|Nov 30, 2013, 10:13 AM|
When do you replace your transmiter batteries ?
Have a DX-7 transmitter that is about 4 years old. Usually recharge the batteries when the voltage gets under 10. Use a peak charger and after an hour or so will get voltage up to 11.8 to 12.0 volts. OK, but a dozen flights later the voltage is down around the 10 volt reading again. It will hold this voltage for many more flights before dropping below 10.
Thinking about making up a pack of Eneloops for next season (wonderful Wisconsin Winters---HA).
|Nov 30, 2013, 11:02 AM|
United States, IA, Keosauqua
Joined Sep 2010
I have a FlySky-(TH9X) that I use NiMh batteries I bought at Wally World. I tested it a while back by turning it on & checking periodically.
At 8:00 A.M. tx read 9.5 volts
At 10:00 A.M. it read 9.2 volts
At 11:00 A.M.--9.2
At 11:50 A.M.--9.2
At 12:00 ---9.1
At 2:10 P.M.-9.0
At 3:55 P.M. it read 8.9 & the beeping told me to re-charge.
So based on that, I recharge after the voltage reads 9.1--that still gives almost a 4 hr. cushion. Having said that, I've heard that voltage readings on transmitters are not accurate, so best to do a similar check with your Tx unless you just want to recharge more frequently than you would have to.
|Nov 30, 2013, 11:57 AM|
Joined Feb 2001
I cycle all my transmitter batteries twice a year with a good charger. Most all LiPo chargers will cycle NiCad and NiMh batteries. I keep a log and replace the battery when it gets to about 80% of new capacity. It pays to have a plan for transmitter battery maintenance.
|Nov 30, 2013, 12:03 PM|
Joined Oct 2004
Recharging at 10 volts is using a very small portion of the capacity of your Tx battery (as you've determined). Repeated shallow discharges are generally not the best thing for any NiXX cell and you would achieve far better performance by allowing your pack to discharge a greater portion of its capacity before recharging.
Over the years I've found that discharge to Transmitter low voltage alarm followed by low current (50-100mA) slow recharge provides the best long term performance.
|Dec 01, 2013, 06:42 AM|
My 9x's and my Radiolink 6EH heli radio all use these and all 3 radios - the NiMH are near 3 yrs old and still delivering fine.
I use a couple of old Futaba M series chargers at 50mA output both Tx and Rx ... plus if I want a real punch in charge - I have a Prolux auto Radio charger that charges at near 1A rate with auto cut off.
Eneloops are a Marketing name and the LSD (Low Self Discharge) format is widespread now ... not exclusive to Enerloops. My cheapo Grundigs are LSD ...
But anyway - get a low rate charger like I have ... the 4.8v output will do your Spekie fine without any need to unplug etc. At 50mA rate - its no problem. Thn you have g'teed full charged Tx.
Some advise that you should change out cells after a reasonable period ... I'm not against that and think it a wise precaution ... If I didn't have a discharger station to check my cells - I would change out maybe each start of season. The old can be relegated to bench use or some other low risk job.
As matter of interest - I use same Grundigs in my biplane with glow engine and used as well in my 15cc Gasoline powered .. Rx packs and ignition ... never any problem.
|Dec 01, 2013, 08:28 AM|
thank you, mrforsyth,
Now that you mention further discharging, I forgot to turn of my xmtr once and ran the batteries down overnight. They charged up fine and seemed to hold their volatage better.
Still, after 4 years of heavy use I think I owe my ol' "Spekie" some new batteries....
|Dec 01, 2013, 08:23 PM|
United States, FL, Orlando
Joined Oct 2013
Unlike LiPO's, NiMh batteries are very tolerant to discharging and can be safely discharged to 0 volts, but NOT further. They are damaged when forced into reverse polarity (negative voltage, basically). If a NiMh pack has a weak cell, it can discharge before the others be forced into reverse polarity, when the pack is fully discharged. Accidentally doing that once most likely did no harm.
I have some old solar lights outside. They are like 7 years old and 2 still work. They take 2 batteries each and I put NiMh cells in them like 5 years ago (when they all still worked). Those cells discharge fully every night and both still hold some charge as the LED is still bright for a few hours a night.
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