Interesting meeting today – it was kind-of a mix of marketing and engineering. The meeting was really about sorting out the confusion (internal and probably mostly limited to me) wrt the new products based on our RBM (Reset, Battery Modulation) technology. I won’t get into an explanation of RBM here – that’s for another person/time/place. In the end the meeting resolved a huge question and that is what to do with what we have internally called “Charge-Buddy”.
I guess, before I go on with the meeting “story”, I need to explain what “Charge Buddy” is/was. (it should have been and maybe is explained many times over in other blog entries but….).
“Charge Buddy” a moniker introduced by Paul Vail, stands for a simple device that stops a battery in a tablet/phone from overcharging. As we all “should” know, a Lithium Battery really really really… should never be trickle charged and should never be overcharged. Trickle charging quickly leads to battery degradation and eventual gassing ie battery bloat. As per overcharging, well modern battery chargers are supposed to stop the charging cycle once a battery reaches full charge but don’t work too well for a simple reason – the battery being charged should have no load during charging otherwise detecting a full charge is impossible.
Put another way: a device with a lithium battery must be completely off when being charged. (as a digression, I should mention here that android devices or for that matter any tablet/phone device is never completely off – but only in a very deep sleep mode and thus always consumes battery power even though the quantity is measured in micro – amps)
Think of it this way – trickle charging occurs because the battery is being trickle discharged. Because there is a continuous trickle discharge occurring the charge controller never sees a full battery so never turns the charge cycle off which leads to trickle charging and so on and so on and so on. End result: BLOATED BATTERY!
Enter “Charge Buddy” – a device that externally terminates the battery charging cycle. OK, so what’s wrong, where am I going with this??
Well, “Charge Buddy” has it’s own little problems as we discovered:
- It seems the name Charge Buddy is used by another company to denote a multiple (octopus like) outlet usb charging device. On top of that – they’ve registered the web site and some within our circle fear the wrath of lawyers if we use this name.
- The term Charge Buddy does not immediately relate to the functionality we are trying to present – namely ensuring that a charge cycle has a definitive start and stop – kind of a fuse that disconnects to protect a device from harm.
And there we have it – add to that the statement that we are really trying to get phone users to buy this device and the name “Phone-Fuze” was born.
PHONE-FUZE – a simple device that sits between the device charger (usually a wall wart) and phone device and detects charge current to the device. Phone-Fuze will terminate a charge cycle by disconnecting power to the charging phone after detection of “lithium battery charge knee” indicating transition from constant current to constant voltage charging (usually around 85% of charge capacity) or after a fixed charge time has been exceeded – won’t say how long as we are still experimenting with that one.
Note 1: really good and simple (within reason) explanation:
Note2 : in practice , Phone-Fuze will keep the device battery bellow the 100% full charge mark and if the user charges before the battery drops bellow 40%, literature shows battery life should be greatly enhanced.
Below I’ve “lifted” a chart from:
to illustrate the point. The article goes into more depth on this subject – recommend reading it.
|Charge level (V/cell)||Discharge cycles||Available stored energy||Table 4: Discharge cycles and capacity as a function of charge voltage limit. Every 0.10V drop below 4.20V/cell doubles the cycle but holds less capacity. Raising the voltage above 4.20V/cell would shorten the life.
Guideline: Every 70mV drop in charge voltage lowers the usable capacity by about 10%.
Note: Partial charging negates the benefit of Li-ion in terms of high specific energy.
30% and less
Roman (Moko) Wynnyckyj
Lava Computer MFG. Inc.