Which Bank minimum DC Voltage to use?

Discussion about the OutBack Mate Remote

Moderators: OutBack, OutBack Moderator Team

Post Reply
Surfpath
Forum Expert
Posts: 59
Joined: Wed Apr 18, 2012 8:46 am
My RE system: Outback Flexpower-1-6 system (VFX3048e, FM80, 48v, 50hz, 240v), 2,750w of PV (4 series of 3 panels/ea, 100v max-combiner to controller), 370amp/hr L16REB battery bank. Honda 2k briefcase generator. 100% offgrid.

Which Bank minimum DC Voltage to use?

Post by Surfpath » Thu Dec 05, 2013 10:46 am

Where on my Outback Flexpower panel (it's got a Mate, FNDC, FX, FM80...) do I find an accurate minimum voltage when I come home around 9-11pm and check on the battery bank? (my sunset ~6pm).

Since I believe Outback starts a new reporting cycle around midnight each night, what I expect to see on a typical day is a minimum voltage recorded earlier that same day sometime before sunrise.

Although I take SG's frequently, I also use the "Min Voltage" on the Charge Controller summary screen as a quick check. It's the value just below "Max voltage" when you are in the "Log" screen.

However, in the Mate (under Status, DC, then Batt, I think) there is also a value for "Battery System Min Voltage". However, usually the MATE's minimum voltage is significantly higher than the minimum the CC reports.

For example, at 11am last night the CC Log screen reported 48.5v as the the min voltage for the day, however at the same time the MATE listed the minimum as 49.1v. That's a significant difference. Which voltage is a true measure of the minimum battery bank voltage so far that day? :smile:

Gordon-Loomberah
Forum Guru
Posts: 403
Joined: Sat Aug 22, 2009 2:15 am
My RE system: Outback FM80 #1 2190W mixed panels + 2400W DQ200, panels, Outback FM80 #2 2800W mixed panels, mostly on trackers, Latronics LS 7048 inverter, 15 * 400AH CALB LiFePO4 cells + 1 400AH winston cell- nominal 53V, installed Dec 2012. Graphtec GL200 data logger for system.
30 evacuated tube 250litre hot water (no elect or gas boost), Hydronic heating- 78 evacuated tube 250litre(+1000l tank which I'll plumb in one of thee days) Heat exchanger to transfer heat from hydronics circuit to hot water when required. Davis VP2 +Solar & UV Wx Station.
Living off-grid since 1991
Location: NSW Australia
Contact:

Re: Which Bank minimum DC Voltage to use?

Post by Gordon-Loomberah » Sat Dec 07, 2013 8:15 pm

The FM80's minimum voltage recording is not accurate, so should not be relied on. I log my system with an accurate and precise data logger, and the voltage never gets as low as the FM80 reports.
http://gunagulla.com Loomberah weather + solar radiation and UV, and astronomy

Surfpath
Forum Expert
Posts: 59
Joined: Wed Apr 18, 2012 8:46 am
My RE system: Outback Flexpower-1-6 system (VFX3048e, FM80, 48v, 50hz, 240v), 2,750w of PV (4 series of 3 panels/ea, 100v max-combiner to controller), 370amp/hr L16REB battery bank. Honda 2k briefcase generator. 100% offgrid.

Re: Which Bank minimum DC Voltage to use?

Post by Surfpath » Mon Dec 09, 2013 6:55 am

Gordon-Loomberah wrote:The FM80's minimum voltage recording is not accurate, so should not be relied on. I log my system with an accurate and precise data logger, and the voltage never gets as low as the FM80 reports.
hi Gordon,
Thanks for the reply. So how do you go about logging your voltage data. Do you use a separate bit of gear to do this? [edit: I now see from your sig: Graphtec GL200 data logger for system." I'll google it]

Is the MATE's minimum DC voltage also rubbish then???

-SP

Post Reply