Receiver Pack
2012-09-11 07:46
A receiver pack which won’t let you down
Receiver packs are often the last component most people worry about despite being the vital link in maintaining control of an expensive model
A couple of things you should know about Nickel based rechargeables:
- New rechargeable cells don’t work well on the first charge
- Rechargeables can loose up to a third of their potential if you charge the night before
- As current demand (servo torque) rises voltage (servo speed) and capacity falls i.e. increasing the likelihood of glitching
- NiCd & NiMH rechargeables perform better if you charge & discharge to 0.9v & 1V respectively per cell using a light bulb or discharger every 6 months or so
- Rechargeables should be discharged and then charged to 40% before storing for a month .NiCd s can be stored at 0.9V per cell
A new pack: go for high discharge avoid unnecessary weight.
- 5 cells rather than 4 cells will ensure you get significantly high voltage longer and under load and your servos will be faster with better torque
- Modern digital servos use a lot of amps. Choose high discharge cells rather than high capacity
- High Capacity AA cells will not perform well as their voltage tends to drop rapidly under load.SubC cells,if weight limitations allow, are the best choice for use with high Amp consuming digital servos on a large boat.
- For competition for example an IB 1400 is a small high discharge cell. It weighs just 21 grams and packs 30 minutes of runtime to 4 large servos. High discharge cells put out huge power before loss in capacity or voltage, are cheaper and charge in 30 to 60 minutes and top up in 10
- A small field charger will let you charge in 30 minutes and top up in 10 from a car battery
- In preparation for use charge and discharge the pack twice. This maximises pack voltage and capacity
- For ultra smooth power add a 5 or 6v output BEC like the Medusa units which will give you the exact voltage from go to wow without radio interference. You can also tailor power output eg in a heli a 6.5v pack can run a 5v BEC feeding a gyro/servo while the other components benefit from the higher pack voltage or a 6v output BEC
Using the pack:
- Charge as close to use as possible and top up between runs. A field charger will charge IB1400 in 30 minutes and let you top up from a car battery in the time it takes to refuel.
- Avoid charging in water-airtight RC boxes unless sufficiently ventilated !!!
- When you finish for the day discharge the pack to .9v per cell (eg 5 cells 5*.9 = 4.5v) using tail light bulb or discharger. Recharge the pack to approx 40% of capacity i.e. 15 minutes and store.
- Charge and discharge (cycle) the pack every 6 months or so to maintain cell balance
When you go out next you will have a pack which will give ultra reliable performance and control for the life of the model.