The problem isn't that you'll completely discharge the part of the bank you're pulling 12v off of, but rather if you discharge the bank unevenly and charge the entire bank in series then you're either overcharging the part you're not pulling 12v off of in order to properly charge the part you are pulling 12v off of -or- you're going to undercharge the part where you are pulling off 12v if you properly charge the part of the bank where you are aren't pulling 12v off. There's just no way around that. Swapping which part of the bank you're using to pull off the 12v will help but you'll want to swap much more frequently thank bi-anullay. You'll want to swap at least once a month.
If you only need 8W of power, then if you use a 24v to 12v regulator that's 90% efficient or better the losses will be negligible. Greg On Mon, Oct 15, 2012 at 7:54 PM, Olufemi Adalemo <[email protected]> wrote: > Thanks Greg, > I can see how putting load on just one part of the battery bank could > cause issues but this load is quite small compared to the total battery > capacity. I will be putting only 8w on two 150Ah 12v batteries (3600Wh > total capacity). It would take 400 hours to deplete the battery bank with > this load only, do you still think this will be a problem? If this will be > a problem I could have the load moved from one bank to the other at a > scheduled maintenance visit say twice a year. I really appreciate the > advice. > > Regards, > - - - > *Olufemi Adalemo* > M: +234-803-5610040 > M: +234-809-8610040 > [email protected] > > > > > On Mon, Oct 15, 2012 at 8:19 PM, Greg Ihnen <[email protected]> wrote: > >> My two cents: If you discharge part of your battery bank unevenly (pull >> off just half of your 24v bank to get 12v for some loads) you will have >> trouble with part of the bank getting over charged and part of the bank not >> getting charged enough. If you were charging the bank with an AC charger >> that charges each battery individually according to it's needs that >> wouldn't be a problem. But if you're charging the entire bank with a single >> device that charges the entire string in series like a 24v solar charger >> that is not a good way to go. You'd be better off with a 24v to 12v >> regulator. >> >> Greg >> >> >> On Mon, Oct 15, 2012 at 1:44 PM, Olufemi Adalemo <[email protected]>wrote: >> >>> It just dawned on me that I may have been barking up the wrong tree >>> I only have the one NSM5 to connect, I could hook this up to the >>> parallel segment of my battery bank and get only 12v while the rest of the >>> installation that's connected in series gets 24v. Do you think this will >>> work? Don't really have to worry about the NSM5 running down the battery >>> cause load is low and the cable run is under 10m so the voltage drop from >>> 12v will be negligible >>> >>> So this is how it would be: >>> 24v solar panel connected to 24v charge controller with 4 x 12v >>> batteries connected in a 2x2 series/parallel array. cable connected to the >>> parallel segment of battery bank (theoretically giving 12v to the NSM5), >>> rest of the load connected to the charge controller at 24v >>> >>> What do you think? >>> - - - >>> *Olufemi Adalemo* >>> M: +234-803-5610040 >>> M: +234-809-8610040 >>> [email protected] >>> >>> > > _______________________________________________ > Wireless mailing list > [email protected] > http://lists.wispa.org/mailman/listinfo/wireless > >
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