I'm not sure. So far, that's been the only drawback I've had with the "inexpensive" cell. I do like the built in DC cord as it eliminates a connection that can go bad over time, but it does make it impossible to read cell voltages. I thought that would be as simple as unplugging the cell and simply checking the 2 wires coming from the board but there's evidently more to it than that. Maybe one of the more experienced guys can give you an idea how to measure when cell terminal posts aren't available. Frankly, I'd like to know myself when board side is only available place to check.
On another note, I went through all the mess in this whole thread, ultimately replacing both the cell and the board. Had to re-strip and terminate multiple wires as original installer hadn't been very careful and some were nicked where outer jacketing had been removed. Can't say if this was initial culprit but what FINALLY got my system working perfectly was redoing the 2 DC connectors that were FACTORY installed on the Jandy side. Weirdest thing I've ever seen, but those just felt kinda loose . . . . probably from all the plugging & unplugging! Re-terminated new connectors there & it's been running fine ever since. At this point, the only thing I can't comment on the aftermarket cell is longevity but my fingers are crossed.