thegoogler
New Member
- Joined
- Apr 15, 2021
- Messages
- 108
Apparently the CALB cells are more tolerant of voltage variations than the CATL cells. Or less tolerant. I actually can't tell which since CATL specifies a voltage cut-off and then two separate over voltage protection limits. Confusing.The charging voltage should be what the manufacturer recomends for a given application, in photovoltaic systems it's undesirable to turn off the charging source because it will then prevent loads from using the PV, resulting in drawing from the battery, until a subsequent charge cycle is initiated, to prevent micro cycles a float cycle is introduced to maintain a lower than maximum SOC, but sufficiently high enough to ensure around 90% of capacity is available when the array can no longer provide energy to support the loads.
This is a discussion I had with a well known EV guru, who claimed was it is impossible to use LiFePo4 in solar applications because the charging source needs to be terminated once an individual celll reaches 3.650V. Obviously he was only comfortable within his knowledge base, not knowing the intricacies of charge controllers, but otherwise extremely knowledgeable. Typically in EV bottom balancing is performed to have the cells aligned at the lower end, perhaps to ensure maximum range, but in my opinion it wouldn't make any difference, top or bottom as ultimately the battery capacity as a whole is only as great as the weakest cell.
Using between 20% and 90% SOC is probably a realistic long term strategy, this is something Battleborne dose on their batteries, although they advertise 100% of capacity is available, they back that up by using a larger capacity than advertised to ensure customer satisfaction, a very smart strategy, they are very forthcoming with information, a welcome change to the average vendor.
Included below is the charging recomendations from the manufacturers manual I received with the cells I purchased, note the reference to photovoltaic and float.
View attachment 61655
302Ah CATL cell info below. I have the 271Ah cells. I'm *assuming* the values are actually the same as the 302Ah appears to be a physically larger version of the 271Ah, but TBH it's just one of probably many misguided assumptions as I can't find a similar doc produced by CATL for any other CATL cells