Customer Care Blog

I know a lot of people wonder if it is OK to use NiMH batteries with the POV.1. NiMH are an environmental and cost effective way to power you POV.1. I will explore NiMH batteries and the POV.1 with this episode of Curiosity Killed the Cat.

Run times on NiMH
2600 mAh - about 6 hrs
2800 mAh - about 8 hrs

About NiMH batteries
Nickel Metal Hydride (NiMH) batteries (actually they are cells, not batteries, which have multiple cells) are now commonly available in most stores. Make sure to buy batteries with at least 2400 mAh rating. The milliamp hours (mAh) rating is way to sort of gauge how much “fuel” a battery has. This is not a guaranteed way to gauge the capacity of the battery, but it will work for the purposes of powering the POV.1. Also be aware that extreme cold and heat will lower the ability of any battery, and that we assume usage of the POV.1 in “standard” conditions (not on Antarctica, nor in the crater of a volcano).

Self Discharge issues
One thing that NiMH have is the self discharge effect. As time goes by the battery will loose power. Alkaline batteries and Lithium-Ion batteries do this as well, but at a much slower rate. At room temperature it will take about 4 years for an alkaline battery to lose about 10% of it’s charge, while would only take about 10 for a NiMH battery to loose 10% of it’s charge. Lithium batteries on the other hand would in theory take 12 months (depends on manufacturer). If you only use your POV.1 occasionally, or if you will be storing it for a long time, you might want to check and make sure the batteries are charged before you use the POV.1.

Recharging your NiMH
Recharging NiMH batteries can be a bit confusing. You do not want to overcharge the unit, which will damage the cell, and possibly cause a dangerous situation if the cell begins to leak. Always use an approved charging unit. The slow or “trickle-charge” units are better for overall battery life and performance, but they take more effort to maintain. Rapid charging units do work well, but you need to make sure you use a smart charging unit, and take care to remove the batteries when they are done charging. Always read the charger’s instruction manual before use.

Battery life as shown on the POV.1.
Many users who us NiMH batteries may notice the fact that when they use freshly charged NiMH batteries in the POV.1 the battery life indicator is not full. The reason this occurs is because the POV.1 measures the life of the battery based on voltage output. Alkaline batteries will deliver less voltage as the charge in the battery is used up. You can see this in flashlights. As the battery drains the light begins to dim and fade. NiMH batteries will output the same voltage through out the life of the battery. So when the POV.1 reads the voltage out put from the NiMH cell it will read it as only about 3 quarters full. This is because NiMH output a smaller voltage than Alkaline batteries. The charge level will remain there unit the NiMH cells are almost completely depleted. If you are using NiMH batteries and the POV.1 is indicating they are almost depleted, please power down the POV.1 at once, in order to avoid loosing footage.

What about Li-Ion batteries?
When we designed the POV.1 we had to incorporate features that would meet the needs of our military/tactical customers as well as our civilian customers. There was also the safety concern, especially since some of the improperly made Li-Ion batteries have ignited and caused fire damage. By using AA batteries you get the following advantages:

Availability - AA batteries are standard and available all around the world. They are standard and cheap. AA batteries in the UK will work with the POV.1 just as well as batteries from Peru or the USA.

Disposable and rechargeable variants available - You can use the rechargeable NiMH batteries as well as cheap disposable batteries from almost any gas station. This is good for when people go on a trip and forget the charging unit, which leads me to the next point:

No need for special charging units - In March of this year I went on a trip to a conference, and I needed a charging unit for my cell phone, laptop, DS Lite, PDA, and my iPod. The iPod and PDA can both charge via a USB cable connected to my laptop, but I still had to have 3 separate chargers taking up space in my bag. The POV.1 was designed to take up as little space as possible, and a charging cord would have taken up more space. I know that charging station for NiMH take up space to, and that extra batteries add space and weight, but if you forgot a charging unit or cord you could buy more batteries locally to where you are. I got to the conference. If had had attended a conference in Europe I would have also needed adapters for the charging cables/units and if I needed a new cable it would have been expensive to order one from the US.

Ultimately we had to make a call, and it was decided that AA batteries were the best way to go. Yes there are times when Li-Ion cells would have been better, but the POV.1 is designed to be as versatile as possible. Just as there are calls for NiMH laptop batteries, it is impossible to have a perfect solution for everyone.

Sources and places to purchase batteries:
http://www.USBcell.com - These are really cool because they can be recharged via a USB port, eliminating the need for a charging station.

http://www.greenbatteries.com - good source for both decent batteries as well as battery information.

http://www.atbatt.com - Place to buy rechargable batteries on the web. Also a source for battery blogs and info.

http://en.wikipedia.org/wiki/Nickel-metal_hydride_battery - One of my sources for this post.

http://www.batteryuniversity.com/ - Another good source for battery information.

Tags: Curiosity Killed the Cat, Customer Care, Digital, POV.1, V.I.O.