| x | Nickel-based (NiCd and NiMH) | Lithium-ion (Li-ion) | Lead-acid (Sealed or flooded) |
| Should I use up all battery energy before charging? | Yes, fully discharge once every 1-3 months to prevent memory. It is not necessary to deplete the battery before each charge. Over cycling wears down NiMH. | No, it is better to recharge more often; avoid frequent full discharges.
Yes, on batteries with a fuel gauge, allow a full discharge once a month to enable reset | No, it is better to recharge more often; avoid frequent full discharges. Deep cycles wear down the battery. Use a larger battery if full cycles are required. |
| Should I charge my battery partially or fully? | Allow full charge without interruptions. Repeated partial charge can cause heat buildup. (Many chargers terminate charge by heat. A fully charged battery will re-heat, causing overcharge.) | Does not matter. Charging in stages is acceptable. Full charge termination occurs by reading the voltage level and charge current. Charging a full battery is safe and does not cause harm. | Does not matter. Charging in stages is acceptable. Full charge termination occurs by reading the voltage level and charge current. Charging a full battery is safe and does not cause harm. |
| Should the battery be kept charged when not in use? | Not critical. Manufacturers recommend a 40% charge for long storage. (Open terminal voltage cannot determine state-of-charge.) Store in a cool place. Battery can be fully depleted and recharged. Priming may be needed. | Best to store at 40% charge or 3.75-3.80V/cell open terminal. Cool storage is more important than state-of-charge. Do not fully deplete battery because Li-ion may turn off its protection circuit. | IMPORTANT: always keep battery fully charged. A discharged battery causes sulfation (insulating layer in the cell). This condition is often irreversible. |
| Will the battery heat up during charge? | Yes, towards full charge. The battery must cool down when ready. Discontinue using a charger that keeps the battery warm on standby. | No, little heating is generated during charge. A large laptop battery may get lukewarm. Do not allow the battery to heat during charge. | No, the battery should remain cool or lukewarm to the touch. The battery must remain cold on maintenance charge. |
| What are the allowable charging temperatures? | Important: Rechargeable batteries can be used under a wide temperature range.
This does not automatically permit charging at these extreme conditions.
The maximum allowable charge temperatures are shown below: |
Slow charge (0.1)
Fast charge (0.5-1C) | 0°C - 45°C (32°F - 113°F)
5°C - 45°C (41°F - 113°F)
Charging a hot battery decreases the charge time. The battery may not fully charge.
| 0°C - 45°C (32°F - 113°F) 5C° - 45°C (41°F - 113°F)
Temperature sensor may prevent charge or cut off the charge prematurely.
| 0°C - 45°C (32°F - 113°F)
5C° - 45°C (41°F - 113°F)
Warm temperature lowers the battery voltage. Serious overcharge occurs if the cut-off voltage is not reached. |
| What should I know about chargers? | Best results are achieved with a fast-charger that terminates the charge by other than temperature alone. Fastest full-charge time: Slightly over 1 hour. | Charger should apply full charge. Avoid economy chargers that advertise one-hours charge. Fastest full-charge time: 2-3 hours. | Multi-level charges shorten charge time. Charge must be fully saturated. Failing to do so will gradually decrease the capacity. Fastest full-charge time: 8-14 hours. |
