New batteries finally

halfcrazy

Well i decided to make a move on my offgrid system and upgrade a few things will be trying the new 48 volt magnum with split voltage 120/240 and in the process will be redoing my battery bank i just ordered 16 trojan l16p batteries.

So i should have somewhere around 780 AH @ the 20 hr rate so coupled with the 12 sq 165 panels i have now i may fall a little short on input but we dont use a lot and the 10 panels that are there now keep the batteries full now so time will tell.

was suprised trojans l16's have a 7 yr warranty 2 years free replacement and 5 pro rated?

will upload a few pictures once the inverter and batteries get here

System2

Re: New batteries finally

Hey halfcrazy,

where did you buy your batteries from? Where do you store them?

TIA,

Lito

halfcrazy

Re: New batteries finally

i purchased the trojans from a local battery warehouse and we have a insulated vented battery box in our mud room to house them

crewzer

Re: New batteries finally

½,

Looks like you’re building a “48 V / 48 V” system with your MX60. The 165’s STC Voc is 44.5 V, so you’ll have to keep ‘em configured as two-per-series to avoid high Voc problems with the MX60 in the winter.

The STC Vmp of two 165’s in series is 70 V. Allowing for voltage drop from summer heat, wiring, and the MX60, I estimate summer operating voltage to be around 61 V. Is that what you see this time of year?

http://www.scsolar.com/PDF_Files/Shell-SQ165-PC-SQ175-PC.pdf

Trojan’s 48 V specs are 59.2 V for absorb stage, and 62 V for EQ stage.

http://www.trojanbattery.com/Tech-Support/BatteryMaintenance/Charging.aspx

Morningstar recommends an absorb voltage of 15 V (60 V for a 48 V configutation) for L-16 batteries.

http://www.morningstarcorp.com/products/TriStar/info/TS_Manual.pdf

I estimate you’ll see maximum sustained summer mid-day MPPT charge current of ~29 A into the new 48 V battery bank. That’s about 3.8% of 780 Ah, so you may want to consider shifting discretionary loads from the morning (controller in MPPT mode) to the afternoon (controller in absorb mode or float modes).

I’m a little nervous about all of this… I hope you keep us posted on performance!

Best of luck,
Jim /crewzer

halfcrazy

Re: New batteries finally

Well with the 10 panels now we routinly see 29-30 amps so with 2 more i hope to be around 35amps and i may add 2 more to get towards 40 amps.

Today it is about 80-83 deg F and we are seeing 78 volts on the input side of the mx so we will hope for the best while we wait for the classic

as for the wiring you are correct right now it will be 48 in 48 out but that will change when we et the high voltage classic i will be able to go 3 or maybe 4 panels in series. so that will help also.

the size of the bank may be a little large but on a good note we routinely see 2-3 hours of float this time of year with just 10 panels and i do have 2 more in the shop to install. and the 3ish months in the winter it wouldnt matter as the days are so short just have to crank the generator and fill them once a week.

crewzer

Re: New batteries finally

Well with the 10 panels now we routinly see 29-30 amps so with 2 more i hope to be around 35amps and i may add 2 more to get towards 40 amps.

Isn't that into your present 24 V battery bank?

Yeah, the Classic may solve any voltage mis-match problem. Is that 78 V input voltage with your MX in MPPT mode or absorb mode? (I suspect the latter...)

Thx,
Jim / crewzer

halfcrazy

Re: New batteries finally

well i halved the amps as my bank now is 24 volt and we see right at 60 amps on the outgoing side of the mx and the 78 volts was in mppt but thats with the mx charging 24 volt batterys so not shure if that will change anything?

Seems if i can make it to the 5% area or right around 40 amps input i should be ok i think we only have the refrigerator and the freezer hat really run whenever needed other then that no real daytime loads.

crewzer

Re: New batteries finally

WOW!! That's extraordinary performance! 60 A at ~28 V into a 24 V battery bank is 1,680 W net from a 1,785 W STC array. That's 94% effective efficiency -- that's terrific! However, 78 V out during the summer from an array rated at 70 Vmp STC has me corn-fuzed...

Enjoy!!
Jim / crewzer

halfcrazy

Re: New batteries finally

My mistake that should say 68 volts not 78. we will keep a close eye on it it just seems like our current battery bank doesnt take us very far in the winter when the circulators are going so i thought we should try to upgrade the size? time will tell and i may have to buy 2 or maybe even 4 more panels we will see?

crewzer

Re: New batteries finally

68 V in the summer from an array rated at 70 Vmp STC is still awfully good... enjoy!

Jim / crewzer

westbranch

Re: New batteries finally

HalfC, what are the circulators?
Eric

halfcrazy

Re: New batteries finally

they are the grundfos equivelent of the taco 007 standard ac powered circulators and i have 2 that run in the winter