Ok, so, I bought CATL 90Ah cells from Liitokala, and so far can't get a refund. Aliexpress's buyer protection plan is worth the paper it's not written on, and it turns out PayPal's is worth about the same.
Anyhow - back to the cells. They test between 55Ah and 68Ah. They bulge, but no signs of leaking (as yet). I have a 100A 8S BMS.
I bought them to make a pack for my mobility scooter which has 36Ah SLA batteries inside that currently test at about 25Ah, so I was wondering if people think it's worth using the Liitokala junk instead of the SLA junk while I scrape together my pennies to buy decent replacements. How many cycles do you think are left in the 55Ah cell? I'm hoping to go out on the scooter 5 times a week to visit the local sports centre for swimming based physiotherapy, so I'm thinking that in a year I might cycle the SLA cells about 125 times (a trip to the pool and back half empties the SLA cells) or maybe 85ish for the Liitokala cells.
Basically I'm after a bit of advice on what to do to keep everything running long enough to save up for new batteries. Could I run the 55Ah cell in parallel with another LiFEPo4 cell temporarily, to reduce the stress on it and artificially extend it's life? Like, if I buy a cheap LiFePo4 cell on Amazon or hobbyking, or maybe an old cell from one of you lovely lot, and just run that one cell in parallel with the lowest cells in order to extend it's Ah rating to match or exceed the rating of the rest of the cells - and let the BMS compensate for the mismatch...?
Also, I have a couple of 5v 20A PSU's. I'm wondering if I bought some cheap 1A step-down voltage regulators, set them to somewhere between 3.4v and 3.65v, and charge each cell to independantly rather than charge the whole pack to 29.2v. Doesn't matter if they charge super slowly, charging for 20+ hours per day is fine, and I think I only need about 10-15Ah per trip anyway. At that point, the BMS only needs to worry about low voltage disconnect.
Thoughts? Anyone got cheap end-of-life cells they might let me buy cheap, if the parallel idea isn't terrible?
Anyhow - back to the cells. They test between 55Ah and 68Ah. They bulge, but no signs of leaking (as yet). I have a 100A 8S BMS.
I bought them to make a pack for my mobility scooter which has 36Ah SLA batteries inside that currently test at about 25Ah, so I was wondering if people think it's worth using the Liitokala junk instead of the SLA junk while I scrape together my pennies to buy decent replacements. How many cycles do you think are left in the 55Ah cell? I'm hoping to go out on the scooter 5 times a week to visit the local sports centre for swimming based physiotherapy, so I'm thinking that in a year I might cycle the SLA cells about 125 times (a trip to the pool and back half empties the SLA cells) or maybe 85ish for the Liitokala cells.
Basically I'm after a bit of advice on what to do to keep everything running long enough to save up for new batteries. Could I run the 55Ah cell in parallel with another LiFEPo4 cell temporarily, to reduce the stress on it and artificially extend it's life? Like, if I buy a cheap LiFePo4 cell on Amazon or hobbyking, or maybe an old cell from one of you lovely lot, and just run that one cell in parallel with the lowest cells in order to extend it's Ah rating to match or exceed the rating of the rest of the cells - and let the BMS compensate for the mismatch...?
Also, I have a couple of 5v 20A PSU's. I'm wondering if I bought some cheap 1A step-down voltage regulators, set them to somewhere between 3.4v and 3.65v, and charge each cell to independantly rather than charge the whole pack to 29.2v. Doesn't matter if they charge super slowly, charging for 20+ hours per day is fine, and I think I only need about 10-15Ah per trip anyway. At that point, the BMS only needs to worry about low voltage disconnect.
Thoughts? Anyone got cheap end-of-life cells they might let me buy cheap, if the parallel idea isn't terrible?