/diy/ - Do It Yourself

>>1628442
also, your reverse polarity protection isn't protecting the dc-dc converter which almost certainly will release its magic smoke. instead just use a large-ish resistor between the battery and the voltage detector input. the comp's bias current is too small to worry about (if you chose your comparator correctly) so a large resistor (100k) won't cause significant error. in fact, as a general principle, a diff-pair (such as used in op amp/comparator inputs) should see the same resistance on both inputs for best balance and minimum offset, so you should add this resistor anyway, equal to the effective resistance to your voltage source on the other input. in the case of a simple voltage divider it's just Ra||Rb
in case of reverse connection, your dc-dc and maybe some stuff on the load side of it will be destroyed (but, thanks to the resistors, exceeding the common-mode range on the opamp/comparator or exceeding the input current rating won't be the direct cause of catastrophe)
anyway chink boost modules use a fair to large amount of current even with no load so don't expect more than a fortnight of operation from full charge