Steve Paavola wrote:

If both batteries are on-line all the time, how do you know when one is
getting weak and needs to be replaced? Or do you replace both batteries
when voltage is marginal at the end of a flight?

You can get fairly inexpensive automatic peak detecting battery
cycler/charger units ($60-$100 at a guess - around GBP 69.00 in the UK)
that will measure the capacity during a discharge cycle. These units
will charge lead-acid, NiCd, NiMH and Li-poly with settable charge and
discharge currents. You can run them off 12v DC (mains or batteries)
they'll charge 12v lead acid and 14 cell NiCd batteries.

Check your local friendly RC model supply shop if you're interested in
this type of charger.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |