Well this was an interesting bit of learning today!
At first glance, the Tracer batteries can seem quite expensive - especially considering you can seemingly get a 12v 22Ah car jump-start power pack from Amazon for around £89.
But here's the thing: Manufacturers rate batteries differently.
The current and power ratings that you see on Amazon for those car jump-start battery packs are based (by convention) on the internal Lithium Polymer voltage of 3.7 volts, not the device output of 12 volts. What this means in practice, is that the Tracer batteries from cpap.co.uk will deliver over three times as much CPAP therapy per charge than a seemingly identically-rated car jump-start battery pack.
So are the Tracer batteries overpriced?
No. Here's the maths of price-per-volt (V) at the time of writing:
Tracer Ultra CPAP Battery:
285(£) / 12(V) = 87.88(£) / 3.7(V) - so, the same price-per-volt as an average 22Ah car jump-starter
Tracer Compact CPAP Battery:
139(£) / 12(V) = 42.86(£) / 3.7(V) - the same price-per-volt as an average 8Ah car jump-starter
So as you can see, those "bargain" jump-starter battery packs now turn out not to be such a good idea after all.
For a third of the price, you just get a third of the CPAP time.
Hope this is helpful.
Jeremy.
At first glance, the Tracer batteries can seem quite expensive - especially considering you can seemingly get a 12v 22Ah car jump-start power pack from Amazon for around £89.
But here's the thing: Manufacturers rate batteries differently.
The current and power ratings that you see on Amazon for those car jump-start battery packs are based (by convention) on the internal Lithium Polymer voltage of 3.7 volts, not the device output of 12 volts. What this means in practice, is that the Tracer batteries from cpap.co.uk will deliver over three times as much CPAP therapy per charge than a seemingly identically-rated car jump-start battery pack.
So are the Tracer batteries overpriced?
No. Here's the maths of price-per-volt (V) at the time of writing:
Tracer Ultra CPAP Battery:
285(£) / 12(V) = 87.88(£) / 3.7(V) - so, the same price-per-volt as an average 22Ah car jump-starter
Tracer Compact CPAP Battery:
139(£) / 12(V) = 42.86(£) / 3.7(V) - the same price-per-volt as an average 8Ah car jump-starter
So as you can see, those "bargain" jump-starter battery packs now turn out not to be such a good idea after all.
For a third of the price, you just get a third of the CPAP time.
Hope this is helpful.
Jeremy.
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