I have a Motorola V3(G8/9/18/19) which uses a BR56 battery.
Unfortunately I've dropped it one too many times and the screen,
Which has been displaying black blobs for the last few months
has now become totally unreadable. I really liked my old Razor
and as luck would have it my son happened to still have his old
Razor which he gave me.

His phone is a slightly different model: V3XX(G8/18/19 WC8/19).
I have no idea what any of that means, however his phone seems
to have more features than mine. His phone takes a BZ60 battery,
and the chargers for both phones are the same. However his
battery is dead.

Both of these batteries appear to have the same rating, (3.7V)
and the same 4 terminal arrangement that mates with the connector
in the phone. Since I recently replaced my BR56 battery in my
phone I decided to try that battery in his. I noted that although
both batteries are the same size, the contacts on my battery will
not touch the contacts on his phone. It seems that there is a
very small raised piece of plastic on his case that protrudes
very slightly. There is a very small notch on his battery that
the protrusion fits into, and since my battery is lacking that
notch it would therefore not make contact with the case.

So admittedly being cheap and not wanting to buy another battery,
I removed the protrusion with my Dremel and got the battery to
fit in perfectly. I then swapped the Simm cards, (ATT network) and
I got his phone working with my battery. I knew that the battery was
in need of a charge from the previous indication on my phone, so I
plugged the new arrangement, (his phone, my battery) into my charger.
I charged it for a day and a half and still noted the battery
indication was in the yellow range. On my phone this usually precedes
a red indication which means that you're about to lose power. So last
night wanting to assess this further, I removed my battery which was
still showing yellow from his phone and put it into mine. My phone
powered up and showed two green stripes, which is about 60% which
indicated more power than the battery indicator showed on his phone.
In any event according to the charge indication it certainly did not
seem to be in any danger of suffering an eminent power down.

So last night I plugged my phone with my battery into the charger and
this morning I took the charged battery out of my phone and put it
into his phone. The state of charge indication on his phone was 100%.

So does anyone know what's going on here? Does the phone, charger,
or even perhaps the battery itself "know" that the wrong
combination of phone/battery is present? Is that what the other
two terminals on the battery are there for, to communicate which
battery is present and perhaps this adjusts the charge rate? If I
have to buy another battery, (the correct number for his phone) I
will, but at this point I don't know if this problem is simply an
incompatibility between his phone and my battery or the charging
circuit in his phone. Lenny