Proper Battery Care and Maintenance

NiCd Batteries

NiCd batteries are the most well known kind of battery but have since been replaced by the NiMh for standard RC application. NiCd batteries have one great downfall, which is the "memory effect" meaning that when the NiCd batteries are not properly charged and discharged that can actually lose that capacity to hold a full charge over time. When NiCd batteries are properly maintained, they are known to be able to produce 1500 cycles of use (meaning charge and discharge) and with the low price point, NiCd batteries are therefore known as a good value.

But, just because NiCd batteries are inexpensive and consistent when cared for properly, the cadmium in these batteries is bad for the environment and must be disposed of properly when the battery is exhausted and can no longer be used.

Exercise your NiCd batteries - If you have NiCd batteries they need to be exercised once per month. Exercise is the process of discharging the battery, usually up to one volt to ensure the maintenance of proper capacity. Discharging properly can actually recondition an NiCd battery that has been subject to the "memory effect." A long slow discharge can break down the crystalline structures that develop over time and that are responsible for the loss of capacity in an NiCd battery.

Proper Charging - Using a proper NiCd battery charger is an excellent way to ensure the longest life possible for your rechargeable batteries. Proper battery chargers sense the voltage change once a battery has been fully charged. You can also purchase special battery chargers or controls that can charge, discharge, cycle and balance your batteries. Many encourage "trickle" charging or slow charging NiCd batteries for long life. Fast charging can be considered more efficient from a time and power usage standpoint, but you can run the danger of damaging the battery by overcharging. Don't forget, NiCd batteries may heat up during charging.

Storing NiCd batteries - You want to store NiCd batteries in a cool, dry place to reduce the risk of corrosion and damage to the batteries. Because batteries lose their charge naturally over time, you need to charge NiCd batteries once per year and exercise them approximately monthly. Generally, an NiCd battery has a shelf life of six months (give or take) so take that into consideration when you make your storage decisions. Specifically, NiCd batteries will lose approximately 10% of their power per month while in optimal storage.

General Rechargeable NiCd Battery Info - Most rechargeable NiCd batteries come completely discharged and need to be fully charged when they arrive. In many instances you won't get the optimal power from the battery until it's been discharged and recharged two or three times. When you're using these cells, its best to fully discharge and recharge them every two to three weeks. This is true of individual cells or of an NiCD battery pack. You'll also want to keep the batteries clean and in good condition to prevent corrosion so if you store them, clean them up with some alcohol and swabs on the contacts.

NiMH Batteries

We know that NiMH batteries are the industry standard in the RC world and that's because they are consistent, reliable and have a long shelf life. NiCd batteries are considered to be a good value for folks just playing around with RC but NiMH with their longer shelf life and high level of performance are really the right choice for today's RC enthusiast.

Lower amp charging is better - When you need to recharge NiMH batteries, a big thing to consider is how quickly you plan to charge them and at what voltage. The higher the amp charge, the more you actually work the battery which can be detrimental. If you charge it at a higher rate there is no performance improvement - only there is the potential that you'll damage the battery. Professionals recommend a charge rate of 3-5 amps. A slower, less amperage charge will yield the best results.

Look for a peak detecting battery charger - Using a NiCd battery charger for NiMH batteries can be a problem. Every battery charger powers a battery up to a certain point and then detects when its fully charged so it doesn't damage the battery by overcharging it. The way that a charger does this is by detecting a voltage fluctuation in the cells themselves that indicates a full charge. The voltage fluctuation in an NiMH battery is more subtle so the NiCd battery charger may not sense it properly. Since NiMH batteries are easily damaged by overcharging, using a proper charger is important.

If you have a mechanical or adjustable battery charger, you can use them on NiMH batteries but you need to use extreme caution. If you have a mechanical timed battery charger, you will need to closely monitor the charge and temperature of the batteries lest you damage them with overcharging or overheating. If you have an adjustable battery charger, you'll need to set it to .02 - .03 volt voltage drop so it can properly sense that the NiMH battery is charged.

Don't Discharge All The Way - If you want to discharge your NiMH battery pack, you can safely do so at pretty much any rate, but you should not discharge them completely. Because NiMH batteries are not susceptible to the same "memory effect" we see with NiCd batteries, you should leave a little charge in them because letting an NiMH battery pack bleed to zero volts could actually damage the battery. This means don't let the NiMH batteries go below .9 volt per cell. In fact, if you are planning to store your batteries for more than a week, you should actually make sure your NiMh batteries are at about half charge. The reason is that when NiMh batteries are left for longer periods, their power bleeds off and you want to avoid that full discharge.

Using and Recharging - You can actually use and recharge your NiMH batteries multiple times in one day. In fact, if they have been stored you may want to fully discharge and recharge them because you'll get better performance the second and third times you use them. You'll need to let the packs cool completely between use and charge because an NiMH battery is more susceptible to heat damage.