Skybox control over generator charge input

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Super Charger
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Joined: Tue Jan 07, 2020 6:00 am

Skybox control over generator charge input

Post by Super Charger » Tue Jan 07, 2020 6:17 am

We recently installed three skyboxes which we will setup for stacking (I know the firmware is not quite available yet!). We have a small generator (30kW). Under a power outage the owner would like the option to STOP charging the batteries with the generator. There is some more backstory to this request by the owner but I don't want to waste your time! Could I install a toggle switch which tells the Skybox: do NOT charge the batteries from Generator? The theory is we will have more capacity from the relatively small generator (12k sq.ft. house) if we are not charging the batteries.

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Kurt Lundquist
Alpha Energy Engineering
Posts: 1447
Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: Skybox control over generator charge input

Post by Kurt Lundquist » Tue Jan 07, 2020 7:22 am

I can't speak for Skybox because I don't know the inverter that well. For all of the other OutBack inverters the load takes priority. If the batteries need charging from an AC source it only happens when the AC output load is less than the AC input amp setting. This doesn't work when the generator is wired to the main house panel where the non-critical loads are located. The inverter(s) cannot see non-critical loads so it doesn't know how much load is on the generator. In that case, you would need to manually tweak charging via OpticsRE or directly at the inverter interface or get a larger genny.

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

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Gwendoly Espe
Applications Engineering
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Joined: Wed Feb 22, 2017 10:04 am

Re: Skybox control over generator charge input

Post by Gwendoly Espe » Tue Jan 07, 2020 1:22 pm

Stacking is available for Skybox! Just need to make sure you have a newer version of the firmware as the stacking feature is not available prior to firmware revision 1.2.22.

Checkout Page 54 of the Skybox Manual if you need more information.

Skybox will prioritize the protected loads over charging and it should use the Generator max input current limit (A) to determine when to send current to the batteries. This setting doesn't limit what goes to the protected loads in pass-thru. On a single Skybox lets say you have that setting set to 15A. The protected loads pull 10A pass-thru, then it will allow the remaining 5A to go toward charging. If the protected loads pull 15A pass-thru, then zero will go toward charging. I would try setting Generator max input current limit (A) to 0A for each Skybox, I would expect that to not allow any charging.


Let us know if that worked for you!
Gwendoly Espe
Applications Engineer


Alpha Technologies Inc. / OutBack Power Technologies
3767 Alpha Way Bellingham WA 98226 USA
http://www.alpha.com

Super Charger
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Re: Skybox control over generator charge input

Post by Super Charger » Wed Jan 08, 2020 5:27 am

Kurt: interesting input thank you. I may ask Outback if the OpticsRE can be used on skybox. We need to stop the Skybox from charging from generator remotely (even tho the generator circuit may be on)
Gwendoly: thank you as well. I understand that there is a potential issue with stacking more than two skyboxes and the latest firmware fixing the (emphasis on potential) issue has not been released - we will cross that bridge soon! That is super interesting about the demand however the generator feeds two different panels: "critical loads" via skybox and "backup loads" via ATS. The oven and dryer is on the "backup loads" panel. We want to install a toggle switch which stops the skybox from charging the batteries via generator. If we were able to stop the batteries from charging (and simply have them float at whichever depleated level they reach [above out DoD limit]) it would give the owner the capacity to run the dryer and/or oven (potentially). I would love to set the generator input to 0 but the owner fiddling with this during a power outage is not an option, frankly they would not want to operate the breaker either.
In such a case that the batteries deplete below 40% the toggle switch will be over ridden and the generator starts charging the batteries until they are full again.
This project is battery backup only so the batteries float at 98% or thereabouts all year around unless there is a power outage. Sorry for not adding this in my first post.

Thanks again!

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Kurt Lundquist
Alpha Energy Engineering
Posts: 1447
Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: Skybox control over generator charge input

Post by Kurt Lundquist » Wed Jan 08, 2020 7:58 am

Skybox works with OpticsRE. :cool:
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

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