I’m starting my experiment to use 3.2v LIFEPO4 battery (lithium iron phosphate) to replace the Energizer lithium battery.
My motivation is to lower cost and reduce waste.
Other rechargeable battery options have been explored by others and most have issues, I’ll summarize them here:
NiMH (1.2v), Voltage is too low and causes unreliable operation.
Lithium ion(3.7v), Voltage is too high and could damage electronics; danger of fire if exposed to high outdoor temperatures.
NiZn (1.7v), high self-discharge and higher cost
LIFEPO4, half the capacity than other solutions, but half of the cost, low self-discharge
LIFEPO4 has potential for low cost, high reliability solution and that’s why I’m exploring this. I have paid $16 so far to get 4 batteries, 2 dummy cells, and charger. $16 paid is good enough to power 4 Blink units for a life time. So this a great saving over Energizer lithium.
My plan is to use use one 3.2v LIFEPO4 with a dummy cell per Blink camera. The 3.2v is slightly lower voltage than the 2 energizer lithium, which are about 3.4v, so there’s no concerns of over voltage damage.
I only have 3 cameras so I will always keep 1 spare battery charged and can replace a lower charge battery anytime with no down time.
It would be highly unlikely that all 3 units would run out of power all at the same time. Even if they do, it only takes 2 hours to recharge the battery so I can still service all 3 units within 4 hours and there will not be any down time.
With the rechargeable batteries in place, I would feel more comfortable about extending the record time beyond the default 5 seconds and not worry about constantly needing to buy lithium batteries.
About LIFEPO4 batteries, they are know to be extremely rugged and able to survive over-charge, over-drain much better than lithium-ion battery. They are also no explosive, so no concerns about exposing them to outdoor heat. They are highly durable and have at least 1000 charge cycles. (500 years @ 6 month recharge intervals).
One severe drawback is that since only 1 3.2v battery is used and the other slot is filled with a dummy, the amount of stored power is about half of other solutions. One idea to improve this would be to rewire the blink unit to use two 3.2v battery in parallel. Though this is much more involved and the unit would not be able take regular Energizer batteries anymore…so unless I get this completely working, I’m not considering doing this.
I will report my finding as I do my experiments on them.