Looking for temperature and charge specifications

9 hours ago, Weldman said:

Read your manual, all threads watched all YouTube videos on the Genetry Solar 6K LF and I don't see what the rated DC amperage is for battery charging, I seen the 60% factor but that's it, what's the numbers? I see it's auto temperature limited but what are it's best results at what temperatures?

Also missing working ambient temperatures, it can get little nippy here (-40F) and little warm (115F) and I need to know those if possible so I can be prepared for those days when it gets out of it's parameters on functionality.

Some very good questions there.

Ambient working temps: the 115F should be OK (though likely a bit warm for full load operation).  -40F is the one I honestly have no idea about, other than to say, "that's real cold 😉." 

As far as the parts internal to the inverter, I have not charted all of the minimum temperatures on all the datasheets.  I know from personal experience that down near 0F, the LCD will update very slowly (~1sec to change)...at -40F it would almost certainly be useless simply due to the "liquid" crystal technology.  (LCD specification minimum temperature is -20 for operation, and -30 for storage.)  Quick check of the CPU datasheet shows an absolute minimum operation temp of -40F (as do all of the other chips I've glanced at datasheets for).  Likely, the main battery filter electrolytic caps will be more an issue--and unfortunately I don't have datasheets on those.

Whoops--the main relay driver chips are specced at a minimum operating temp of -13F (-25C).  Not sure if this is a characterized specification or not, but...!

If you buy a GS inverter and subject it to said temperatures, I will be very curious to be kept up to date on how it behaves in such conditions.  I'm in Ohio: we say it's real cold when it dips below 0F for a night or 2 in January 😉.

I would think that your batteries would be more of the temperature limit--as according to this cart, a lead-acid battery at 60% charge will freeze solid at -22F.  https://modernsurvivalblog.com/alternative-energy/lead-acid-batteries-state-of-charge-versus-freezing-temperature/

If you're using lithium-based batteries instead, you probably know that they really don't like to run below freezing (definitely don't charge them below freezing).  With this in mind, I would say that if your batteries are kept in their ideal temperature range, and the inverter is in the same environment...you'll be just fine.

As far as battery charging: you ask a lot of very pertinent and necessary questions.  The problem is...I have enough solar that my generator is still BNIB...and Sean switches back to grid if the batteries are low--so neither of us are using the charge function!

Due to the (frankly) low efficiency...I would think the charge current limit would be more of an AC input current limit--at least for me it is, as with 120v charge, 15A comes up pretty quick.  Unfortunately, I haven't been able to run sustained charge loads on a GS inverter to watch internal temps (for determining max charge current); the "auto temperature limit" means that the inverter will linearly throttle back if the internal temps are getting near the alarm thresholds (instead of abruptly shutting down).

To the best of my knowledge, all other LF inverters also will have a similarly low charge efficiency--just they don't publicize it.  However, I do plan in the near future (so much to do though!) to rewrite the charge function to a more PFC-style methodology--which hopefully will bump the charge efficiency at least into the mid 70s.  It also likely will increase max charge output--but how much, I don't know.

P.S. Here's the AC amperage waveform on the present charge implementation...yeah, that needs corrected to a PFC-style waveform 😉

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Maybe I should ask this: what kind of charge currents are you looking for / need?

Last winter I ran (8) golf cart batteries at those temperatures of -40F and windchill of -60 the Aim's 6KW inverter kept up no problem though came summer and due to using high loads more than panels could replenish I ran the Aims at 115F to charge the batteries and it cut off on me till I put a room size fan on it to cool off. With current set up I am pushing 440 AH @24V but new set up will be 2010 AH @36V (18-85-31 forklift battery) if I can find good enough buck converters, (if not I can kick it down to 24V) that way I won't need another CC and can have 3 to 4KW worth of solar. Which with those numbers I'm running FLA which means I need around 100 amps at minimum to equalize. This will be for a pole barn workshop which shares same power as my RV temporary.

All the LCD's went dead at those cold temperatures, Midnite Classic 150 and the Renogy battery monitor, was relying on freezer to tell me the voltage which I could translate to how low it was. Plastic becomes brittle along with few other things at those temperatures, I think we broke some records too. We have hit 10 degrees so far since this fall began, I foresee a brutal winter with La Nina in effect.

I do have the Aims 6kw I mentioned but that is for the RV and I want to keep it there so it's why I either will run with 36V inverter or 24V inverter and I will put it through it's paces besides temperatures, maybe even fry it when I weld with it...

10 hours ago, Weldman said:

if I can find good enough buck converters,

Are these step-downs for running 12v appliances?

11 hours ago, Weldman said:

Which with those numbers I'm running FLA which means I need around 100 amps at minimum to equalize.

Oooookkkkkk then.  That's a few amps 😉.  I've only got 2 large car batteries under the bench for testing, which is kinda not quite enough to test that scenario.

At 36v, a 6kw GS will run roughly 180A at full load discharge, so it should technically be possible to run 100A charge (though not tested/confirmed).  FETs will definitely dissipate more heat in charge mode than in inverter mode...but as they dissipate so little in inverter mode, it should be technically feasible.  This will have to be tested, obviously.

11 hours ago, Weldman said:

All the LCD's went dead at those cold temperatures, Midnite Classic 150 and the Renogy battery monitor, was relying on freezer to tell me the voltage which I could translate to how low it was.

Betcha you kept your cellphone warm; the GS inverter has a local server where you can pull up the inverter stats on your phone via WiFi network.  Can pretty much guarantee you that the GS LCD will also be completely unusable at those temps.

Though if I used an OLED screen...while considerably more costly, they aren't temp limited like an LCD screen...

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...though honestly this is a very fringe usecase.

11 hours ago, Weldman said:

and I will put it through it's paces besides temperatures, maybe even fry it when I weld with it...

Hope not 😉.  The GS 6kw should be quite robust due to mathematical limitations (i.e. deadshort transformer current is lower than the absolute maximum peak FET current)...I don't believe we've ever had inverter failure due to overloading.  Backfeeding AC mains into the output, yes (at least twice!)  Most common failure point on the A.1 / B boards actually has been the main power IC--which on the Rev. C boards has triple protection as a result!  (All inverters shipping now use the Rev. C board.)

Let's put it this way: if an Aims can do it, a GS should be able to do it better 😉.  If it can be done in software, I can always provide a firmware update to accomplish the needed function--though that in itself might be a bit of a challenge for you if you don't have an Internet-connected WiFi network..........

Yes and no, the fans are 12V which already has a 24V to 12V step down the diesel heater, lights, and freezer are 24V so won't be that much loss if I stepped it down. If it can send 180 amps on charging then the battery will definitely take that and then some more up to 200 amps 2010 AH @ .1C = 200A. This battery weighed in at 3780 lbs when I got it, poor backhoe had fun moving it to finally resting spot.

I'm sure it can do better than a Aims, just got lucky and found it on FleaBay half it's price cause it was dropped and bent the case. Won't be buying a GS right away, will be a month or two I have a project of building a pole barn myself from grain bin metal and I need to buy some supplies to secure a few things.

Hopefully that'll give me time to get a software PFC charge implemented, raise the efficiency, and hope it can run at least 100A @ 36v inverter mode.

Not sure what step down converters you're using, but I've been quite happy with the Chinese metal case sealed step-down converters.  ( https://www.ebay.com/itm/372890495513 for example).  I'm running a 16S ("48v") LFP bank...and am using the "60v" (38-75v) step-down converters for 12v and 24v outputs.  (Most "DC" loads are either 48v lighting--my LED driver design--or 12v "car charger" appliances.  The only 24v things I have are 2 DC water pumps.)

For 36v, you could safely use the "48v" (24-60v) step-down converters.  My concern about using said "48v" converters on a 48v system...is because I know how much China likes to push the limits of part ratings.  A converter rated for a maximum of 60v will often use 60v FETs--which work fine unless there's a surge on a 48v system running @ 56v when fully charged (like flipping the breaker connected to your inverter.  Been there, done THAT!)

I've been using those metal case bucks for a while too and so far none of them has failed but I still have a crowbar on the output just in case.  Avoid the black plastic rectangular ones, pretty much guaranteed to fail, even if you only ever put a light load on them, and kill what ever is connected to them.

Ha, so do I 😉.  TO-220 TRIAC across the DC input (to trip the breaker) and a zener diode/resistor to the TRIAC gate so it'll trip if the output voltage goes too high.

Never had one trip, but I can't quite trust the Chinese converters...

...though the one running our laptops DOESN'T have a crowbar circuit, I'm slacking 😉

Been there, done that.  Nice and cheap, "10A output current."  Well, the internal transformer/inductor (looks like the former, is used as the latter) will start to ooze molten goo at around 6A; at 8A, the output voltage drops to 8v, and much beyond that it cut out.  Started out with 'em because they were cheap, soon learned they were junk.

Don't have any converters as of yet I have been shopping for them and the one that stands out the best I've seen is RSD-300E-24 and hopefully don't need any crowbar circuits. My RV is 24V so I could put more solar panels up, more efficient, can power more up and the rig itself is 24V system. I will disconnect 6 of the cells on the 36V battery and just reconnect them when I get a inverter and converters to handle the voltage. Best one I found in the Chinese version is 36V to 24V 15A. if I go that route.

49 minutes ago, Weldman said:

I have been shopping for them and the one that stands out the best I've seen is RSD-300E-24 and hopefully don't need any crowbar circuits.

Being electrically isolated, I will expect that they will have a very significant no-load draw (casual glance through the datasheet did not see this specified...but I know a 3kw 48v MeanWell TS-3000 HF inverter ran 1.0A no load.)  For a small solar system, these quiescent losses add up really quickly.

The Chinese converters run roughly 15mA no load.  That's quite good IMO...but they also are not isolated.  Haven't had any issues with one--and I even got the leads mixed up one, forcing 55vDC from my battery into the 12v output leads for a dozen seconds or so until I realized my mistake.  Heard a little "bubbling" from inside (likely a 25v output cap), but the converter after wired correctly still works perfectly 4 years later.  Regularly sees 60-80% load, too.

Here is reason I am going to 36V, rather 48V but couldn't pass up a $1500 5 year old 2010 AH forklift battery. With another CC I can put all my bi-facial panels up and a battery to take the load.

Chinese converter it is then! Rather like the Chinese numbers cause I can put multiple in to handle the load than loading up one with the whole load, same reason I don't like all in one units, one goes down all goes down.

I did a quick experiment last night with charging.  I had an input voltage of 249vac and my battery bank was just under 60v with the bulk charge set to 64v. At 25% inverter setting I was putting in 9 amps DC and was 54% efficient.  At 50% I was at 69% efficiency.  Both 75% and 100% charge rate dropped to 64% efficient.  I would be curious to try this again with a lower battery voltage as I was only putting in 37amps dc at 100%

I will be very interested to see how these numbers change when I get PFC charge implemented via firmware update.

I wouldn't be surprised if adjusting the FET frequency would also adjust/improve efficiency--but that is extremely difficult to do in the firmware.