Basic Battery Review
April 18, 2012
|Alkaline (specially marked "rechargeable" only)||Gradual charge loss, 1.5v/cell instead of 1.2v, low self-discharge rate, no toxic metals (throw them in the trash when done in the US)||Fewer recharge cycles, diminishing charge capacity over battery life|
|Lithium Polymer (LiPo)||Faster recharge, good "power to rate ratio" (?), several use cylces even in a day, relatively cheap||These batteries catch fire or blow up airplanes. Special disposal required.1.2v cells|
|Nickel Cadmium (NiCad)||Cheap, formerly ubiquitous||Special disposal required, harder to find because of NiMHs replacing them, memory effect, low capacity, 1.2v cells, relatively heavy|
|Nickel Metal Hydride(NiMH)||Light weight, high capacity,no toxic metals (US)||High self discharge rate of 25%/month, High capacity versions won't fully charge in all chargers, very heavy, 1.2v cells|
That chart was all the original material I got I totally pirated this from zbattery.com:
We frequently get asked the question, "How am I supposed to connect my battery if I want to double the capacity but not the voltage?", or similar questions. It can be confusing if you've never done it, but hopefully this'll make it simpler. Be sure to read the important notes at the bottom to protect yourself from damaging any equipment!
Connecting in Series
When connecting your batteries in Series you are doubling the voltage while maintaining the same capacity rating (amp hours). This might be used in a scooter, Power Wheels kids vehicle, or other applications. Just use a jumper wire between the negative of the first battery and the positive of the second battery. Run your negative wire off of the open connector from the first battery and your positive off of the open connector on your second battery.
Connecting in Parallel
When connecting in Parallel you are doubling the capacity (amp hours) of the battery while maintaining the voltage of one of the individual batteries. This would be used in applications such as laptop batteries, some scooters, some ups backups, etc. Use a jumper wire between the positives of both batteries and another jumper wire between the negatives of both batteries. Connect your positive and negative wires to the same battery to run to your application.
Important notes: When connecting batteries in a pack there are some important things to keep in mind - - Find out the requirements of your application. For example: Don't double the capacity on your Power Wheels vehicle if you're not supposed to...you could burn up the engine. Follow the recommended guidelines for your application. - Don't use two different chemistries when connecting a pack. Usually the voltages will be different, but more importantly the charge rates will be different and the capacities may be different, thus resulting in a shortened life span. - Try to match capacities as much as possible. When connecting batteries in a pack you should try to match the capacities as much as possible to avoid discharging one battery quicker than another. A pack operates at a combined voltage so your one cell that discharges quicker will likely discharge deeper than it may be able to recover from.
...and from rccartips.com:
What to do to get the best performance from batteries
Secrets to making your batteries perform better and last longer...
- Discharge completely before charging.
- Use a peak detection charger.
- Charge at a consistent rate, usually 3.5 Amps.
- Use or cycle the battery (charge, full discharge) at least once a week. (Note: this does not apply to LIPO)
- Avoid using a battery more than once a day for NiCad and NiMH. For LIPOs you can use several times a day.
- Avoid charging a warm or hot battery. Let it cool first.
Tips: The higher the charge rate, the higher the voltage and performance, at the sacrifice of lifespan. I usually charge at a 3.5 Amp rate.
What not to do to your batteries
Avoid doing these at all costs...
- Overcharging. This will permanently destroy a battery pack.
- Do not let the battery get too hot. This may happen if you are over-geared, using the wrong motor, running the rc car in grass or uphill, or not enough air to cool the battery.
- Do not "short" the battery. This happens when you accidentally touch the positive (+) end with the negative (-) end.
- Do not throw batteries in the trash. Dispose of old batteries at a recycling facility.
(This next part I can't remember the source of-Max)
Volts, Amps and Watts
WATTS are the units of POWER. A hairdryer full-on might be 500 WATTS; on the low-power setting it might be 200 WATTS. The higher the POWER the bigger the charger.
VOLTAGE must be matched to the equipment in use (usually 5v for μCs, 4.5-6v or even 7.2 for servos, just about anything for motors...)
CURRENT indicates the flow of energy from the battery and is measured in AMPERES (or AMPS). Zero current and the battery is not discharging. The higher the current the faster the battery will discharge.
A battery is rated in AMPERE-HOURS (abbreviated Ah) and this is called the BATTERY CAPACITY. For example, a small boat might have a 12 volt 100Ah battery. This battery will provide 100 AMPERE-HOURS before needing to be re-charged. This may be taken from the battery as
1 AMP for 100 hours
2 AMPS for 50 hours
10 AMPS for 10 hours etc.
WATTS are VOLTAGE multiplied by CURRENT, so taking the above example with the 12 volt battery
1 AMP x 12 VOLTS = 12 WATTS for 100 hours
2 AMPS x 12 VOLTS = 24 WATTS for 50 hours
10 AMPS x 12 VOLTS = 120 WATTS for 10 hours
Re-charging a battery follows the same principle. The requirement is usually to re-charge the battery over-night - say in 10 hours.
Because a battery is not totally efficient at converting electrical energy into chemical energyand vice-versa, re-charging a 100Ah battery requires about 120Ah to be put back into it, andthis can be achieved by either
120 Amp-hours / 10 hours = 12 Amps for 10 hours
120 Amp-hours / 15 hours = 8 Amps for 15 hours
120 Amp-hours / 24 hours = 5 Amps for 24 hours etc.
CURRENT = WATTS / VOLTS
therefore if, say, the lights add up to 36 WATTS and the battery VOLTAGE is 12 VOLTS then the CURRENT taken from the battery will be
36 WATTS / 12 VOLTS = 3 AMPS
If these lights are on whilst the battery is being charged, then the battery charger must also provide an extra 3 AMPS to power them.
Hope that's useful for people using more than 4 AA cells!