Perry's Blog

OK... so we didn't get to test the SteriPen on our last walk because it was defective , but that was an opportunity for their customer service to shine Which they did... but that left me not knowing how heavy the SteriPen was going to be on our rechargeable batteries. So I decided to do a battery test from full to empty to see how this specific unit when with our batteries.

The Test
The purpose of this test is to both test the unit over an extended period, and run one set of batteries flat, so that we'd know how long a set will last. I used the Powerex Imedion 2400mHh AA batteries bought from PROTog.

Each morning and each evening we conducted several 1 litre treatments, until the SteriPen ran out of batteries.

The Results
The test ended up running over 8 days; we tested the equivalent of 75 litres of water during that time. All four batteries started off at around 1.48V and ended up averaging at 1.15V (although there was one a bit lower than that).

The low battery warning (Slow green blinking with Red flashes) started early on in the test (after only about 10 litre treatments) and continued intermittently for the rest of the test.

Comments
I was surprised when the SteriPen stopped working with the lowest battery at 1.12V: That battery (in this instance) was the weak link in the chain and stopped the pen from working. A quick test by swapping out that battery for a more charged one and off the SteiPen went again.

Jeff from ProTog told me that rechargeables are considered discharged at 1.0V, although Wikipedia has them discharged at 1.0-1.1V.

I asked SteriPen about this, as their litterature definitely says that the SteriPen is designed with rechargeables in mind. Their reply was:

With rechargeable batteries, you can expect about 80L of water treatment.

This is a little less that what their litterature quotes: The User Guide says that

average NiMH batteries should deliver 180-210 0.5 litre treatments

So I was about 15 litres short , but that was probably due to the one extra discharged battery, so I'm not overly worried.

Jeff at PROTog was adamant that if the SteriPen failed to draw power from a rechargeable at 1.12V then it was not designed to work with NiMH batteries. I've asked SteriPen for their comments on this but have not received a reply as yet.

Conclusion
Although there is some question if the SteriPen is using all of the rechargeables' power, getting 75-80 litres of treated water on one set should give us around 15-20 days worth of water (depending on weather and hydration needs), which is fine.

I was pretty happy and relieved that the unit treated the equivalent of about 15 days' walking withoug a glitch or hic-up. Hopefully we'll get the same results out on the track (Note: A SteriPen does not mean that we don't take purification tablets with us!! It just means we don't use them )

This should work in very well with our battery requirements that will be served by our Voltaix Fuse Solar Charger when doing the Bibbulmun Track later in the year, where on these results we'll only have to recharge 12 batteries over the 60 day walk.