I was told that leaving it on was what caused me to be charged for 15 gbs of data. I do email and Facebook only, no movies or music. My normal usage up until receiving the 4g device was less than 5 gb per month. I did not change my usage nor did I add any devices that were not on my 3g plan.
When I called Customer Service, it was about the inconsistent service with the 3g device. Oh, they said, you can fix that if you upgrade to the 4g device and it will only cost you buy $50 per month. It will be a long time before you get to 5 gbs of data per month that would require more than $50 per month. Their statement was based on previous usage with the 3g device which had never come close to 5 gb. So I upgraded and overnight my data went to 15 gb. So they lied...actually, this is more like fraud. I filed a complaint with the FCC. I am on fixed income and cannot afford the bill and it will also cost me money to get another service because of their lies.
According to CS, If I leave it plugged in, I can expect these huge data overages. Hey guys, anyone else ready to do something about this absurd problem
Toyota uses the same cells (Li-ion) to make the battery for their Prius. Toyota says that they get better battery life if they never completely charge or completely discharge the battery. Li-ion cells are about 3.7 volts. A phone charger is 5 volts. If you had a 4 volt charger with enough available current the cell wouldn't charge as fast but the cell would last longer. It's been my experience that the less you charge and discharge a cell the longer the cell lasts.
Search Li-ion cell battery life.
I know this is an old post ( but google found it ) and it takes time to actually know if you can or cannot leave the MiFi 5510L plugged in to AC power 24 x 7 x 365. Yes, you can !!! My MiFi has been plugged in for 3 YEARS, now. The battery has just started to swell up, so it is time for a new battery. They only cost $10. The convenience of leaving it plugged in 24 x 7 x 365 out-weighs any small extra increase in battery life from unplugging every morning, waiting for it to discharge and then re-connecting. Seriously, who wants to do that? Just leave it plugged in. Verizon has to be "safe" by saying "Don't leave it plugged in 24 x 67 x 365".
Ignore the person who suggested getting a l"Lower voltage" Charger. They simply do not know what they are talking about. Use the correct charger.
The person who had complained about Huge Data usage: someone, with or without your permission, consumed that data. My data usage is extremely low and we have two computers and one or both are on most of the day. It was not the MiFi, it was your computer.
There is a ton of mis-information in this thread.