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Rechargeable Batteries and Chargers

This review covers all types of rechargeable batteries and chargers, and how they affect GPS devices in all types of situations and weather. We cover mainly AA and AAA batteries. These are the two types used by GPS devices and headlights for hiking.

Listed below are the types of rechargeable batteries and their advantages and disadvanatages:

Nickel-Metal Hydride (NiMh) - are the most common type of rechargeable batteries in use today. They are common because they are less toxic then some of the other options, and are considered green. Their disadvantage is that they cannot be used below freezing. The other disadvantage is that they self-discharge 4% per day. Below freezing they will stop functioning after about 30-45 minutes. It also changes the voltage and will shut off the GPS unit. NiMh batteries are known to output a fairly steady voltage of 1.2 volts. When fully charged, they have a voltage of 1.5 volts. This higher voltage can cause problems with GPS devices not working correctly. Some people charge their NiMh batteries a couple days before hiking, and they let them discharge a couple days to allow them to bring their voltage to the 1.2 volts. When they are almost completely discharged, the voltage will drop below 1.2 volts and may shut off the GPS device. Most GPS devices have a setting specifically for NiMh. If you are using NiMh batteries, you should make sure your GPS is set to this type of battery. NiMh batteries have capacity range of 700 mAh to 2900 mAh. The higher the capacity, the longer the batteries will last. Some battery manufacturers advertise high mAh but the batteries do not last as long as would be expected.

Nickel-Metal Hydride (LSD NiMh) - These are a new type of battery. LSD stands for Low-self-discharge. They will discharge 15% per year. Once charged, they will stay charged for an extended period of time. They are sometimes advertised as "Pre-Charged" or "Ready-to-Use" NiMh batteries. These are NiMh batteries are preferred to the standard NiMh batteries.

Nickel-Cadmium (NiCd) - are being used less in the AA and AAA battery world. They are still the primary choice on power tools. They are rarely used in the GPS world. The primary reason is that they are toxic when discarded, so they are considered less green. The main advantage is that they work well in the winter. If you are a winter hiker, this is your ONLY choice. All other batteries will discharge very rapidly and fail. They discharge about 1% per day. When used in Garmin devices, we recommend that you use the battery setting of Alkaline. Alkaline allows voltages of 1.0 to 1.5 volts, and this allows the NiCd batteries to continue working at a variety of temperatures. This will also make the batteries look like they are half-charged all day long. You just cannot rely on Garmin's battery gauge. Try to buy NiCd batteries with 900 mAh or more.

Nickel-Zinc (NiZn) - These batteries have a low discharge rate. They are non-toxic. They can be used below freezing. They seem like the perfect battery except for one very important problem. They are advertised to have 1.65 volts, but in the real world they sometimes have 1.85 volts, which is too high for GPS devices. We strongly recommend that you do NOT use them in GPS devices unless the manufacturer has a battery setting for NiZn.

Rechargeable batteries have a number of issues you need to be aware of:

1. For LSD NiMh batteries used for headlights should be recharged several times a year. Some people prefer to use non-chargeable Alkaline batteries instead.

2. Rechargeable batteries have a problem with "discharge memory". What this means is that if you replace the battery when it is half discharged and recharge it numerous times, it will completely stop working when it gets half discharged. The best way to avoid Discharge Memory is to "recondition" the batteries. Better battery chargers have the ability to completely discharge batteries before recharging them. Some call this "reconditioning".

3. Some battery manufactures might advertise that their batteries have 2600 mAhs, but in reality they only perform at 1500 mAh. Brand names are not good insurance for selecting the right batteries. Pick batteries that are best rated.

4. When rechargeable batteries are overcharged, this drastically reduces their life. And, it might even ruin them. ONLY use battery chargers that will automatically shut off when they are fully charged.

5. Some better battery chargers have the ability to "trickle charge" your batteries. This means that the charger will recharge your batteries when they self-discharge over time. This is okay over a short period of time. But, over an extended period of time this will reduce the life of the batteries. Rechargeable batteries can only be recharged a number of times.

6. Do not allow your GPS to completely discharge your batteries to a completely discharged state. This can damage your batteries. It is better to replace the batteries in your GPS when they still have a charge left. When there is a limited amount of electrons left in the battery, the voltage will start to drop and makes your readings on your GPS inaccurate. Replace them, when they are about 15-25% of battery power left.

7. Rechargeable batteries can be recharged 100-500 times. After a while, they will not hold a charge very long. This is when they need to be replaced.

8. During Winter hiking when it is below 40 degrees, I recommend that you use NiCd batteries. Keep your GPS in your jacket pocket, which will be a little warmer. Additionally, sunlight will not cause the display to light up more and discharge the batteries faster.

9. Keep your GPS display light at the lowest setting. This can make your batteries last 200-400% longer. Also keep the GPS display out of the sunlight. When sunlight hits the GPS display, it causes the display to light up more. Also keep the GPS topo maps turned off. Making the GPS topo map refreshing consumes battery power very quickly.

LaCrosse Battery Charger

There are a couple things you should look for in a battery charger:

1. The battery charger should be able to charge both NiMh and NiCd batteries.

2. The battery charger should be able to charge each battery individually.

3. Make sure that the battery charger will shut off each battery from charging when the battery is completely full.

4. Make sure that the battery charger has the ability to charge at different rates. The slower it charges, the longer the battery life will be. Whenever possible, I charge ar the slowest rate.

5. Make sure that the battery charger can charge both AA and AAA batteries.

6. Make sure that the battery charger can Recondition the battery.

The LaCrosse battery charger comes with a manual to help you learn how to use the charger. The LaCrosse battery charger has lot of features. Many of the features you will never use. And some of the features you wish it had, it doesn't. But, in 2009 it was the best charger on the market. The one feature that I very much wanted was the ability to determine what percentage of the battery is charged. The company that makes it, states that it does have this feature, but we found that it doesn't work. But, it does do all of the features above. This battery charger will extend the life of your batteries dramatically. If you buy a battery charger, I would recommend that you buy this one.

One of the biggest mistakes that most people in buying a battery charger is that they don't get a good one the first time. Most people have to go back later and buy a good one. Good ones, like the LaCrosse battery charger, are not found in most stores. You really need to order it on-line.

eneloop battery
Sanyo Eneloop AA Batteries
LSD NiMh Rechargeable Batteries
Best NiMh batteries of 2009
NiCd Rechargeable Batteries
Use for Winter Hiking
LaCrosse Charger
Best battery charger in 2009

Links and References:

Catskill Mountaineer Forum - Discuss batteries, chargers, and GPS devices here

California Information sheet on rechargeable batteries - very informative.
Source of batteries and chargers
Source of batteries and chargers
Source of batteries and chargers

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