[RE-wrenches] Dual battery bank switch for 48 VDC system

[greg egan]

William, thanks for the reply.  In the scenario I'm thinking we use the Blue Seas #3002 switch which has a battery bank A, bank B or A & B option.

Under normal circumstances he has it set to A&B.  When he wants to eq / condition his Concorde PVX series AGM's he switches to bank A and begins charging.
When the bank is fully charged he switches to B.  The switch is make before break so the lights stay on.
Bank A sits there fully charged with no load.  Loses less than .5% /month at 25C.
Next day he charges Bank B fully and then flips the switch to A + B and marks on his calendar to do this again in 2 months.

This site is mostly charged with generator in winter (Fairbanks AK).  Exclusively with PV in spring/summer.

Customer is smart.  Understands what's involved.  Kind of an ideal customer in that he figures out most
things by reading the manuals and when he has a question, he calls or emails me.

I'm guessing now that I've told you more you no longer think he'd need to manage the system hourly.  Or am I missing something?

Thank you,

Greg Egan
Remote Power Inc.


  


Greg:

Let me say I think the idea is generally bad.  Your client would need to be
actively involved managing this system on an hour by hour basis or both
battery banks are likely to be ruined.  If you want to switch between
batteries, unless both battery arrays are at a very similar voltage (+/- 0.5
volts) you should not parallel them.  In that scenario you would need to
shut down the inverter(s), switch battery banks, then restart the inverter.
A breaker interlock may be in order to prevent bad things from happening.
Like I said, a bad idea.  If you have too much battery to match the PV
capabilities you need to reduce the battery bank capacity.

If this system includes valid BOS components, and you still want to
experiment, integrate within that system by adding a battery breaker.  If it
does not have a decent BOS (Outback Flexware, Midnite DC breaker panel, for
example) that is a problem in itself.  Add the BOS.  The PV charge needs to
have either two battery breakers or be wired on the inverter side of the
battery breaker, an arrangement that I do not recommend.

Did I mention I think this is a bad idea?

William Miller
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20240620/efd16d6c/attachment.htm>