Hi Jallum,
Yes, I am concerned! The offgrid system is CO, so it gets rather cold in the winter. I have the BMS set for trip at -2DegC and I have placed copious amount of insolation around the battery . For next winter I do need to think how to have this system heated, any thoughts?
For temperature monitoring I'm thinking of using the Sonoff Temperature sensor (Link below) This allows for wifi monitoring from anywhere, operates on 110V and and can take up to 15amps. I have a similar set up in battery box for my remote gate, and as along as there is 2.4 GHz wifi available it seems to monitor quite well.
Just out of curiosity, what size wiring are you using? I'm using 2AWG for the series connections to each battery module, with the plan of parallel x4 14S batteries to heavy duty bus bars (can just be seen in the stacked battery pic) and from the bus bar to the main breaker (300amp) I'm using 4/0.
I’ve got a similar setup that needs float, absorption, and equalization settings. What voltage settings did you end up using in your charger and are they working well?For temperature monitoring I'm thinking of using the Sonoff Temperature sensor (Link below) This allows for wifi monitoring from anywhere, operates on 110V and and can take up to 15amps. I have a similar set up in battery box for my remote gate, and as along as there is 2.4 GHz wifi available it seems to monitor quite well.
Just out of curiosity, what size wiring are you using? I'm using 2AWG for the series connections to each battery module, with the plan of parallel x4 14S batteries to heavy duty bus bars (can just be seen in the stacked battery pic) and from the bus bar to the main breaker (300amp) I'm using 4/0.
Any how, recently I set at these to 50amps charging for each inverter, and increased the bulk voltage to 58V and 56V float. I'm getting so much more out these, I'm still in experiential mode but the previous setting didn't get me much more than 15KW. On what should be a 54KW system, I now belive I'm much closer to the 54KW, but I'll have to wait for my next trip test.I have mine set up with x2 5KW offgrid Growatt inverters in my vacation home. I initially had them set at 55bulk and 52 float but this didn't give me good results, and one time I had to travel 1k miles to reset the system. I tried to automate as much as possible but I thought a low voltage reset would be automatic on the growatt but it isn't. Next trip I'll be installing a ups and a wifi reset.
Good to hear. I’m also babying my batteries because my tiny solar array will only send about 22 amps into the battery at peak and I’ve limited my charging from grid to a similar 20A.I have three of the six batteries online at the moment. Because the house loads are more "gentle" than their previous jobs, the batteries are doing much better than expected.
Things I have learned:
- When I bought them, they were being sold as ~2.2kwh, per unit. I'm seeing about 2.6kwh per due to the more gentle cycling they're receiving. The three packs are totalling ~62kwh (3x 16S) and I was only expecting ~50kwh.
- Cold weather hasn't been a problem with the NMC chemistry, at all. I regularly charge/discharge them at -10° to 0°F without issue. The large capacity of the batteries means that the batteries never see more than ~0.12C when charging. (I'm using a gas generator, once a week to charge them @ ~8kw because my solar is not up and running yet.) Bringing the other three online will halve the charging amps each battery sees.
- My Daly BMS's SoC estimation is junk. Each of the three units will report wildly different values, even with regular synchronisation.
Things I would do differently:
- I wouldn't use one large, central inverter. I'd use one less battery-cell per box and I'd put a Multiplus II in each. This would make each box a potential standalone unit, and I could save money on interconnection cable by being able to run thosenat 240v AC instead of 60v DC. As a bonus, the waste heat from the inverter would warm the batteries in the winter. The primary downside would be that it'd be a bit more expensive to start.
1k miles for a reset is brutal. How did you get so low that you tripped on low voltage? No alarms or alerts configured?Hi Jallum,
I have all 4 modules up and running now, that's 28 units in x4 14s configuration. I wasn't pushing them hard at all at first, but after a low voltage trip and a 1,000 Mile trip to reset them, I increased the voltage setting from 56V to 58V (4.14V per cell) max and float at 56V. Now they perform a lot better, I'm still not sure of the KW from each unit but they were advertised at 2KW each, which would be 54KW I'm definitely getting 30-35KW which is more than enough at the moment.
It's very encouraging to hear about your temperature use. I keep mine heated above 32F, I use around 800Watts on really cold days (single digits). One day when I get time I will put them through their paces and report back.