Two SW4024 Xantrex inverters on a 48v system

[d34]

What type of problems would this cause?  I have a transformer to balance the 120v loads.  I know half of the 48v bank could get out of balance with the other half without a balancing transformer.  The only problems I could see is if/when the inverters are in charge mode one might put out more than the other, but as long as the bank stays balanced I would say they would put out the same. 

[mike90045]

SMOKE and dead inverters.

Not sure how you think it would work.   2 inverters in series, or split across 2 batteries in the bank.

A transformer will not solve un-equal battery discharge issues. 

Simplest to just split the battery bank into 2 parallel 24V banks, and kiss 48V good bye.

[d34]

The only way I can see the SMOKE release is if they are chassis grounded.

A transformer will solve the unequal discharge problems if the inverters are setup at 240v only and the transformer splits the 240v into 240v/120v.  

[Tom Reed]

+1 on what Mike said. My prediction is that while it may work, the batteries will die an early death. What's the issue with splitting the bank?

[d34]

I have 2 systems one 24v and one 48v.  The 24v bank batts are about done.  So I thought it may work to run them off of the 48v bank and only use 240v so that they both (24v inverters) use the same amount of power.  Just thinking out loud here hopin for some insight. 

[mike90045]

I have 2 systems one 24v and one 48v.  The 24v bank batts are about done.  So I thought it may work to run them off of the 48v bank and only use 240v so that they both (24v inverters) use the same amount of power.  Just thinking out loud here hopin for some insight. 

IF you have the sync/bridge cable to wire the inverters for 240,  you stand a change of it working. For a while.  But you will be exercising the 48V bank harder then ever, and it's expiration will happen sooner.   And you still have a fair chance of getting the battery bank unbalanced.  You have the summer with long days to plan your next step, and line up new batteries.  Or maybe consider a new, larger inverter that may have less overhead then 3 smaller inverters.  Tom & I will both have suggestions.

I currently can't recommend anyone getting a NiFe bank, unless you like picking up 80# batteries to drain and rinse them every 7 years, and then mix up a new batch of electrolyte to refill.

[d34]

They are bridged.  I have been working 14+ hour days 7 days a week for the past 3.5 months getting my new business goin.  So I am exhausted and didn't explain my setup very well, I apologize for that.  How will I exercise the 48v bank any harder than I normally do with the 48v inverters?  The 48v inverters wont sync for 240v hence the reason to use the 24v inverters.  I have another crazy idea I will save for later lol.

[mike90045]

....How will I exercise the 48v bank any harder than I normally do with the 48v inverterS?  .....

Say you have 400w of existing load on the 48V bank, and 300W loads on the 24V bank.   Moving all the loads to the 48V bank, and you now have the same battery bank, (400W) also picking up and additional 300W, (+75% of the original load) and your battery charge will not last as long, deeper cycles, and shorter bank life.   Plus, you have the additional potential for un-equally loading the batteries.

So to help you best, we need the whole story, in load KWh, charger KWh, battery specs....

ie
3KW solar array
50 - 350 w variable household loads
1/2 hp deep well pump @ 240VAC
48V 800 ah battery bank
XW6048 (6KW, 48V inverter/charger/transfer switch)

[d34]

Basically I wont be runnin any more loads than before.  So the bank will get used about the same daily, if not a little less due to using the additional panels from the 24v system to help charge the 48v bank.  I will list my complete setup later when I have more time to post. 

[Tom Reed]

Another option that will be a bit more conventional would be to use a transformer to up your 120v to 240v. That way you don't have the over head of the additional inverters. But like Mike says we need to know more about your system.