mixing forklift batteries, ?

[biff]

evening all.
          been pondering batteries, i have 72volt forklift and have been wanting to charge it from my 120volt turbine for some time now, it meant stepping down from 120volt charge to a 72volt charge,did not want to go to too much trouble , not being a electro genius i oppted for the easy way out and purchased a further 48volt forklift battery,
      so 48volt plus 72 volt = 120 volt.( nice one) however,, however the 48 pack is 750ah while the 72pack is in doubt,its not as deep or as big,,perhaps 600 or 550ah,,
      the question to ponder is,, would the battery mix be a problem,?and if so ,is there a way to overcome this,?
     i have nice little battery house,which houses 2 sets of 20 piece(10x2) 100ahx12volt batteries,i have set up a nice way of switching from bank to bank without depriving the turbine of the necessary outlet,,i intend to carry the current through the wall a few feet to the combined 48volt and 72volt so the forklift should charge automaticall when the charge is switched in its direction,,it seems a cute way to solve the problem but perhaps the difference in ah might cause trouble between the cells,,it would be nice to be able to use the forklift now and then as well as using its batteries to power the house,
                                    biff.

[Justme]

Will the 120 volt turbine actually be 120v for much of the time?

Mixing bats of dif ah tends to get frowned on but I have it from some one that really knows his stuff & its ok to do so.


Why not get a MPPT controller for the turbine?

But the only one I know of max's out at 145v (to close for comfort) & bats of 48v.

Oh I have also been told that using a turbine that is rated higher than the bank is not an issue as the bank will hold the voltage down. But it alters the power curve to lower the start up wind speed & also lowers the max watts / amps. I looked at 24 & 48v ones on a 12v bank. On 24 you would half the watts & on 48 get 1/4. So on your 120v / 72v set up you would look at about 72/120 lol (thats 6/10ths or 60%). You would need the right controller too.

 Justme

[biff]

thanks for the info justme, ;
                    the turbine is indeed 120volt most of the time,it normally reads 130 and we ease of the power when it goes down to 126, this past month the wind has been very reliable and we have had to burn off excess energy with halogen fires in the house,(rather than having the controller getting heated)its easy to figure out,just set one fire(400watt) to force 5 or 6 and the voltage comes down to 131,if the wind eases off,switch off fire but all the rest of the appliances run normally,this controller goes onto the dump load at 138, but it does so in a very easy and gentle fashion, keeping the voltage up,the controller is yangzhou shenzhou with "made in china" stamped in big bold black letters across the front.it has a little smiley face on it like the inverter has which goes all sad if overloaded and in shut down mode.the inverter is only 2kw but very heavy.(i think they might have put a lump of concrete inside it,like they have in washing machines)
      i know it is possible to wire the controller to work a water heater but i am loath to interfere with something that works so well as it is.i am installing the base to park the forklift and the 48pack so it should be in operation in a week or so.
                             biff.