Two Battery Banks?

Hi, I also have a 70w solar panel, miller welder/generator, both invertors are chargers.Problem is that you cant use a 2nd battery bank as a diversion load, it will draw to much current, messes up the controller.
I'm getting it figured out. Like you suggest, I will have two systems.Hydro/solar to a battery isolator (FET type, not diode type, almost no voltage drop), charging both banks. I'll put a solenoid in the leg to the shop bank, activated by the house diversion load out. That way the shop bank will only charge after the house bank is in absorbtion, or float mode.
I looked at the balmar Duo-charge, and the Xantrex echo-charge, but like my circuit better, as it allows both systems to go through complete charging cycles, with the house set prioritized.
Russell

Yep, thats how its set up now. The hydro is 10' from one corner of the shop, one panel on the roof (38'x42'shop, good solar on the SE pitch of the roof, READY FOR MORE PANELS!-in the plan).The batteries and power center are all in that corner. 
I'm getting the two bank thing figured out. Lots of info about it for sailing/boating folks, but it mostly pertains to keeping an engine starting battery charged as a 2nd battery bank.
Just picked up one of those little kubota DC gensets for a good price- havent plugged it in yet, but if the specs of 140amps at a pint of diesel an hour are true I'll be happy
My RE energy income is more than sufficient for the house, and for 60-70% of what I do in the shop. The house use is fairly consistant, but the shop power draws vary a lot,and sometimes infringes on house power.I think it will be easier to manage my power usage by seperating these very different situations.
Any ideas about slaving a silenoid off of the diversion load circuit of a charge controller? Problem with an automotive type is that the coil would have to be activated at <4vdc, yet withstand up to 15vdc continuous duty.Maybe another type of relay?
Thanks, Russell

Hi Tom, each bank has a charge control, and a diversion load. If I deplete the shop bank (not to the point of damage of course) I have power in the house and by the time I'm in the shop next they will be charged again. When I'm in the shop late and draw down the whole bank, it takes a while to charge back up. Also has to do with the reliability of the hydro. I'm 2nd in line on a long pipeline thats from my neighbors place. I have water rights to it, but it's a long story, kindof like having 2nd rights on an irrigation ditch that usually runs, but sometimes not.
Russell

Thats where I'm at. Hydro/solar to a FET battery isolator,to basically two stand alone systems. My idea of prioritizing the house bank entails running a on/off relay set in the shop side of the isolator, activated by the charge control for the house batteries. It will only close when the house batteries are in absorption,or float mode.
Now, what kind of relay? A continuous duty solenoid doesn't activate till it gets to >8 volts. I checked the voltage on the controller as it began divertion, and the voltage slowly comes up as it diverts more current.
I'd like to find a relay that will activate at <4volts, yet withstand 15volts, and will pass up to 35-40 amps.
power-io.com has one that looks interesting, but $60 is kind of pricey for a simple relay (?).
I might try the setup without it and see what happens, maybe try an automotive relay to see if that works.
Russell

Hmmm, I'm thinking that the 1st charge controller will work as the battery monitor for the first battery set. When the house batteries fall below the float voltage setting, there is no current out at the diversion load terminals, = relay (between isolator and 2nd batts) is open (off). All the current from the hydro flows to the house batteries until it goes to absorption mode, and begins diverting current, closing the relay, and allowing current to flow to the second set, till it is charged, then both charge controllers would be in diversion mode until the house batteries are low again.
The idea is to let the 1st charge controller complete its bulk charging cycle on the house batteries before diverting current.
Each charge controllers have 300 watt diversion loads, the relay would be pigtailed to the load so it doesn't receive all the current from that controller.