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Charging multiple high power USB devices without cigarette lighter

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  • Charging multiple high power USB devices without cigarette lighter

    Wow! Just found the forum and am likely to get sidetracked from my original project. Lots of cool stuff to do.

    Ok, the project that got me here is as follows:
    I am sick of the multiple chargers for the iPad, iPhone, blackberry, Bluetooth, etc in my truck. I have decided to bypass the cigarette lighters and replace them with the waterproof USB panel jacks from l-com with retractable cables for each device.

    The problem I need help with is what to use for the12v-5v dc dc conversion. I have the fuse block and want to direct wire the jacks in. I am looking to add 4 ports that are all 10-15 watt capable.

    I have no problem in doing the wiring but am looking for suggestions in the following specific areas:
    1) is there a single component that can source that much power? If so, ok to run these in parallel?
    2) am I better off with multiple components (prefer less than 1:1)?
    3) any suggestions on parts to consider using?
    4) any other considerations?
    5) any links to others that have done this? I can't be the first.

    Thanks for any help you can provide!

  • #2
    this might be a good solution for you, rugged and simple to wire up SNO
    Last edited by SNOtwistR; 08-21-2011, 04:42 PM.


    • #3
      Was looking at the opus dcl11 but it would not cover all the ports I want with one device. I could use 2 or 3 of these. Not too concerned with power draw as this is coming off of my aux battery which is deep cycle agm. There has got to be an easier way.


      • #4
        IMO all you need is any 3A or higher 5V converter. It could even be linear (~30% efficient with 30W of heat from ~14V @ 3A), though with the price of typical dc-dc converters (!90% efficient) I'd avoid linear.

        Someone on mp3car did have an (IMO) great 5A or 10A 5V converter for a reasonable price.
        Otherwise there are various commonly available 2A 5V converters.

        But I'd recommend some form of cut-out - even deep cycles do not like being flattened. (Most recommend not discharging more than 50%; that typically increases deep-cycle battery-life 3-fold compared to 80% discharge.)
        The ~$25 MW728 could be used - even with an extra relay to disconnect its sense circuit after its normal low-voltage load-disconnect (in that case with a manual-on push-button to re-activate it).


        • #5
          PaulF recommended me a good one (5v 10A converter) but I don't recall what it was off-hand... I'll find the info for it and edit this post when I do.

          I recommend hooking it up on an accessory line so it can't kill the battery without the keys in the ignition.


          • #6
            Looking at one by calex that supplies 30a. More than I will ever need but if I mount it under the hood from my aux fuse panel I can run a 5v rail inside the cab and then I will have a fused 5v panel next to my fused 12v panel.

            Summary of the system:
            12v from alternator to hellroaring battery isolator
            To exide 100ah agm starting / deep cycle battery
            To blue sea 12 position ATC fuse panel
            30a leg from fuse panel using 10 ga to inside of cab to blue sea 6 position 12v panel
            30a leg from 12v fuse panel under hood to calex dc dc converter also under hood
            10 ga from calex to cab mounted blue sea 5v fuse panel
            14ga leg from 5v fuse panel to each of 4 panel mounted l-com waterproof USB jacks, fused at 2a each.
            14 ga leg to window mount gps
            Calex has a leg to shut it off when shunted to grd
            Calex will also auto shut down at 9.something v, too low.
            Will probably switch the feed to calex to be able to park for extended periods of time without killing aux battery.

            Lots of info there. Can post fills and part numbers and cut sheets if requested.
            All above under the hood.


            • #7
              The latter can be overcome with a timer that disconnects after a preset period. I'd suggest it disconnects itself too (especially if it's a 555 circuit - they take 10mA) - it could break the "feedback" connection in the latching SPST relay I described in Powering carpc with SPDT relay. (The IGN or ACC could parallel or replace the ON switch's +12V pulse that turns it on, noting that that relay is on whenever the ON switch leg remains +12V.)

              Or a low-voltage disconnect. Maybe the MW-728 I often mention, and in conjunction with that latching circuit above....


              • #8
                Here is the Calex converter link. Talked to the engineers and it seems to be fairly bullet proof. Sells for about $165, steep but should never need another 5V supply again.


                • #9
                  I'd search for that mp3car 10A USB supply (which may be what Ryven referred to).

                  My view is that it doesn't matter how bullet proof it is, one day it will fail.
                  That's why I consider redundancy - ie, have access to a spare.
                  And I'd probably buy 2 cheaper units up front than a single $165 device. (I wouldn't invest and extra $165 "just in case" - unless it really was IMO critical. But then I'd probably have TWO spares!)

                  PS... 25Aug11 05:55 UCT: I searched this morning but couldn't find the 5V PSU I was thinking of. I'm sure is was built by an mp3car member. As I recall, I was impressed by its price and specs etc.
                  But the MeanWell unit that Ryven Found in the next reply seems good. (Not that I have used MeanWell, but my readings suggest they are good & reliable. Certainly IMO a great price!)
                  Last edited by OldSpark; 08-25-2011, 12:03 AM. Reason: PS...


                  • #10
                    Found it!

                    This is what PaulF recommended for me & I picked up 2. The price is good and the efficiency and especially power output for a 12v input are difficult to beat.


                    • #11
                      Thanks guys!! I like the looks of the 5v/10a converter. Much better price. The 30 A might be one to file away for later but probably dont need it just now for what I am doing.

                      Has anybody measured the no-load draw? If not I can post it once it gets here.

                      Also, a couple of options for shut off. I want to be able to leave devices charging while I am not in the vehicle (shopping, etc) and know I will need some kind of shut off to protect the battery. I dont think I want a timer as that is not necessarily the behavior i want the system to have. I could certainly switch it with a relay and put the switch on the dash but then I have to look at another switch and remember to actually shut it off. (for extended periods of the truck being parked I can just pull the fuse).

                      I like the idea of a low voltage shutoff but being a noob to the forum (not to things electrical / electronic) I am having trouble finding the reference to the mw-728. Any links would be most appreciated.

                      How low should I set the shutoff? Somewhere in the 10.5v - 11v range??? I dont mind draining the battery as I consider that a consumable, just dont want to over do the deep discharge.