Lipo differences

[Ashley Davis]

hehehe nice try

I see you are having as much of a laugh with this as me

[Thomas]

so you are saying you have problems not only with Flightpower lipos but also their other electric stuff?

Trev

My first heli was an Eolo and I had no idea about LiPos whan I bought it, they were pretty good when I needed help.

The other electric flight stuff I got from them was a JETI 77 ESC for my Trex and an Axi 2826/10 for my hotliner - didn't have a problem, they were just helpful when I phoned, they've also sent me cable and big heat shrink free of charge when I needed it for a ESC I overheated.

I nearly went the Kokam route in the summer but found they were too heavy for the heli compared with the FP, I was slightly put off them by the bloke on the phone constantly knocking other products in order to sell his.

[Smoothound]

I was slightly put off them by the bloke on the phone constantly knocking other products in order to sell his.

This is the main reason I've not got a Medusa in my T-Rex yet...

[Ashley Davis]

Mike can get a bit carried away sometimes, he's just passionate about what he sells (and not so passionate about what other people sell). But I can understand that putting people off, it's better to sell your products merits than pick holes in the competition. So that's fair criticism in my book

[SimonN]

Blimey, what have I started ! I was hoping I might get one or two replies and it's already on two pages..... I take it from the "not another lipo thread" comment this has been a common question in the past ! Sorry.....

Anyway, back to the thread... I have an Align balance charger that I got at the same time as the heli, is this ok for the lipos you are suggesting? My local model shop has Flightpower in stock for about £48 for a 2150, I presume this should be ok.

Thanks
Simon

[Smoothound]

As can we all

[Ashley Davis]

The flightpower balance connector won't fit the connector on the Align charger....but for that matter neither will most other connectors. The Align balance charger has had a rather chequered past with it not detecting the fully charged condition on a cell properly and continuing to trickle charge beyond the cells capacity. This has the effect of overcharging the cell and damaging it, usually permanently, leading to short lifetime. I think later Align chargers have been better/fixed. To fit the FP pack you will need to make up an adapter or buy one (if there is such a thing).

[Ashley Davis]

and my I take this opportunity to congratulate everyone on a very civil debate, much better than the last time

[Smoothound]

Ash,


We can soon change that

[SimonN]

My charger is only a few months old, but I'm not sure whether it would be referred to as the later sort !. It's this one...

[Ashley Davis]

We can soon change that

doh!

I'm not sure whether it would be referred to as the later sort

I suspect if it's that recent you should be fine. The old charger was pretty easy to diagnose as faulty, at the end of a charge it would carry on trickle charging, so if there is any current flowing at the end of your charge (easily checked with a multimeter) then it's got problems.

[robgt]

My local model shop has Flightpower in stock for about £48 for a 2150, I presume this should be ok

Yes, it will work fine in a Trex 450.
You'll have bags of power/punch and it will likely last you for quite a while, depending on how hard you push the pack, how well you look after them generally, and how often you fly.

Your balancer will probably not fit it though.

If I were in your shoes now, but with the knowledge and experience I have gained so far, I would (and do) buy Kokam HD from the choices available on the market.
Most people are on a budget - we immediately see a low price and jump at it. But as has been proven time and time again, buy cheap, buy twice.
Lithium cell makers are not regulated and as such can make bold claims - we, the consumer have very little comeback when it turns out to be a crock. So how do we tell the difference?
We need to read independent test reviews - those without bias and without any gain from the results published to the publisher.

I know Kokam packs are more expensive than an equivalent (or perhaps seemingly better) alternative pack, but when it comes to cost per flight, you simply cannot beat the Kokams.
When used correctly (as with all Lithium packs to get the fullest life from them), you will very likely see 400 to 500 charge cycles.

Due to the cell chemistry in other manufacturers cells being modified, their cycle life is a vastly reduced number than that of the Kokam cells - not even half the amount, and more likely around 100 cycles, if you are lucky.

Cheers,
Rob

[Smoothound]

When used correctly (as with all Lithium packs to get the fullest life fromthem), you will very likely see 400 to 500 charge cycles.

Not even the most devout Kokam worshipper would claim that sort of life in general use

[Ashley Davis]

Actually the motorbike racing crowd have been using the scorpion packs for some time (kokam racing pack) in the formula 1 racing and there are real examples of packs with well over 500 cycles on them that are still being used and placing high in international competition.

These aren't sponsored people, they are people who are running the pack in competition and it's a very serious business indeed. The kokam cycle life is not a myth, it's real and proven by independent people running the packs in true racing conditions. These packs are also more heavily stressed than we would ever achieve in a heli, on acceleration these electric bikes put out huge current spikes, well beyond what we see. The packs are constructed from exactly the same cells and using the same techniques as for the heli packs we normally buy.

Sorry but what robgt said is completely true and had you watched the racing you'd have seen the guys talking about it as it was broadcast live to the internet. You'd also have seen the packs and their extreme usage in these electric bikes, they are wikedly fast.

[Ashley Davis]

just to add a bit of techie info......

Normally cell life is calculated on a single cell, continually discharging at 1C. A typical kokam cell will do this around 1200 times before hitting 80% capacity. As you up the discharge rate the number of cycles reduces, not massively, until you get into the 18-20C type discharge range where a real impact starts to occur and cell life can be reduced by 25% or so. When you put cells into a pack you typically reduce the cycle life by a factor of 3. So an average kokam pack, with average usage should hit around 400 cycles. Run it above 15C constantly for the whole discharge each time it discharges and you get a loss of cycle life. So based on this pack lifetimes of 500 cycles are not uncommon, the cells are just perfroming slightly above average spec.