A BASIC GUIDE TO SUCCESSFUL |
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| chapter six | |
| Battery Chargers | |
| The difference
between a great flight and a disappointing flop (all
other things being equal) is a good charge in the flight
battery. Only a peak or thermal detect fast charger will
provide this on a regular basis. Most of the reasonably
priced (compared to a few years ago read cheap!) chargers
use the 'peak detect' system. As a battery is being fast
charged the voltage rises to a peak then descends a
little before rising rapidly towards it's dramatic demise.
This first peak is what the charger detects and then in
most cases drops to a trickle charge. HiTech amongst
others produce a number of 'peak detect' fast chargers of
varying specification, be sure that whichever you choose
it is capable of charging at least 7 cells. Unfortunately in life, as those of you over 30 will know by now, things are rarely that simple. When a battery pack is on charge it may well throw 'false peaks' which will cause a basic peak detect charger to end the fast charge as above. If you have been away chatting you will be unaware that the battery is incompletely charged, until you launch the model that is, with varying consequences dependant upon the type of model. The cheap solution is to start a stop watch at the beginning of the fast charge and stay within hearing distance of your charger's irritating little switch off tune (if it has one). Assuming that you started with a discharged battery and knowing the approximate charging period* you will then be able to assess whether the battery really is charged or not. (Here you may be wondering why you did not buy that cheap clockwork timer charger...). The expensive solution is to buy a more sophisticated charger which incorporates 'peak detect delay' circuitry or some other complex sensing and checking circuitry enabling it to pause after a peak is detected and confirm whether this is indeed the fully charged peak or not. * Battery capacity in mAh divided by 1000, divided by the charging rate in Amps = the charge time as a part of an Hour. For example Where a charger allows manual setting of the charging rate it should be set in the range of 2x to 2.5x C where 'C' is the cell capacity (in mAh) divided by 1000. For example Again this assumes the use of good quality rechargeable cells designed to be fast charged. Flight batteries should be slow charged occasionally as this improves their overall performance. In effect it brings the cells back 'in line' as regards their individual charge state. Trying to fly with a slow charged pack may, however, give disappointing results. Fast charging at the appropriate rate for the cells will always produce more thrust and better flights, the sooner you fly after charging the better. |
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