Announcement

Collapse
No announcement yet.

Fully 100% automatic battery charger

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Fully 100% automatic battery charger

    I'm looking for a fully automatic battery charger. Usually in the battery charger world, fully automatic just means it switches amps/volts automatically to suit the battery's charge state. That still requires a user interaction to start the charge process, however. I need a charger that I can just mount in the car and when you plug it in it starts, no questions asked.

    These are extremely common in boats but boat models are extremely expensive. I'm looking to get 15+ amps at a sub 100 price. Anyone know where I can find one of these?
    My Nearly Complete Car:
    http://www.mp3car.com/vbulletin/show...ed-car-pc.html

    Micro Control Center... Control Your Car Across the Internet
    http://www.mp3car.com/fusion-brain/1...-internet.html

    Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
    http://paulfurtado.com/

  • #2
    Guess not... Looks like I'll do one of two things: get a solar charge controller and have a desktop atx supply pretend to be a solar panel, or hack up my black and decker charger to get controlled by a fusion brain.
    My Nearly Complete Car:
    http://www.mp3car.com/vbulletin/show...ed-car-pc.html

    Micro Control Center... Control Your Car Across the Internet
    http://www.mp3car.com/fusion-brain/1...-internet.html

    Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
    http://paulfurtado.com/

    Comment


    • #3
      this is the one i have- http://www.amazon.com/Schumacher-SS-...709713&sr=8-11

      had it for a year now. a couple things. first, its rugged as hell. i mounted mine to the back of the truck bed, so it gets rained/snowed on all the time.

      it doesnt need user interaction, just plug it in and it will start charging. however, it needs about 2 minutes without any major load on the battery... or any varying load. so if i have just my computer on (3amps) it still detects the battery normally and starts charging. however, if i have the stereo on (10a+ with varying load) the battery charger goes into default mode and i think it just trickles the battery until you unplug the charger.

      whats cool is that it DOES work as a power supply. just plug it in, wait for the bulk charge mode to engage (after a couple minutes) and then turn on your stereo or whatever you want. it will push up to 20a at 14v, so you can play music and leave your headlights on indefinitely and your battery will not discharge.

      the price is a little high i think, but free shipping makes it worth it. you might find it elsewhere. and its also large. look at the specs for size, basically its about the size of a basketball. its also heavy. weighs like 15 pounds. like i said though, this type of transformer/ecu charger should virtually never break.

      Comment


      • #4
        Have you searched for circuits? There are various add-ons to add "smarts" to dump chargers.
        And there's always the CTEKs (LOL! Since I get 8 years from my batteries, it's cheaper buying new batteries!)

        Using a solar charger is a good idea - they are cheap for the Amps. (I got my ~15A/30A solar reg (kit) for ~$20 & 8A/2A 12V/6V AC charger for $30 - I've seen less for over $80 respectively).
        But you'd have to retune the ATX for over 14V...

        Comment


        • #5
          trader007: Yeah that looks like a bad*** charger. Problem is I have no room to put the thing in my volvo S60 and yes it is on the pricey side, but nowhere near some of the other chargers I've seen!

          oldspark: CTEK does have quite a few cheap chargers, but it looks like none of them come in the amperage range I need. They have a 7 amp model which I could settle for, but it's 150 bucks. Other brands make chargers at that amperage cheaper.
          The input voltage on a solar regulator expects an input of over 14 volts?
          My Nearly Complete Car:
          http://www.mp3car.com/vbulletin/show...ed-car-pc.html

          Micro Control Center... Control Your Car Across the Internet
          http://www.mp3car.com/fusion-brain/1...-internet.html

          Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
          http://paulfurtado.com/

          Comment


          • #6
            Originally posted by PaulF View Post
            The input voltage on a solar regulator expects an input of over 14 volts?
            You can't charge a 12 volt lead acid battery fully unless you can get at least 14.4V to the terminals. Proper topping charge voltage for a lead acid battery is 2.4V/cell.

            There may also be some cheap RV chargers out there.
            2000 Ford Expedition Eddie Bauer - Bi-Fuel Gasoline/CNG
            Intel D945GCLF2 w/512MB RAM, CL Audigy w/KxProject, M2-ATX, Lilliput EBY701

            Comment


            • #7
              Originally posted by CraziFuzzy View Post
              You can't charge a 12 volt lead acid battery fully unless you can get at least 14.4V to the terminals. Proper topping charge voltage for a lead acid battery is 2.4V/cell.
              Oh I know that.... I just figured the regulator actually regulated and would be able to take the 12 volts and convert up/down. Guess it only goes down....
              My Nearly Complete Car:
              http://www.mp3car.com/vbulletin/show...ed-car-pc.html

              Micro Control Center... Control Your Car Across the Internet
              http://www.mp3car.com/fusion-brain/1...-internet.html

              Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
              http://paulfurtado.com/

              Comment


              • #8
                No - regulators are usually linear step downs. You are thinking of dc-dc converters (like some MPPTs etc).

                But if considering a solar charger, some simple PWM voltage regulator should be fine - ie, drop 14-20V (whatever) to the typical 14.4V & 13.8V for battery charging.
                If you want to add charging profiles (boost, pulsing, etc), that's a different story. (So is dropping from 14.4V to 13.8V, but that's merely current sensing - maybe with temp as a backup.)

                If you can get any PWM charger, you should be able to modify it for higher current - swap its output (transistor or FET) for an appropriate MOSFET (>60A being common & cheap - from $2 upwards). And using a FET is much simpler than a transistor - no bias currents etc - just a suitable minimum on voltage (eg, 5V or more above GND or below the +ve supply rail).

                12V Solar regulators usually expect 22V or more input (21V being a common OC output voltage for many 12V panels).

                Comment


                • #9
                  i need one too :s
                  then i could bring the sound system into the house in the winter and still enjoy tha baassss?

                  Comment


                  • #10
                    Well, looking at the Optima website, the suggested charge rate is 10 amps.
                    During lunch today I stopped by Advance Auto Parts to pick up some spade terminals and I happened to see this guy: http://shop.advanceautoparts.com/web...ci_sku=9200002

                    10 amps. Automatic. Fairly small. $40. Perfect.
                    My Nearly Complete Car:
                    http://www.mp3car.com/vbulletin/show...ed-car-pc.html

                    Micro Control Center... Control Your Car Across the Internet
                    http://www.mp3car.com/fusion-brain/1...-internet.html

                    Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
                    http://paulfurtado.com/

                    Comment


                    • #11
                      Originally posted by vull View Post
                      i need one too :s
                      then i could bring the sound system into the house in the winter and still enjoy tha baassss?
                      A charger won't run the sound system, unless you're planning on using a battery and a charger to power the system.

                      You shouldn't charge a battery while draining it though or else you'll overcharge it. Unless you know that the constant load is more than what the charger puts out.

                      Doing something with like a 1 amp load and a 20 amp charger connected will make most chargers think the battery isn't fully charged and overcharge the thing.
                      My Nearly Complete Car:
                      http://www.mp3car.com/vbulletin/show...ed-car-pc.html

                      Micro Control Center... Control Your Car Across the Internet
                      http://www.mp3car.com/fusion-brain/1...-internet.html

                      Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
                      http://paulfurtado.com/

                      Comment


                      • #12
                        Originally posted by PaulF View Post
                        Well, looking at the Optima website, the suggested charge rate is 10 amps
                        And yet they also say "No current limit as long as battery temperature remains below 125F (51.7C)" for both Rapid (15.6V) and Cyclic (14.7V) charging.
                        And I recall seeing recommendations to charge them at much higher rates (eg, 40A).

                        I presume that in the linked Schumacher Battery Maintainer, "fully automatic" means it switches to 13.8V etc once fully charged.


                        Originally posted by PaulF View Post
                        You shouldn't charge a battery while draining it though or else you'll overcharge it
                        Sorry Paul, that's incorrect.
                        It is done all the time - eg, vehicles, planes etc.

                        A vehicle's charging system is effectively a constant voltage charger - it tries to maintain a certain voltage (eg, 13.8V, 14.4V max etc).

                        However CHEAP chargers often output above 14.4V.
                        This is often true for trickle chargers (to quote.. "because they are only 1-2A, what damage can they do?". LOL! bang!)
                        Bigger chargers should have a 14.4V limit or cutoff but usually don't.
                        And once full, the charger should reduce to below 13.8V anyhow....


                        Batteries - so simple - a true Scientific Art.

                        Comment


                        • #13
                          I understand that it's done all the time, but it hasn't worked for me at all. The problem is most chargers don't recognize the battery as full when there is a load. I killed two optima batteries at this point by failing to recognize this. It appears the chargers use current monitoring to sense when the battery is full and they would never sense it being full and overcharge it.

                          Also, often it's quite possible that 125F is the ambient temp in the trunk, so that could be an issue too. My new setup cuts the load off of the battery and runs it off a 12 volt supply while charging. Faster charging and it gives me peace of mind that I'm not going to kill another.
                          My Nearly Complete Car:
                          http://www.mp3car.com/vbulletin/show...ed-car-pc.html

                          Micro Control Center... Control Your Car Across the Internet
                          http://www.mp3car.com/fusion-brain/1...-internet.html

                          Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
                          http://paulfurtado.com/

                          Comment


                          • #14
                            No - incorrect. A battery's charging is based on voltage.

                            The only time current play a part is (1) if current limiting is required, & (2) that a battery will always have a minimum current draw even when full - ie "float current" (typically 2A for car batteries; less for AGM).
                            The latter may be a method for some "smart" or automatic chargers to detect when to drop voltage to float level, but they shouldn't be above 14.4V anyhow....


                            When you have a load connected to the battery, the charger has no way of knowing what is going to the battery and what is going to the load.

                            It doesn't matter anyhow - the charger (alternator) should output up to 14.4V and that should not wreck the battery(s). Whether 10A of this is going to the battery, or 9A to load and 1A to battery etc etc doesn't matter.


                            However, if you are saying that Optima batteries cannot handle (say) 14.4V when full....


                            But I suspect you have a charger that goes overvoltage.
                            Strange that it goes over-voltage WITH a load, and not without, but that suggest a switching load that is confusing the charger's voltage sensing - ie, a low quality charger.

                            Think about it - car batteries are connected and charged with a load. My car batteries last 8 years - and they are not Optimas!
                            If what you said was generally true, all Optimas in cars would be wrecked...


                            But temperatures - yes - lower voltages for higher temperatures.
                            No if you battery were at boot ambient temperature, you;d be fine with an Optima - they specify 14.7V is ok with no current limit as long as battery temperature remains below 125F (51.7C).
                            But the battery will be warmer than ambient, so you'd have to get more specs from Optima - is 14.4V ok at 135F or 145F etc.
                            But IMO that's not hot - our engine bays are much hotter.


                            We can get in to temp & voltage sensing the battery; or each battery. But hey - most people see to prefer a single-wire (D+) alternator because more than that is "too complicated". If I dare suggest extending the Sense wire to the boot battery, or that alternators should have external temp sensors (mounted on the battery)...


                            FYI:
                            A 30C increase in cell temperature means a ~0.1V/cell DROP in charging voltage - ie, ~0.6V for a 12V battery.
                            So from 13.8V to 13.2V, or 14.4V to 13.7V f temp increases from 70F/20C to 125F/50C.
                            OTR, if a 100% charged AGM is [email protected]F/25C, it should be about [email protected]F/50C - about a 0.1% change.

                            Comment


                            • #15
                              cars only run for a few hours at a time, thats why they dont overcharge the battery. when the battery is outside its normal vehicle environment, it needs a charger that can tell when full is full.

                              Comment

                              Working...
                              X