Electric vs IC

[Dave Hopkin]

Posted by The Wright Stuff on 25/07/2016 17:08:25:

Posted by Dave Hopkin on 25/07/2016 16:57:27:

"which is better IC or Electric" has much the same answer as "do you prefer blondes or brunettes" - each system has its own advantages and disadvantages - for club sized models the costs are pretty much the same - with the current state of batteries and as your model sizes grow then (with current battery technology) the cost of electric gradually becomes prohibitive - but I'm pretty sure that will change dramatically over the next few years as IC is essentially a dead end technology that has reached the peak of its development whilst battery technology is the subject of intense world wide research

But which are better to learn on when you are just getting started, Dave? Blondes or brunettes?

Sorry, couldn't resist!

I could tell you, but I would have to kill you afterwards.................

[..]

Posted by MattyB on 25/07/2016 17:44:57:

Posted by Justin K. on 25/07/2016 16:19:55:

Another consideration is your time , Charging LiPo 's is a laborious task but one that's necessary after a day flying. I personally prefer to wipe a model down , put it away and get on with my day. I'm unsure of the comments on how hard a task it is cleaning down an airframe? Some people must of run engines incredibly rich for them to get that oily.

As a seasoned electric flier I can confidently state that success is only assured if you charge the batteries before you fly...!

TBH since I got my meaty setup (1kW+ dual output) charging is no longer a laborious task - I can charge any packs I need for an afternoon's flying in under an hour with two parallel boards attached. Discharging unused packs after a days flying though I agree is annoying, especially given most chargers have a very low wattage rating on discharge. If you have large packs they can take hours and probably put a fair bit of wear on your charger, but the relatively high cost of these packs means it's even more important to ensure they are stored at the recommended 3.85V/cell to avoid a loss of capacity and increased IR.

Having done some reading on RCGroups though I have found a solution, and am about to create a 450W discharging setup based on some highly affordable commercial discharger units. I will probably post a mini build blog when I get round to doing this in the next few weeks.

Edited By MattyB on 25/07/2016 17:54:03

So you leave your cells in a discharged state after flying and the charge them before your next outing ?

Interesting especially in regard to our unpredictable weather.

[trebor]

I have tried both, but for me I like the smell, sound of an engine. A quick wipe down is less boring than charging batteries. It's bad enough remembering to charge the flight packs and transmitter.

[Trevor Crook]

I think Matty means he discharges them to a storage level, around half charged. They don't take as long to recharge after that. Must admit I don't bother myself, certainly during the summer when I do most flying. Just charge them all up after each session so they are ready for next time. Not sure what this does to overall battery life but mine seem to last reasonably well.

[Biggles' Elder Brother - Moderator]

I do the same Trevor. I only put batteries to storage level if I know that I'm not going to use them for several weeks. Otherwise I just charge them up. As I say I have some batteries that have given years of service. I'm sure going to storage everytime would be beneficial - I'm just not sure I'd notice the benefit!

BEB

[MattyB]

Posted by Justin K. on 25/07/2016 21:03:24:

So you leave your cells in a discharged state after flying and the charge them before your next outing ?

Interesting especially in regard to our unpredictable weather.

Yes, my packs are always left at storage charge (3.80-3.85V/cell) as per acknowledged best practice for retaining max capacity and current delivery capability from lipos. The only exception to this is if I am going to fly again within 48hrs. All my timers are all set to leave the packs at this voltage after flight, so any flown pack can simply be left as is; those at full charger go on one of my 150W auto dischargers (I am going to turn these into a single 450W discharger with integrated parallel board in the near future).

I would agree that small packs are now cheap enough for many that maximising batt capacity and performance in this way may not always be necessary. However for the bigger packs that cost more I am very careful to treat them carefully, and as a result my batteries do seem to last longer than many of my friends - I have several packs with over 500 cycles now that are still performing well. You don't have to agree with this approach but I am a chemist by training and have done plenty of reading on lithium batteries; there is no doubt in my mind that the crystal build up in lithium packs is a real performance affecting effect. Besides, I can charge all the batteries I need for an afternoons flying in 40 mins so there is little value in keeping them charged all the time.

Edited By MattyB on 25/07/2016 22:46:47

[Owdlad]

If you regard your lipo packs as a gallon of fuel.... ie 10% @ £20 per gal and on average you get 20 flights per gallon + cost of replacement glow plugs at £5 each. The costs soon add up over time.

On a decent lipo pack you can get well in excess of 100+ cycles..... so effectively in the long term electric is more cost effective.

Basically when:-

1) using ic.......the costs per flight increase because of consumables

2) using electric......the costs per flight decrease

[iqon]

Price does not come into it - ic puts a smile on your face, elec puts on a frown.....

[The real Ron Truth]

Even though i fly electric , id suggest you visit your local club and test the water yourself. Also observe what others fly and why. Is your site noise sensitive? What do the locals prefer ? etc .

If you aren't pushed in a particular direction, try both disciplines .Ask to fly both types, observe the pit routine etc.

Do you prefer to fettle a engine or plug and fly? Proper engine noise or silent clean power?

I used to fly IC but a combo of mess/ fuel rot and the past loss of 2 sites to noise ( damn loud petrol engine!!!) made me change. I do miss a nice burbling 4 stroke banging away but now have access to 6 local electric only sites as compensation. No restrictions whatsoever and clean models.

[Trevor Crook]

I have been vaguely considering buying a Nissan Leaf as a second car, and have done quite a lot of research. These have an overall battery capacity indicator, and most used cars I've looked at show full capacity, even after several years and tens of thousands of miles. I doubt that many owners leave them in a part charged state, so that's part of my rationale for my cavalier battery maintenance regime (apart from laziness!).

[The Wright Stuff]

It's probably true to say that the amount of maintenance for both IC and battery technology spans a range from bare necessities to true loving care and affection. How dedicated you are really just depends on personal choice.

Just as you could choose to carefully cycle batteries to storage charge after flying in the hope that it will prolong their life, equally you could do a full clean of the IC engine, rinse out the carb and put after-run oil into it. Same with cleaning residue. A quick wipe down, or a full clean, degrease and polish?

It's as much about your own choice (and the relative importance/cost of your time to do it) as it is about fundamentally IC versus electric.

[Andy48]

Posted by Trevor Crook on 26/07/2016 07:57:10:

I have been vaguely considering buying a Nissan Leaf as a second car, and have done quite a lot of research. These have an overall battery capacity indicator, and most used cars I've looked at show full capacity, even after several years and tens of thousands of miles. I doubt that many owners leave them in a part charged state, so that's part of my rationale for my cavalier battery maintenance regime (apart from laziness!).

Exactly, and also consider all the other things powered by lipos too. I wonder if those people who always keep batteries at storage charge level ever consider the damaging effect of the extra charging/discharging this involves.

[David Tayler]

I have a Nissan Leaf and unless I expect to do a long run I always charge the battery to 80%, in the hope of prolonging the lifespan of the battery. Indeed this is what Nissan reccomend.

[MattyB]

Posted by Trevor Crook on 26/07/2016 07:57:10:

I have been vaguely considering buying a Nissan Leaf as a second car, and have done quite a lot of research. These have an overall battery capacity indicator, and most used cars I've looked at show full capacity, even after several years and tens of thousands of miles. I doubt that many owners leave them in a part charged state, so that's part of my rationale for my cavalier battery maintenance regime (apart from laziness!).

The Leaf has a Li-ion pack that is very similar to our flight packs in terms of cell chemistry, and has had some well documented issues with capacity degradation caused by storage at elevated state of charge (even more technical info here). This is has shown up particularly in hotter climates. That may be less of an issue in the chilly UK, but it does not mean the effect of capacity loss due to elevated storage at elevated state of charge does not exist. Nissan do not recommend the 80% charge as a standard for no reason!

Posted by Andy48 on 26/07/2016 09:12:31:

Exactly, and also consider all the other things powered by lipos too. I wonder if those people who always keep batteries at storage charge level ever consider the damaging effect of the extra charging/discharging this involves.

Most low discharge rate commercial devices powered by lipos do not tend to charge to the full 4.2V/cell for this very reason - the small reduction in capacity associated with charging to a lower SOC is better than the longer term capacity loss associated with higher SOC storage. Even so, most modern phones spend a fair percentage of their lives at high state of charge, and in my experience they tend to need a new battery after 400-600 cycles (both my iPhones have followed this pattern). YMMV.

As for the loss of capacity due to additional cycles associated with discharging to storage, these are always going to be comparatively low C discharges that generate little heat in the battery. As a result any damage should be minimal, certainly less than is done by flying the pack which pulls much higher currents. Anyway, as someone who can only fly at w/es most of the time my attitude is that these are not "additional" cycles at all - I charged them to fly with, therefore in discharging them I am not doing anything I did not intend to do at the start of the day! I rarely come home with any more than a pack or two that requires this and in most cases all have been flown, so I don't see it as an issue, though to prove that I agree a long term scientific test would be needed. Again, if you fly every day or every other day will probably have a different view (I would not bother discharging if I flew like that).

Edited By MattyB on 26/07/2016 09:53:46

[Former Member]

[This posting has been removed]

[Simon Chaddock]

Also remember that compared to virtually all other Lithium battery applications electric planes tend to work their LiPo very hard with a substantial high rate discharge in 10 minutes or less. Such use does nothing to prolong battery life.

[MattyB]

Posted by Simon Chaddock on 26/07/2016 10:15:04:

Also remember that compared to virtually all other Lithium battery applications electric planes tend to work their LiPo very hard with a substantial high rate discharge in 10 minutes or less. Such use does nothing to prolong battery life.

Agreed. The only vaguely equivalent use case for  that I can think of is in electric vehicles, but even they are operating at much lower discharge rates, and therefore generating far less heat in the battery. For example the Leaf is quoted as having a range of 124-155 miles depending on the version; I'm sure that is probably an exaggeration vs. it's real world performance, but if we assume that range would be operating at a cruise speed of say 50-55mph average current draw is just less than ~0.5C/30A. Even if we cut that to a real world max range of 85 miles then average current is only up to ~0.65C/43A.

Battery operated power tools are I suppose similar too, but they tend to be LiFe rather than LiPo these days.

Edited By MattyB on 26/07/2016 11:38:35

[Former Member]

[This posting has been removed]

[John F]

Posted by Tom Sharp 2 on 26/07/2016 12:39:41:

Lipo batteries were developed for the power tool application, known as li-iron in a hard case. Still very much in use.

Tom, it's Li-ion, not iron.

Li-po batteries were first devised by John Goodenough and used commercially by Sony, after improvements, in 1991, in a video recorder by Sony. **LINK**

They were not developed with a specific use in mind, just as a rechargeable battery.

[Jonathan M]

Going electric when I started three years ago was a good decision. My local club does both IC and EP, but its rules meant that I could only train with an instructor or A-Cert holder by my side, which wasn't always available. Electric allowed me to find any old field with flat enough ground for takeoffs/landing and get in plenty of flying practice without anyone being bothered.

The cost of electric wasn't excessive, nor was the kit required: a mid-size foam aileron trainer, three 2200mAh Li-Po batteries, a checker/balancer, and an inexpensive charger that runs off both mains and a small 12v lead-acid for field charging. Sometimes I just take and fly three batts then go home, but 1C charging takes 40 mins per batt which is fast enough to allow a whole afternoon at the patch - given the time one spends chatting with other members or quietly relaxing or spectating.

I got my A-Cert a year ago and moved onto a second-hand foam electric warbird, more powerful than the trainer with three 3300mAh batts giving 7mins flying before I'm down to 40%, which has helped keep up and advance my flying, yet feels fake and unsatisfying.

So I'm moving to IC, with a bit more up-front capital expenditure. The electric kit will still be used, especially if I've only got a brief window of time to fly then get home again. Maybe I'll even ditch the foam warbird (the fake bit) and recycle the gubbins to power something like a balsa Wot 4 or similar?

[Denis Watkins]

Mobile phone technology has driven cell research for sometime now, and next year manufacturers are hoping to market 40% more power from the same pack, or conversely, the same power from say a 1200ma pack, 40% smaller in its dimensions. This will benefit all manner of appliances, and modellers