Which battery type?

[Declan Barry]

Hi Guys..

 Which batteries are the best to go for now? Nicad or Nimh?? and does it matter whether theya re AA,AAA, Sub C etc

I'm looking to replace some of my RX batteries.

Regards

Declan

[260 Flyer]

Declan

Nimh - Without a doubt!

You can pick up a 4 AA cell 2600mah for around a fiver if you know where to LOOK!

To charge them you might need a more powerful charger.

Rob

[Chris Bott - Moderator]

If you're talking AA sized then take care.. 

I've had some problems with NiMh's  the bigger the capacity (for the same can size) the less current they seem to want to give.  The also seem to go poor in the cold.  Combine the two and I've had voltage problems under high servo load.

It's a shame you can't easily get NiCads now.

The new eneloop type seem to be the answer, they come fully charged, don't appear to suffer in the cold at all, and so far seem to be happy holding volts with all servos working hard.

They also keep thier charge for very long periods (very little self discharge), so no need to top up before a session just because they have been on the shelf.

I'd be interested to know anyone elses experiences with these cells.

Just google eneloop - other manufacturers seem to be using different names, but eneloop seems to bring up plenty.. 

[Bruce Richards]

I have been using Vapextech Instant NmHi for most of my Rx packs and have never had a problem. I still charge before each session but it only takes about 5-10 minutes. Many of my club members have started using them as well and I have not here of any problems from them.

[Chris Bott - Moderator]

Thats great thanks

"Instant" seems to be Vapextech's name for the same technology as eneloops.

I'd like to know for sure if they really do have the advantages over standard NiMh's ??

[Chris Bott - Moderator]

Sanyo actually make a thing of the low temp characteristics of eneloops here. Saying that they are the battery of choice for ski resorts  Should do us proud in the winter then.

Sanyo Eneloop

[260 Flyer]

Does anyone know of a supplier Eneloop cells with solder tags or do you have to use a battery box?

[Declan Barry]

Hi Bruce..

 I've actually order up a couple of these Vapextech batteries (4.8v - 2100mAh) but am curious about something.  They quote the charging current as 1200mAh for a 2100mAh battery.

Can these batteries not handle a C charge?

Regards

Declan

[Chris Bott - Moderator]

one of the traders at Weston Park was selling made up eneloop Rx packs.
'course I have no recollection which one - sorry.
As I recall they were facing the flightline - near the middle??

[Chris Bott - Moderator]

Theres a couple called "instant" here may have been these guys at Weston

Modelpower

 They also have lots of other options..

[inspector9566]

ive been using the vapextech packs for a while now i was so impressed with them that i bought a load more 6v pack they dont lose there charge like nmhi packs do and yes they have been re badged as instant and i got mine through ebay i am well impressed and wouldn use anything else i fly anything from an os 46la to dl50 petrol

[260 Flyer]

Thanks guys

I was ready to order some packs but when clicked on the "more information" tab and saw this..

6.0 Volt 2100mAh 'Instant 'NiMh AA Flat Pack
For these cells to keep there ability of storing the capacity for long periods of time, it is best that these cells be cycled not just topped up, When these cells are topped up they loose there ability to store capacity for long periods of time.

Hmmm... sounds familiar.

[Bruce Richards]

Declan,

I always charge mine at 1C or slightly less. I found that  that the delta peek detection did not work well at lower charge rates.

[Chris Bott - Moderator]

Rob, having to cycle sounds disappointing.

Did that refer to a particular manufacturers type?

I wonder if these are all a generic type or are the different manufacturers acheiving the charge retention by using different methods? 

[260 Flyer]

Chris

It's from the link that you posted for Model Power Instant packs. At the bottom of the product desctiption there is a "More Information" link.

[Chris Bott - Moderator]

Thanks Rob I'd missed that.

This seemed like a magic bullet! Now I'm not so sure..

I've had a packet of Vapextech Instant's arrive. On a banner right accross the packet it says "READY-TO-USE" "1000x times" and in big letters "instant"

Then in the small writing instructions below, it says "Must be charged before use!"

Wish they'd make their mind up

They also show a graphic of 2 circles overlapping. In one it shows advantages of rechargeables (enviromentally frendly, re-useable etc.) In the other about Alkaline (Instant use, long shelf life etc) Theres a big plus sign between the 2 circles.

(This is after I'd had to send back the ordinary Vapextech NiMh's that the ebayer had wrongly sent.)

[Frank Skilbeck]

Watch some of the higher capacity AA cells, I have a pack of 2400 mah AA cells (4.8v) and the voltage drops right off if I try to pull more than 0.5amps from it. If I cycle it a few times it seems to improve but then will revert to what it was. Note these are not the newer instant type cells.

The GP NimH cells (AA & Sub C) seem very good in this respect.  

[Former Member]

[This posting has been removed]

[Myron Beaumont]

Eric He;s gone for more sticky buns I think !  Blowing a near gale up here .Loads of rain too .Typical weekend Eh! Just converted my proper trainer ie ic  (for 'er indoors ) As I've said else- where -Sounds like a hair drier (with a life span of 20 mins,)  Say no more !

[Tim Mackey]

Well yes I have been up the Orme actually - superb weather for sloping here !

I have already posted a short piece about nickel batteries and their little quirks some time ago, and have little or nothing to add to the thread

- suggesting a Lipo is off topic and unhelpful to this particular question.

[Frank Skilbeck]

I posted these results on another site of some  VP 2400 mah AA 4 & 5 cellNimH RX packs vs a 4 cell 4/5's sub C Sanyo 1650 mah NiCd and a 5 cell 4/5's sub C EnrichPower 2200 mah NimH. I ran a series of tests on them using the discharge function on my cycler to measure the performance.

Results are as follows

            VP 4 cell        Sanyo 4 cell         VP 5 cell          Enrich 5 Cell
Amps       Volts               Volts                Volts                Volts
0.2          5.48                5.32                 6.8                   6.77
0.4          5.3                  5.22                 6.62                 6.67
0.6          5.1                  5.12                 6.45                 6.57
0.8          4.92                5.05                 6.21                 6.45
1.0          4.71                4.95                 5.58                 6.13
1.5          4.1                 4.57                  5.48                 5.62
2.0          3.63                4.33                 5.1                   5.62
3.0          2.65                3.92                 4.4                   5.2

Note the VP cells were fresh off the charger, the Sanyo cells had been used briefly earlier in the day and the enrich cells had been charged the previous day. Note at 3 maps my cycler basically shut the VP cells off after a couple of ma had been discharged and went into pause before starting the charge cycle. 3 Amps is a lot, but if you are running a 6 servo set up they recommend that you use at least a SBEC on an ESC rated to 3amp continuous, so the same recommendation should go for regular RX packs. So if you are running smallish planes (say 40 size and below) with 4/5 servo's then NimH AA's should be fine but for bigger models and more servo's you might want to go up a battery size, (note size not mah), as these have less internal resistance and can deliver more amps.

[Chris Bott - Moderator]

Wow Frank that really demonstrates what I thought I was seeing with the higher capacity but smaller cells.

Looks to me that to pack mAh into an AA package, they have to compromise on current capability. Or at least that's the effect.

I'll do the same test with the Sanyo Eneloops when i get a chance, that will be interesting.

Might be a few days though. 

[Tim Mackey]

I must say I am very surprised at the very poor capability of your AA cells. I have only 1x pack ( literally ) of nickel cells in my current armoury - a "relic" from a friends small MS composit wing which was the source for both his geared brushed motor/gearbox powertrian, and his onboard radio via the ESC BEC. This drew well in excess of 3A and provide a good 5 - 7 minute flight with varying throttle settings. It is a Sanyo R6 1700 mah 4sAA pack. I presently use it in my slipstream wing ( radio power only as its a sloper ) and happened to have just finished charging it in prep for a session tomorrow so I put it onto a comparative test by setting a dischrge current of 3A on my 1010B charger, and as you can see...it holds MUCH higher voltage - and for longer than yours did.

4.83V after over 1M-10sec and only 1700 mahr versus your 2400 mahr.

This was also via the feeble thin wires of the pack.

Heres a picture of the data.

I suspect your AA pack is goosed !

[Chris Bott - Moderator]

Timbo my impression before we started this, was that in NiMh's for the same size can, then the higher the capacity, the lower the current capability. Particularly in AA's.

IF this is indeed the case, then as NiMh's get higher and higher in capacity, we should watch what we use them for.

That's one reason I'm investigating the Eneloops.

I was with a well respected flyer at our club the other day, he had a voltspy installed in his plane.  When he waggled all servos at once, it was dipping off the scale beyond the red.

His comment - "these volyspys are rubbish, this is a brand new pack, and they are 2300's so they should be really good"  (They were AA's)  (He really has problems with electric planes too by the way)

I did try to help, but you can't help some people.

[Frank Skilbeck]

Timbo, the VP cells have been like this from new, if you do a test on them discharging at say 500 ma then they will give over 2200 mah, I don't think they are goosed just not upto delivering large amps. I first noticed it when I put the 4 cell pack in a 7 servo plane to set it up and the onboard battery checker was going into the red when I deployed the flaps (on the ground ) so that's when I did the check.

But I think the issue here is don't be fooled by the mah hour rating of the cells as they may not deliver the amps when required.

You were cheating and using Sanyo cells