So you are probably wondering why there is a section on batteries, the reason for this is because most cavers love and respect nature, and if you fall in to this category, you could help out the environment by not using disposable batteries such as alkalines and lithiums. However if you are using a blue or black colored Petzl Myo XP, you should not use rechargeables because they found out that doing so could set fire to the wire that attaches the headlamp to the battery pack. Don't use lithiums in the MYO XP either since the manufacturer states that it can brake the circuitry. So what are some other reasons I should use rechargeables if my headlamp allows it? * They will save you money since you can recharge them many times. * They have longer run times than alkaline batteries. * Their voltage has a much flatter curve than alkalines (they don’t keep dimming and dimming at a constant pace). Here is a graph to show how long 5 different batteries lasted and what their voltages were as they were being discharged. Don’t forget to note the flatter voltage curve on the lithiums and rechargables compared to the alkalines: My brother once went through a set of Energizer 2500’s after something like 10 charges. Energizers tend to last nowhere as long as Eneloops, but Energizer has a new rechargeable out that claims you can get up to 100 charges out of it, but it’s capacity is only 1830 mAh. Still this is nothing compared to the claims of Eneloop; they say you can recharge them for 1000 times, and they work so well that nobody has been able to prove them wrong so far. Most people experienced with batteries say to stay away from rechargeables with a high mAh rating if you want them to last for many charges. An example of a high mAh would be anything over 2000 mAh. Here is what you can do to make your rechargables last longer: * Don’t fully drain them, instead recharge them after they are about %50 drained. This is the same technique that electric cars are using right now to add much more longevity to their batteries. * Condition them, this is a must if you want them to last a long time, and here is how to do it: after every 7 charges, charge them up and discharge them as slow as you can until they are fully discharged. For instance on the Apex, set it to flood mode and then set it to low. Some chargers are so smart they actually tell you when the batteries need conditioning and they can actually do it for you. * Don’t discharge them at a fast rate by using your headlamp on it’s highest setting the entire time you are caving (unless that is the only mode where you can see properly). * Don’t let your charger keep charging the batteries even though the batteries are fully charged. Some chargers are smart enough to not let this happen, but most are not. Say for instance your Energizer batteries are only half discharged, and you charge them with an Energizer charger, well here is what will happen: the charger is preprogrammed to shut off after lets say 8 hours, but since your batteries are already half charged they will be fully charged after 4 hours. The remaining 4 hours they will get really hot and this heat will cut in to their lifespan. There is only 1 type of battery that highly experienced battery users recommend: Eneloop. Even though the Eneloops runtime is lower than the Energizers, they are better than Energizers for the following reasons: * They are low self discharge which means that if you charge them up, they will only loose %15 of their charge if they sit on the shelf for a whole year. Normally rechargeables loose %1 a day if you charge them up and then sit them on the shelf (or in your cave pack). * They can be charged 1000 times compared to Energizers best battery that can only be charged 100 times. * They are the same price as store bought rechargeables, but they are a much better value. You can get either 4 AA's and an smart Sanyo charger, or just 8 AA’s for around $20 (before shipping) at Batteryjunction.com (Note: they accept payments through Paypal). The smart charger will automatically stop charging when the batteries are fully charged, but the only downside to the charger is that it charges very slowly (about 8 hours). I recently saw 4 Energizer 1830 mAh rechargeables at Best Buy for $15, and I would rather wait a few days for the Eneloops myself. * They run at a higher voltage than most rechargeables, and so for some applications your light might actually be brighter than using a different brand rechargeable. * 1000’s of people on the net swear by them and claim they are the only rechargeable you should buy. * They are extremely reliable. Well that concludes the article, you are now more knowledgeable than %99.9 of the masses who use them.