Low mAh batteries pack for cell processing

My first round of battery searching had me collecting a lot of drill packs. Since these are low mAh, I was wondering what to do with them. I have about 45-50 cells that average around 1500mAh. Would a pack made up of these be suitable for connecting a couple of Opus chargers to cycle the newbatteries I'm processing? I have a 24volt solar panel for charging and would like to use solar for most of my processing. I know I could not charge all night, but on nice clear days I figured it would work? Also would a 3s or 4s pack be best with a buck converter?

yes you can use them for running the opus, when running it consumes less then 3 amps, usually even less, even when charging 4 batteries. At 1500 mah per cell, a3s16p (48 cells) will get you about 24ah.

If charging with solar go with 3s, most solar charge controllers will have trouble fully charging a 4s li-ion pack (which is in the 16 volt range). The only thing to look out for with solar is to try and not let the BMS stop the charging, this creates voltage surges, which might damage the opus if its connected to the battery. I use a voltage stabilizer on any equipment that is connected to the battery and issensitive to voltage surges(fans/lights).

If you go really high in total capacity, and you average only a maximum (dis)charge of 0,5A every cell. Then you can use them. Then it counts as as much capacity as possible. I use as low as 1500mAh. But then again i have 25kWh. Average of 2100mAh/cell

Would like your opinion on a lot of batteries I just got a call on. Went to the persons house who is a recycler. He let me have some of his batteries at .50 a pound. But here is the catch. They are stored outside and in the weather! I know we have only had a couple of days this year below freezing. But they are all rain soaked. I bought 60lbs to try. He has about 200lbs worth left. I opened up a few and some were okay, while others had some rust in them. For the price should I pick up the rest? Or get these tested and see how they turn out before buying more?

I would pass*. Water and batteries are not a good combination. The BMSs could have shorted out and that can cause the cells to go down to 0 or even negative voltages. The cells rusting is also bad because the steel casing of the 18650 is only so thick and sooner or later, the rust will eat all the way through and electrolyte will leak causing more rust and venting.

* Unless, you can still sell them back to him at 0.50 per pound, then all you will be out is labor, and you might find a few good cells that were not exposed to the elements.

planepilot said:

Would like your opinion on a lot of batteries I just got a call on. Went to the persons house who is a recycler. He let me have some of his batteries at .50 a pound. But here is the catch. They are stored outside and in the weather! I know we have only had a couple of days this year below freezing. But they are all rain soaked. I bought 60lbs to try. He has about 200lbs worth left. I opened up a few and some were okay, while others had some rust in them. For the price should I pick up the rest? Or get these tested and see how they turn out before buying more?

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Had a few water damaged packs in a lot of batteries some time ago. My advice is dont touch them, mine were corroded and had to be recycled. If they were free them maybe you could salvage some from the pile otherwise not worth it.
J