48 volt battery recomendation

[jonathon w]

I have a trailer with 9 295w panels to 48 volts. to start I have 4 interstate group 29. due to that I sell interstate car batteries. but would like to no what would be the best rout to go.
i am looking for 9 to 12k wh if poss with out adding a 1000 lb to the trailer.
Thank you JOHN.

[jflorey2]

i am looking for 9 to 12k wh if poss with out adding a 1000 lb to the trailer.

Going to be very hard to do with lead acid. With surplus EV li-ion batteries you could get 12kwhr for about 200 lbs, but you'd need to do your own BMS. You could go the SimpliPhi route (LiFePO4) and then 12kwhr would weigh about 300 lbs - and it comes with a BMS built in so it would be almost a drop in replacement for lead acid. Of course, it's also going to cost you $15K.

[jonathon w]

what I was hoping to do is run a 1500 watt a/c for 3 to 4 hours at night with out using the generator so my math is probably off. I do not no if it is doable or not. what do you recomend.

[Sunking]

what I was hoping to do is run a 1500 watt a/c for 3 to 4 hours at night with out using the generator so my math is probably off. I do not no if it is doable or not. what do you recomend.

Not doable. Last thing you would use is car batteries or anything Interstate sells. Interstate does not make batteries. To have 6 Kwh usable in a Pb battery is going to require at least a 18 to 24 Kwh reserve capacity and at 48 volts is 400 to 450 AH and is going to weigh in at 1100 to 1300 pounds at a cost $$2500 to $3500 for something like Trojan L16H 6-Volt 420 AH battery

As Jflorey mentioned to get under 1000 pounds would require a LFP battery and that could be sized down to 15 to 20 Kwh capacity, that would get you down to 300 pounds but you will pay up over $10,000 and they will not last as long as a good Trojan and can be destroyed with one over discharge. You are well beyond off-grid limitations.

[jflorey2]

what I was hoping to do is run a 1500 watt a/c for 3 to 4 hours at night with out using the generator so my math is probably off.

1) Your A/C is probably not 1500 watts. That sounds like the nameplate rating, not the actual power. Did you measure it?
2) A generator is ALWAYS cheaper. If you don't like the noise, get a 2000 watt inverter generator and put it 20 feet away behind a berm or something.
3) If you still don't like running a generator at night, consider a system that allows you to run for a few hours without the generator. That requires a much smaller battery bank and lets you run more silently. (Of course the A/C still makes a lot of noise.)

For 48 volts, 8 T105's is going to be your best bet, which gives you 10kwhr (so 5 kwhr usable) for 500 lbs. It will support a load like that for a few hours. You should probably also invest in a 12V to 48V converter so you can charge while driving.

[jonathon w]

thank you for the replies I do have a 6k 48 volt inverter/charger with auto gen start. when I tested the a/c it is pulling 1560 to 1750 depending on temp. so I think the 8 t105 is my best bet.can I still use the interstate as well since I have them

[jonathon w]

interstate has a 6 volt cart battery gc2-ecl-s with the same specs as the t105 and a 2300s that is a bit higher. do you now anything about them. thank you John

[Sunking]

You can get away with the T-105's but hammering them everyday with 70% DOD, do not expect them to last more than a year.

[jonathon w]

thank you for the replies I well put the t-105s in for the solar panels and use the gen at night so I do not damage the batteries. well 8 t105 be good for the 9 295w panels that I have. I saw on another post that you have to have a certain # of amp hours for the amount of panel watts. I have a 60 amp 48 volt mppt controler to 6k inverter/charger with a peak of 18k for 20 sec. and should I run strait off the gen at night or use it to power the pure sin inverter.

[jflorey2]

thank you for the replies I well put the t-105s in for the solar panels and use the gen at night so I do not damage the batteries. well 8 t105 be good for the 9 295w panels that I have. I saw on another post that you have to have a certain # of amp hours for the amount of panel watts.

Normally you want to charge at between C/8 and C/13 for batteries in a standalone solar system. So for your system you'd want between 28 and 17 amps, which at 54 volts is 1200-1900 watts of panels. So if you want to keep your current 2600 watt array you'd have to current limit to 28 amps. Most MPPT controllers will do this. (You really want to limit _charge_ current not total current, but most MPPT controllers do not provide a way to differentiate the two.)

Note that this system is not going to be really charged via solar much; most of the energy will come from the generator. In such cases you don't have to worry about going under 17 amps since the solar will not be relied on to provide a full charge.

I have a 60 amp 48 volt mppt controler to 6k inverter/charger with a peak of 18k for 20 sec. and should I run strait off the gen at night or use it to power the pure sin inverter.

The "right" way to do it is with a good inverter/charger - it will manage charging loads and generator input so that the generator is not overloaded and as much power comes from the genny as possible. In your case you are probably best off running the A/C directly off the gen, then turning on the charger once the starting surge has passed.

[jonathon w]

thank you for that I well limit the controler. I did not no where to set it at so I left it on the factory settings. now I can set it at the proper charge amps. the controler is set for 58 volt and the floats at 56 volts is the float to high for 48 volt system.

[Sunking]

thank you for that I well limit the controler. I did not no where to set it at so I left it on the factory settings. now I can set it at the proper charge amps. the controler is set for 58 volt and the floats at 56 volts is the float to high for 48 volt system.

Too high. Trojan T-105 configured for 48 volts Float = 54 volts

[jonathon w]

I though it might be I can set it man. so 54 it well be.
Thank you john

[Matrix]

(You really want to limit _charge_ current not total current, but most MPPT controllers do not provide a way to differentiate the two.)

I was just having this discussion the other day in another post. FWIW MidNite Classics equipped with a Whiz-Bang Jr can do it ...

[jonathon w]

thank you for the link