Thursday, January 25, 2018

Upgrading the Petzl Nao Battery

Petzl Nao and Nao+ represent truly excellent Trail Running headlamps.  And hey, if you have the funds you can buy a Nao+ and use it for trivialities like a torch for emptying out the bins, or taking the dog for a walk, but it would be a waste.

There are now 2 principle versions of the torch

2013-2016 Nao  
2017  Nao+  including Bluetooth  (red colour on front) and red battery back with red rear LED.

The Bluetooth model connects to your Smartphone via an app which you use to change the modes of the Headtorch and solves the problem or having to install a program on your PC/Mac and connect the torch which was time consuming and fiddly.

If you have the money (135 GBP) the 2017 Nao+ is still the ultimate head torch. 

Note that on some races a rear Red light is mandatory and so the Nao+ is pretty unique in providing a one stop solution.

I reviewed the Nao here, please read the review to understand about reactive lighting.

Enough of the fanboy PR

Both Nao and Nao+ suffer from a crippling issue

Replacement Battery Cost!

Predatory Pricing
For both the Nao and and Nao plus, Petzl does not offer a replacement battery, you have to buy a battery in a housing.

Now that is expensive!  But most of my annoyance is the very proprietary design that I shall explain.

This is my original Nao battery removed from the waterproof housing.  In fact it is a 18650 battery whose cost is under 5GBP.  But wait,  they tagged on some electronics

Yep, so you can't just buy a new 18650 battery unless you are further prepared to disassemble your existing battery and solder back these electronics.   I know, unbelievable

Further inside the housing are more electronics

So you can't either connect a new 18650 to that either

Really really annoying

Battery Compatibility

To make matters worse the new 2B battery for the Nao+ is shown to be incompatible with the earlier Nao.  So if you buy an old style battery in housing today and then buy a Nao+ tomorrow you can't take that expensive battery collection to your new headtorch.

Well apparently :-)

The Workaround

You need to order this 3500mAh battery from Amazon UK for under 20 GBP including shipping.  It is a battery with the necessary electronics attached.  You will open up your existing housing

Original Petzl battery on top and below the one I received from Amazon

I marked the batteries to avoid confusion and here is the new battery in the Original waterproof  (notice the seal) housing.

The Testing
I thoroughly tested the Amazon bought battery with both my 2012 genre Nao headtorches.   Absolutely everything works, by which I mean

- The new battery is inserted into  the old existing Nao compartment

- I charge the lamp battery via a standard USB socket as before

- I connect the battery to my PC laptop and configure it using the Petzl program as before

- The battery is recognised but the extra capacity is not (3500mAh vs original 2300mAh).  Therefore the times reported in the configurator I assume will be easily beaten by the new battery.

- In a rundown test, using Constant Mode, both wide and far beams on, new battery, 4 hour battery life predicted

Time    Bat Life
15:52   99%
19:00   32%
20:19   Low battery flash
22:54   Still going, wide beam off
00:16   Still going, only far beam on
01:51   Still going!

So in this practical test, starting with Constant mode, 10 hours later I still have the far beam  (long range) light on, dimmed but on.

Now in reactive mode the torch will use either the short range wide beam or the long range focused beam.  So typically you get greater battery life than a similar constant mode.   I am pretty sure therefore that the same test repeated using reactive mode would give a 12 hour+ result, assuming it was on Long beam only during the test.

What does it all Mean?

- I recently wrote  about preparations for our long Ultra Marathon

- I estimate worst case I need 14 hours of lighting

- Using these replacement enhanced batteries I believe that one torch and 2 batteries should be sufficient

- By race rules I still have to carry a second torch and its spare battery, but this can be minimalist.

- As a paranoid Android I will aim to open up the used battery at the 50% checkpoint and place a fully charged older 2300mAh battery into the housing so I can start the last half of race with guaranteed lighting

- I can tweak the profiles so that there is a 6 hour Reactive profile (7 hours)  and a more powerful  Constant Mode  (4 hours) profile pair.  So that I can run with Reactive and switch to brighter Constant for more difficult Race sections.


In Summary
This 20GBP replacement battery will revive your original Petzl Nao headtorch to full health in 2018
Petzl Nao+ from Wiggle UK