Built in LiPos

[Andy Muckley]

Hi Chris is there a size/ power capacity/ weight, difference between the two types, i have never used A123 cells but if they're safer and quicker to charge then i would use them for sure, or are they old hat now ?

[Pete B]

Certainly, CS. I deleted it as a one-word criticism of a fellow forumite's choice of propulsion contributes nothing to the subject of this thread.

Your dislike of electric power and constant harping-on about IC is well-known to forumites and is, IMHO, becoming rather tedious and not a little bit irritating - and I'm a very easy-going type.....

The overwhelming majority of folk here have their preferred choice of motive power, whether IC or electric, yet do not find it necessary to constantly remind the world at large or try to push their preference upon others at every opportunity.

Indeed, I suspect that there are very many who use both forms of propulsion quite happily, depending upon circumstances - perhaps environmental - and suitability for a particular model. Equally, I am quite sure that, banter apart, the overwhelming majority of IC and leccy flyers co-exist very happily indeed......

In my own case, I restrict my activities to leccy models out of regard for neighbours, so I don't have much choice. Others may be in a similar position and don't need a sermon every time they post on the subject.

CS, I know you are passionate about IC but, when you post, please consider the effect your rubbishing of electric has on those of us who have chosen an alternative....

Pete

.

[Concorde Speedbird]

Well I meant by PM, but here we are. PM sent.

CS

[Tom Sharp]

At the fIying field, I would not want my precious model to be parked alongside a model with it's Lipo being charged in situ. So I would object most strongly to this practice.

[Simon Chaddock]

savedbytheground made an interesting point

Can we expect a time when multiple battereis for a days flying are no longer required?

Whilst I do not charge insitu (more for practical reasons than safety worries) I have several models that can (and do) perform several 10 to 15 minute flights on one charge. As a result with these I tend not to change the battery but fly another plane.

I would agree with the observation and my own observation that an insitu 'runaway' fire (from even a single 3000mAh LiPo cell) would almost certainly destroy a plane.

Edited By Simon Chaddock on 09/08/2013 21:09:22

[Bob Cotsford]

Posted by Tom Sharp on 09/08/2013 20:22:13:

At the fIying field, I would not want my precious model to be parked alongside a model with it's Lipo being charged in situ. So I would object most strongly to this practice.

I don't know, on a chilly day it could come in quite handy

[Chris Bott - Moderator]

BEB's A123 questions then.

Where to get them from:-

All have mine were salvaged from brand new Dewalt power tool packs, either the DE9360 36V or the DE9280 28V.
These were bought on Ebay if ever I saw one at a nice low price. (That's quite rare these days).
The advantage here was that many of the inter cell connections were already made.

Ready made packs are available from the likes of Puffin, Robotbirds and Electricwingman, it may be worth contacting them to ask about having specials custom made.

Our HK freinds list single cells with tabs ready welded on, but these show as out of stock right now.
So it looks quite hard to get hold of them now

Setups:-

Not answering your question directly, the general answer is that you need an extra cell or two to give the same discharge voltage. The only useful capacity available is 2300mAh. This lack of a range of sizes is a real limitation. However, every last drop of juice can be used, and power stays constant right to the end, so they are equicalent to say a 2800mAh Lipo.

Our Seagul Sea Furys started out on 8S1P, this worked OK but duration was a bit low. We decided that 8S2P would be too heavy, so changed the motor and went to 6S2P. (i.e.12 Cells worth of fuel). This works really well for this 10.5lb warbird.

Some useful info will be posted in a min. Mr F and I are looking for the relevant info.

Charging:

Most up to date chargers have a LiFe program. This charges to 3.6V/Cell. 2300mAh A123's are quite happy being charged at 10A, although you do then need a charger with a decent wattage, and a good supply of power.

[Devcon1]

I beleive the risks of in situ charging are a little overstated and in the event of an issue the risk to adjacent models would be pretty much non existent for the reason listed below, in fact far greater risks populate the average flying field.

How many people are present when (including the owner) LiPos are charged at home ready to intervene. Versus

How many people typically would be present in the pits area of your average club ready to be alert to a problem.

I know LiPos should be charged in fireproof environment but I'd be interested in a poll to see what actually happens'

I wonder if the growth in petrol as an energy souirce poses a greater risk to models and modellers than LiPos ever will....

.

[Danny Fenton]

It is an interesting debate, and I know at least one modeller that charges lipos in his models quite happily.

Here are the numbers BEB we chose the 350kv motor with the 18 x 10 prop. the numbers make you think it will be marginal, that is most certainly NOT the case, big prop big efficiency, but you know all that

As Chris ahs alluded to tha vailability has become a bit scarce, I think this is because they last years and have killed their own market I must have nearly 80 cells in total, and nearly all of them are more than 5 years old. They are still going strong, and without balance charging.....

ignore the green figures that was for another project

At the end of the day, go with what you want, If a purring four stroke floats your boat then thats fine, if you want to use lipos as they have distinct weight advantages these days then thats also great. I am a little reluctant to push this technology vociferously these days as LiPo's have made up a great deal of ground. I would however disagree that modern LiPos only take an hour or less to charge some of my recalcitrant lipos can take nearly 2 hours on a 5C charge. The balance goes out and therefore the current is throttled........

Cheers

Danny

Edited By Danny Fenton on 09/08/2013 22:44:12

[Richard Brown 3]

Hello

I've been flying a 38lb CARF Spitfire for about 3 years now with a Hacker A100 motor and 26X15prop. First year was on a built in pack of 48 A123 charged at the field. A123s are great for warbirds which usually need some nose weight with about 1/4 more weight than LiPos of the same power.

When one A123 started to go off I switched to NanoTech 130c burst LiPos because it was now cheaper than A123s. 4 X 5S 5000mah ( 10S 10000mah ) now power the Spitty with power to burn. A simple hatch gives access to the motor/battery compartment for chargeing and radio/motor arming switches.

I charge with a PowerLab8 1344watt charger running on 2 X 12 volt deep cycle batteries and it charges all 4 batteries at once in about 20mins. An afternoon's flying easily sees 3 flights and a good bit of talking.

For me the other must have Item to make this all work is telemetry. My DX18 not only gives me real time battery voltage so there are no surprses but also battery temp.I fly in Bunaberg, Australia which is in the sub-tropics. Afternoon temps are usually around 30 degrees plus and until I got telemetry I had no idea my battery temp was hitting 55 degrees after landing which can't be good for batteries. With a ducting system now out through the radiators battery temp now drops below ambient during flight and once the cover is removed on the ground, charge and flying is almost continous.

It's all been so succussful that I'm currently making a my own composite fully moulded 1/4 scale Mustang whhich will operate on built in lipos.

Richard

[Biggles' Elder Brother - Moderator]

Thanks Chris and Danny excellent quality information and fascinating stuff. I shall certainly bear this option in mind. If I was going down this route then making up a custom battery for the specific model starts become an option. I need a good think and a play with some numbers now,...

Thanks again.

BEB