With the arrival of those last four "lost cells" this week, I'm officially kicking off the build stage with an initial top balance. And while I knew there'd be some head-scratching moments ahead, despite iterating and poring over the design details for months (first, second, third, most recent) and going back and forth on all the "what-ifs" with all of you, I didn't realize how quickly the first one would hit me.
So, unpacked all 16 150Ah cells from BLS, hooked 'em all up in parallel (all cells arrived @ 3.29-3.30V) to my charger, set it for 3.4V/10A for the first step and, lo and behold, the 10A (charger's max) CC didn't kick in cuz the charger was reading a battery voltage of 3.4! What the hey??
So, after checking to make sure the charger wasn't the problem, I turned my attention to the wires. Swapped 'em out for bigger ones. Same thing. Could it be the battery? A bad connection somewhere? Or is it just the LFPs? Voltage at the bank terminals was 3.30V but the charger terminals less than a foot away were 3.41V (see above).
Then it dawned on me. If hooking up CC panels to an LFP battery brings their V down to batt V, why should I expect they wouldn't do the same to any other charging source? [Edit: Nope] What I probably needed to do was to hook up those remote V-sensing wires on my Phillips (-S and +S in pic above) to let it know what the TRUE batt voltage was and then everything would be ok, right? [Edit: Yup ... see below]
Yep. As soon as I hooked 'em up and flipped the sensing switch from "local" to "remote" the Phillips then saw the batt V and kicked into CC charging.
Wow. One thing to understand something theoretically. Quite another to connect the RW dots and see it in action (if in fact, I'm connecting the right dots ... seems so [Edit: Nope, see below]). Quite literally feel like I'm relearning this stuff as I go.
So, having reached this milestone, REALLY want to to thank @Will Prowse for his YT channel, launching this forum, and ALL the folks here who've helped get me to this point. Six months ago I had no thought of doing something like this, no solar knowledge and only distant memories of Physics 101. Five months ago I joined the forum. Today I started building a system and have managed to troubleshoot problem numero uno relying on what I've learned here. And it really wasn't a problem at all. So, we're off to the races ... albeit at only 10A *sigh* ...
Stay tuned. Plan to update this thread as things proceed. Once these guys are topped, I'll be using my SBMS to perform 2 capacity tests (8 cells at a time ... twice) so my 8S SBMS can monitor individual cell voltages. I'll be using SBMS's logging as well to graph it all up when I'm done.
So, unpacked all 16 150Ah cells from BLS, hooked 'em all up in parallel (all cells arrived @ 3.29-3.30V) to my charger, set it for 3.4V/10A for the first step and, lo and behold, the 10A (charger's max) CC didn't kick in cuz the charger was reading a battery voltage of 3.4! What the hey??
So, after checking to make sure the charger wasn't the problem, I turned my attention to the wires. Swapped 'em out for bigger ones. Same thing. Could it be the battery? A bad connection somewhere? Or is it just the LFPs? Voltage at the bank terminals was 3.30V but the charger terminals less than a foot away were 3.41V (see above).
Yep. As soon as I hooked 'em up and flipped the sensing switch from "local" to "remote" the Phillips then saw the batt V and kicked into CC charging.
Wow. One thing to understand something theoretically. Quite another to connect the RW dots and see it in action (if in fact, I'm connecting the right dots ... seems so [Edit: Nope, see below]). Quite literally feel like I'm relearning this stuff as I go.
So, having reached this milestone, REALLY want to to thank @Will Prowse for his YT channel, launching this forum, and ALL the folks here who've helped get me to this point. Six months ago I had no thought of doing something like this, no solar knowledge and only distant memories of Physics 101. Five months ago I joined the forum. Today I started building a system and have managed to troubleshoot problem numero uno relying on what I've learned here. And it really wasn't a problem at all. So, we're off to the races ... albeit at only 10A *sigh* ...
Stay tuned. Plan to update this thread as things proceed. Once these guys are topped, I'll be using my SBMS to perform 2 capacity tests (8 cells at a time ... twice) so my 8S SBMS can monitor individual cell voltages. I'll be using SBMS's logging as well to graph it all up when I'm done.
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