This is a question every new sailor wants an answer to. There is no precise answer due to the number of factors involved. These include battery type & quality, wind & atmospheric conditions and the range you have been sailing at.
If you were to check out the fine print on a range of different batteries (although many don’t even have the fine print), you will find that not all batteries are equal. Rechargeable AAs typically range between 600mAh and 2000mAh. The mAh rating is a linear measure of battery life; ie. A 1200mAh battery will theoretically last twice as long as one rated at 600mAh. Be aware that the bargain pack at the supermarket may well have a low rating. This is not necessarily a bad thing ? if you get a good day’s sailing with them you can re-load a new set next time you sail.
Improvements in battery technology mean that each year, manufacturers are coming out with new batteries that will outlast the previous year’s top performer. This of course is great news for us!
The transmitter batteries should last at least a day and probably a lot longer (good batteries will last for 8-16 hours sailing depending upon conditions). Your transmitter has two LED lights to indicate battery condition – one red one green. When the green light is lit it is safe to sail. When the red light starts flashing it is time to change the batteries.
The boat pack will have a shorter life, depending on the strength of the wind. In strong winds you will need to change the batteries more frequently. As a rough guide you can expect the boat pack to last just a morning (say 4 hours) in strong winds but longer in light winds. Even in light winds do not try to get more than one full day’s sailing from them – it’s not worth the risk (unless you have a rescue boat to hand). If at any time you sense the response of the winch is slowing down bring the boat ashore and change the batteries.
Alkaline or Rechargeable Batteries?
You may use either normal dry cell batteries or rechargeables. Both are acceptable under the RC Laser class rules
An important point to be aware of is that dry cell batteries deliver 1.5 volts, whereas most rechargeable batteries only deliver 1.2 volts. For the transmitter this does not matter but if you want to use 1.2 V rechargeable batteries for the boat, you will require a 5-cell pack fitted with a Futaba plug. The science behind this is that the servos we use in our RC Lasers have more grunt and speed when fed with a 6 volt system. The steering servo is not a problem as it is working a small load. The sail winch however has a good appetite and needs the full 6 Volts to function well.
Any of the available rechargeable batteries are suitable. The common types are Nickel Cadmium (NiCad) and Nickel Metal Hydride (NiMH). NiMH batteries are more expensive. The main advantage of NiMH batteries is that they do not have ?memory’ like the NiCads. (The problem with batteries with ?memory’ is that they need to be fully drained and fully charged with each cycle to maintain optimum cycle life).
If you elect to use rechargeable batteries you will need a suitable charger. We have a 10 battery charger (we are still hunting for a 13 battery model!) available for purchase at a very reasonable price (it accepts either AA or AAA). This particular charger is recommended because it has a discharge feature that enables you to drain the batteries prior to charging. This eliminates the ?memory’ problem with NiCad batteries. The other attractive feature of this particular charger is that it drains/charges each battery on its own circuit. This means each battery will be fully discharged and then fully charged. It also means you can charge any number up to 10 at a time. It is a slow speed (trickle) charger, the recommended type. To fully charge a set of batteries will take close to 24 hours ? particularly after allowing for an hour or two at the start to drain any residual charge (recommended procedure for NiCad batteries; not required for NiMH batteries)