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Some questions about LiFePo4 battery install

nelsonjrgomes

New Member
Joined
Jul 30, 2021
Messages
15
Location
Portugal
Hi to all!

I already have a Growatt SPH3000 installed with 5x455W Q.Cells, for about one year - this was installed by a local company. The inverter is grid-tied. Now I'm going to install 2x100Ah LiFePo4 batteries, that I bought from Aliexpress - it's BMS communicates with my inverter (or so it's advertised), and I hope I'll not regret this decision.

- https://pt.aliexpress.com/item/1005..._list.0.0.1524caa4ojlSEW&gatewayAdapt=glo2bra.

Now, regarding the connection, I have read thoroughly the available resources, so I'll be using 35 mm2 cable to connect the batteries to the inverter (Inverter max draw from battery is 3000w, 66 amp). Round trip cable of no more than 8 meters, about 26 feet, in one of the possible locations (more on that later).

I'm looking for a class T 100 Amp fuse, but in Europe, they are hard to find - more so, if I'll include fuse holder (are there fuse holders for 100 Amp fuses?!?). I've been reading this forum, and it seems that in US there seems to be a shortage too. So, I'm leaning for a MCCB from Schneider Electric - https://www.se.com/ww/en/product/C1...ac-dc-25ka-415vac-2-poles-tmd-trip-unit-100a/

The calculations for cable sizing and circuit breaker are correct?

I have another question, regarding where I'll install the batteries. My inverter is installed in a balcony, away from direct sunlight (balcony facing north), as it is IP65 rated. I can install the batteries in this same balcony, inside a cabinet, right under the inverter - but I'm afraid as the balcony is open for the exterior, so they'll have to face cold in the winter and hot in the summer. It's very uncommon that the temperature goes under 0 ºC, and when it happens, it's usually at night. In the summer, we'll have peaks of about 40 ºC, like in this last few days (I'm in Lisbon, Portugal). I was thinking of insulate the cabinet with rock wool or XPS/EPS, so the batteries would be more isolated from the cold/hot - but, if they heat up during charge in the summer, am I going to create a mini oven? The insulation is sufficient to keep the batteries on operating temperature? The other possibility is to install the batteries in the kitchen right next to the balcony (in this case, I'd need 8 meters round trip cable), with much more controlled temperature - but they would have to be installed right next to the kitchen cabinets, with lots of wood, and if something goes wrong, there is a massive fire waiting to happen.

What would be, in your opinion, the best location for the battery?

Thank you in advance!
 
Last edited:
Temp extremes are bad for the cells, low temp can be controlled with heaters in the insulated cabinet, but high temps are harder to alleviate… indoors in temp controlled is better for the batteries, but if ANYTHING goes wrong, would your homeowners insurance cover it?
 
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