Battery Facts FAQ

What is the difference between Nickel Cadmium, Nickel Metal Hydride, Lithium Ion and Lead Acid batteries?
Nickel Cadmium-NiCd
Nickel Cadmium  batteries may suffer from reduced run time if they are are not discharged completely before being recharged. This is the so called memory effect which reduces battery life but can be reversed by completely discharging (Not to zero volts but 1 volt per cell. Running the device until it powers down is sufficient.) and recharging, sometimes over a number of cycles (at least 3 times). A more common reason for reduced life is overcharging by poorly designed battery chargers which continue to charge the battery rather than automatically shutting off and is not reversible. You can determine if this is occurring by checking if the battery is warm or hot sometime after the charger indicates a full charge.
Ni-Cd batteries use cadmium which is highly toxic to the environment if not disposed of properly. They have a life of approximately 800 cycles or 3-5 years but in practice this is probably much less due to memory and overcharging.
Nickel Metal Hydride-NiMH
Nickel Metal Hydride batteries have an approximately 40% higher charge density and will run longer on a charge than an equivalent NiCd. They do not suffer to the same extent from the memory effect and do not need to be fully discharged before recharging although occasional discharging may be beneficial. They have a life of approximately 400-600 charge cycles. They can be stored charged or discharged but should be charged every 6 months to prevent them from drying out. They have a higher self discharge rate that other types of batteries when no in use.
Ni-MH batteries are a more environmental friendly alternative to Ni-Cd.
Lithium Ion - Li-Ion
Lithium ion batteries have the greatest charge density (twice that of Ni-Cd) and do not suffer from memory effect. Although more expensive they offer longer use, lighter weight and less self-discharge than other battery chemistries. They have a life of approximately 400 charge cycles . They are more environmentally friendly as they don't contain toxic materials such as Mercury or Cadmium.
The biggest shortcoming of rechargeable lithium ion batteries which is seldom mentioned is that they lose some of their capacity after one year and may fail after 2 or more years even when they are not in use. Another good reason to not buy cheap, discount batteries.
Lead Acid and SLA (Sealed Lead Acid)
Lead Acid batteries are the same as the one in your car and are generally very reliable . They should be kept fully charged and there is no requirement for discharging prior to recharging. They should not be totally discharged to 0 volts which will shorten the batteries life. They have a life of approximately 400 charge cycles which can be increased by not fully discharging them in normal use. They can be stored for up to six months fully charged at which point they should be charged again.

Can I upgrade my batteries to lithium-ion or a different battery chemistry?
Different battery chemistries have different voltages and charge characteristics so unless another type is shown in the cross reference or manufacturer's information the answer is no. NiCd batteries can normally be replaced by their NiMH equivalent and require a different battery charger if the charger was designed for NiCd only. NiMH batteries charged in a NiCd charger could overcharge the battery as would be indicated by the charger light staying on continuously even after charging is complete. In this case turn the charger off and remove the battery which will be fully charged. A NiMH charger can charge either NiCd or NiMH.  NiCd and NiMH batteries are interchangeable in cordless phones because of the type of charger they use.

Can NiMH batteries be substituted for alkaline batteries?
Usually they can in spite of the fact that NiMH batteries are 1.2 volts and alkaline batteries are 1.5 volts. Alkaline batteries start their life at 1.5 volts and gradually drop to 1.0 volts whereas NiMH batteries stay at about 1.2 volts for 80% of their discharge cycle.

What are Amp-Hour ratings?
Amp-Hour rating of battery capacity is calculated by multiplying the current in amperes times the time in hours. Battery run-times are a rule of thumb and may differ significantly in different equipment depending on current consumption and usage.

What if the mAh current rating is different than my original battery?
If the mAh rating is higher then the replacement battery will last longer than the original. In some cases the replacement current rating may be less in which case it won't last as long the the original when it was new but is otherwise compatible.

Care of new batteries.
New batteries come partially discharged and should be fully charged before using them. They generally do not reach their rated capacity until they have been charged and discharged at least 4 times. It is recommended that new batteries be charged overnight even though the charger may indicate that the charge is complete after a few hours. Sometimes charging may stop during the initial charge and it is necessary to remove the battery for approximately 15 minutes to let it rest and then put it back on charge.

Battery Storage
NiCd, NiMH and lithium-ion batteries will discharge during storage which is normal. Lead Acid batteries should be stored charged and trickle charged if storage is longer than 3 months.

What is the expected life span of a battery?
Generally between 400 and 800 charge cycles or 2 to 4 years under normal conditions. As a battery ages it's hours of use on a charge decrease and it may finally not accept a charge in some cells.

Should batteries be recycled?
In the interest of the environment all batteries, particularly NiCd and lead acid, should be recycled and not thrown in the garbage. Call 1-880-8-BATTERY or visit www.rbrc.org  for the location of a recycling depot.