Here is a link to the data sheet for the SIND 06 610, since it is the one that looked superior in his video.
https://www.trojanbattery.com/pdf/datasheets/SIND_06_610_DS.pdf
Couple of things that jump out right away that he didn't talk about.
First, the Peukert effect, ie loss of capacity due to internal resistance. He gives this battery's capacity as 6 volt and 610 amp hour, which would imply that it can supply about 3.5 kwh of energy. However, that rating only applies if you slowly discharge at 6.1 amps for 100 hours. If you want to draw energy from the battery at 30.5 amps, the capacity drops to 2.8 kwh and at 60 amps 2.5 kwh. So if you take his recommendation that you discharge it to only 25%, at a 30 amp rate, its capacity is only going to be 0.7 kwh.
This compares with the lithium cells, which are often rated at discharge rates of 1 C, which means that the battery is completely discharge within the hour. This would mean that the Battleborn could provide 1.2 kwh or energy even if you discharged it at 100 amps.
Then there's the charge current. The Trojan SIND 06 610 data sheet says the maximum charge current is 13% of the C20 discharge rate. The battery nominal capacity is 610 ah, so C20 is 30.5 Amps, and 13% of that is about 4 amps. THIS SEEMS RIDICULOUSLY LOW. Can someone tell me if I'm misunderstanding something or doing this wrong? I assume at higher rates it begins to off-gas or lose water more rapidly.
This compares with LiFePO4 cells that are often allowed to be charged at 0.5 to 1 C. So you could probably charge the Battleborn at 50 amps. (the spec sheet on their website is really light on data compared to the cell datasheets)
Finally on cycle life. The Trojan's datasheet says they can get 7000 cycles if you only discharge them to 25% capacity. However, in the foot notes, there is a big caveat to this. This is only true if you operate the battery at 77° or below. If you operate the battery at 95° F each cycle counts as two cycles, so the battery life is only 3500 cycles. The interesting catch is that the temperature chart says that the battery capacity is reduced below about 83° F. At 70° F the capacity is 90% of nominal.
This compares to the LiFePO4 batteries that are usually rated at their 3500 cycle lifespan going to 90% to 100% of their discharge capacity. The video really short changes lithium here by saying he would only use 60% of the capacity.
So what does this mean? If you have a system in place to cover an occasional outage where your current draw will be within the capability of the Trojans and you will have days to recharge, and otherwise it just sits there on a float charge, then the SIND 06 610 batteries might be a great deal. There is a reason why they exist. However, if you want to come home in the evening and crank on the AC and induction cooktop at your off grid home every night and then have your massive solar array fully charge the batteries even if you only get two hours of sun the next day, then you will be very disappointed in the Trojans, and a LiFePO4 pack will be much better suited to your use.
