Low battery SG's - How to get them a bit higher

A place where users can meetup with other FlexPower One users and can find support for one another. A great place for people who have not purchased the FlexPower One yet to look up information.
Post Reply
Ghostpower
Forum Junior Member
Posts: 2
Joined: Mon Aug 28, 2017 9:20 pm
My RE system: Off Grid Outback FlexPOWER One with additional FM80 controller for 2nd array.
Two arrays on different azimuths 1260 watt and 1890 watt respectively. CDN Solar CS6X 315W x 10.
428 AH Rolls battery bank at 24 volts. Inverter VFXR3524
Location: Calgary Alberta

Low battery SG's - How to get them a bit higher

Post by Ghostpower » Wed Jan 17, 2018 11:45 am

Hello;m

I'm finding it a bit difficult get my battery specific gravity readings up to optimal. I recently purchased a refractometer and have been measuring my battery SG's when my MATE3 is showing 100% and my system is in float or snoozing. I do this with no or very small loads on the batteries. I am consistently getting readings between 1.22 and 1.25 for all cells. Optimally these should be 1.265 for my particular batteries. I have recently bumped up my absorb voltage from 29.8 vdc to 30 vdc. I haven't had many good sunny days since doing that to see if its made a difference.
I'm wondering if someone can provide me with some advice on things to check and settings to manipulate to try to get my battery SG's up closer to 1.265 so that the true SOC of the batteries matches the SOC on the MATE3

My system is off grid on a remote area in western Alberta (about 54 deg Latitude) my battery bank is a single string of four Rolls S-550's that are 428 AH and a 24 v system.

I would appreciate any advice anyone can offer.

Mike Curran
Forum Emperor
Posts: 1344
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one MX60 (2007)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied, no longer AC- coupled

Outback Skybox - Barn roof: (2019)
- 14 (2x7) Talesun 275W (DC array input to SB charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 modules

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Low battery SG's - How to get them a bit higher

Post by Mike Curran » Wed Jan 17, 2018 1:48 pm

How long is your absorb time? Off grid plus lack of sun (plus no generator?) is a definite formula for low SG's. You need to run an absorb cycle for 4-5 hours and check SG's, if still not up to 1.265, continue absorb until they are.

My FM80 charging settings shown below.
Screenshot_20180117-163833.jpg
Rolls manual instructions for setting absorb time and current:
20180117_164530.png
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

Solarmusher
Forum Member
Posts: 15
Joined: Mon Jul 22, 2013 11:00 am
My RE system: Off grid with VFX3648 x2 on Midnite Epanel x2, Hub + Mate, PSX-240, 750Ah Rolls S-480 battery bank, +/-3.2kw Pv array on roof, 2x Midnite Classic 200 controllers + Whizbang battery monitor, Trimetric 2030, SPD300 x4, various/cheap gas generators x3, 1200 watts solar electric DC water heater.
Location: Quebec, CA

Re: Low battery SG's - How to get them a bit higher

Post by Solarmusher » Wed Jan 17, 2018 1:50 pm

Ghostpower wrote:Hello;m

I'm finding it a bit difficult get my battery specific gravity readings up to optimal. I recently purchased a refractometer and have been measuring my battery SG's when my MATE3 is showing 100% and my system is in float or snoozing. I do this with no or very small loads on the batteries. I am consistently getting readings between 1.22 and 1.25 for all cells. Optimally these should be 1.265 for my particular batteries. I have recently bumped up my absorb voltage from 29.8 vdc to 30 vdc. I haven't had many good sunny days since doing that to see if its made a difference.
I'm wondering if someone can provide me with some advice on things to check and settings to manipulate to try to get my battery SG's up closer to 1.265 so that the true SOC of the batteries matches the SOC on the MATE3

My system is off grid on a remote area in western Alberta (about 54 deg Latitude) my battery bank is a single string of four Rolls S-550's that are 428 AH and a 24 v system.

I would appreciate any advice anyone can offer.
Hi Ghost,
In January, the only way to get them higher is to use your gen early in the morning and charge your Rolls until they reach 30Vabs for one hour. Let your solar arrays absorb for the rest of the day (another 3hr30).
Another way is to charge with your gen in the evening until they hit 13A end current (+/-3%) and let solar charge and absorb on next day for 4hr30 (if you have this time).
Erik

Ghostpower
Forum Junior Member
Posts: 2
Joined: Mon Aug 28, 2017 9:20 pm
My RE system: Off Grid Outback FlexPOWER One with additional FM80 controller for 2nd array.
Two arrays on different azimuths 1260 watt and 1890 watt respectively. CDN Solar CS6X 315W x 10.
428 AH Rolls battery bank at 24 volts. Inverter VFXR3524
Location: Calgary Alberta

Re: Low battery SG's - How to get them a bit higher

Post by Ghostpower » Thu Jan 18, 2018 8:17 am

Thanks Mike. I do appreciate your feedback and seeing your settings does help give me some idea for comparison. As mentioned I have bumped up my adsorb voltage to 30 VDC, which seems on the high side already. My absorb time is 4.5 hours. I guess what I really need is just more sun. I do have a generator wired into my system, so that is possibly an option to support battery charging. As I'm only at the property with the system one or two days per week running the generator everyday is not possible.
One thing that I find a bit confusing is why the MATE3 says it achieves 100% SoC. The Rolls battery manual has a chart that shows an SG of 1.25 is about 75% SoC. Is there some way to get the system to reflect that it only at 75% when the battery SG's are only at 1.25. What settings control the calibration of the system to the real SoC of the batteries.
The good thing is we are gaining more than two minutes of sunlight per day now so my ability to get 4.5 full hours of 30 vdc absorb time. I'm going to have 4 days of back to back sun into the weekend so I'll have a good opportunity to see if the higher voltage brings my SG's up. Thanks again for sharing your settings. If you think of anything else I might try to get my SG's up and to get my system to reflect the true state of charge of my battery bank, please let me know.

Mike Curran
Forum Emperor
Posts: 1344
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one MX60 (2007)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied, no longer AC- coupled

Outback Skybox - Barn roof: (2019)
- 14 (2x7) Talesun 275W (DC array input to SB charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 modules

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Low battery SG's - How to get them a bit higher

Post by Mike Curran » Thu Jan 18, 2018 8:35 am

Ghostpower wrote:Thanks Mike. I do appreciate your feedback and seeing your settings does help give me some idea for comparison. As mentioned I have bumped up my adsorb voltage to 30 VDC, which seems on the high side already. My absorb time is 4.5 hours. I guess what I really need is just more sun. I do have a generator wired into my system, so that is possibly an option to support battery charging. As I'm only at the property with the system one or two days per week running the generator everyday is not possible.
One thing that I find a bit confusing is why the MATE3 says it achieves 100% SoC. The Rolls battery manual has a chart that shows an SG of 1.25 is about 75% SoC. Is there some way to get the system to reflect that it only at 75% when the battery SG's are only at 1.25. What settings control the calibration of the system to the real SoC of the batteries.
The good thing is we are gaining more than two minutes of sunlight per day now so my ability to get 4.5 full hours of 30 vdc absorb time. I'm going to have 4 days of back to back sun into the weekend so I'll have a good opportunity to see if the higher voltage brings my SG's up. Thanks again for sharing your settings. If you think of anything else I might try to get my SG's up and to get my system to reflect the true state of charge of my battery bank, please let me know.
The secret to getting your system to indicate true SOC is in setup of your Flexnet DC. Here's what I would do:
1) Unplug the FNDC's LAN cable from your Hub
2) Perform an absorb cycle on your batteries until all of them have SG's within .025 of "full", around 1.270.
3) Plug your FNDC LAN cable back in to your Hub.

Now it will indicate 100% SOC but beware, over time this calibration may drift. SG's are your best indicator of SOC. The attached photo is from OB's FNDC application notes, hope it helps:
Screenshot_20180118-113130.jpg
- Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

Post Reply