3slithium for tx?

[chris higdon]

would it be possible to use a 3spack of tp2100s in a jr3810

<the 3s1p pack is about the same size as the 8cell600 mah AA pack in it now

is the voltage close enough or would i need a regulator?

8s AA 600mah 9.6vnominal what is the max voltage of a charged pack?
3s tp2100 2.8volt min=8.4v and 12.6 max
12vot gellcell 12volts <at least> how many volts can a sla battery get at fullcharge?

my tx has a low battery alarm at 9v <i think , but it could be 8.5>
this means that the alarm should go off before the voltage is low enough to cause lipo damage
also the lipos should last ages at the low amp discharge they would see

i have seen a guy using a 12v gell cell as a reciever pack with an extension lead<glider guys tend to fly for hours at a time>i am not sure what brand his radio was though

can a tx tolerate up to 12.6v, withought damage?


thanks for any input, i have a hunch that this might work but i just wanted to run it past you guys to see if my idea is plausible

[everydayflyer]

Some of the Transmitters do not seem to mind the higher (12.4-12.6) voltage and some do. I use 2300-2500 nIMH cells 8 each AAs and routinely get 7-9 hours of transmitter on time. I fly an extreme amount and very often recharge every 3 to 4 days but have found the self discharge rate of the Sanyo HR AA NiMH cells lower than many others.

Paste from my Transmitter Battery Thread:

Sanyo HR 2500 AA update.Charged on Friday. Today is Wednesday, five days since charged. Nine hours Transmitter on time displays showing 9.3 volts which is right around time for low voltage alarm to sound. Hope to have some more decent flying weather tomorrow(6 flights today) so they are on the charger.

and another paste

Sanyo AA 2500 mA HR charged 23 days ago.
Under a 300 mA load 10.25 volts.
Discharged on Triton at 500 mA rate, approx. twice Transmitter drain.
165 minutes to reach 9.3 volts. (last test 193 min. fresh of charge)
187 minutes to reach 9.0 volts capacity 1,580 mA to here.
This is 343 mA less capacity than when tested fresh off of charge.

18% capacity lost during 23 days of storage.
Sanyo HRs look like the transmitter batteries for me. They also would make a great flight pack for slimers.

___________________________

It seems that atleast Li Ion cells more closely match Ni cells in voltage mutiplies. 8 Ni cell equal approx. 11.70 volts , 3S Li Poly equaly approx. 12.45-12.6 and recent Li Io cells tested in Battery And Chargers Forum by RD would appear to be 3 cell equals 11.4 volts not long after charging.

http://www.rcgroups.com/forums/showpost.php?p=4229973&postcount=112

Charles

[chris higdon]

well i have a spare transmitter <my first 4channel tx> that is that same brand that i use as a trainer occasionally, i think i will have to put a crystal in that one and see how it goes with the 3s lithuim

[Ib Jensen]

The 2400 ma Lith cells used in many computer packs and available for 8.16 each from Battery space make a good TX pack when used with a three cell protection circuit also available from BatterSpace. I put together a 4800 ma pack for my EVO TX and flew with it for the first time Sunday. The voltage didn't move after a day of leaving the TX on a lot of the time just to see if the voltage would drop. The Lith cells have a lower discharge rate than the NiMH. Since the cells are larger than standard, fitting them into the TX may be a consideration.

Ib