Announcement

Collapse
No announcement yet.

Does an alternator charge a battery to 100%

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

  • Does an alternator charge a battery to 100%

    From my googling, it feels like I need the mythbusters for this one but does an alternator charge a battery to 100% charge? (obviously measured correctly at the right temperature and after resting for 8hrs+ after driving).

    According to Redarc, the answer is no (although I think the stated 60-70% is a bit exaggerated):
    https://www.redarc.com.au/forum/disc...attery-charger

    From my testing with an Odyssey PC1700, I can only get it to 12.71V compared to a 100% charge at 12.84V (no dual battery setup just the stock alternator with and without a diode).

  • #2
    There's plenty of info on here and other sites, but essentially the alternator reduces output after 20 mins or so to reduce emmisions, potentially leaving your battery undercharged. The diode works well... I got >5 years out of both my factory starting battery and the aux, so I was pretty happy with that.
    2010 Prado GX 3.0L TD - "Paul" - TJM XGS 40mm Lift Kit, Firestone Coilrite Airbags, 5000kg Rated Front Recovery Points, Sure Power Battery Isolator and Dual Battery Setup, Airtec Snorkel, HID High Beam Headlights.
    2008 Jayco Dove Outback - "Davo"

    Comment


    • #3
      Yes, there is plenty of info but is your answer yes or no?

      Comment


      • #4
        No - no smart alternator does - that is why you need a diode or a BCDC unit!

        Comment


        • #5
          Originally posted by matt12 View Post
          From my testing with an Odyssey PC1700, I can only get it to 12.71V compared to a 100% charge at 12.84V (no dual battery setup just the stock alternator with and without a diode).
          Hi matt and was that voltage measurement taken while the battery was still in the vehicle.

          Or did you disconnect it and let it settle for the 8+ hours.

          If the battery was still in the vehicle, then the 12.84v is not applicable as this is the OPEN CIRCUIT voltage, and the battery has to be in a “No-Charge/No-Load” state for that period of time.

          If the battery was still connected up to the vehicle, then the 12.71v would indicate your battery was at a 100% charged state, or that close it does not matter.

          And NOTE, your own figures clearly show that an alternator can FULLY CHARGE a battery.

          Comment


          • #6
            Originally posted by drivesafe View Post
            Hi matt and was that voltage measurement taken while the battery was still in the vehicle. Or did you disconnect it and let it settle for the 8+ hours.

            If the battery was still connected up to the vehicle, then the 12.71v would indicate your battery was at a 100% charged state, or that close it does not matter.
            Hi drivesafe,

            Prior to my diode install, I checked the readings about 1 week of city-driving after a 2,000km drive over 4 days. The results with the battery connected vs disconnected were:

            12.68V with battery connected and car turned-off overnight, then
            12.70V with battery disconnected and car turned-off (only waiting a few minutes after disconnecting the battery).

            Based on that test, the difference was pretty minimal so I was just going to work from 'in-vehicle connected' readings after waiting 8 hrs.

            I wasn't driving the car this weekend, so I popped the battery on the charger and it is now sitting at 12.78V after resting for 5 hrs but still connected.

            Measurements with a multimeter.

            I'll take some more measurements this week with my usual 30 min drives to/from work. See if it stays at 12.78V or drops back to 12.7V.
            matt12
            Junior Member
            Last edited by matt12; 25-04-2017, 10:17 PM.

            Comment


            • #7
              Hi again Matt and all your readings put your battery at well over 95% and this is all that is important.

              It should also Kibosh this crap that your alternator can not fully charge a battery, and 60% to 70% is all that it can achieve. these sorts of claims are nothing but salesman's hype while they try to convince you that you need to buy something that you actually will get no benefit from.

              BTW, for your information, and everybody else's, a battery at 95% is accepted as being fully charged, because there are so many effects that need to be factored in when determining the actual state of charge of a battery, such as you have already mentioned, temperature, that again, a battery at or better than 95% SoC is fully charged.

              Comment


              • #8
                Originally posted by matt12 View Post
                I'll take some more measurements this week with my usual 30 min drives to/from work. See if it stays at 12.78V or drops back to 12.7V.
                You're doing a lot better than many of us with the 2.8L engine (where there is no diode solution AFAIK). After lots of runs of short city driving we're seeing the OEM cranking battery resting at a voltage of about 12.2V. A night or two on an AC charger (thanks for the suggestion Drivesafe) has brought it back to life nicely.

                Comment


                • #9
                  Update ... with the diode putting out the 14.7V to about 13.8V ...

                  I usually only drive about 2 trips of 30 mins per day in light traffic, but went for a longer 2 hour drive on the weekend with a couple of stops on the way home, but the final stage was a 20min drive then into the garage. Then I let the car rest for 8 hours and checked the voltage. Then put the car on the 240 multi-stage charger overnight to see if it boosted the voltage any higher then let it rest for 8 hrs and checked the voltage (at about the same time of the day so the temp would be similar). Results are below.

                  Alternator = 12.70V
                  240 DC Charger = 12.75V

                  Pretty close. I will try to test again after the next long drive. Perhaps those final 2 or 3 starts and only a final 20 min drive could have dropped the voltage a bit with the alternator.

                  Still didn't reach the magical Odyssey 12.84V. Perhaps the trickle needed longer than 8 hrs overnight? or a longer drive? ... Actually I just read the Odyssey tech manual. 12.84V is at 25 degrees, so at 20 degrees perhaps 12.75V is pretty good?

                  Comment


                  • #10
                    Originally posted by matt12 View Post
                    Alternator = 12.70V
                    240 DC Charger = 12.75V

                    Pretty close. I will try to test again after the next long drive. Perhaps those final 2 or 3 starts and only a final 20 min drive could have dropped the voltage a bit with the alternator.

                    Still didn't reach the magical Odyssey 12.84V. Perhaps the trickle needed longer than 8 hrs overnight? or a longer drive? ... Actually I just read the Odyssey tech manual. 12.84V is at 25 degrees, so at 20 degrees perhaps 12.75V is pretty good?
                    Did you disconnect the battery after completion of the drive/AC charger?

                    Comment


                    • #11
                      Originally posted by amts View Post
                      Did you disconnect the battery after completion of the drive/AC charger?
                      No. Per my post above, the difference with my test was 0.02V.

                      Comment


                      • #12
                        matt12 - can you post up the tech manual or link you refer to.
                        Cheers
                        Micheal.

                        2008 GXL D4D Auto. GOING... GOING... GONE
                        2015 GXL 1GD Auto. And it begins again...

                        Comment


                        • #13
                          Originally posted by 120D4D View Post
                          matt12 - can you post up the tech manual or link you refer to.
                          http://www.odysseybattery.com/docume...M-002_1214.pdf

                          Comment


                          • #14
                            Thanks Matt.

                            I'm with drivesafe, your battery is that close to 100% it probably doesn't matter.

                            That said, you'll never see the magical 12.84V or higher whilst the battery remains connected as that is it Open Circuit voltage.

                            Also, FWIW how old is the battery and how much cycling has it seen? - It might just be slowing getting old like the rest of us!
                            Cheers
                            Micheal.

                            2008 GXL D4D Auto. GOING... GOING... GONE
                            2015 GXL 1GD Auto. And it begins again...

                            Comment


                            • #15
                              The battery is about 9 months old and has only been used as a starter.

                              Yes, I think it's pretty close not to worry. Just out of interest, I will try the same process again but disconnect the battery to check the results.

                              I have a new PC1400 arriving soon as an aux battery, so i will be able to test with that too

                              The 240 DC charger was not an Odyssey approved charger, but the specs matched ok.

                              Comment

                              canli bahis siteleri bahis siteleri ecebet.net
                              mencisport.com
                              antalya escort
                              tsyd.org deneme bonusu veren siteler
                              deneme bonusu veren siteler
                              gaziantep escort
                              gaziantep escort
                              asyabahis maltcasino olabahis olabahis
                              erotik film izle Rus escort gaziantep rus escort
                              atasehir escort tuzla escort
                              sikis sex hatti
                              en iyi casino siteleri
                              deneme bonusu veren siteler
                              casibom
                              deneme bonusu veren siteler
                              deneme bonusu veren siteler
                              betticket istanbulbahis
                              Working...
                              X