RX NiMh voltage

[Russ P]

I'm really neurotic about my RX batteries and check the voltage before every flight. My question is, how low should I allow the voltage get before charging them. I use 4 cell sanyo eneloop 4.8v.

Luckily I checked them at the field today prior to my 3rd flight and found that one of the cells had failed!

[Garbo]

Russ can I suggest you get some on board volt checkers the are available for about £1.50 and they'll save you from your neurosis.

[Frank Skilbeck]

Russ,the other issue is the voltage under load,ideally you should put a load on thr battery while checking the voltage. If you use the battery checkers that Garbo mentions then you can twiddle the sticks and as long as the lights don't go into the red under load you should be fine.

But if you are really neurotic then a telemetry radio set next time will give you more piece of mind, I use the Multiplex M Link stuff and the inbuilt Rx battery voltage on some of their recievers is really good and you can set the alarm to what ever level you want and it will alarm when the voltage drops below this.

[Garbo]

I have started the change over to 2s Life batteries

[Russ P]

Thanks for your help.

[Bob Cotsford]

I used to use a figure of 1.1v per cell under load and check after landing rather than let the pack sit and recover. These days I use the on-board monitors already mentioned and wiggle the sticks in addition to which my FrSky gear has telemetry monitoring of the rx voltage. I'm also changing my models over to LiFe cells as the older Nixx packs get retired. You can get on-board monitors for these packs too.

[Russ P]

Garbo - could you explain how you use life batteries as the rx battery. The wiring arrangement, how many flights per charge for a normal sport model (5 standard servos).

Thanks

[Garbo]

Life batteries are available with the same plugs as your enelope battery one. you can run

most modern receivers from their 6.6v or through an ubec.

They have multitudes of sizes, so how long they last is variable but a 2mah version will fly a

stort model like yours for as many flights as you like in a session. And they charge in about a hour

so you don't miss a days flying when the weather turns out better than expected.

But you cheapest option at the moment is to get a few on board checkers

[Bob Cotsford]

Russ, I'm using cheap soft 2S LiFe packs from HK which are marked as 1100 mAhrs and come with universal receiver type plugs fitted for around a fiver. 100mAhr per flight seems about average for a 40-60 size model with standard servos so I'm more than happy to fly 4 or 5 times between charges. As I usually take at least two models to the field this is plenty for me. I just plug them in through a switch exactly as you would a Nixx pack. You do need a charger with a LiFe setting though. 2S = 6.6 volts, which is in the same ballpark as a 5 cell nickel pack. I've had no problems running Futaba 3003, 3001, 3152, 148, JR591 and various Emax and HiTec servos on them.

 

edit - one big bonus with LiFe is that they only lose a few mAhr over a couple of weeks - I now charge AFTER flying and when I want to take a model out again less than 30 seconds on the charger confirms that they're full.

Edited By Bob Cotsford on 08/09/2012 10:04:29

[Russ P]

Thanks again.