Cell Car Chargers

boisblancboy
boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
Instead of using an inverter and plugging a cell wall charger into it to charge a cell phone, is there any reason why I could just use a car charger and hook it directly to the battery terminals?

Another question, are Solar Cynergy with Q-Cells, a good type of panel? If not why? Just noticed they are cheaper than most per wattage and wasnt sure why.

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Cell Car Chargers

    Probably would work OK... You might not want the cell phone charger plugged in while equalizing the battery (15-15.5 volts typically).

    Also, cell phone chargers may not be very efficient--my own 12 vdc charger gets pretty warm when charging my phone--feels like it is an analog regulator.

    The losses of one cell phone charger are probably not worrying about... If you were charging 10 cell phones on a small system--then the losses may be much worst and it would be more efficient to run efficient 120 VAC chargers off of an inverter.

    Sort of--you have to measure the power usage in both cases and see what the results are.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: Cell Car Chargers

    I wasnt sure if some cell car chargers had anything built into them to protect the phone from surges from the vehicals electrical system. I would say that it would be a good idea as well not to have the charger plugged in, or at least while charging a phone while the battery is equalizing.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Cell Car Chargers

    Be careful with voltages,
    If you are just going to cut the plug off and wire it to 12vc you may be in for smoke. Make sure you match the voltage of the cell battery.

    It would be an interesting question which is more efficient, lighter plug, or 120vac plus inverter losses.

    Tony
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: Cell Car Chargers

    No I didnt plan on just cutting the wires and attaching to the battery. I wanted to get a car charger that i could take apart the light plug apart to see if there was anything inside besides a direct connection. I am pretty sure some car chargers will only charge for a certain amount of time to prevent overcharging, along with some phones which have a setting for car charging.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Cell Car Chargers
    No I didnt plan on just cutting the wires and attaching to the battery. I wanted to get a car charger that i could take apart the light plug apart to see if there was anything inside besides a direct connection. I am pretty sure some car chargers will only charge for a certain amount of time to prevent overcharging, along with some phones which have a setting for car charging.

    Go to your auto parts store and buy a female lighter plug, or plug extension. Cut one end off that (or find one with allagator clips) and wire it to the battery that way.

    Tony
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: Cell Car Chargers
    icarus wrote: »
    Go to your auto parts store and buy a female lighter plug, or plug extension. Cut one end off that (or find one with allagator clips) and wire it to the battery that way.

    Tony

    Yeah thanks, thats what I planned on doing. I just figured it made a whole lot more sense charging a phone this way then using a wall charger and using an inverter for something so small.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Cell Car Chargers

    i too think it should be ok to charge from the battery and be careful of polarity. as to those pvs, i've never heard of them. they may be fine, but do they have the nrtl or ul type approvals that the nec calls for? that may account for a lower price if they don't. it says for grid tie, but it doesn't say it's good for here in the us. my opinion as to which is better would be from the battery and not 120vac as 120vac usually needs transformed down and rectified before entering the same circuits encountered with the battery connection.
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: Cell Car Chargers
    niel wrote: »
    my opinion as to which is better would be from the battery and not 120vac as 120vac usually needs transformed down and rectified before entering the same circuits encountered with the battery connection.

    Just to make sure we are on the same page, I wouldnt be using a inverter to transform 120vac to 12v dc to use the car charger. I want to use a car charger off my battery, not get an inverter to transform 12v dc to 120vac to use my wall charger.


    Those solar panels I was inquiring about, I did find their website and they said in 2008 they were going to get those approvals, but I didnt see if they made it or not. I guess I am not too worried about those approvals cause i wouldnt be using them for grid tie, but just for a very small battery charging system.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Cell Car Chargers

    i wasn't even counting inverter losses which would add even more inefficiency and losses to the overall scheme of things and this was directed to icarus as he posed that general question. inverter losses do vary as do the dc charging circuits and depends on the designs and methods used in each to directly compare efficiencies, but as i said ac power needs the extra step of transforming and rectifying it making it mute in discussing it. simplified 12v charger goes, battery > charging circuits > battery 120v inverter goes, battery, inverter, tranformed down into a builtin phone charger or to an external phone charger through a 12v battery. the bottom line is more steps are involved with the ac even if it were to come from the utility and that would cut out some steps used in inverting.
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: Cell Car Chargers

    Thats why I wanted to stay away from an inverter and just directly connect to the battery with a car charger. As I am new to all of this stuff, I was pretty sure that doing it in this manner would be the most efficient way as long as I am understanding it correctly.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Cell Car Chargers

    forgive the lack of spacing or lack of empty lines used in making my posting easier to read, but for some strange reason hitting enter isn't putting that in here. restarted pc and placing this separately. will it work? stay tuned. not working and smilies aren't working either. hmm. i guess i'll try my other pc.

    ok this should have a space if the problem was only with my other pc.:D smilies work.
    yes, it's my other pc. i wonder what got screwed up this time.:cry: will it work?
    yes, so i have no idea what the reason was it didn't work before.:roll:
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: Cell Car Chargers
    niel wrote: »
    the bottom line is more steps are involved with the ac even if it were to come from the utility and that would cut out some steps used in inverting.


    So bottom line and simply said, from the battery with a car charger is most efficient with the least steps?

    Haha, its great when computers always do "exactly" what you want them too!
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Cell Car Chargers

    No, you cannot generalize the answer...

    For example, say your phone requires 5v to charge (many are using USB now for optional charger).

    With an analog 3-T type regulator, the efficiency would be:

    1 - (14.2 volts - 5 volts) / 14.2 volts = 35%

    For a 12 volt charger, assuming 85% inverter and 80% switching wall charger (just guessing):

    85% * 80% = 68% efficient for Batt->inverter-AC Wall Charger

    Again, for small loads, a typical AC Inverter is going to have a minimum DC load of 6-8 watts without any charger connected... Way more energy lost via standby losses vs the smaller overall losses of a 3-T Regulator on a (cheap) DC charge adapter.

    Of course, it is possible that the DC charge adapter is also an 80% efficient charger--So, the answer is to measure and compare between the two and see which is more efficient.

    My guess is that if you already have an inverter running (lights, TV, etc.), that the AC Phone charger could be, overall somewhat more efficient.

    But, in the grand scheme of things, unless you are charging 20 cell phones at a time--it is probably a "don't care" situation.

    For one cell phone charger, no matter if it is a switched or 3-T, 12 volt DC charger will be fine.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: Cell Car Chargers

    Ahhhh now I get it! Either way there is some inefficiencies, which is obvious, but I wasnt thinking about the voltage difference with the 12v car charger to the phone battery, which now makes perfect sense. Since I am only going to be charging one phone, once a day either way is not going to make a significant difference.
    BB. wrote: »
    Again, for small loads, a typical AC Inverter is going to have a minimum DC load of 6-8 watts without any charger connected... Way more energy lost via standby losses vs the smaller overall losses of a 3-T Regulator on a (cheap) DC charge adapter.

    Question on an inverter.

    If for example an inverter is using 6-8 watts with no load in standby, then you connect say a 10 watt load, are you now consuming 16-18 watts or once loaded does the standby load decrease?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Cell Car Chargers

    I probably should have called a "tare" loss... But yes, more than likely you would see the DC Input Power consumption approximated by something like:

    6W + XX Watts * 1/85% = total power consumed

    Some inverters will publish an efficiency graph like this one (PDF; Morning Star 300 watt TSW 12 volt inverter).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bajasurfer
    bajasurfer Solar Expert Posts: 30 ✭✭
    Re: Cell Car Chargers

    I installed a dual-port car adapter in my Baja shack: on ~220 A/hr 12V batt bank using 8' 12AWG wire one way. My Motorola Q9C is always done charging in less than an hour, due to liberal adapter use in car, so total load isn't an issue. The adapter has an LED-ON indicator, so I wired a switch inline to turn that off, too.
    12v_dual-auto.jpg
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: Cell Car Chargers

    Very nice! I am thinking of doing pretty much the same thing. Should be fun and interesting to at least try.