USB charging on a 12v boat, fie on Apple?

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now pleased to have Ben Stein as a very able publisher, webmaster, and editing colleague. Please don't regard him as an "expert"; he's getting quite old and thinks that "fadiddling fumble-putz" is a more accurate description.

37 Responses

  1. R says:

    Cruisers should have a Starbright Corrosion Buster Pen aboard to deal with situations like your corroded lightning connector. They also are great for tarnished battery contacts in portable electronic devices. Unlike sand paper or emery cloth they usually polish away corrosion without removing metal plating. I think mine has lasted a decade and they are still around ten bucks.

  2. Mark Mongold says:

    You might want to check the contacts on the female socket of your iPad. If you are having multiple lighting cables all fail with arcing or pitting corrosion, it could be bad contacts in the iPad damaging several good cables. I know that is hard or near impossible to look in and see them, but maybe with a strong light and a magnifying glass or loupe you might be able to see if the contacts on the female side are good and clean.
    I have two “12 v cigarette plug 2.1a USB chargers” that have never failed to charge both of my iPads on my boat. I do know the issue of ipad not charging with a lower 1a USB source, but they both have always charged consistently with any of the 2.1 rated 12v adapters I have. It could be all the issues you are having stem from a corroded connector on the iPad.
    I also have never had a lighting cable go bad at the lighting plug end. I have had several fail at the USB end with insulation pulling out of the strain relief, and broken wires.

  3. jason says:

    What a great post. Just bought 2 of the blue sea. I like to leave my iPad on as an anchor alarm but don’t like to have the inverter on. And my charger gets hot as well.
    Also nice seeing you in the channel today.

  4. Howard says:

    The Blue Seas USB outlets will charge an iPad and keep a charge on it,while in use, but they will not support full recharging while browsing the net. They also struggle when a iPhone is plugged into the second USB.
    We travel with 3 iPhones (his, hers, my work), 2 iPads, and a Bluetooth wireless speaker that needs occasional charging. I ended up adding more of the outlets. We started with one at the helm and then we added two in the v berth on our 28′ boat.
    I agree on the higher quality of the Amazon cables. We have a long (3m?) that works great on our nightstand. We keep 4 cables on the boat, 2 in each car, kitchen, living room and 2 in the bedroom. Learned our lesson as the original Apple cables seem to fail at the worst time.

  5. Jason says:

    I went the DIY route.
    I ordered some buck regulators and a bunch of 2-port USB connectors, like the kind found on computer motherboards. I wired up 5 of these for a bank of 10 USB ports and two regulators to provide 3A across 8 USB ports and 3A on 2 USB ports. I coated the whole thing with a conformal coating spray from a local electronics shop and it’s worked a treat for the past couple of years. Mind you, I am on a fresh water lake and the ports are all installed at the nav desk, down below, where it’s dry…

  6. Sam Moore says:

    Two comments:
    Starbrite corrosion buster for the Lightning connector?
    I have used a pencil eraser for sometime to remove both visible and invisible corrosion. Yes you can get corrosion that is not visible to the naked eye and that may effect the connection between two items.
    For charging USB devices aboard, we converted our standard 120V AC outlets in each stateroom to ones that also do USB charging. The downside with the unit we purchased has only 1 120v AC adapter but has 2 USB adapters with LED’s that light up when connected. We rarely use one 120v device muchness 2. When underway we turn on the inverter with the outlets on and charge up 4 devices. Our guests like having their chargers in their room and it keeps the gang of chargers and devices away from the nav table. We picked up the outlet receptacles at Lowes. They were about ~$20 each.
    Sam Moore

  7. Bill Lentz says:

    I’m guessing the aggregate output is 3amps maximum? Blue Seas makes some quality equipment perhaps they will upgrade to the newer 2.4amp standard in the future?

  8. JLin says:

    You might check into the Duracell Powermats that work directly with devices that are built for inductive charging or have special charging cases, like for Apple (not cheap, boo Apple), to allow them to inductive charge. Just lay the device on the Powermat and walk away. The pad helps guide the device into the proper charging position. No wires. Mats for up to 3 devices simultaneously. The mat signals when each device is fully charged. This unit apparently passed a Consumer Reports moisture test.
    The Nokia DT-900 comes at far less cost but it only handle one device at a time. It has 12v output though. Devices can be in a silicon or plastic case and still charge.

  9. John K says:

    Pretty extensive discussion of Lightning cables here:
    I never realized it before, but I recently read on their website, “Tef-Gel applied between electrical contacts and connectors does not increase the resistance of the connections even at hundreds of amps, maintaining the integrity of EMI shielding.”
    Might be a good idea to apply a very thin layer to the plug to avoid the corrosion.

  10. Redline says:

    I use
    Wagan Travel Charge 9.6 Amp Quad USB Power Hub
    bought from ThinkGeek at
    with which our iPads, iPhone4S, iPhone5, FRS radios, Sony camera and a handful of other devices seem to be happy and charge at full capacity. It has a permanent place at Redline’s station.

  11. sailoutbound says:

    I was just about to post about my Wagan power hubs, but Redline beat me to it. I have two of these on the boat, mounted and wired in permanently. The one issue I had is that with the first one I ordered, the 12V plug had a bad fuse, so I thought the unit was DOA. Luckily I checked that before sending it back. I was cutting the cord anyway, but I just wanted to make sure the thing worked before I mounted it permanently. Having these aboard has significantly cut down the need to use the inverter, and the competition for whose device was next in line for our previous two 12V chargers.
    As far as the lightning plug goes, I really haven’t had any issues, but I know that some people have had issues. I did just order one of the Amazon ones that Ben mentioned. I am still looking for a very low profile plug for wall mounting an iPad mini without a big plug sticking out of it. I found this wireless charging system that has a very thin, flexible cable and zero profile plug like I was thinking of, but I haven’t been able to find just a charging cable like that.

  12. Ted says:

    Actually, not so sure it’s fair to blame Apple– and you can overcome this issue with a little electronics skill.
    To make a long story short, Apple devices need analog voltage on the communications pins to signal available current.
    Four resistors will do it; you can modify either the charger or an extension cable. Google “apple usb charger pinouts”– many websites show how to do it.

  13. Jon says:

    I installed the 12v Blue Sea twin USB charger (pictured above) on my boat with the amazon lighting cable and it charges my iPad Air better than the (apple included) wall charger used on land.

  14. I’ve been fighting some USB power issues myself lately – and I’ve found an extremely handy device to troubleshoot the goings-on. Just do a search on Amazon or eBay for “usb power meter” – I paid less than $10 each on ePay for a couple different ones (one is just volts and amps, the other will totalize the charge)- just the thing for a gadget geek and very handy in seeing what devices REALLY want and need to charge. Also spots defective USB ports in a flash.

  15. Slingthehook says:

    Ben, good discussion, but I don’t think it’s entirely fair to single out Apple. Other manufacturers do the same.
    I also use a Dell Venue 8 pro tablet as as Windows 8 device for OpenCPN and SSB comms onboard and its Dell USB charge cable is proprietary.
    Although it looks like a normal USB to micro USB cable, the data pins are actually shorted together and the tablet will not charge with a normal USB cable (or without a 2.1Amp supply either).
    IMO this is actually worse than Apple, as it pretends to be something it isn’t.
    I’ve installed a bunch of 12v to USB charge sockets around our boat and have actually opened them up and joined the data pins together do I don’t have to use the special Dell cable.
    Readers may also be interested that there is a plug-in 12v cigarette adaptor made by InCase that provides dual 2.4A outlets so you can properly charge two hungry modern devices simultaneously. (The cheap ones only supply 2.1 to one of the USB sockets)
    Adrian (crossing the Atlantic in a months time)

  16. Matt Marsh says:

    I’m cautiously optimistic that USB Type-C, due to start showing up next year, will solve a lot of these problems once it becomes widespread.
    Type-C provides up to 5A 20V and the connector works in any orientation. (Power levels must be software-negotiated; the device has to tell the power source what voltage/current it wants.) It looks like the USB-IF will recommend that all new USB-capable devices use the Type-C connector.
    For the next couple of years, though, expect the charger confusion to continue. I have come across a lot of chargers that don’t perform as advertised, and a few that have dangerous design faults (eg. the potential for 120VAC to appear on the USB end if the humidity’s high).

  17. Brown Cow says:

    I have used the Scosche DC charger for a couple of years on boats and car and it works great in my opinion…..

  18. Richard C says:

    Based on the recommendation in this post I purchased the “Amazon’s Own Apple Certified Lightening cable”, (6′ long version) It arrived today, Oct 27 2014, and DOES NOT fit the iPhone 5s or the iPad Air.
    I believe they are defective so shipped them back to Amazon. It seems to me the lightening connector is too fat to fit the plug on the iPhone or iPad. This is unfortunate because the cable itself is much more robust then anything Apple has. Even the cable to plug connection appears stronger and more durable. But, there is just no way the lightening end slides into the phone or iPad. I’m sure this is a defective batch since Ben obviously has working cables from Amazon.

  19. Jeff says:

    I installed the Blue Sea Systems panel mount 12V DC to dual USB outlet. It charges anything that I have thrown at it so far: iPhone 4, iPhone 5, iPad 3

  20. Jovini says:

    I’m curious, when any of these chargers are attached to your 12v supply but are not supplying 5v to a device are they still drawing a tiny current from your battery? I know my old fashion “wall wart” transformers for various home devices stay warm all the time, so they must be using a little juice all the time. I’d hate to have any device on my boat putting a constant parasitic load on my battery bank. Anyone? Thanks.

  21. Redline says:

    Yes, all these draw some small current when idle; one thing I liked about the Wagan 4-port is that it has a power switch so it can be shut off when not in use, without having to pull the plug.

  22. Out of curiosity, I tested a cheap eBay model I had here – two ports, one of which is supposedly 2a (best it does with my iPad is 1.4a), but with no external lights or other indications of being powered. With 13.8v applied, it draws 4.95 milliamps. 5 ma = 1 amp hour every 100 hours — not a lot, but of concern if your boat is left uncharged for many weeks.
    Interestingly, I noted that when I turned off the power supply and the voltage decayed, the device drew more and more current (as much as 8 ma) until it dropped to zero at about 3v applied – clearly an indication of a switching power supply..:-)

  23. Jovini says:

    Redline – nice quick test there. Very useful. Thanks.

  24. Steve says:

    I definitely encountered some noise from the switching power supplies on the Blue Seas USB plugs. Seems to create noise on VHF and FM reception. Not sure how it effects FM transmit. It increases with the USB load, and is not present when the Blue Seas device is in standby. I have three of thse Blue Seas plugs.
    I called Blue Seas and they said pretty much all USB power plugs do this. They suggested twisting the power wires, which I tried, but it didn’t seem to have much effect. I suspect they meant twisting the power wires of the Stereo and VHF radio.
    As it is, I turn off the usb power when radio use is important. I’m hoping to find a more permanent solution at some point.

  25. Rob S says:

    A EMI filter should fix your problem.
    Disconnect the wires going into the power plug. Loop the power wires through the ferrite core, and reconnect the wires …

  26. Practical Pirate says:

    I used the 4 port type 2.0 version of startech’s industrial rail mount for powering my Raspberry Pi media center. Hard wire it in and it takes anything from 7 to 24 volts, down converts it to 5.0 volts and provides whatever amperage your toys want.
    5 stars. No affiliation. Just a happy customer.

  27. Ben Ellison Ben Ellison says:

    Note the new PS added to this entry about Carling Technologies’ new heavy duty USB charger that will fit in many existing Contura switch panels

  28. Interesting (and potentially useful) PS, Ben. I also noted your reference to inductive charging – since that works only with AC, how would it apply to boat use, short of leaving the inverter/generator on all the time? Also, how would the magnetic field issues be addressed? I see the potential for a real compass-killer..;-)
    AS a side note, one of the things I am most concerned with regarding guests on our boat (when we’re going out, especially offshore) is magnets – you would be amazed how many magnets are floating around in today’s stuff – and you DON’T want ’em near your compass or heading sensor!

  29. Guru says:

    Didn’t read the entire thread, but thought I’d leave my 2 cents…
    17′ Crestliner (90HP)
    iPad 3 (with all peripheral services disabled)
    Vexilar SonarPhone running Navionics
    Driveway test with my new “gack” was successful in getting everything to communicate, I quickly realized that the connectors (cigarette) weren’t good enough to supply the iPad with enough power to keep up with the demand of both apps. I tried all the different cig connectors I had in my collection, but none we’re able to keep with the task while running these resource heavy apps.
    When all this failed I decided to try a 175W inverter I had laying around. At first I used the the battery clamps that came supplied with the inverter and it worked. Then I tried connecting to cig port and with the same results. It charges very slowly, mind you, but the iPad does charge.
    Once I had the inverter hooked up and happy I decided to plug a USB cable into the port on the inverter to charge my BadElf GPS unit, much to my dismay… The order of operations I chose to do this fried my BadElf. Fortunately, BadElf replaced my unit free of charge. DON’T plug in your devices then plug in the cig adapter! Bad things can happen. Probably why the BadElf cig adapter came with a 1A fuse built into it. The unit must be very sensitive to electrical spikes.
    Hope this helps someone. Cheers!

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  31. Anonymous says:

    BlueSea systems finally makes a “fast charge” model:
    Panel Mount
    They also have the rocker switch mount style:
    Rocker Switch Mount

  32. Ben Ellison Ben Ellison says:

    Sounds good and I like seeing the 4.8 amp total output, but I wonder if the “intelligent device recognition” will apply to my Samsung Note4 phone, which can charge at more than twice the normal speed with Samsung’s own AC USB charger. I do know that 3rd party devices can handle Samsung Fast Charge because I’ve seen the new Weego 44 power pack do it.

  33. Good question. I suspect the answer is no. The websites which talk about fast charge don’t usually talk about how it works, but this one does:
    The Samsung fast charger puts out up to 9 Volts. Future fast chargers will go up to 20 Volts.
    And I thought USB was 5 Volts. Times change!
    The specs for the Blue Sea Fast Charge USB charger say 5 VDC plus/minus 5%. That’s a clear “no’, but on the other hand they also say “intelligent device recognition allows rapid charging of phones, tablets, or other mobile devices”, which seems to say “yes”.

  34. Ben Ellison Ben Ellison says:

    Thanks, Norse, that’s a great reference. I just checked the fine print on my Samsung “Adaptive Fast Charging” USB source and sure enough it outputs 5.0v @ 2.0A OR 9.0v @ 1.67A.
    According to tech support at Blue Sea Systems, Samsung is using one of the Qualcomm fast charging standards, which their new 12/24v USB outlets do not support.
    So apparently the Weego 44 does support at least the Qualcomm 9v fast charging standard that the Samsung Note4 uses. I received a sample 44 yesterday and can confirm that it fast charges my phone even with its battery pack more than half empty (by its LED indicators) and is also recognized as a valid charger by my iPad Pro 9.7″.
    But I notice that Apple now also offers a multi-voltage USB charger, though its fast charge is 14.8v!

  35. All trickery to get more power through those tiny little wires (and contacts) in the charging system. It would be more encouraging if there were an industry-wide specification for the required intelligent handshake instead of each manufacturer doing it on their own. Maybe the manufacturers will at least publish their interface specs so someone can make a multi-device charger.
    Of course, once you get to about 12-13 volts, it leaves the non-AC chargers out.

  36. Bo Collier says:

    Found these recepticals on Amazon. Put one on each side of master bed, one in the forward cabin for guests and one in the salon.
    Just need them on an inverter circuit and your good to go.

  37. Ben Ellison Ben Ellison says:

    Dang! The nice marine USB charge ports discussed in this entry are now “old technology” in a pretty significant way. It took me a while to figure out, but the “fast charger” that came with my Samsung Note4 is a rapidly spreading tech called Qualcomm Quick Charge that uses higher voltages, not amperage, to charge devices MUCH faster:
    Sigh, but USB-C with the possibility of USB Power Delivery (USB PD) — mas 100 W (20 V / 5 A) — is also coming along, especially in Apple world:

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