How to Charge Rechargeable Batteries for Peak Performance
Ni-Cad (Nickel Cadmium) Batteries
1/ All Ni-Cad Batteries have to be Discharged soon after use. This is to avoid the dreaded "Memory" effect that on subsequent re-charges can cause a momentary drop in performance during a race. A simple discharger can be made from a car 12v bulb.
2/ Try to time your charge to complete just before a race. This will ensure maximum punch and duration. If a Ni-Cad is left to cool after a charge this advantage dissipates.
3/ The higher the charge current the more Punch the Ni-Cad battery will have (up to around 8 amps), however, the downside to this is a reduction in duration and effective battery life.
4/ Ni-Cad Batteries should be left to cool for about an hour after use before recharging. This will increase the effective life of the battery.
Ni-Mh (Nickel Metal Hydride) Batteries
1/ Never charge Ni-Mh batteries at a current higher than 4.5 amps. Although these batteries can give a higher voltage than Ni-Cad Batteries, they are much more sensitive and easy to damage if charged too quickly.
2/ Charging methods for Ni-Mh batteries can also be detrimental. The best I found was the "Slope" method. Avoid "Pulse" charging as this tends to effect crystal formation detrimentally and (it seems to kill them off) thus reduces duration over time.
3/ If using a temperature cut off charger on Ni-Mh batteries set to no more than 40 Degrees Centigrade. Any higher than this can damage the crystals.
4/ It is not necessary to discharge Ni-Mh Batteries. Unlike Ni-Cad batteries they do not develop a memory. Also, if they are totally discharged they sometimes will not charge straight after and need to be coaxed with a 10 minute trickle charge.
5/ Ni Mh Batteries can be recharged shortly after use without any discernable detrimental effects.
Li-Po (Lithium-Polymer) Batteries
1/ Li-Po batteries are a huge step forward in performance compared with Ni-Cad and Ni-Mh batteries. However, care has to be taken when charging. If certain procedures are not followed they could burst into flames or even explode, therefore I do not recommend Li-Po batteries for RC beginners.
2/ Li-Po batteries are more expensive and have a shorter effective life. Generally considered to be between 200 to 400 charge cycles compared to 1000+ for Ni-Cad and Ni-Mh.
3/ Consider a Battery pack listed as "2S 5000Mah 40c 2C".
"2S" is the number of cells in the pack, in this case 2 cells. Each cell provides around 3.7 Volts, so a 2S pack is around 7.4 Volts.
"5000Mah" (Mili-Amp-Hours) is the capacity. The amount of charge the pack can hold.
"40c" is the maximum Discharge rate. Which in our example would be calculated as 5000 (Mah) x 40 = 200000Ma (200 Amps).
"2C" is the maximum Charge rate. 1C being 5 Amps, so in our example 2 x 5 = 10 Amps.
4/ To safely charge your Li-Po Battery I would recommend a good Computerised charger, preferably one that can handle a Charge current of around 25A and always place the charging battery on a fireproof surface.
5/ Finally. NEVER leave your charging Li-Po battery unattended and NEVER EVER charge it above the recommended rate. When not in use, store with around 60% charge remaining in a fireproof box or bag.
For More Tips, Advice and Setup Information, check out our RC Model Car Setup Guide.
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