I find it interesting that Amazon has changed the PRODUCT that is available at the URL I posted earlier.
Here is the battery monitor that I bought; https://www.amazon.com/BUNKER-INDUST...e%2C141&sr=1-4
This SAME unit is available from several sellers on Amazon. Prices range from $30 to $40.
I am still using the unit. And after one season with it I find that it was money well spent.
Thanks for the new link. Yes, that is really strange that Amazon flipped the product.
And there is something else strange, in fact very strange.
The gizmo itself looks pretty cool, mainly for the access by BT app and for the storage function. Seeing a plot of the voltage for a whole month, while the boat is in use or not, being charged by solar and other sources seems like a useful thing, in particular given the price.
When looking at some of the other sellers on amazon (the product seems to be identical, prices vary a little, as you said), I noticed several reviewers however who feel that what you pay in dollars may not be all what you pay: they have serious privacy concerns. Apparently, for the thing to do anything you have to give it privilege to the location of the phone at all times (!), even when the voltage monitor is turned off (!!!), see e.g. the top review at this link https://www.amazon.com/dp/B0714DT87F...ustomerReviews
The software that you have to install on your phone is (I am quoting from the review) "written in China and you need to enable location tracking even when the software isn't running. There doesn't seem to be any technical reason why this should be necessary and it could allow a back channel to the developers to track all of your movements"
I am not particularly paranoid about the guvmint or someone spying on me but this seems really fishy: why in the world would an app reading the battery voltage need to know where I am at all times? What are they doing with this information? It goes to some server in China where they have total control about my whereabouts even if I use the app once and never again?
There is another (independent) review of the same thing who actually looked in detail at the permissions, top review here:
"since the app looked suspicious, I downloaded it on a spare, empty phone I have. It requires all kinds of permissions from the phone and downloads all kinds of Chinese tracking software just to run a bluetooth app. It was scary intrusive. I decided not to use it."
As attractive as the voltage monitoring function sounds, I am not too fond of having Chinese tracking software installed on my phone. I think I'll pass on this thing.