IIRC there are a number of other Forum Threads about OBD2
That is not the correct mindset, IMHO. What you need to find are the specifications.
Alternatively, choose parts that can withstand the errant voltages on the normal 12v system - as, for example, I suggested in Reply #3
...R
Ok, i took a look into the best shop i can find here and the pololu module which seems perfect, cost almost 8 USD, too much for me.
Then i tried to search for other ic's step down but i didn't even know how to search for them because the site has only text based search no filters
I took a look on google with those keywords to find some models then to search back to my shop but i only found a few, and none of them exists here
If you know any model number or where i can found them can you tell me?
Or if you want to search for yourself a few models that you have in your mind here is the site: http://www.adelectrocom.ro/advanced_search.php
Note that this is the most popular shop in my country, the rest of them are very over priced and china like shipping.
Anyway i don't really understand why a 16v maximum linear reg won't be safe to use, maybe it can resist upon those spikes that you are so sure about
prologikus:
Anyway i don't really understand why a 16v maximum linear reg won't be safe to use, maybe it can resist upon those spikes that you are so sure about
I don't think a 16v component would be suitable for a car - but that's just my opinion and I could well be wrong.
And I am not sure about spikes - it is the uncertainty that is the problem.
You need to ask yourself what would be the impact of your system failing because it was hit by a high-voltage spike that you were not expecting. If the consequences are small then by all means take the risk. It might work fine for the next 20 years. And if it does fail just repair or replace it when you get a few free minutes.
But if the consequences are serious then you need to take steps to avoid the problem.
Is there some reason why you are against the idea in Reply #3?
Robin2:
I don't think a 16v component would be suitable for a car - but that's just my opinion and I could well be wrong.
And I am not sure about spikes - it is the uncertainty that is the problem.
You need to ask yourself what would be the impact of your system failing because it was hit by a high-voltage spike that you were not expecting. If the consequences are small then by all means take the risk. It might work fine for the next 20 years. And if it does fail just repair or replace it when you get a few free minutes.
But if the consequences are serious then you need to take steps to avoid the problem.
Is there some reason why you are against the idea in Reply #3?
...R
If i'll use capacitors and zener diodes of 16V also fuses, i'll reduce the risk to a minimum i'll say, also because i don't think they didn't thought about those voltage spikes when they designed the car itself (Opel)
The reason i don't like it because i still need to buy a regulator for the charging and also the batterys and also my arduino doesn't instantly go to sleep after the contact js off and this causes big battery drain for those little nihm also the arduino wakes up time to time which again consume it, eventually it will consume all the current from the batterys(in long term).
I know you didn't know those thing and this is why you suggested it, if there was only 1mA of current, using batterys would last long and would be a good idea.
I wanted to make the post as little as possible. So it would be more likely to get an answer
TomGeorge:
Hi,
Why does you project have to be powered from the battery continuously?
Does it really need to be powered when the vehicle has been switched OFF?
Thanks.. Tom...
Yes because i have a 433mhz receiver attached to an interrupt pin on the arduino so when the transmitter is ardound, the arduino is waked up and then after 500ms it will receive another message but this time arduino will read it's content to see whatever the transmitter is truly my key which will unlock the car
Robin2:
How often do you drive the car? Once per day? Once per week?
...R
It's not about how often i drive it's about making sure that even if i won't drive the car for 2 months i'll be still able to turn it on :d...
The thing is that i'm still on my" parents money" and i also have other things to do with money and maybe i could afford buying the pololu step down but all i did to this point was by choosing the best way to the lowest price and this is why i don't accept it so fast.
Currently there are 3 things in my mind to solve this
-buy the regulator that i found (the one with maximum 16V)& and use zener to protect from higher V
I still have this on my mind because as you said the only problem are spikes which i didn't find one so far but i won't exclude it.
-find another same cheap, low drop V, low quiescent, but which can support higher voltage or even have a spikes like proection
-buy from aliexpress/ebay a step down converter with a low quiescent current and high voltage capable, like those: http://s.aliexpress.com/bMVrmQVr
Or something similar to it
-in addition i could also find a ic that protect the regulator from the spikes but this is unlikely to happend because one thing that I forget to mention is that i'm currently running the arduino on my car powered by a step down conv (4-5mA quiescent) for 2months and power the lm358(433mhz receiver) from a regulator with maximum of 14.5V for 1 month and i checked the voltage to see if it's changed and it isn't... This isn't the proof that they are not damaged but it's still a clue, right?
You may notice the "right?" and realise that I'm stubborn but still not sure of myself
From the point of view of someone who has forgotten most of what little he knew about electronics years ago ......
It seems to me like powering an Arduino in a car would be as simple as wiring one of these items to a 12v source, plug it in and go. Or am I really missing something here?
DangerToMyself:
From the point of view of someone who has forgotten most of what little he knew about electronics years ago ......
It seems to me like powering an Arduino in a car would be as simple as wiring one of these items to a 12v source, plug it in and go. Or am I really missing something here?
Right now i went into my garage grab an original 700mA Samsung adaptor and plugged in with my multimeter to check the quiescent current of it when i draw nothing from it.. And the result was beyond my expectation, 4 mA, low i'll say, but still... There is no load so if i'll use at least 5mA i think that 4mA will increase
Here we talk about quiescent current lower then 30 microamps
It's not about how often i drive it's about making sure that even if i won't drive the car for 2 months i'll be still able to turn it on :d...
If you are leaving the car for 2 months, switch the "keyless entry OFF"
AND
Use the key Luke!!!
Tom...
PS. Cars these days are designed for very high loads, due to all the accessories some people demand, this includes expensive batteries and alternator systems so can support such constant load devices.
prologikus:
Right now i went into my garage grab an original 700mA Samsung adaptor and plugged in with my multimeter to check the quiescent current of it when i draw nothing from it.. And the result was beyond my expectation, 4 mA, low i'll say, but still... There is no load so if i'll use at least 5mA i think that 4mA will increase
Here we talk about quiescent current lower then 30 microamps
I'm not sure why 4 or 5 mA is too much. But I'll hush up and hide over here in the corner and try to learn something from this thread.
prologikus:
It's not about how often i drive it's about making sure that even if i won't drive the car for 2 months i'll be still able to turn it on :d...
How about a little bit of "outside the box" thinking. Not to mention telling us ALL about the project.
Are you trying to implement key-less door locks or a key-less ignition switch?
Am I correct to think this is an older car that does not now have key-less whatever?
Do you plan to disable the regular key lock()s when you install your key-less system. Assuming you are sensible and do not disable the key locks then won't it be possible to use them if your key-less system fails?
No matter what power system you choose for your key-less entry you will need to have an alternative system in case it fails. So why not use that alternative in a constructive way to minimize the complexity of other parts of the system.
My guess is that a few AA NiMh cells would be more than adequate to power a microprocessor for 3 months when it is mostly asleep. And don't use a power-hungry Mega for a wake-up system. Use an Atmega 328 or an Attiny on a breadboard.
Have you the option to use a small solar panel to keep your battery topped up?
Robin2:
How about a little bit of "outside the box" thinking. Not to mention telling us ALL about the project.
Are you trying to implement key-less door locks or a key-less ignition switch?
Am I correct to think this is an older car that does not now have key-less whatever?
Do you plan to disable the regular key lock()s when you install your key-less system. Assuming you are sensible and do not disable the key locks then won't it be possible to use them if your key-less system fails?
No matter what power system you choose for your key-less entry you will need to have an alternative system in case it fails. So why not use that alternative in a constructive way to minimize the complexity of other parts of the system.
My guess is that a few AA NiMh cells would be more than adequate to power a microprocessor for 3 months when it is mostly asleep. And don't use a power-hungry Mega for a wake-up system. Use an Atmega 328 or an Attiny on a breadboard.
Have you the option to use a small solar panel to keep your battery topped up?
...R
Ok, i didn't wanted to go that deep
The project is already done and working, this step is about upgrading it.
Of course i didn't disable the key fob, it's mecanical and it would be a stupid idea to disable it.
And why should i have 2 batterys in my car? Only to isolate the 12v lane from the arduino when the car is off? Also when the car is running it won't be isolated anymore because i still need to use a charger for them.
wvmarle:
How much does the regulator really add to quiescent power drain, if you also have this 433 MHz receiver active all the time?
Can't find your receiver online, as the LM358 chip is an OpAmp.
I really don't know, the datasheet of it doesn't say anything about the quiescent current when i drain some current(or i didn't see it)
mcp1703
The 433mhz module is a really cheap common one from aliexpress, and it's output come from the lm358 op amp
Three pages in and we can finish this finally, thanks to this bit of information. I should have asked about it right away, but like the rest of the posters got completely blindsided by the discussion about regulators, converters, and voltage spikes.
Your regulator is NOT the problem. That 4 mA is the quiescent current of your FS1000A receiver. So no matter what regulator or converter you're going to use, you're not going to get below that 4 mA, unless you completely switch off your receiver (as in, your keyless entry).
wvmarle:
Three pages in and we can finish this finally, thanks to this bit of information. I should have asked about it right away, but like the rest of the posters got completely blindsided by the discussion about regulators, converters, and voltage spikes.
Your regulator is NOT the problem. That 4 mA is the quiescent current of your FS1000A receiver. So no matter what regulator or converter you're going to use, you're not going to get below that 4 mA, unless you completely switch off your receiver (as in, your keyless entry).
So anyway, the 4-5 mA you mention, that's what you can expect if you have this receiver active.
I like that we finnaly talk straight about the subject
I knew that my receiver is using 4-5mA, but beside this, my curretly step down convertor also consume 4-5mA as a quiescent current.
And this post was made because i wanted to replace it(the old step down conv) with a Linear regulator, to reduce as much as possible the quiescent current of it
prologikus:
And this post was made because i wanted to replace it(the old step down conv) with a Linear regulator, to reduce as much as possible the quiescent current of it
First of all most of the buck regulators that I find on a quick Google search draw microamps quiescent current, so 2-3 orders of magnitude less than your receiver takes. That's nothing. Just get a basic converter that can take up to 35-40V and produces 5V output - check the data sheet for exact quiescent current.
Secondly, your receiver draws 5 mA at 5V, that means at a rather poor 90% conversion rate you draw 2.3 mA of your 12V battery supply (less if your battery is at higher voltage). Regulators like this one are designed for use in cars, I found a very similar one (same brand) reported to draw 1.5 mA. So if that's really on top of your 2.3 mA you end up at 3.8 mA. I'm sure you can find better ones, with less draw (I guess it's the protection circuitry that adds to this).
On the other hand, a linear regulator takes in 5 mA at 12V to put out 5 mA at 5V. It's a linear converter after all.
So a buck converter with 1.5 mA quiescent current still draws less current overall than a linear one with no quiescent current.
