Eneloop battery

[fly boy3]

Hi all, has any one used the Eneloop 4.8v Rx battery. Are they Nicads or NiMh ? thanks.

[FlyinBrian]

They are NiMH but have very low self discharge rate so you can charge them then go flying a couple ot three weeks later without worry.

[PeterF]

They are Nimh, I have used the AAA 800mAh ones for Rx power only on Hitec Optimas using either BEC or larger battery for the servo power to make sure of no brown outs. Have gone OK with that and they do hold their charge well.

I aldo have a AA 2000mAh pack in the Tx.

[MattyB]

Be aware that they are only rated by Sanyo for 1-2C (that's 2-4A for the 2000s) discharge, so don't use them for RX packs on anything with lots of fast or high torque servos.

[Peter Jenkins]

Posted by MattyB on 28/09/2015 23:50:07:

Be aware that they are only rated by Sanyo for 1-2C (that's 2-4A for the 2000s) discharge, so don't use them for RX packs on anything with lots of fast or high torque servos.

[stu knowles]

I have been using then as an RX battery in several models until the moment I bought a Futaba battery checker (which tests under a 1 amp load)

Checker said 'No' in every case.

[Peter Christy]

Never had a problem with them as receiver batteries, but don't use them on a CD ignition system! It took me ages to work out why my gasser helicopter (always a bit marginal on power) was suddenly unable to lift off at all. Reverting to an old NiCad restored full - if marginal - power!

It seems the Eneloops were unable to deliver the short duration, high current pulse required by an ignition system, although they handled 5 digital servos and a gyro quite happily! (Note: this is a scale model, gently flown! I wouldn't recommend them for a full-on, 3D machine!)

Unfortunately we represent only a very small minority of the battery manufacturers customers. Most users want the highest possible capacity in the smallest possible package. Such a design does nothing to help the internal resistance of the cells, where a physically larger design is much better.

And before anyone suggests LiPo or LiFe cells for my ignition system, it has an absolute maximum voltage limit of 6V, so that route is also closed off to me..... (And the bigger batteries help with the CofG, too!)

--

Pete

[PeterF]

Which is why I only use them for the Rx circuit with a low power draw. On the Hitec Optima Rx you can have two independent battery supplies, one for radio function, one for servo power, like an opto isolator unit. I would not use them for servo side with high power draw.

[MaxG]

Posted by MattyB on 28/09/2015 23:50:07:

Be aware that they are only rated by Sanyo for 1-2C (that's 2-4A for the 2000s) discharge, so don't use them for RX packs on anything with lots of fast or high torque servos.

When I wanted to get some more batteries recently for my gliders I looked to see what the glider guiders were using.

I found out that most of the F3B people were using 2000 eneloops and they use fast high power servos for their models.

Maxg

[MattyB]

You are right, I have seen the F3X guys using them, but they are normally doing very short flights in a competition environment. Also from observation it seems fairly standard to top up the batteries between rounds.

As a slope flier who frequently operates for a long day on a cold hillside I have never thought them to be worth the risk - I can see the internal resistance on my charger and it is very high compared to the 2/3 AF size cells I tend to use. They are not perfect either (they are not low self discharge), but they can provide far more punch. A brownout on a £1-2k F3X machine is not my idea of fun! I also recently added a lightweight charger from HK to my field pack; coupled with a small 3S Lipo this gives me the ability to top up on the hill without having to carry any heavy kit.

Edited By MattyB on 29/09/2015 12:55:54

[Phil Green]

Like most batteries, they're absolutely fine if used within their spec. I've used them almost exclusively since they came out and have no problems whatsoever, but then I dont try to draw 5A peaks

Almost every criticism you hear of eneloop/instants is from people pushing them beyond their spec.

Cheers
Phil

[Old Geezer]

I use Eneloops at "the other end", in that I have them in my Spektrum and Cockpit Tx's. I find it difficult to predict from one day to another when I will be able to go out to play, so not having to top up my Tx batteries the night before a flying day is an enormous advantage. My only problem now, is knowing when/how often I should recharge my Tx batteries. ( 2000s )

Or should I give them a couple of hours top up every time I come back from flying?

[Phil Green]

I use Instants and the peak-charger sold by Vapex themselves. Now & then I'll do a full capacity check, but the little charger has been 100% reliable for several years now. Unforch a lot of trannies have a protection diode so you cant peak-charge them properly in situ, Like most people I always short the diode out, in my case with 1A fuse wire.

The charger is the £11 one at the bottom of this page:

**LINK**

[fly boy3]

Thanks guys for all the info, quite interesting. Most of my models are sports Acrowot type using Futaba 148,s, I think the Eneloop 2000 should be ok ? Cheers

[MattyB]

Should be fine, but if you really want to use Eneloops but still have some concerns just go to a 5 cell pack - that will give you some extra headroom to prevent RX brownouts.

[Phil Green]

I would suggest that if the 4-cell pack is dipping under load then a lower esr pack is a better approach, rather than propping up a sagging battery with another cell. The dip seen by the servos will be 25% worse with a 5-cell pack. Ok, 5 cells raise the '25% worse' dip point by a volt or so, but any pack with adequate current capability would avoid the dip, whilst giving far greater voltage stability at the servos. The receiver of course doesnt care as long as its 3.3v regulator sees at least 3.5 volts

Cheers
Phil

[robert chamberlain]

Hello all,--my peak detection charger has a setting of "Default' to set the peak shut off point, I suppose. It also offers the ability to set the M/V of my choice. What would be a good number, or just leave it alone. "Let sleeping dogs lie' Bob C

[Rob Tothill]

I use 6v Nimh for all my rxs, which mostly have analog servos - so no enormous current draw. In one of my aeroplanes I fitted a more powerful digital servo to the rudder and was slightly concerned about brownouts (probably unnecessarily). One of our club members worked in electronics and suggested putting a capacitor in parallel to deal with any peaks. I wired one to a plug and plugged into a spare port on the receiver. Apparently it's very important to fit it the right way around otherwise it will explode!

This is another option that can add an extra bit of protection when using Nimh. I don't know if it would work for multiple high torque servos though. Rob

Edited By Rob Tothill on 03/10/2017 08:42:48

[Peter Christy]

Maybe I've been lucky, but I've never had a problem with brown-outs with 4-cell, 2000mAH Eneloops - even when using Spektrum receivers in helicopters with 5 servos and a gyro! Mind you, I don't fly "full-on 3D", and always use a heavy duty switch harness.

Looking at some of the installations I've seen down the years, it makes me wonder how those pilots ever managed to get a reliable flight! Cheap switches, poorly repaired harnesses and much abused receivers and servos..... And then they blame eneloops when they get a brown-out!

I'm not saying it doesn't happen, just that I've never experienced it - and I've been using Spektrum receivers, on and off, since they came out!

Yes, NiMh cells in general have a higher internal resistance, and the volts drop under load will be greater than with old-fashioned NiCads. Further, the internal resistance generally increases with an increase in capacity for a given size cell. That's one reason why I've stuck with the 2000mAH AA (or 800AAA in small models) capacity cells rather than going for the maximum capacity. And for my biggest model (the Bell 47 gasser mentioned earlier in this thread), I use sub-C cells.

PhilG is absolutely right, as long as you use equipment *within its design limits*, you won't have a problem.

BobC: All my chargers are left at the "default" setting for NiMh peak detection, and I've never had a problem with that. I generally charge at 0.5C unless I'm in a hurry, when I push it up to 1C.

--

Pete