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Nano-3 will not charge
On 4/30/2021 6:01 AM, Martin Gregorie wrote:
... I didn't realise it has Li-ion batteries: using any power switch other than mechanical is bad news for those: if you don't check their charge state regularly the batteries WILL self-destruct if their voltage falls below 2.5v per cell or they're charged above 4.2v. On top of that a Li- ion battery self-discharges at about 2% per month, even when not connected to anything. If the Nano's charger (external or built-in) has an automatic cutoff at full charge and can 'float' when the battery reaches full charge, I'd leave it permanently on charge when its not being used. This style of charger has been common for years for SLA batteries and is often supplied with the device. My camera chargers (both built-in and separate) do this and so does the charger for my Yaesu FTA-250 hand-held radio. Right in theory, but in reality it seems that many of those push-button-to-start devices hold their charge for many months, even years, with no problem. I have several such devices, including rarely used old smartphones and tablets, e-readers, goTenna gizmos, flashlights, etc. The circuit of such on/off buttons can be designed to use mere microamps *. LiIon batteries usually have a protection circuit built in to prevent them from over-discharging. The PLB I carry with me when flying has a push button to turn it on, and its non-rechargable lithium battery pack is officially good for 5 years - and then is still supposed to be strong enough to transmit (in pulses) for 24 hours. And I've read warnings in various places NOT to use a "float" charger on lithium batteries. E.g., if you use a 12V LiFePO4 battery instead of SLA in your glider (highly recommended!) do not leave it on a float charger designed for SLAs when not flying. Ideally you'd use a charger designed for LiFePO4, and it shuts the charge off completely when it decides that the battery is "full". You can use a charger designed for SLA, the battery will be mostly but not fully charged, and you should manually disconnect it after it thinks the charge is done. * Math appendix: if the battery capacity is 1 amp-hour and the pushbutton circuit uses 10 microamps it will take 100,000 hours to discharge the battery. That is more than 10 years. |
#2
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Nano-3 will not charge
On 4/30/2021 6:01 AM, Martin Gregorie wrote:
... On top of that a Li- ion battery self-discharges at about 2% per month, even when not connected to anything. Please, there are MANY different kinds of Li-ion batteries, and some of them have MUCH lower self-discharge than 2%/month... |
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