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How can I raise the voltage?

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  • How can I raise the voltage?

    I converted all my batteries to alum. All of their max voltges are now 10.6 volts. How can I raise it so I can use my 700 watt inverter w/ my drill? How do I add 2 volts in series that can handle 700 watts?...

  • #2

    Originally posted by liveaboardl View Post
    I converted all my batteries to alum. All of their max voltges are now 10.6 volts. How can I raise it so I can use my 700 watt inverter w/ my drill? How do I add 2 volts in series that can handle 700 watts?...
    OK, so, I just spent a few hours looking at resistors on ebay. I found this:
    I can basically pay $60 to get a 1.8 ohm 600 watt set of resistors that I could wire all together and connect the 2 10.6 batteries in series & connect that to all those resistors in parallel, and come up with a reasonable voltage around 12 volts. Not really worth it.
    I think I found a better bargain for a set of 1.8 ohm resistors, something like 600 watts for $30 but @ 1.8 ohm, it would bring the voltage to 11.44 volts if the batteries are at 10.3 volts which would be likely. Which might get the inverter by OK for a while.

    So is this probably my best bet to get that corded drill working on my alum batteries?

    I looked at the step-down (buck) voltage regulators & they're rarely both voltage adjustable and above 150 watts.
    As for stepping it up, I don't recall seeing any of those in the 600 watt range.

    I'd like to be able to use my corded drill and maybe even an ice-maker machine on my boat to work off the alum batteries. 1 will draw around 320 watts A/C and the other about 180 watts A/C.

    I read a lot of good things about these batteries, and of course the 1 bad thing, the low voltage, yup, I can verify that. Someone reported that the inventor got high voltage after the conversion, like 12.3 or so. Nope. Not me. I raised the temperature of the water on the stove & got 3 oz to dissolve w/ one battery, and w/ the other battery I just used room temperature & 3 oz. No difference.

    This voltage is really an issue, however, I must admit that these batteries are much stronger than they have ever been, even after I bought them from the Sears store brand-new, although I must admit I didn't get them from the shelf. The men brought them from the back, where they were stored in some area I couldnt see, and it did take a while, quite a while. I recall waiting in line about 15 minutes for them to get it out to me.

    Anyways, I should have bought Walmart batteries. I'll never buy Sears again if I can help it... well, perhaps if it's off the shelf & heavily discounted. I have a feeling the might have stored these on cement & you know how that goes :/ ble


    • #3
      Hi liveaboardl,

      Have you considered starting over with a couple of 8 volt (four cell) batteries converted to alum and hooked in series? It seems you're getting 1.766 volts per cell, so eight cells would give you 14.13 volts to run the inverter with.

      Using expensive resistors to drop the voltage will waste a lot of power and possibly create a fire hazard.
      Last edited by Gary Hammond; 11-22-2014, 12:13 AM.


      • #4
        would converting 6 cell car batteries to 4 cell be an easy process with modern car batteries or not worth it? as these are most easily found vs 4 cell.

        I am looking at ways to get inverters to work also from alum battery banks, and although I am working to raise standing voltage I am thinking 11 volts will be as high as I can get and they seem to be solid performers all the way down to 5 volts.

        Is there an easy way to use capacitors for this? Ie dump power from battery bank into capacitor bank and run inverter from that (inverter i bought is 24volts to 230v 1500w), and can anyone point me to a solution that I could build or buy? many thanks


        • #5
          if you convert 4 6 cell battery's to alum = 24 cells, I am not for sure what the standing voltage will be for 24 fully charged Alum cells, so long as you stay under the 32V input limit on this model, it will run down to 19V......
          32V / 24 = 1.333V per cell max, close to what my Alum/copper/magnesium Crystal Cells stand at when dry.....
          19V / 24 = 0.791V min per cell

          per Gary's post above at 1.766V per cell
          3 battery's = 18 cells X 1.766V standing = 31.788V 18 X 1.8V standing = 32.4V

          I have owned a MIL spec 24V inverter that had a higher upper V limit than 32V......

          AIMS Sign Wave inverter
          Continuous output power: 1500 Watt
          Surge power capability (peak power): 3000 Watt
          DC input / operating voltage: 19 to 32 V
          DC input: 24VDC
          Output voltage: 120 volts AC +/- 10%
          Output wave form: pure sine wave
          Output frequency: 60 Hz
          Battery low voltage alarm: 19.6 +/- 0.5 volts
          Battery low voltage shutdown: 19 +/- 0.5 volts
          Last edited by RS_; 09-30-2018, 07:53 PM.


          • #6
            Thanks for fast response RS, yeah i think each cell will average above that with 6 coming in at 10.75v approx. Perhaps a 36 volt battery configuration would work, just switch on a load before inverter to drop voltage under 30.5 (cut off for my inverter) and then switch on inverter. 3 in series should only be about 32 volts at a guess so wont have to drop much for inverter to run. Your a genius thanks.

            If this is the solution it seems way to easy (good) and avoids me trying to figure out super caps and other methods to make it work.

            Might also be able to set charge controller to only charge bank to 30 volts perhaps! now that solves everything i think.


            • #7

              you want to fully charge the battery's every time. you want a charged battery to rest a while so that the peak voltage reached settles down to a standing voltage after a rest period before hooking up to the inverter..... if that standing voltage is less than your inverter high V limit than it will work with no mods.....


              • #8
                yeah this should work, I think the bank will be over slightly on the voltage front but that seems like an easy problem to fix given it wont be over by much and certainly not all the time. I can always get an inverter like the one you mentioned with higher cutoff also. This solution is excellent as it will let me use down to just under 7 volts per battery which is great, given the bank will be made out of many small car batteries being able to use that wide range of voltage will be priceless. I think that's the key to making this sort of setup work. Thanks RS. I have seen so many people with this issue in my internet travels but none seemed to have this solution, they were all like me, seeking an inverter with a lower voltage cutt off.


                • #9
                  you could put a 30V Zener Diode on the inverter input, and it would clamp any V over 30V down to 30V. Need a high Amp Zener, as it could pull a lot of current during the clamp down.......


                  • #10
                    Cheers I will make note of that, I just noticed this style of inverter that is designed to be connected directly to pv array via controller without battery bank, they support a much wider range of voltages, could these work connected directly to battery bank given overdraw is no concern? Then I could use the 10.5-30v version and keep bank at 24v or 21 to 22 in this case, that would allow a draw down of 50% on the bank which would be even better.

                    10.5-30V : use for 18v 36cells solar panel.

                    20 - 45V ; use for 24v/36v solar panel.

                    Heres the link, looks low quality but I am sure there are better versions


                    • #11
                      That looks cool with the input voltages, but this part is the kicker, as it is grid tie only.....

                      "Please be noted, This grid tie inverter cannot be used as off grid/stand alone solar system.

                      The output need to be connected to the grid power. Can not supply power directly to the AC loads"