative inputs,build voice activated features that worked 60% of the time.

I have done many things that only new cars have...my motto is what you have in your new car i can build it in a old car:D.

Now the time has come for a new project which i need so many feedbacks from this excellent forum.
My next project from scratch is *drum roll*BUilding a circuit that will monitor your battery in your car and when the battery gets flat(enough amperage to start the car) the car will start itself and when full charged it will switch off gain...and this will cycle all the time until the kill switch get applied .

This application will be great for those guys that play there audio system when the car is off.
So far i have the circuit for the low voltage .But getting a buzzers output to trigger a relay is a bit tough.What you guys think.I still need help on the full charge part

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the only interesting answers are the one that destroys the question.

Instead of starting the car when battery voltage is low why not disconnect the battery? That way, the car won't run for days on end (until it is out of gas) if you leave the lights on. I would much rather come back to a dead battery then a dead battery AND a car with no gas!

I think there is a relatively inexpensive part out there called a "Battery Buddy" that does this already. If the charge on the battery drops past a preset point the battery is physically disconnected from the car. The driver can then reset the battery buddy by pushing a button on the battery.

If you want to get creative, build your module and have it send you a text message when the battery gets low. That would be much more useful then just starting the car and letting it run (imo).

I'm not a battery charge expert but I would question how reliable a circuit would work just monitoring voltage (with no load on the battery). Hopefully OldSpark will chime in on this!

What do you mean by "getting a buzzers output to drive a relay is a bit tough"? What has a buzzer on it? What is hard about getting it to trip a relay? What is the relay going to do? It seems to me that you could do pretty much the entire thing with one chip - monitor battery voltage and start the car. The only relays you should need are for the ignition, accessory, and starter.

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Kevin Pierson

thanks for the reply.What i mean is that the cheapest circuit i can build has a buzzer or led.the thing is that the voltage and amps might be to low for a relay coil for triggering.I could use a very small 5amp smd relay to drive a standard relay,This could work...and like you said pulse the starter relay and ignition(pulse to latched)and when the battery is fully charged the latched relay will engage again to switch off the car.

In South Africa we dont really have those gadgets and if we wanted them the price would be staggering.....hence the trying to build this for us poor folks ;D

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the only interesting answers are the one that destroys the question.

I'd suggest forget it.

You need a battery condition monitor (BCM) to be of practical use, and they are not cheap. (It involves impedance testing, history tracking, load monitoring etc.)

It is not merely a case of voltage monitoring.

The best is a voltmeter that tells you the battery or charging system is low, and the brain to interpret that.

The brain can be human with a bit of knowledge, or a chip with LOTS of programing.... (see BCM above).

There are various voltage alerters (with inside/outside thermometers, clocks etc) from ~$20-$50.

PS - If you know enough about batteries, you'll start to understand.
EG - how do you determine when the battery is full?
Plus, normally you would be talking about a faulty battery else alternator else system, and the solution for that is a new battery or fix the problem.

If it has a buzzer or LED output a simple transistor will fix that. However, I would think the LED output would be a usable signal to trigger the remote start.

Are you designing this system from scratch or just piecing things together to get it to work? How are you planning on starting the car?

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Kevin Pierson

In retrospect, I was going to suggest a solar panel - with regulator!

KPierson wrote:

If it has a buzzer or LED output a simple transistor will fix that. However, I would think the LED output would be a usable signal to trigger the remote start.

Are you designing this system from scratch or just piecing things together to get it to work? How are you planning on starting the car?

I am designing the system from scratch with the use of many kits and making them unison.The way i figured to start the car would be by using a output from the led(latched to pulse operation)To stop the starter swing i would have a circuit built in series with the d+ wire to tell the starter to stop engaging(this circuit will have to be very intelligent hey)we dont want over swing.
This sets me up for a headache..lol.

I am good in what i do and and for years i have pleased many a customer at custom car shows.This will be a difficult feat from scratch but in the end all will end well :D

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the only interesting answers are the one that destroys the question.

Peter, email me on this.
We don't know if you're highly skilled, we've never heard of you, your use of English unless it's a second language makes me doubt that. Low battery monitoring and remote start has been available for many years with remote starters.
Any way working 60% of the time = total fail.
Any further comments, Kevin or Peter?

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I don't think it is a terrible idea, it just needs to work perfectly and have numerous safeties built in (like only two or three starts of the car before the key is used to start the car, tach monitoring, etc.)

I don't know enough about battery monitoring but I would think if you used a 10 ohm resistor and apply voltage to it for a second every 15 minutes you could possibly accurately judge the state of the battery without draining the battery too much. It would be a 1A load for 4s every 60 minutes.

I think once the car has started you let it run for 25 minutes and then shut it down. You then lock the system out for an hour or two before checking for voltage again. The thing I would NOT want is for the module to consistently try to start the car over and over and over again.

Of course I think it is a terrible idea to hack modules together to try to do something this advanced. Do it right or don't do it at all. I don't consider myself to be "highly skilled in the art of madness for electronics" but I am confident I could design one module to do all of this (from the firmware programming to the circuit board layout and everything in between) and get it working in a car!

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Kevin Pierson

Yes - my first reply....

I didn't even mention the complications and hazards for self-starting... I think of all the interlocks - timings to ensure non-repetitive starts; exhaust fumes killing eveything; starting in the dead of night; suitability for EFI only; anti-theft; etc etc.

Thee are many safety if not legal issues...

And using a flattening battery to start a vehicle to recharge itself.... If it is a faulty battery, that ruins any chance of a "normal" start later....

Then there is the complication of determining a "low voltage" battery - ie, accounting for different wiring and normal loads; battery resistances; temperature effects.
That is something that has to be user configurable, but with some internal smarts for battery capacity etc.

I am well known for doing the impossible.
This can be done - with a lot of work (especially for non-specific or public use!) - but it will not be worth the effort.

It won't succeed as a product because it will be too expensive and complicated (for the near future).
I consider my "smart EFI & Ignition" simpler than this project.

But nevertheless, simple voltage alerts or voltmeters (which should be considered "mandatory" for anyone worried about charging and batteries) will probably win hands-down for price, simplicity & outcomes.
And maybe a solar panel with regulator to keep the battery topped up - hence also extending battery life by avoiding sulfation.

I suspect many still do not understand how difficult it is to measure battery condition and remaining capacity.
[ It seems the "experts" still replace batteries ahead of time rather than try condition monitoring - eg, replace 10-year UPS batteries after 5 years unless used several times before then.... ]

Morning Peter, evening Kevin, I'm just going to bed, had some lovely blizzard driving today, then trying to find a minor electric fault and discovering the Transit Connect's lighting switch whilst looking the same as a Transit is wired differently! All at -10c with the snow going down my neck so I'm a bit grumpy. we get this sort of question come up every so often. Please there really is nothing new in the automotive world. Most ideas are stolen or hand-me-downs from the avionics/computer worlds.
Yes I do know* Kevin could make something but I agree with Peter, install a voltmeter and I agree with me, carry a power pack, fully charged, especially with the current low temps. in the the Northern Hemisphere.
*Been on your web site Mr. P, seen your wonderful devices, to me your mirror aids are a lot more useful than most things.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Sorry KP - I missed your reply....

Excluding "in principal energy discussions", it is a great idea, but ultimately IMO not practical.

Starting from its reverse....
Say you have a dead battery - what is the solution? (IE, a spare)
Say you have a flat battery - what is the solution? (IE, a spare, or a charger like solar or generator)

Those are simple solutions with the spare battery being the ultimate including piece of mind.

You (KP) hit on some of the base constraints - no restarts etc.
The system will not fix a faulty battery.
And if the alternator is faulty....
(That's what a dash voltmeter is for. Or a spare battery.)

The start-to-charge system is simply a self-start system (how cheap are they?) with the added trigger - like self-heating cars etc - and the smarts.

But monitoring a battery as in trying to judge its condition or capacity.... no.
I would assume a simple voltage monitoring only - eg - if battery voltage measures under 12.2V for 5 minutes (which equates to an OC voltage of 12.4V @ 25C; ie, ~30% discharged), then start and charge until battery current drops to 3A or for 30 minutes (whichever first) and stay off for 24 (or 12) hours.

I would also add thermal sensors so the battery temp above ambient can be monitored and cause shutdown if required.

But to test for battery condition other than its (apparent) OC voltage - nope; too difficult, and I argue, there is no point.

To release this as a product IMO would be fraught with claims etc.
But maybe do as the little "emergency cig-socket battery chargers" manufacturers will do (it has a small AGM battery probably equivalent to 6V-4AH or less) - be gone before people start their claims.

I get what you guys are saying.I don't want to build a permanent battery monitor as a serious project for mass production.What i would like to achieve is have a electronic box, tell my client that this can be used for starting his car when the battery runs down for example he is at a barbeque and the car is right next to him(pumping the sound system).This should never be a permanent thing for his car.

You guys have given me lots of advice and i will take heed of all the dangers.I am much more aware of this little project of mine.I have to correct many errors in my project and you have helped me see this.

Well let me get going with this project and i will keep you updated.
I see there are many electronic engineers on this forum.In cape town where i stay it seems i am the only guy that thinks out the box:D

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the only interesting answers are the one that destroys the question.

Well in the example you give, it's simply a (low) voltage sensor to trigger the autostart, and a battery current sensing to tell when it's full; and a timeout timer.

But that could also be done with the voltage sensor (or $20 MW728 "battery protector" etc) triggering a lamp or klaxon or audio to signal manual starting is due, or turn off the audio etc.

And yet again, I recommend a dual-battery circuit anyhow.
What if the main battery is weak and won't crank? Or the circuit fails?

That's simple. It's only the autostart that is complex.

What i find difficult is some cars need a certain amount of amps for one full crank and start,and others like jeeps with a v8 needs more amps to crank.How could i really set up for what is maximum.i would have to have a serious over the top amp meter across the battery in series.
Tell me this https://www.conrad-international.com/BATTERY-GUARD-MW-728.htm?websale7=conrad-int&pi=851744&ci=SHOP_AREA_14724_0312032 is 20 dollars.So that means i will have to x7.5 for our currency which works out to R137.This looks cheap but shipping cost is gonna be heavy.

Let me order one and see what mods i can perform.

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the only interesting answers are the one that destroys the question.

What has cranking amps got to do with it?

If wanting to modify the voltage switch, I recommend the Oatley kit K227 - 12-24V Dual Battery Adapter For A Vehicle instead for AUD$22. I'd suggest a spare relay in case... (see here; AUD$6.50)

The K227 is a typical "smart battery isolator" (but cheaper!).
But since it describes the circuit operation and needs you to construct it, it may be more versatile. You may be able to have it provide the maximum timeout (though the RC for the off delay may be excessive).
And it is voltage adjustable (unlike the MW728 in standard form) with your choice of housing.

The answer to your rather obvious question is the size of the engine you're trying to start such as its inertias.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

It's not only size of motor, it's compression ratio as well. I would be willing to bet a 13:1 four cylinder would take more power to crank then an 8:1 V8.

If all you want is simple voltage monitoring the entire thing is easy. Auto starts, in general, are pretty straight forward. The only thing that requires any thought is the tach threshold programming and even that isn't too bad. Past that, it's just writing the logic for max restarts and safeties. Most of those, even, can be copied from remote starts (hood pin shutdown, brake pedal shut down). It would be awesome to somehow work a CO3 detector in as well just in case someone forgets to shut it off and parks indoors. I've never seen that in a car before!

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Kevin Pierson

CO3 Kevin? Carbon trioxide?

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Check this out!

https://www.sparkfun.com/products/9403

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Kevin Pierson

CO CO3 what's the difference? (besides a few oxygen atoms!)

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Kevin Pierson

And like I did in stinks 50 years ago it's CO not CO3. That link calls it CO. In fact if I remember any stinks it would have to be C2O6, I think. I hated chemistry.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Novel - an indoor bbq. (Though yes - I have been to a few...)

A COx monitor - but where would you mount it?
But that's all part of the due-diligence and legal liability associated with its operation.

I'd go for a CO monitor myself (despite a medical student claiming CO never killed anyone), though CO2 is handy before people black out (and maybe burn or die).

But I am still wondering what dablakmark8 thinks cranking current has to do with this?

OK, you got in first although I would yield to your compression ratio comment, which is why the equivalent (in engine size) diesel always requires a bigger battery, it's just that I was gobsmacked by the ignorant question. It's the sort of thing my 12 year old grandson would ask if he saw his father or myself under the hood.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I do not disagree with you. I just don't want to actively agree given the credentials.... After all, we all have gaps (speaking for myself that is).

But time & replies can tell.

As some brilliant person once wrote, the idea or "invention" is only 1%....
It's the next 9% that takes the skill.

Now you're doing it Peter! Write 99% 1 hundred times. Is being a moron contagious?
Did you get my email about 1/2 hour ago ref the job offer?

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

37%
(That's 99% 100 times.)

Yes - I got the job offer. I'm on the next plane....
Ah - to quote the Rusky in "RED" (a current cinema film, yes, red current, not DC) - there are things I too miss...
I will respond...
But first - breakfast!

And yes, moronism is contagious. Look at me! (But I bet I'd still pick errors in Mensa tests! (After breakfast.))

That's the problem, I remember the ex flame who actually belonged to Mensa, she was taking her maths degree, she wrote a three page theorem on finding the area of a triangle, I just doubled it to an oblong, got the answer and halved it, why don't people think out of the box...but not too far like our first poster and to help his "practical" education he should go to Kevin's own web site and see the fabulous stuff he makes, even if he doesn't know the correct formula for carbon monoxide.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Not that I like hijacking, but since this is a very public site, and since I can repeat yet again...

The thing that got me with the Mensa tests was that of those I checked, from memory, they had an average of 3 errors each out of ~140 questions.
That's an error rate a bit over 2%.
Now, if Mensa was allegedly the top 2% of intelligent people (was that IQ? posted_image

LOL!), and assuming that required no more that 2% incorrect answers in their tests, they eliminated their apparent top 2% - the very ones they were seeking.
And by extension, they consisted of the 2%-4%'ers.
(To paraphrase, they would have included those that had incorrect answers to 3 questions, and probably eliminated those that were correct.)
At least that did explain why I had so many problems with Mensa members - not so much that they were wrong, but somehow they believed that they weren't!

As to lateral thinking - that's a totally different area.
Mensa only measured "IQ". They did not measure intelligence!

I wonder if they have changed since then?
Maybe they have since joined a religious group to avoid taxes?

Everybody has a right to my opinion!

Thanks oldspark for battery monitor kit which you linked.Reason why i was worried about the crank amps was that if the amperage was to low the car would not swing but you made it clear all i need is the low voltage adjustments.10v might be a bit to low imho,what you think.

That co2 sensor could also be incorporated in the box but its sensitivity is questionable.Could it be that easy..lol,electronics is never easy .

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the only interesting answers are the one that destroys the question.

The voltage to set depends on the battery and its drain.
EG - battery varies from ~11.3V to 12.7V (fully discharged to fully charged; Open Circuit voltage).
Cranking batteries normally should not be discharged more than 30% (& deep cycle no more than 50% for good life).
Hence - using my conservative rule of 0.1V per 10% discharge, 30% discharged is 12.7 - 0.3V = 12.4V.

So you want to set the voltage to an open-circuit voltage of 12.3V to 12.4V.
But that might be 11.5V or 11.0V depending on the load (and battery internal resistance - which increases as the battery discharges).

10V is too low. (Even under very high discharge rates - even UPS batteries at a 10 minute discharge rate are rarely taken as low as 10V, though they are AGM batteries....)

As to what is enough to crank the vehicle - you will simple have to trial and error. Calculations could be done for a known battery and vehicle assuming reasonable staring time, but as the battery ages or temperatures drop or....

And you don't want a COx sensor in the box, nor car - you want it wherever living things are likely to be effected.
But hopefully the bbq'er will notice people passing out and be able to stop the vehicle - unless they too have passed out, or the vehicle is locked etc.

oldspark wrote:

The voltage to set depends on the battery and its drain.
EG - battery varies from ~11.3V to 12.7V (fully discharged to fully charged; Open Circuit voltage).
Cranking batteries normally should not be discharged more than 30% (& deep cycle no more than 50% for good life).
Hence - using my conservative rule of 0.1V per 10% discharge, 30% discharged is 12.7 - 0.3V = 12.4V.

So you want to set the voltage to an open-circuit voltage of 12.3V to 12.4V.
But that might be 11.5V or 11.0V depending on the load (and battery internal resistance - which increases as the battery discharges).

10V is too low. (Even under very high discharge rates - even UPS batteries at a 10 minute discharge rate are rarely taken as low as 10V, though they are AGM batteries....)

As to what is enough to crank the vehicle - you will simple have to trial and error. Calculations could be done for a known battery and vehicle assuming reasonable staring time, but as the battery ages or temperatures drop or....

And you don't want a COx sensor in the box, nor car - you want it wherever living things are likely to be effected.
But hopefully the bbq'er will notice people passing out and be able to stop the vehicle - unless they too have passed out, or the vehicle is locked etc.

But hopefully the bbq'er will notice people passing out and be able to stop the vehicle - unless they too have passed out, or the vehicle is locked etc

Thanks again,i am beginning to understand more about car batteries.
I think the comment in bold is very funny and i burst put laughing just now

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the only interesting answers are the one that destroys the question.

I think a CO detector exposed in the vehicle would be better then nothing. Like other things, you would have to trial it out. I would think if you detect even low amounts of CO inside the car that would indicate that it isn't outside. There would be quite a bit of lag on it, but it is better then nothing at all.

The sensor looks pretty straight forward - you would just need to determine where you would want the cut off and run it through an adc. I think, in this case, it really could be that easy!

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Kevin Pierson

Dei has some stand alone remote starters that accomplish this with minimum hassle and are programmable, as regard minimum voltage and run time for re-charge, and isn't that costly, imo. Can i get a link to kevin's site please? Or a web address? Sadly the heading of this topic made for dissapointment had it not been for the input of howard, the oldspark and KP.

And frankly Peter and I were taking the wiz, Kevin was tying to shut the poster up with knowledge!
Look at his profile, I think he also mentions his company in one of these posts, Google it.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Yeah - I googled... Some links don't work but you will find stuff...

I think I said something akin to "it's a good idea, but stupid" - ie, it seems like a good idea until you really think about it. (In tis case though, it may may need a bit of expertise - like the auto-starters that you guys know about, and battery behavior that I know about, and safety that most experienced know about.
(Maybe a cat-converter to convert CO2 to CO since CO doesn't kill...?)
[That's a joke - a medical student once wrote that...]

Anyone seen my wheel? I don't want to have to invent it again!