Anyway to reprogram TX low battery alarm?

[WBFAir]

Hello all

I have a Futaba 7C 2.4 Ghz transmitter that I have replaced the transmitters battery in with a LightingPower 11.1v 2650mAh pack and its just assume, so far it run for 8.5 hrs straight and its barely down to 11.2 volts !

The only thing is that the manufacturer highly recommends that you don't run the pack any lower then 10.0 volts but the Futaba alarm is programed to go off at 8.5 so I was wondering if there was anyway to reprogram this level as I've gone over the manual I can't seem to find one, not that I would think there would be one as Futaba probably expects you to only use their battery.

Again I haven't found it in the manual but I have herd that there are advanced menus you can get into via jumpers although I don't know for sure if thats possible with this radio but if it is, is it possible via that way?

Thanks

[Wyn]

I think you're just going to have to charge at least once a month ;). Seriously, I don't have a 7C, but even with the service menu enabled on a 9Z the battery alarm couldn't be changed. Haven't seen that feature on any radio.

[WBFAir]

Thanks Wyn yeah I know it can go fast if its being used but I did a test where I used it for for about half Simming and the other half just letting is sit and the pack lasted for about 12Hrs!

So as this post has been up for about a week and this is the only reply I got I think it safe to say that even with the advanced menu theres no way to change that, thanks good to know.

[BarracudaHockey]

Thats the drawback, if you let it go to low voltage alarm the pack will be shot at best, puff up and do some damage at worst. The 9z is nice where it will shut off after a while of no activity, the 9c and the 7c aren't so fancy.

[heliphil]

with the latest low self discharge Nimh batteries why risk ruining a set of lipos in a TX?

[WBFAir]

Well I'm hardly an authority on the world of batteries but first of all even with one of the most mAh NiMH pack I could find which was a 1650mAh pack that cost me about $38.00 bucks and lasted about 4 hrs, it pails in comparison to the 2650mAh pack I got from Lighting Power for about $50.00 bucks that lasts about 12.

Plus for me since I have a CellPro4, I just pop it into that and without really having to set up much or more importantly, monitor it at all, @ 1C in like 45 minutes is fully balanced and charged, all with an alarm telling me when its done!

With the NiMH, and maybe theres some charges that you don't have to do this with but, with the one I got from the seller of the pack, I had to sweat over the charging amps, monitor the charging voltage with a volt meter and the only real way I would know if it was fully charged or not was to attach a temp meter to it to see "when" it started to get hot, which all in all was about a 12-13 hrs ordeal of me having to stay around time, check and monitor all of that on a regular basis so I didn't end up damaging the pack.

Granted some may not feel the need to resort to all of that but with all the warnings and heedings I got from the seller of how easy it is to destroy the pack if you over charge it, with no automatic system available, I really didn't see any other way of doing it.

So for me the advantages of the LiPo over the NiMH was really a no brainier.

[rothman]

What about 2 diodes in series? That would lower the voltage with about 1.8 volt. The alarm should go off about 3.43 volt / cell and that would be OK?

[WBFAir]

What about 2 diodes in series? That would lower the voltage with about 1.8 volt. The alarm should go off about 3.43 volt / cell and that would be OK?humm, now thats a really good idea, I'll have to give that a try.

Kinda like doubling up the stepdowns for the S9257.

Thats pretty good thinin Lincoln!

That would even give me a little bit of buffer too so that I wouldn't be dead drop low at the time of the alarm as well as at this point I've even been finding that even at 10V on the TX meter that my CelPro4 is reporting below 20% so that could help with that a bit too.

Plus too I've been thinking about making a little extension for the plug anyways as it is a little bit of a pain to have to deal with the plugging in an out of the pack as the TX's plug is a little hard to get to and I've been a little worried about damaging the pins on the TX. So I could just incorporate those into the extension.

Nice rothman

I'll give it a try and let you know how it works out.

[DavidH]

but first of all even with one of the most mAh NiMH pack I could find which was a 1650mAh pack that cost me about $38.00 bucks and lasted about 4 hrs, it pails in comparison to the 2650mAh pack I got from Lighting Power for about $50.00 bucks that lasts about 12.


That doesn't make sense. The radio uses the same milliamps per hour no matter what size capacity battery is in it.
If the 1650 only got 4 hours, then the 2650mah pac should only get 6.5 -7 hrs.

I used a 1300 mah pack on the 9Z and I assure you it uses more mah than the 7C. The battery would last 6 hours from fully charged till it needed recharging.
As for nimh batteries. They need cycled several times till they will reach full capacity. So if you just get a nimh battery new and start using it without cycling it. It will never reach the capacity that it is rated.

David