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Thread: Taking the plunge...

  1. #21
    Constant Bitrate eugenweij's Avatar
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    Sweet! I got my battery today and they accidentally sent me the 30000mAh version.

    I didn't buy the 30000mAh version because it was too expensive , guess I get the sweet end of the deal.
    View my worklog here

  2. #22
    Constant Bitrate eugenweij's Avatar
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    Well, that sucked.


    I received my order from Hardkernel, everything is complete and seems to function correctly , I hooked up my odroid to my micro hdmi to vga adapter and discovered that the adapter won't function.

    After some researching I learned that only specific adapters work with odroid boards.
    The Samsung AA-AH1NAMB is one that has been verified by hardkernel so I ordered one , seems I still have to wait a few more days till the tinkering starts.

    I did test the odroid on my tv but that isn't an ideal place to to play around with the U3.

    On the bright side, Hardkernel did send 2 bluetooth sticks instead of one , guess it could come in handy at some point.

    It also looks like I will need a powered usb hub , but my question today is, how do you guys power a powered usb hub in the car?
    View my worklog here

  3. #23
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    About the powered hub:
    I power mine by the state of the PC. How?
    I've taken a 12v wire from the PC which controls an relay. So when the PC is ON, the relay's coil is engaged and all the devices hooked after that rely gets power.
    In fact this way I control a whole set of fuses, and for each device I got individual fuse. This way I got: 1. Protection; 2. Info about which device has blown a fuse (or it's wiring); 3. A possibility for easy reseting each individual device by removing it's fuse.

    About how you could use my idea (if you wish of course): Well I've search but I didn't found the pinout of the expansion header. Hopefully there you'll got a 5V or 3.3v on any pin telling you when the board is ON or OFF and giving the possibility to control a relay with that pin. All that remains is to find out the pinout and the given voltage. 5V relays are easy to find in local shops but for 3v relay I had to make an order and wait.
    My worklog: VOLVO S80 CarPC

  4. #24
    Constant Bitrate eugenweij's Avatar
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    that is a nice way with a pc , but my odroid is going to be in an always on state, and I don't want peripherals to be draining the battery when my car isnt moving, this to prolong the the time I can keep the odroid alive on a charge.
    View my worklog here

  5. #25
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    FYI - just to clarify...
    Quote Originally Posted by eugenweij View Post
    20000 mAh is a discharge of 20Ah , 20 amps per hour , so when the odroid board is on and taking the full 2A current draw it would take 10 hours to drain the battery.
    The '20 amps per hour' for 20AH is incorrect unless it means '20 amps for one hour'. (In which case it has a C1 20AH rating, but a C10 or C20 20AH will be (much?) less than 20AH at C1 (I'll het back to that).

    20,000mAH is 20AH.
    By the sounds of it, that's a C10 rating - ie, it has a capacity of 20AH over 10 hours, hence 2A per hour for 10 hours. (Yes, just as you said.)

    Car batteries are usually specified at C10 or C20 discharge rates. Many think that that C10 20AH would still have a the 20AH capacity spread over 20 hours (C20 20AH) but in practice its AH would be higher (maybe C20 24AH) because total output capacity increases with lower discharge currents. Or as I think of it, the higher the current, the greater the internal resistance losses (P = i x i x R) and hence the total output power - aka capacity - is lower. (It's not just a resistance issue, chemical etc issues also play a role.)


    Not that it's a big deal - you got the 2A for 10 hours correct - but I just wanted to clarify the a Ct aAH battery will supply a/t Amps for t


    PS - 0.05C is equivalent to C20; 0.1C = C10 etc.
    Last edited by OldSpark; 02-16-2014 at 03:17 AM.

  6. #26
    Variable Bitrate camo.b's Avatar
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    Quote Originally Posted by eugenweij View Post
    that is a nice way with a pc , but my odroid is going to be in an always on state, and I don't want peripherals to be draining the battery when my car isnt moving, this to prolong the the time I can keep the odroid alive on a charge.
    How does the odroid handle usb devices while sleeping?

  7. #27
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    Quote Originally Posted by eugenweij View Post
    that is a nice way with a pc , but my odroid is going...
    Oh yes, I forgot the allays on part. OK, again - it's a power satate (working at full/sleeping). If there is a signal for that - you could use it.
    Even a SMD LED could do the job, but then you should make an Arduino pro micro project to sense the LED and to do sth. Forget about the power consumption of the arduino - it can be made in microamps range, which for a car battery or even your 2000A is close to nothing. Yeas, to reach this low consumption you got to tweek it a bit, but there is alot info on the internet.

    OldSpark, on the previous page there is a video showing the real power consumption at full speed (while booting) and idle. I didn't see an value of even a half an A.
    My worklog: VOLVO S80 CarPC

  8. #28
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    Quote Originally Posted by VolvoCarPC View Post
    OldSpark, on the previous page there is a video showing the real power consumption at full speed (while booting) and idle. I didn't see an value of even a half an A.
    Fair enough. I haven't followed this thread, I merely saw that reply I commented on. (I was googling...)

    As to its 2A plugpack, I've oft written how PSUs must handle the load but are usually upsized to the next economical device, or whatever stock device the supplier has. Hence you often get 1.5A or 2A supplies for mA devices.
    OEM PSUs or plugpacks are a good way of designing the MAXimum power involved but can way exceed actual or even peak consumptions.

    But if there are inrush currents, and if you only measured Watts (ie, it may be a pf under 0.6 with crest factors >3 etc).
    Last edited by OldSpark; 02-16-2014 at 06:35 AM.

  9. #29
    Constant Bitrate eugenweij's Avatar
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    thanks for the clarification OldSpark.

    About the peripherals, I am thinking of putting a powered usb hub in place, connect it to the cigarette lighter connector (behind the dash) with a voltage regulator in between to make the 14.1V~go down to either 12V if thats what the adapter spits out or to 5V and connect it straight to the hub.

    My cigarette lighter connection only gets power when the acc is on , so that would effectively solve my problem with minimal issues, turning peripherals off when car is not in use.

    I am not sure how the odroid will be handling usb devices, something I will have to dive into after I get the touchscreen issue sorted, which is a pain in the butt for someone with minimal linux and no android experience.

    But I will get there ...
    View my worklog here

  10. #30
    FLAC PhilG's Avatar
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    Quote Originally Posted by eugenweij View Post
    My cigarette lighter connection only gets power when the acc is on , so that would effectively solve my problem with minimal issues, turning peripherals off when car is not in use.
    But I will get there ...
    Just remember that by connecting the hub to the ACC circuit, it will get power for a split second while you turn the key, then lose power while cranking then get power back in the run position (assuming your vehicle behaves like most). IDK if this will be an issue for your peripherals but it's probably worth considering in your plans.
    My 2007 Ford F350 Work Log located HERE

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