Charging

wellbuilt · March 2019

I have a question for the board .

I’ve been charging with my inverter /charger since the sun vanished in November

i use a Honda 2800 watt inverter generator and a out back 3600 48volt FP1 system .

Generator output is 2100 watts the charger takes 2000 watts in , seams a little low to me .

i use about 25% of a 430 ah battery in 3 days.

‘My absorb is set to 59.2v but as I’m nearing full 94% I’m seeing 62 .1 volts and delivering 900 watts or so .

The battery’s are cold 35 o F the tempcompensation is on ?

The temp sender is plugged to the inverter .

I’ve been getting some good sun and noticed the fm80 CC stays around 59.2 and under 60volts at all times .

MyCC puts out 3000 watts in good sun at noon then tapers off . Down to300 watts before it go’s to float .

It dosent seam to share the temperature compensation information from the inverter through mate into the charger controller.

I’m seeing 27 amp at 62 + volts at times thru the inverter charger .

I may of missed a setting when I set the system up .

My SG seams to stay between 12.265 low battery to 12.275 + hi battery

I’ll admit I’m not to good with the hydrometer yet

i use a hydra volt .

My CC. Charges the bank down to 300watts with 2hrs of absorb time then gos to float .

the inverter charger will hit 100 % full on the battery Monitor at 500 /600watts going in the battery and I turn it off .

The absorb time is set for 2 hrs on both chargers but I just charge to 500/ 600 watts with the inverter charger we are usually waiting to go home .

Is the 62 volts to high at 35o f when charging both chargers read about the same # my volt meter also runs about the same voltage and the batteries are cold to the touch and I’m not using any water after 12 charging sessions

Im Due to check The sg and eq if necessary . Any idea what going on here

Thanks so much John

Estragon · March 2019

62.1v seems a bit high for 35°f, but not unreasonably so. Under 60v sounds low. Mine would be ~61.5v at that temp.

My mate seems to not be any more accurate than ~100w, so I wouldn't read much into the generator vs mate current reading.

1.265 - 1.275 sounds ok to me, as long as that's consistent over time. If it used to be 1.30 and is dropping over time though, I'd be concerned.

IMHO, having the inverter temp compensation wouldn't mean much to me, as I rarely do a full absorb with the genny anyway. I'd probably hook it up to the CC (assuming the RTS is compatible on both) instead, as I'd want to get proper absorb via solar. I think 2hrs might be a bit short on my bank. It takes me closer to 3hrs to get to ~1.5% of capacity. I'm not sure offhand if temp sensor data is shared via the mate. I have separate sensors for OB inverter and midnite and morningstar CCs.

A 430ah bank will likely be more like 330ah in the cold. 1.5% x 330 = ~5a end amps or ~250w

wellbuilt · March 2019

Hi estragon ,

in my out back quick start guide it tells me to run the the sender to the inverter ? So I did .

I do get some sun in January but my panels are covered with snow .

‘It takes 2/3 days to clean off the snow , my top 9 panels get clean pretty fast but I don’t really want to leave the system on if I’m not there , in the summer it stays on and I dropped the absorb time because it sits for 5bdays to 2 weeks with out a load .

I’m not sure how to handle this ..

So I’ve been running the generator .

It should be getting warmer over the next few weeks thanks john

Estragon · March 2019

Yeah, I usually end up using the generator a lot in winter too. Most of the year solar keeps me between 75% and near full. In fall/winter, it's more like 60% to ~90% using the genny. If need be, I use an eu2000i in eco to get an absorb in every week or two.

IMHO, your fm should be set so end-amps ends absorb at ~ 5-8a, and the absorb timer set for longer (maybe 3-4hrs). That way, if a long absorb isn't needed (eg idle system), end-amps will make it go to float. If a longer absorb is needed though, the longer timer will let it happen. You want the bank to gas and bubble a bit every couple weeks or so to mix the acid.

In summer, if you want to prevent unwanted absorbs when idle, I'd be inclined to just set absorb voltage down to near float while away. I set "skip days" on my classics, which does much the same thing.

wellbuilt · March 2019

i think I understand , so 5 amps would be 5x 60 volts 300 watts .

I’m not sure if the CC has amps on the main screen , it probably set in amps in the mate .

Would it be better to just turn the system off when in not there ? Nothing to worry about .

Or do the battery’s benefit from float charge.

My battery’s stay at 65 o all summer.

I’m there most every weekend with a rare 3 week stretch .

Vic · March 2019

wellbuilt,

Your FM80 will show the CC output current. The FNDC should have a shunt to measure the current into/out of the battery.

Cold batteries have considerably lower self-discharge current than do warm ones.

Constant Floating deep-cycle Flooded LA batteries may not be the best thing to do.

Am not in the cold North, some folks turn off the entire system. Others turn off the inverter and all other DC loads on the system, have at least a few PVs facing South, which are perfectly vertical, to better shed snow and ice, and let the CC charge at some nominally low voltage. Others only have the CC run an Auto EQ, at a fairly low voltage every week, or few weeks.

Estragon is a much better person to advise on hibernating a solar power system, than am I.

FWIW, Good Luck, Vic

Estragon · March 2019

In winter, turned off completely (with bank fully charged) is probably best. Like vic said, self discharge is really low when cold.

In summer, with the bank at ~65°f, turned off might still be best if only left for a couple weeks, but floating doesn't hurt IMHO. The bank shouldn't gas much on float, and shouldn't sulfate much if the acid stratifies a bit.

I think the end-amps setting should be in amps. The mate display is watts or kw, but IIRC the setting should be amps.

wellbuilt · March 2019

I guess thefm80 dose read in watts and amps I just looked at a pic I had in my phone.

It would be nice to leave my frig on in the summer sowe can leave some food from week to week .

And have cold beer at all times . I don’t even use the frig on trips in the winter I have plenty of cold and ice for drinks and food.

This time of year .

We have a month to go and it should warm up .

Charging

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