I looked to the Miady option, the only available models are the 6 and 8AH, the later would be equivalent to the original 7AH, the starting price is not as high as the one I found here locally, my question is how to charge it? using the supplied 15v charger or something special!!
The 20Ah Miady comes and goes on Amazon, if you wait another week or two it might come back. As far as I know, none of these batteries come with a charger, so you'll have to buy one of those separately.
As for Miady, it's definitely what would qualify as a "cheap" product and I found one review on the internet where someone took one of their batteries apart and concluded that he couldn't recommend it because of the construction and the state of the individual battery cells (they weren't balanced even after a full charge). His comment on the latter is that he didn't think the Miady would last very long.
In any case, for just $66 I considered it worth the risk and thus far it has worked well for me. As yet, I only have about 5 discharge cycles on the Miady, but it recharges fairly quickly (I have a 10A Noco Genius charger) and I've run it out to 240Wh on at least two nights (it's rated for 256Wh) and as yet the output voltage have never dropped below about 12.5VDC. At this rate it even seems to have a bit more capacity than my 35Ah AGM batteries.
In terms of a getting a certain number of charge cycles, even if the Miady goes for only 100 cycles it will probably still be worth the cost, given that 100 cycles would likely last somewhere between 2 and 3 years (I probably average only about three full nights per month given the weather, where some months are zero and a very few are five or six nights). But, if the Miady goes for 200 or 300 cycles that will probably outlive me (let's be serious, how many are going to be able to use thousands of cycles for just their astrophotography needs).
One last thing to note, the Miady runs at just over 14VDC when fully charged and that MAY be too high of a voltage for some devices. In fact, I think most LiFePO4 batteries output higher voltages than do typical AGM/SLA batteries. In my case, however, I use voltage regulators for each of my sensitive devices (like my mini PC and the other computer equipment). In fact, I think that's a good idea even if using AGM/SLA batteries.
Edited by james7ca, 10 March 2021 - 03:26 AM.