question on interpreting MPPT controller display

BFL13 wrote:
"On a positive note, I do hook up to shore power and/or run my generator enough, so I'm sure my battery bank is getting to full charge regularly."

Unless you have an AH counter and an hydrometer I would not be so confident you are getting those batts fully charged.

"But ****, 14.00 is so much lower than the batt manufacturer's 14.7 requirement! "

Also the higher voltage could get them recharged faster by increasing their amps acceptance rate if the charger can do that many. Can get more done in the same length of daylight.

"The system does product more power than I'm using in my first couple months of operating, not counting the absorption refer on AC. I seem to burn about 175AHish a day or so and haven't needed to run my Honda 2000, except a couple 3-4 day rain events"

I have not done a detailed calculation (your job) but I doubt you can restore 175AH during daylight with only a 55amp charger. Just not enough time in the day. Most folks in that situation have to run their gens and use high amp chargers for an hour or two in the morning before they can leave the rest to solar, and hope to get to full before dark.

Perhaps look at reducing the size of that battery bank. Do more of the 175AH recharge at a lower SOC range where battery will accept higher amps. Right now those 175AH are coming from the slow to recharge top end of the SOC range.

Interesting. Thanks.
If plugging the 125amp magnum charger into a 30 or 50 amp pedestal for a day or so won't charge the batteries, I guess they won't be charged. Don't know what else to do. I'm having trouble getting reliable readings on the battery volts, because getting them settled and resting with no load seems a rare event.

Note sure about charging 175 amps. If I'm harvesting say 45AH, 175/45 is 3.9 hours. I suspect the tapering adds to this time considerably, which I'm not accounting for. I'll run the batteries down 175AH by am on a sunny day and see what happens. I downloaded a spreadsheet built by Jack Mayer, who does some RV solar work. It essentially backs into the morning genset time requirement. If it appears that I'm going to have to use a generator that often, I'll have an ONAN 3.6Kw installed, cuz I'm not fooling with that Honda 2000 that much.

I understand the inverse relationship of lower SOC, higher charge rates you mention, but I just bought the bank, so I'll see if I can make it work.

My batts are (4) 6v, 415AH bats serial/parallel for 830AH @ 12Vdc. Do you know how often they should be brought to full charge in order NOT do damage them?

pianotuna wrote:
Hi,

For now I'd definitely move to the flooded setting.

Since you already have the remote for the Magnum I'd lean towards the PT-100. Best price for that may be at Imarine.

I agree that an 80 amp controller will leave no room for growth.

I'd likely put all six panels in series. I know that is a risk for shading. It could easily be undone since you have adequate wire already in place. If you added 2 more panels, I'd do two strings of four in series/parallel.

The other option is to switch the battery bank to 24 volts (or even 48), and add a Dc to Dc converter for the (minor) 12 volt needs. Unfortunately that means replacing the (lovely) Magnum 3012. That is a bit of an "ouch", unless you can find a buyer.

It would be simple to put the 6 in a series, if and only if I disposed of the BZ controllers. I'll figure this out over winter after I've had more time to use the system. At this point, "as is" is making more than I use and I don't use the generator much at all. I'm using surround sound TV, microwave, coffee pot, laptop and numerous other items. Seems ok so far, but we'll see.

I have no knowledge in this particular area, but why would the sealed battery profile have no equalization? This poses no risk if they get equalized every 29 days in the flooded profile?

I decided to stay 12Vdc on the bank. Too much brain damage to change!

outwestbound,

How often do you see less than 9 amps of charging from the solar?

Hi BFL13,

175 amp-hours per day / 24 =~ 7.3 amps per hour. (but we don't know how that 175 amp-hours has been arrived at)

During the day time (lets say 10 hours) all of that 7.3 amps is going to be provided by the solar panels.

That leaves approximately 102 amp-hours to be replaced.

The 55 amp charger less the 7.3 =~48 amps to replace the 102 used from the bank.

The bank is AGM and they start to taper at about 95% state of charge. The bank is 830 amps so the last 5% is about 41.5 amps. He gets 55 less the 7.3.

I can see no reason why a generator needs to be run at all under that scenario unless there are several rainy days in a row.

The controllers are less than optimal. I used the voltages from the flooded choice.

BFL13 wrote:
I have not done a detailed calculation (your job) but I doubt you can restore 175AH during daylight with only a 55amp charger. Just not enough time in the day. Most folks in that situation have to run their gens and use high amp chargers for an hour or two in the morning before they can leave the rest to solar, and hope to get to full before dark.

Hi,

For now I'd definitely move to the flooded setting.

Since you already have the remote for the Magnum I'd lean towards the PT-100. Best price for that may be at Imarine.

I agree that an 80 amp controller will leave no room for growth.

I'd likely put all six panels in series. I know that is a risk for shading. It could easily be undone since you have adequate wire already in place. If you added 2 more panels, I'd do two strings of four in series/parallel.

The other option is to switch the battery bank to 24 volts (or even 48), and add a Dc to Dc converter for the (minor) 12 volt needs. Unfortunately that means replacing the (lovely) Magnum 3012. That is a bit of an "ouch", unless you can find a buyer.

N/A

pianotuna wrote:
outboundwest,

I would change to the flooded settings. Do you know how long the BZ will stay at the various stages?

I had a switch added to my Blue Sky controller that allows me to flip one of the dip switches without pulling the case apart. I'll sometimes use that setting late or early in the day to get the voltage up.

Your system is working ok--but I think you might garner another 10 to 15 amps by changing to a better quality MPPT controller. I'd suggest a single 80 amp unit be used.

The Magnum PT-100 has some quirks. To get to the 100 amp rating, input voltage may need to be 72 volts or higher.

Thanks so much Yes, the manual is here: http://nebula.wsimg.com/cb072ae482f8e0e9544e6469c9ae5b70?AccessKeyId=F8EC79241F00CCD2742B&disposition=0&alloworigin=1

and the answer to your question is, from the manual:

Flooded
bulk - no amount shown; 14.4Vdc
absorb - 2 hours; 14.4Vdc
float - none shown; 13.7Vdc
equalization voltage @ 29 days; 2 hours; 14.9Vdc

VRLA
bulk - 2 hours; 14.00Vdc
absorb - no amount shown; 14.0Vdc
float - no amount shown; 13.7Vdc
Note: No equalization is defaulted to in this VRLA profile. Manual says the dip switch for flooded profile may be manually thrown to equalize for 2 hours, then it resumes float in VRLA profile mode.

I'm a finance/ economics guy, so I've had lots of math and I get this stuff pretty much, when I focus on it, but I just don't consider it a hobby, so I forget the technical stuff rapidly. I recall in January 2016 being frustrated trying to size the controller, because folks selling equipment would not be strait forward, in my opinion, which may have been wrong.

My system was installed April 2016, but I'm really only getting around to using it in the last few months.

I wanted redundant capacity to add 2 more 160 watt panels, which would take me from 960 watts now to 1,280 watts. I bought AM Solar's tiltable panel brackes also, but have never tilted. Anyway, I was looking at the Outback FM80-150VDC MPPT, the Magnum (which I figured might make sense since I got the Magnum 3012 hybrid inverter/charger, but was brand new and unproven), the MidNite Solar Classic Lite 150 MPPT Charge Controller, which I think has been discontinued, and pairing 2 Morningstar TS-MPPT-60. I suspect going back to the market today will yield better alternatives.

At 8 panels, that 18.5 x 8 = 148Vdc at max from both 4 panel arrays into the controller or controllers, and 69.2 amps per the PV panel labels at 8.65 per. I'm wired from the roof in (2) 3 panel serial arrays now, so I'd planned to add 1 panel, if needed, to each array. Splitting the panels made sense in case I get shade, bird poop or whatever, plus to have redundancy. When these BZ 50 amp controllers were offered to me, the 100amps looked good so I punted because I was out of time due to family matters.

Because MPPT's require high voltage, I do not know if it's better to run a single controller near it's max capacity, or get two controllers running at lower capacity. I say this from a safety perspective, because I don't like putting avoidable stress on equipment.

If I bag these BZ controllers this winter, do you have an opinion of how to configure the panel inputs and what controller(s) make sense?

If I use a single 80 amp, buy some calcualtions, 960watts/12 is 80amps, would the single 80 amp controller be at it's max with no room to grow? Even ignoring the consideration to add 2 more panels, is operating at max ok? What I don't know is the efficiency loss parameters, which would reduce the load on the controller.

"On a positive note, I do hook up to shore power and/or run my generator enough, so I'm sure my battery bank is getting to full charge regularly."

Unless you have an AH counter and an hydrometer I would not be so confident you are getting those batts fully charged.

"But ****, 14.00 is so much lower than the batt manufacturer's 14.7 requirement! "

Also the higher voltage could get them recharged faster by increasing their amps acceptance rate if the charger can do that many. Can get more done in the same length of daylight.

"The system does product more power than I'm using in my first couple months of operating, not counting the absorption refer on AC. I seem to burn about 175AHish a day or so and haven't needed to run my Honda 2000, except a couple 3-4 day rain events"

I have not done a detailed calculation (your job) but I doubt you can restore 175AH during daylight with only a 55amp charger. Just not enough time in the day. Most folks in that situation have to run their gens and use high amp chargers for an hour or two in the morning before they can leave the rest to solar, and hope to get to full before dark.

Perhaps look at reducing the size of that battery bank. Do more of the 175AH recharge at a lower SOC range where battery will accept higher amps. Right now those 175AH are coming from the slow to recharge top end of the SOC range.

outboundwest,

I would change to the flooded settings. Do you know how long the BZ will stay at the various stages?

I had a switch added to my Blue Sky controller that allows me to flip one of the dip switches without pulling the case apart. I'll sometimes use that setting late or early in the day to get the voltage up.

Your system is working ok--but I think you might garner another 10 to 15 amps by changing to a better quality MPPT controller. I'd suggest a single 80 amp unit be used.

The Magnum PT-100 has some quirks. To get to the 100 amp rating, input voltage may need to be 72 volts or higher.

BFL13 wrote:

Darn, the factory has the furnace running off the battery, not from the solar controller. But I only use the furnace at night. I can't figure out what to do! I think my brain is wired wrong.

don't tell us they wired it for watts instead of ahs :B