Dynamic Li-Po's

[Bob Archbold]

Hi

Does anyone have any experience and / or views on Dynamic Li-Po's?

They seem incredibly reasonable in price and seem to have a good write up but wonder what they are like in use...

Bob

[John Privett]

Not heard of those particular ones Bob. Where have you seen them?

I currently use Turnigy and Zippy LiPos from HobbyKing. They're very reasonably priced and have given me good service so far.

[Bob Archbold]

Hi

There are a number of dealers although i have some on order from Inwood Models. Just over £20 for a 4 Cell 3200 maH and around £7 for a 3 cell 1200maH. Seems cheap but we shall see, the proof of the pudding is......

[avtur]

Posted by John Privett on 07/07/2013 12:30:11:

Not heard of those particular ones Bob. Where have you seen them?

Full page advert in this months RCM&E ... try page 97 ... prices are very competitve ... the dealer listing suggests a linkage with HobbyStores.

Edited By avtur on 07/07/2013 14:23:57

[Martin Harris - Moderator]

I bought one a couple of months ago (2200 3s) and so far it's performed very well over 15 or 20 cycles for a princely £10-50p from my local Hobbystore. Early days of course.

[JayCee]

Just ordered 2 x 3200 4s to try in my Sebart Sokhi if they come in at 313 grams as advertised that will be a bonus. Using Zippy compact 3300mah at present heavier at 350 grams! £21.93 from HK UK Warehouse so very similar in price.

However, Slough RC is free delivery on orders over £30.00!

Must be worth a try.

[Frank Skilbeck]

I bought a couple of 3200 3s to try in my Tucan, they don't have quite the same punch as the Multiplex 3200 3s or a Zippy 3,000 3s I am also using, mid flight the Multiplex Lipo can deliver 40A at WOT and Dynamics only 35A due to the higher voltage sag under load, all measured on the telemetry, so the plane is not quite as sprightly.

[JayCee]

Ahh 'Telemetry' dear Watson! <grin>

If only... Still using my Futaba 10cg no such goodies I'm afraid!

[Daves42]

I have 6 x 2200 mAh 3s and 2 x 3300 mAh 4s. All but 2 purchased in July/August this year and used a lot.

I am delighted with all of them. I have no empiric measurements to back this up but they appear to perform as well (if not better) than the nano-techs that I was using before. Unlike the nano-techs, after many charge cycles there is no evidence of any swelling and they remain in the same shape as when purchased.

At the price, they are great value for money.

[Martin Harris - Moderator]

Posted by Martin Harris on 07/07/2013 21:34:36:

I bought one a couple of months ago (2200 3s) and so far it's performed very well over 15 or 20 cycles for a princely £10-50p from my local Hobbystore. Early days of course.

Still working fine after regular usage since my previous post in July...and easily outperforming an equivalent Nanotech. I can't fault mine.

I also bought a 2200 4S for an EDF which has been given a typically hard life (3 1/2 minute discharges often down to 3.6 - 3.7 volts and going strong after an average of 2 or 3 cycles a week since a couple of days after Wings and Wheels where I bought a brilliant (but sadly no longer available) Max Thrust F18 from Century UK which has been an ever present in the back of the car on visits to the field since.

Edited By Martin Harris on 10/12/2013 23:30:45

[Martin Harris - Moderator]

I've championed Dynamic batteries in the past but I seem to be having a bad experience with the last ones I bought earlier this year. A pair of 3S 2200s that I bought for a Dynam Me163 have both puffed noticeable in a total of 20 flights or so.

Anyone else noticed a decline in the quality of these packs or have I just been unlucky?

[gangster]

I have had a similar situation Martin. I have been delighted with them in the past I have had a couple of 3s 3200 for over three years they have delivered full capacity and are still good having been left charged and not been given any special treatment. I however bought three 4s 3200 over the last couple of years and am not happy with them

One puffed up last week but went down as it cooled and after a gentle balanced charge gave a five minute flight yesterday and was puffed up a second one bought at the nats last year again gave a five minute flight and was definitely saggy on landing a check showed one cell down to 2.9 volts. I have put all this down to the fact that I am pushing these a bit harder ie 50 amps for some of the flight and as a cheap battery the quoted spec being a bit optimistic

I am in a dilemma now having started flying electric with nice light scale or vintage models I have gone back to the sport models I like to fly and although 700 watts is small in the big scheme of things to go to 5s or 5000 mah pushes the battery price way up So what to do now I am now flying oily and smelly again and am wondering whether to migrate to this for all my 46 to 60 size models

I would be interested to hear other people's experience with newer dynamics but could quite believe that they don't like to be pushed too hard

[Shaunie]

Hmmm,
I have two that are two or three years old and still performing ok. However I bought four last year, two for myself and two for a friend and we have one each that has gone high internal resistance.
Might be a trend here.

Shaunie.

[rcaddict]

mmmm - just got one free with an acrowot foamie purchase (3s 2200mah) - I will need to keep an eye on it

for some reason I find my 3s 2200 turnigy's are the most reliable

[Peter Christy]

I bought two a while back, for a 450 size helicopter. One died in flight, after only a few weeks use and I was lucky to get away with minor damage. The other is still in service, but I only use it in aircraft now, as I don't trust it!

You get what you pay for, and if something seems too cheap to be true, it usually is! May be OK in planks, where you have a bit more lee-way when the donkey quits, but I wouldn't trust them in a heli again.

Thunder Power only for me, from now on.....

--

Pete

[Former Member]

[This posting has been removed]

[MattyB]

What you are seeing here - inconsistent performance and longevity - is a widespread problem with cheaper lipos. It happens because there aren't many companies in the world that actually produce the cells, far fewer than there are lipo brands. That means that many pack brands use the same cells, but because of different construction methods there is natural variance associated with the process, and not all cells are born equal; some have higher IR and reduced current delivery capability, with lower cycle life as another by-product.

The bigger higher priced brands tend to get first choice and can match all the lowest IR cells carefully, whilst the cheaper brands generally (but not always) get second or third pick. That means there is always more likely to be variance between packs of the same brand at the lower priced end of the market compared to the established brands. But there is another source of variance too. Margins for the likes of HK are very slim, so if one of the original manufacturers offers them cells at a few pence cheaper they will change supplier; after all it's only the outer sleeve that easily distinguished one pack from another, 99.5% of buyers will never dissemble a pack and see any difference in construction.

Ultimately these factors mean that even if you get a series of good packs in a given value brand, you can't guarantee your next order of the same batteries wil perform identically. However if you aren't pushing your batteries hard in EDFs or other very high current applications the cheaper packs will generally still serve you well on average and deliver substantial savings in the process.

Main source: Battery load tests RCGroups thread detailing comparative performance and cell construction.

Edited By MattyB on 02/09/2016 23:56:20

[Martin Harris - Moderator]

It does seem that several others have experienced similar issues with more recent examples of these batteries. They seemed to disprove the theory that you had to buy more expensive packs in order to get reliable and decent performance and in the absence of any response from the distributor, I think I shall be looking elsewhere for my next replacements.

[Former Member]

[This posting has been removed]

[MattyB]

Posted by Tom Sharp 2 on 03/09/2016 05:10:44:

I wonder where Samsung got their exploding phone lipo's from.

Indeed, though I suspect that is much more likely to be an issue with the charging circuit not stopping the charge at the correct voltage than it is a faulty battery itself.

Edited By MattyB on 03/09/2016 07:44:31

[gangster]

Interesting point about the different construction. I bought 2 dynamic 3s 3200 in 2013 just a few months apart from the same supplier

One of them was too wide to fit the tray in one of my models. The reason it sis not fit was the construction was such that one of the leads ran down the side inside the heat shrink incidentally this battery altately started to swell