K8055 log format YYYY MM DD HHMM timestamp;digital;analog1;analog2;counter1;counter2.
Equipment Change/Upgrade Notes
These should be read alongside the numbers above:
2018/04/22: removed the bubble insulation from the battery bank.
2017/10/29: wired in direct-to-battery circuit to kitchen, fused 20A, estimated impedance ~70mΩ.
2017/10/20: adjusted VHIGH to also require having reached absorption stage,
2017/10/01: adjusted voltage thresholds down a bit since LOW was at ~100% capacity; VLOW is still above sulphation ~12.4V.
2017/09/23: put the bubble insulation back on the battery bank because temperatures are dropping.
2017/09/18: significantly raised the LOW and VLOW voltage thresholds to try to tackle sulphation and capacity loss; will mean that the networking equipment dumpload is off-grid less, especially at night.
2017/08/13: verified that all seems fine in outside connector box; attempted to tighten all connection screws also.
2016/10/31: dump relay seems to have stuck again.
2016/10/30: ~14:30Z: mounted the 40W amorphous panel in bay b and connected up.
2016/10/22: eve: dump load apparently not drawing power from off-grid system when activated. Have reseated 12V connection, but no change; only drawing power when mains switched off at wall which implies relay stuck on, though it can still be heard moving when its state is toggled. Went into service ~2014/08. May need replacing sharpish, probably with another OpenTRV boiler-control relay, though some percussive maintenance seems to have fixed it temporarily.
2016/10/04: pm: laid layer of plastic bubble-wrap over battery bank to attempt to reduce cooling rate at night or when otherwise could out; seemed to only drop 1°C overnight where usual has been 2 recently (graph).
2016/10/04: am: large tree to SE being trimmed may reduce shading of on- and off- grid systems in morning in shoulder months such as now; may be ~1kWh/d of extra generation on sunny days.
2016/09/12: replaced 16WW OpenTRV nodes with secure transport versions.
2016/09/10: parallelled +ve connection (and generally improved) from power cupboard to desk to better support heavy recharge demand from laptop, and shortened power route to RPi in hope of reducing measured supply impedance and red power light blinking (but it is still blinking when RPi is working hard).
2016/08/29: router seemed to hang today needing power-cycling to fix.
2016/08/19: ~10am: replaced main 20A MAXI load fuse with 20A DC breaker in fairly prominent easy-to-reach position.
2016/08/16: ~2am: system stopped: must fix flickering red light in case significant power issues involved; replugged microusb power cable.
2016/08/12: eve: using PC Meterbus adaptor to SS-MPPT-15L to get more accurate battery voltage measure and deduce other parameters; eg resistance from controller to RPi appears to be ~0.1Ω.
2016/08/04: am: mounted and connected second CS 255W panel.
2016/08/03: pm: removed 40W amorphous and 20W 'floating' panel.
2016/08/02: dusk: fitted blocking diode for first CS 255Wp, <0.3Vf.
2016/08/01: mounted first CS 255W panel (actually the second in the batch).
2016/07/22: installed first CS 255W panel, connected to SS-MPPT-15L; 100W and 20W panels removed from 12V-nominal string.
2016/07/16: adjusted powermng.cpp to try to ride through brief dips in sunshine, eg from passing clouds.
2016/06/29: installed LS2024RP PWM 20A controller and moved ~40W of 12V-nominal solar to it; battery type set to 2 (gel); in progress ~10am/09:00Z. Noon moved 60Wp panel (~15Vmp) to PWM controller
2016/06/11: significantly re-arranged and tidyied (and shortened) wiring from panels, now not coming into the house at all, to make separate running of ~17Vmp and ~30Vmp strings to controllers near battery bank possible; currently the two circuits are combined at the controller and the '30Vmp' circuit is still being fed by the ES-62T panel.
2016/05/31: wall-mounting the (10kg) ES-62T (ES62) panel; not a great location for mid-winter (will get little direct sun), nor the slickest mounting skill, but makes space for bigger things later and gets me some practice with the mounting brackets. Maybe I could add a mirror or white panel later.
2016/05/22: in the process of messing things around I seem to have bust the RPi B+ (it will no longer power up) so I am trying its SD card in the RPi2 B that I have to hand, and miraculously it just works!
2016/05/22: tidied exterior wiring; removing LiFePO4 from system (near full SoC); joined 2 external PV strings to feed LA solar controller.
2016/05/21: reinstated off-grid 12V MR16 4.5W desk light, RPi controlled; seem to have broken INA219 power monitoring somehow (I2C device no longer visible at 0x40), possibly by still having power across it with RPi powered off, but probably by physically breaking some weak connections.
2016/05/07: 10:44Z: reconnected old 40Ah battery; observing.
2016/05/06: trying to work out why battery bank not getting to absorption and (and having re-adjusted levels in software) then checking forward voltage on blocking diodes at wiring centre indicated that 100W panel not supplying much power; turned out to be defective MC3/4 connector, temporatily replaced by terminal block.
2016/05/05: battery (2A MAXI) fuse seemed to be dropping up to 150mV eg under decent charge from bright sun; replaced with 20a breaker at ~20mV.
2016/05/03: connection to one end of battery bank not tight; system seems to have been supported by old 40Ah gel still attached, with apparently ~14Ah remaining effective/available capacity judging by performance with dump load.
2016/05/02: measuring 12V power draw by Maplin N03GC adaptor with inline power meter gives ~12W for modem/FTTC downstream (13.3W shown, but no draw shown as 1.2W/100mA) and a total of ~15W/1.3A (16.6W shown; mains draw indicated as 13.6W with N67HH) with Loop power monitor nominal 2.5W USB load added; not great efficiency (~80%) but not terrible; total draw from battery probably 18--20W including RPi, controller self-draw, etc...
2016/05/01: major rejig of 'dump' logic for: genuine dumping of excess, supporting maximum spill to grid during peak demand/intensity, and attempting to take load off-grid overnight.
2016/04/30: (18:00h UTC) fitted (4x) 35mm^2 30cm battery jumpers (M8 lugs) and 2x 10mm^2 (M8 lugs) battery leads to charge controller 1@~2m and 1@~1.3m+; now looks like decent implementation of Method 2; preliminary experiments suggest that the instantaneous sag at the load is now ~150mV at ~10W, but these numbers, while the B1 supply was disconnected, look like offsets from ground currents (if not leakage from the supply wire-OR):
2016/04/30T17:30:06Z AL 170 B1 12666 B2 14336 P 1858 BV 13856 ST OK -
2016/04/30T17:40:07Z AL 170 B1 234 B2 14251 P 1887 BV 13892 ST VL -
2016/04/30T17:50:06Z AL 170 B1 150 B2 14336 P 1876 BV 13856 ST VL -
2016/04/30T18:00:07Z AL 170 B1 131 B2 14345 P 1943 BV 13856 ST VL -
2016/04/30T18:10:07Z AL 170 B1 140 B2 14036 P 1881 BV 13668 ST VL -
2016/04/30T18:20:06Z AL 170 B1 12506 B2 13820 P 2117 BV 13324 ST OK D
2016/04/24: sample voltages in overcast afternoon with dump in progress: 12.56V near load at measurement point, 12.62V at controller battery terminals, 12.66V at one of middle batteries in pack, so 100mV losses from battery to (near) load.
2016/04/23: fitted (2x) 35mm^2 30cm battery jumpers (M8 lugs) in middle of 4x12V bank to avoid causing imbalance vs existing 2.5mm^2 17cm cables; found possible small drop at -ve power-take-off corner of bank where existing cable slightly damaged.
2016/04/18: considering addition of 60W--100W+ of semi-flexible panel such as Biard 60W Semi-Flexible to be vertically mounted on south-facing wall to help create some excess to 'dump' to move load off-grid more of the year.
2016/04/10: continuing to tweak powermgr.c to cycle the (LA) battery less and to be more finely responsive to grid intensity as practice for larger loads and stores...
2016/04/06: checked wiring from battery to controller to load; slump of ~0.2-0.3V at 1A/12W seems excessive:
2016/04/19T04:30:06Z AL 168 B1 12525 B2 13247 P 1847 BV 12880 ST L -
2016/04/19T04:40:06Z AL 168 B1 12525 B2 13247 P 1858 BV 12880 ST L -
2016/04/19T04:50:07Z AL 168 B1 12525 B2 13247 P 1858 BV 12880 ST L -
2016/04/19T05:00:06Z AL 168 B1 12525 B2 13247 P 1876 BV 12880 ST OK D
2016/04/19T05:10:06Z AL 168 B1 12290 B2 13229 P 2159 BV 12848 ST OK D
2016/04/19T05:20:07Z AL 168 B1 12272 B2 13229 P 2102 BV 12860 ST OK D
2016/04/19T05:30:06Z AL 168 B1 12225 B2 13229 P 2079 BV 12860 ST OK D
2016/04/19T05:40:06Z AL 168 B1 12253 B2 13229 P 2184 BV 12848 ST OK D
Seems to be ~60mV in cables from controller to load (~4m one way, 4mm^2 cabling: 4mm2 is 9.22mOhm/m (supply and return) so 4m should be 36.88mOhms or 37mV drop at ~1A), ~20mV through controller, ~40mV across (each?) 20A MAXI fuse (either side of controller), with some possible extra losses on -ve battery wiring side to fix and generally beef up. (20A MAXI fuse resistance should be ~3.1mΩ 3mV drop at ~1A.)
2016/03/31: now have off-grid system take FTTC/router load also when grid intensity is high, and here it is responding to morning peak.
2015/09/19: running the MacBook Air gently (1 core at 70%, so no fan needed) for SETI@Home uses ~15W, and ~40Wh per unit (~200TFLOPS), when running as a manual dump load on the Li battery and its PV. All cores flat out hits ~26W.
2015/08/20: moved FTTC adaptor (~4W) to same 12V supply as Internet router (~8W) thus bringing total load that can be switched off-grid to ~12W ie ~0.3kWh/day (2015/09/18: FTTC adaptor and Internet router load measured at mains via 12V supply to be ~10W with N67HH; rising to ~16W with Fairphone (FP1) recharging via USB.)
2015/07/26: upgraded (REV2) OpenTRV stats hub to use interrupt-driven OTRFM23BLink code which should improve reception reliability.
2015/06/07: Internet router (8W) kept off-grid completely overnight (saving 0.2kWh grid draw); should now extend potential battery support to additional 4W FTTC device which would also give resilience in a power cut.
2015/05/04: MacBookAir running directly from Li battery via Mikegyver.com custom adaptor lead works well and can run indefinitely off-grid given current levels of sunshine.
2014/12/06: adjusted solar panel layout in garden to better capture winter sun angles. Tweaked Li powermgr voltage thresholds too very slightly.
2014/11/14: adjusted LA powermgr voltage thresholds to allow discharge to ~70% for dumping given that getting over 80%SoC is relatively inefficient and requires lots of full sun which may not happen often in winter.
2014/10/13: moved ADSL entry point and this WiFi router and entire server downstairs to kitchen cupboard; note gaps and glitches in various data streams ~5pm.
2014/10/11: adjusted dump algorithm to try to keep load off grid in winter weekday evening peak ~15:30 to 19:30.
2014/08/09: ADSL power dump hardware reconstructed using modified (NC rather than NO) OpenTRV boiler relay control; draws ~250mW to energise and LA (B1) voltage drops ~0.1V at the sense point for assumed total ~8W load including relay overhead.
2014/07/21: (9:35am) SunnyBeam continuously plugged in as an experiment; expected ~150mW extra load (partly because display is permanently on.
2014/07/20: RPi +B ~1.5W typical power draw measured from upstream of 12V-to-5V converter.
2014/07/16: SheevaPlug tentatively off 21:33BST, with RPi providing services.
2014/07/13: official battery voltage monitoring now on RPi and live power monitoring has been added with high-side AdaFruit INA219 I2C board.
2014/07/11: moving services from SheevaPlug to RPi; removed ADSL dump load for now.
2014/06/08: increased the basic battery/power sampling interval from 2m to 10m, with intermediate (5m) samples taken and logged when extra energy likely available (eg not overnight or mid-winter).
2014/05/04: moved outside (OpenTRV) sensor from inside shed where it was getting rather warm, to porch out of direct sunlight (~3pm); may be ~2°C higher than EGLL temperatures. Bruno's screw slots worked just as designed! Updated s/w on all nodes 8pm--9pm which caused interesting temperature wobbles.
2014/04/27: ADSL auto-off-grid hardware finally wired up today after keeping an eye on s/w control behaviour for a while.
2014/04/26: all OpenTRV sensors now collecting data, including new one outside under cover.
2014/04/10: large (weeping willow) tree more or less due east of us ~30m taken down today; may get less shadowing and thus more generation in the early morning through the summer.
2014/03/16: ADSL off-grid given SLA bank showing sign of decent charge (including float); considering auto-changeover between mains and off-grid using latching relay (eg RS 686-7212 / Omron G6EK134PSTUS5DC) on mains side and possibly DC side also controled by digital outputs under main system s/w control or on basis of (say) 13V/14V thresholds and PICAXE/AVR control. Manually switching on/off grid as necessary for now.
2014/03/16: note that 60Wp extra 'winter' panel set not deployed this winter.
2013/07/07: removed some wire-OR diodes where panels already have built-in blocking diode and leakage/failure of wiring/diode/panel seems low-risk; may be good for a few % more output when feeding MPPT controller, eg as much as 0.7V/14V.
2013/07/07: ADSL back off-grid (for a couple of weeks) after a couple of good sunny days and more predicted (will need taking off for poor days and/or SSR-driven mechanism eg to drop mains input so reg uses 12V when not at 14V for a day).
2013/07/01: SLA seems to be struggling with ASDL + SheevaPlug load, so ADSL back to mains for time being.
2013/06/25: reconnected dump load for LiFePO4 battery and un-parked MotorWind turbine upstream of LiFePO4 battery. Also transferred SheevaPlug and ADSL modem off-grid (~0.3kWh/d).
2013/06/24: reconnected LiFePO4 battery; having to assume that C- is (-ve) charge and D- is (-ve) discharge. Secondary voltage sense line and power to desk also reconnected.
2013/06/21: primary 12V panel set reconnected to charge controller and thus batteries (and primary voltage sense line); battery state LED moved from amber to green shortly thereafter. Rest of system will be reconnected over next few days.
2013/06/16: 12V system still not restored after building works, and MPPT charged showing red for connected old 40Ah gel, so made direct connection from ~24Wp on shed to charger and reconnected main gel set to charger also.
2013/04/29: temporarily taking SheevaPlug and ADSL on-grid and disconnecting panels/controllers/etc, for rewiring.
2013/04/21: put away nominal-60Wp winter off-grid PV panel set.
2013/04/11: ADSL modem/router taken off-grid this evening; ~0.25V drop (non-drooping) in overnight LA battery voltage, presumably from cable losses.
2013/01/26: noticed that solar controller amber LED was lit mid-morning with SLA voltage ~12.2V; sunshine forcast for a good chunk of today and tomorrow and voltage already showing ~12.7V on charge. Server has stayed off-grid so far this winter.
2013/01/01: lowered LiFePO4 upper threshold to 13.1V to allow for more measurement noise and the fact that it is 'sacrificial'.
2012/11/30: winter ~60Wp amorphous panel set put out after run of dark weather and SLA battery consistently under 13V overnight.
2012/10/05: ADSL modem moved on-grid until spring on the basis of SLA @ 12.3V at 9am and only intermittent sunshine forecast over next week or so. (Immediate jump to 12.6V after!)
2012/09/14: finally installed Maplin [defunct link "http://www.maplin.co.uk/12v-40w-solar-panel-kit-510795"] N27JL 40W 12V amophorous panel in afternoon via own 5A Si diode; may want to shorten/fatten connection cables at some point to minimise losses.
2012/09/05: given another day with the SLA voltage only reaching ~13.2V (@<25°C) I have experimentally removed the ADSL modem load (back on grid instead) to see what difference that makes beyond instant 0.2V rise. Tightened all connections for external and internal screw-blocks (nothing was worryingly loose this time). Note that as of today only 60Wp Unisolar panel and MotorWind are charging the LiPO4 battery with everything else directed to the SLA. (Just after noon 2 days later SLA voltage at ~14.4V ie getting good charge.) Taking back off grid morning of 2012/09/09 at least briefly as SLA battery has been at 13.2V all night. I'm currently of the opinion that the ADSL's power management had stopped working properly and power cycling it is the main fix, but giving the SLA a good charge was fine anyway.
2012/09/04: some evidence of poor connections from 100Wp panel (poor charging even in good sun, silly/low voltages at connection box; seemed better after breaking and remaking in-line connections, but will need monitoring.
2012/08/05: removed dead 12Wp panel (nearest house, likely to capture least energy anyway) from front porch / shed roof 36Wp set currently running to LiFePO4 as spotted 2012/02/21. Attempted to clean two remaining panels and also very slightly increase tilt of one now nearest the house.
2012/07/25: adjusted SLA 'high and charging' down further to 13.2V (from 13.3V) to allow for temperature/voltage compensation at ~30°C ambient.
2012/07/08: adjusted SLA 'high and charging' down further to 13.3V (from 13.4V) to allow for temperature/voltage compensation.
2012/07/07: bought Maplin [defunct link "http://www.maplin.co.uk/12v-40w-solar-panel-kit-510795"] N27JL 40W 12V amophorous panel £80 (ie £2/Wp) on offer to install vertically on south-facing wall in September.
2012/06/17: retightened all connections, topped-up stand-alone 3.2Ah SLA direct with 1.5W panel in sunshine to ~13.1V, adjusted SLA 'high and charging' to 13.4V (from 13.5V) as previously slightly too conservative I think.
2012/05/13: put away 'summer' 60Wp amorphous panel set connected to SLA for the summer.
2012/03/15: ADSL modem moved off-grid until autumn; SLA voltage now seen dipping below LiFePO4 ~0.2V at night.
2012/02/21: systematically tightened all terminal-block connections because observed deep voltage dips/sags suggested poor connections and high-resistance somewhere. Found one very loose (SheevaPlug ground) and plug rebooted at some point suggesting at least one very bad connection that did indeed need fixing. Noted also that one 12W panel at front seems to be dead.
2011/12/11: measurements at noon show voltages at wiring centre 13.05V, but 12.65V at sensor wire terminals upstairs and reading via k8055 as 12.6V/12.7V, which suggests higher sensor input impedances may be needed for accuracy (and battery drain not as dire as advertised), so adjusting pots ~12:50 to get true reading as at voltage probes downstairs, not locally, so about 2% high locally given 1kΩ probe resistance and 50kΩ input pots in series. At 15:30 reading 12.6V/12.7V on k8055 vs 13.0xV downstairs possibly due to drop in 0V side, so have tweaked a little further to compensate. As of 2011/12/14 just after sunny noon reading of ~14.9V (LA) and ~13.6V (Li) corresponded to ~14.5V and ~13.3V at the wiring centre/probe.
2011/12/05: used sensor wiring already in place to measure battery voltages closer to source (yellow for Li, red for LA) via 1kΩ resistors tapping wiring centre downstairs, to suffer less from the voltage drop to SheevaPlug at higher supply currents. May require voltage threshold adjustments.
2011/11/06: added 'extra' nominal 60Wp south-facing ground-mounted panels to off-grid SLA-charging circuit as the system has missed coming out of low-power mode a couple of times in the last week or so. One of the panels seems to be effectively dead (~2Voc or less) but the others are still showing a respectable 16--23Voc, so swapped in separate 15W panel of same dimensions from nearby (though its rear glass plate is cracked and so performance is probably below nominal) and replaced that with a new [defunct link: "http://www.maplin.co.uk/solar-powered-12v-15w-battery-charger-508575"] Maplin N70JK 15W with metal stand.
2011/09/10: wired old 40Ah gel into main battery bank, direct to MPPT controller via long-ish cable and self-resetting thermal fuse with aim of it being slightly-higher impedance route than to main bank, thus avoiding 40Ah taking too much strain in parallel with much newer ~400Ah set.
2011/07/11: fitted Morningstar Remote Temperature Sensor (RTS) to MPPT controller to help protect the LA battery bank. Fixed the sensor to the -ve lug of a battery in the middle of the bank: have thermally insulated it (with an old sponge as it happens) from the air to ensure that it reflects battery core temperature as accurately as possible.
2011/07/04: ADSL off-grid again; 0.20V drop from controller battery terminals to bus upstairs near power take off for modem at 12.78V (bat).
2011/04/22: found and fixed wiring problem which had smallest (2Wp) panel reversed and fighting against 60Wp winter panel set, so not contributing to SLA input.
2011/04/22: moved 12Wp panel from LiFePO4 to SLA input so former is dumping less and latter is full more, ie better balancing.
2011/04/16: wired in dump load (currently only ~16R/15W) for LiFePO4 battery.
2011/04/15: adjusted turbine crowbar trip to 18V, ie above max output voltage from LiFePO4 battery and below Voc of the PV inputs, so presumably 'safe' for the BMS input, to try to reduce spurious and potentially damaging repeated operation a little when the battery is full.
2011/04/11: took down (60Wp amorphous) 'winter' solar panel set.
2011/04/10: experimentally taking ADSL router off-grid using lap-top adaptor (previously using mains via same adaptor). Initially until 2011/05/12 when battery getting a bit low.
2010/11/20--2010/11/21: inserting 30A automotive 'MAXI' fuse into SLA +ve connection to Morningstar controller, then next day 20A in load side from controller, thus SLA side voltage reading glitches to 0V, while LiFePO4 side keeps the SheevaPlug running.
2010/10/11: moved MotorWind turbine over-voltage crowbar circuit to outside junction box and plumbed output via blocking diode to secondary/LiFePO4 array circuit, ie any wind power now charges the LiFePO4 battery unless already full.
2010/10/11: split main PV (motley) array into two isolated parts, in particular the lower-voltage Uni-Solar triple-junction (Voc ~ 17V) is now in the section feeding the LiFePO4 battery.
2010/10/11: added 100Wp mono panel to main off-grid PV array.
2010/10/09: upgraded battery voltage sensing to include second battery and reduce noise, and improve accuracy using external 50kΩ trimpots.
2010/10/05: added LiFePO4 12V 20A battery to system fed from a sub-set of the panels and powering the SheevaPlug from a diode-OR with the normal SLA output.
2010/10/01: now reducing sampling rate (to no more than one sample each 10 minutes from previous sample each even minute) if battery voltage/SoC very low so as to save energy associated with the sampling, logging to disc, etc...
2010/09/30: reconnection of approx 60Wp of south-facing ~70°-tilt panels as battery crept down to 'amber' at controller (<12V) after several successive gloomy days, plus other minor reconfiguration for robustness/winter.
2010/04/05: temporary removal of approx 60Wp of south-facing ~70°-tilt panels now battery is reaching float every day and turbine 'emergency brake' is repeatedly operating!
~2009/10/15: addition of approx ~72Wp of south-facing ~70°-tilt amorphous panels from Maplin.
~2009/09/21--2009/10/03: major reconfig with laptop off battery, SheevaPlug
permanently on battery, battery voltage measured via analogue input rather than
via two opto digital inputs (LVD/high), and solar controller(s) being upgraded
to a single Morningstar MPPT device (SS-MPPT-15L).
2008/07/01 (~0900UTC) new laptop/server internal battery fitted.
2008/06/26 Input1 NOW UNALLOCATED; no longer 'DC-DC converter output OK'. Current allocation/meaning of inputs:
"Battery Voltage High" (Input0) reports essentially when the battery is full and still charging, so the system should dump some energy.
"LVD Output On" (Input2) reports when the battery is fairly full and is running the server/laptop.
"Wind Power" (Input3) reports when a turbine is turning, though not necessarily generating useful energy.
2008/06/24 laptop internal battery died so 2008/06/26 replaced mains/off-grif switchover mechanism with an 'instant' diode-based scheme.
2008/06/05 (~1600UTC) rewiring to reduce impedance and improve behaviour under heavy load.
2008/06/01 (~1700UTC) addition of 2x12Wp amorphous panels (Maplin N32CX, TopRay TPS-102-12) on east-facing near-flat porch roof, bringing off-grid total to ~120Wp.
2008/05/24 (~1200UTC) addition of 12Wp amorphous panel (Maplin N32CX, TopRay TPS-102-12) on east-facing near-flat porch roof (in place of 13Wp test panel).
2008/05/24 (~0700UTC) addition of tiny 2.4Wp (Maplin N59FU, Nikkai) amorphous panel on west-facing near-flat shed roof.
2008/05/10 (~1430UTC) to 2008/05/24 (~1200UTC): temporary/intermittent addition of 13Wp horizontal PV on east side of house to catch morning sun and extend off-grid period for server.
2008/04/17 (~0800UTC) to 2008/04/23 (~1100UTC): major rewiring.
2008/04/10 (~2000UTC): disconnection of 2x1W turbines for wiring rearrangement.
2007/12/01 (~1600UTC): installation and connection of MotorWind 8-turbine device.