- Thu Jan 21, 2016 10:28 am
#39365
Alkaline batteries have a relatively high series resistance that gets higher as they discharge. To solve this by adding capacitors accross the supply isn't really all that practical as even relatively big capacitors may not supply enough current for long enough when in active TX - so the battery technology is really where I think you need to focus.
al1fch has the right idea as LiFePO4 batteries maintain a constant discharge voltage that stays close to 3.2V until exhausted. But you should take care not to let them discharge below 2V otherwise they will become useless. Also note that Lithium Polymer battery chargers (the most commmon type) terminate at 4.2V which will damage LiFePO4. So you'd need a suitable charger... check out http://www.hobbyking.com/ for batteries and chargers
Hybrid NiMh is another possibility (look for Eneloop or Maplin Hybrid batteries) as these have low internal impedance and low self-discharge characteristics, plus they can be charged by conventional NiMh chargers - but they have the disadvantage that their terminal voltage varies widely from min to max charge. 2V to 3.2V for two in series and 3V to 4.8V for three - so you'd need three and a Low Dropout regulator.
al1fch has the right idea as LiFePO4 batteries maintain a constant discharge voltage that stays close to 3.2V until exhausted. But you should take care not to let them discharge below 2V otherwise they will become useless. Also note that Lithium Polymer battery chargers (the most commmon type) terminate at 4.2V which will damage LiFePO4. So you'd need a suitable charger... check out http://www.hobbyking.com/ for batteries and chargers
Hybrid NiMh is another possibility (look for Eneloop or Maplin Hybrid batteries) as these have low internal impedance and low self-discharge characteristics, plus they can be charged by conventional NiMh chargers - but they have the disadvantage that their terminal voltage varies widely from min to max charge. 2V to 3.2V for two in series and 3V to 4.8V for three - so you'd need three and a Low Dropout regulator.
