TOU low rates can save a ton of money
What’s your daily SOC range?
- Thread starter Skypower
- Start date
TOU low rates can save a ton of money
ksmithaz1
Solar / EV Junkie
I should probably knock on wood, but I don't think my power has been out more than 5-10 times in the 12 odd years I've lived here. Never longer than an hour. I'm playing around here so I know what it might take/cost me if I move off grid when I retire.
Keep in mind, If the air is warmer than the batteries it doesn’t help to use a fan. It can make it worse.
That’s exactly what I’m doing. Find out what works while I’ve got grid to fall back on. My ideal retirement spread is land, water, sky and few people with probably no grid or too expensive to have it brought in.
ksmithaz1
Solar / EV Junkie
That would assume of course they somehow got cooler than ambient. Without the fan in the room ambient is +5. My new plan is to vent the room with an attic style fan, just suck it off the ceiling and out.
EastTexCowboy
Solar Wizard
That's pretty warm, yep. I had a fan blowing on my inverters this spring before I got the mini split installed and it helped a LOT. The batteries weren't heating up then so that part didn't matter. The heat index is supposed to be pushing 120 here for the next several days. I try to stay out of the worst of it but sometimes things happen and you just gotta suck it up.
Do cool the room with fresh air however keep the batteries low and if possible with no breeze on them unless they are hotter than ambient room temperature. It’s amazing how much cooler things are near the floor than at waist level. A mini split would be ideal but not practical for every location.
Projected to be 111 degrees here this weekend(always hotter in my neighborhood)
Hot air sucks;
I do the same at night and with a small 3 watt fan and good insulation for the batt compartment I can get all the batts cooled down to about 60 / 65 F by morn… after about 9-10 am I’m running with no fan on batts all day Untill dark then I repeat…they slowly rise to about 75 to 82 by end of the afternoon then start cooling again after dark. Get em cool at night and they pretty much coast all day staying coolish Even when working pretty good.
I am assuming a high of about 80F and low of about 60 ambient we had this week,and that’s pretty warm for here… There is no A/C where the system is located ..
With A small 3 watt fan blowing up thru the SCC heat sinks (Vic 150/100) I can keep it about 90F max during midday heat when running strong..( about 5 to 10F above ambient) .it’s happy at 90F
But, the multiplus is a challenge without cool weather or A/C ..that rascal wants to get warm..I mounted a seperate high speed fan (25 watts) 2 days ago running 6 -7 hours a day and can keep it down to about 87to 92F at 75% output…it was running 105 to 115F before fan installation.
It is much happier now with a stout breeze aimed in the right areas.
The fans definitely help the whole system run cooler and work better…much better..
this is my first summer with the system running… it take a bit of tweaking to find the best way to manage its health and operation..but it’s coming right along .
J.
Having LiFePO4 sit at high states of charge isn't really the problem. Keeping them at a high voltage is. As long as your float setting is turned off or set at 3.375V per cell or something - which allows the cell to settle - you should be fine. I'm at 100% on a daily basis in summer, and don't drop below 90% most days.
Have you considered liquid cooling? At those temperatures you would benefit from cooling the batteries.One thing to remember when having concerns about elevated SoC and LFP... temperature plays a huge role:
Insights for understanding multiscale degradation of LiFePO4 cathodes
Lithium-ion batteries (LIBs) based on olivine LiFePO4 (LFP) offer long cycle/calendar life and good safety, making them one of the dominant batteries …www.sciencedirect.com
I have a 40°C alarm set for my batteries - It's triggering daily now. I only charge the NMC to 75% anyway, but I've lowered it to about 65% now since DoD while we're away is only about 9%.
OffGridForGood
Catch, make or grow everything you can.
Ambient 60-F last night, 75-F will be the high today,
The shop is metal building well insulated, doesn't heat up even in hot sunny day with metal roofing and solar above that.
Typical interior temp 24/7 72 degrees F without A/C.
The shop is metal building well insulated, doesn't heat up even in hot sunny day with metal roofing and solar above that.
Typical interior temp 24/7 72 degrees F without A/C.
timselectric
If I can do it, you can do it.
- Joined
- Feb 5, 2022
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- 19,434
All of my equipment is in a conditioned space (except for the panels, of course). Batteries stay at 20 to 25c , and AIO's don't get above 40c. (When really working)
sunshine_eggo
Happy Breffast!
Not even for a nanosecond. Liquid cooling my battery, or most batteries for that matter, is beyond impractical.
Insulation and ventilation of the shipping container is a far more practical option with benefits beyond the battery temp.
These are high end Panasonic PHEV cells. They see higher temperatures in the car, and they're air cooled in that application.
Cool air across the top seems to do well when it’s there. My biggest surprise was the difference in temperature in a room in regards to elevation. The top of the lower battery is 11” off the floor and the top of the two others are 27” off the floor. The lower battery has no powered airflow, just natural convection. The other two have a timed fan that blows over them. This is the a typical hottest summer battery peak temperature (fan now off). Blue is the bottom convection, yellow is upper closest to fan and green is down stream. The two upper batteries would be way hotter if not for the morning cool downs. I’m working on an enclosure with fan for the bottom unit and control but it hardly made an improvement in the first test. I would like to close it up for the point of safety(vermin accidents).
Ampster
Renewable Energy Hobbyist
In the Summer, 75 to 100 percent. In the Winter 55 to 100 percent
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After 2 month of experimenting with different techniques with fans/ No fans / some fans …on the batts it seems the best thing i have found is to get them as cool as possible all night using a fan .then kill the fan early…they will have momentum to stay cool,for a while …..leave the fan off Untill the battery temps start to exceed ambient temps ( if it happens) late in the day Then the turn the fans back on high and just roll with what ya get from ambient temp.…as it gets later in the day it will slowly cool and start bringing the bat temp down with it..
there a lot of mass and weight in a whole bank…it slower to react compared to the other gear…
2 inches of insulation on my batt box has been the salvation of keeping them cool all day compared to ambient temp…if I had known when building it Inwould have used more foam board.
I have no idea how I would do that if they were open to free air …other than A/C.
I also have no idea what the guys who live in a naturally hot place , 90 - 100 + F do .
Im sure there’s an answer ,but I don’t know what it is…
J.
Sound like we’re running down the same path lol. I found dual sensor differential thermostatic control so the fan will blow any time the battery is warmer than the air. But figuring out how it works has been interesting. The instructions are in Chinese so I searched and found an English version translation. My impression is that even the Chinese version must be a mess ?. The control’s voltage was 220 AC but it actually had a drop down transformer and rectifier that landed on 12VDC and it was a cakewalk pop those two components out so I could feed it my 12VDC. But now I’m lost in translation, dead bug, winging it. I may just go with the 12V timer I have and 12V fans for K.I.S.S.
