LG Cosmos 2 phones lose all of its battery juice even after charging?

Question

Hello.
Very rarely, this happened a few times already and quite annoying since I have seen a couple LG Cosmos 2 phones show this same problem/symptoms. My m(o(m/ther)/a) and I have the same exact phones from a local Verizon Wireless retail store as a family package about two years ago. In my past experience, I have seen my phone lose all of its battery juice the next day even after a full charge at night even though I did not use the phone. Basically, the phone doesn't turn on because of no battery power. Connecting to its power charger will make it work again, but charging fully takes a few hours to be portable again. This happened twice so far for me.
Yesterday, the same thing happened with my m(a/o(m/ther))'s phone. She said she charged her the night before it ran out of battery power (dead as well) in the day time. She was able to turn it back on when she plugged a power charger (her SUV and at home). It also took hours to fully recharge and no problems.
We both use our own chargers and phones. We did not change any hardwares like batteries, chargers, etc. They are the same ones that we got when bought our phone as a family package from a local Verizon Wireless store. We don't know when the next incident will happen again, but this is annoying and concerning since there seems to be no exact patterns to see when this happen again. Why is this happening? Is this a known issue?
Thank you in advance.

Answer 1

B33 . wrote:
O i'm sorry missed that on how old it was my eye's on here sometimes get a bit tired.. well since your using it for calls only is this your primary Home phone?  if so and you use it to talk to family and such especially over the weekend as that's when most of us tend talk to our Love one's,  that can run down even a fully charged phone and even when it's setting on the table in a Idle position if the phone is far enough away from the Towers it can tend to want to stay connected to them and this can run the battery down.. b
For me, it is mainly an emergency phone since I rarely talk on the phones (maybe a few times a month for a few minutes). My phone only turns on when it is being charged. My mom uses it almost daily though. As you can see, very different phone usages but same rare symptoms.
When you say idle, do you mean the one that turns off automatically? I never manually turn mine off. Is being far away or no signal the one show in the signal bars when the phone is on? If so, then I don't re(call/member) seeing it being very low or unavailable but then how often do I use my phone?