lithium batteries

[Bruce Tuncks]

Has anyone tried a lithium phosphate battery yet?

 

Will the 10 amp-hour one (only 2.2 kg, but $315) work in a 2.2 Jabiru?

 

The weight saving would be great, but it sounds too good to be true.

 

Personally, I've had good value from Odyssey batteries in my 2.2 Jab, but wow a weight saving from down to less than half would be good.

 

I've used lithium polymer in model planes, they have the performance but not the safety for a real aircraft.

 

cheers, Bruce

 

 

[markendee]

I have and yes "TGTBT"

 

 

[Yenn]

OK what is TGTBT

 

 

[Tomo]

OK what is TGTBT

Is it ...TO GOOD TO BE TRUE....??i_dunno

 

 

[Geoff]

Think I may have heard this story when visiting with Big Pete :yuk:

 

 

[BigPete]

Hey Mark - the last I heard was the battery was faulty and sent back.

 

So - the new one was no better

 

(Please reply non cryptic and at least six words in the sentence) :big_grin::big_grin:

 

regards

 

:big_grin::big_grin:

 

 

[markendee]

Big Pete wrote:

 

"Hey Mark - the last I heard was the battery was faulty and sent back. "

 

Correct.

 

"So - the new one was no better "

 

Correct.

 

"(Please reply non cryptic and at least six words in the sentence) :big_grin::big_grin:"

 

Am waiting on a beefed up replacement - will report the whole saga once it arrives and is tried. In the meantime I fitted a Yuasa lead acid out of stock (YTX14-BS) and it spins the Rotax like a Battling Top.

 

Mark D

 

 

[markendee]

OK the full story.

 

Mate sees an add in Pacific Flyer for LiPO4 batteries. Shows Mark, Mark likes.

 

Mark buys and receives 10 AH battery with all the bells and whistles. (in built computer board, button to release ten starts if battery inadvertently drained etc)

 

Didn't think 10 AH would be enough zapp but went ahead anyway.

 

Battery did start the 80 Rotax but only if handled with kid gloves. If cranked willy nilly it would trip out and require the button to be pushed. (Mark on back under aeroplane removing belly hatch to access button)

 

Was sure it would let us down sooner or later and of course it did.

 

Sent battery back to dealer, tested and sent back to me.

 

Let me down so sent back again.

 

Dealer pulled it apart, doubled the cells (20AH) deleted all said you beaut computer gizmos (including button) and Mark refitted to small funny looking yellow aeroplane.

 

Playing game so far.

 

Final outcome:

 

2Kg lighter than motorcycle battery, no nasty battery acid, no nasty hydrogen produced and if the story is to be believed (fingers tightly crossed) longer lasting than lead acid.

 

Sooooooooooooooooo, am glad I persevered.

 

(as long as it does last a looooooooooooong time.

 

Mark D

 

 

[Bruce Tuncks]

thanks Mark

 

Thanks for the full story ... I reckon 2 kg is a lot in a Jabiru, even though its not halving the battery weight its still pretty good.

 

Please let us know how it stands the test of time.

 

cheers, Bruce

 

 

[markendee]

Test completed.

 

Time for an update.

 

My Savannah has now 142.8hrs up and completed 352 take off and landings in 16 1/2 months. I always crank the engine until oil pressure begins to rise (about 6 or 7 seconds for 2 bar) before flipping the switches.

 

The Li PO4 battery is a pearler!

 

Totally recommend it. (Of course the 20AH version)

 

Only thing left to test is longevity. Still performing like new!

 

Mark D

 

 

[Spin]

Good to get feedback on the battery, so often these u beaut jobs get discussed up front but you never hear how it all turned out.

 

I'm a bit :puzzled:by the bit quoted below though, how is your starter holding up under that sort of load?

 

I always crank the engine until oil pressure begins to rise (about 6 or 7 seconds for 2 bar) before flipping the switches. Mark D

[markendee]

Spin,

 

Doesn't seem a problem. Do you suggest this is not good practice?

 

I am pretty paranoid re starting a dry engine. I love to know the oil pump is bringing something to the party before she fires. Perhaps you know something I don't and I should.

 

All ears.

 

Mark.

 

 

[Thalass]

Generally speaking LiFePO4 batteries aren't designed for hard cranking like that. Though they will take it. The main disadvantage of these cells (other than the price) is that they require a good battery management system to prevent undervolt cell reversal during discharge, and to manage charging. It could be that the system they gave you wasn't expecting such a sudden huge discharge current? The BMS will extend the life of the battery pack quite a bit, so it is worth the effort.

 

The main advantage is of course the weight saving. I'm planning an electric car conversion and swapping from lead acid wet cells to LiFePO4 cells halves the weight with an increased range! But it'll cost me $10k+

 

If you're just starting the engine and then letting it charge up, it shouldn't be too bad. A BMS is still advisable, but you aren't relying on it to stay in the air, as such, so it shouldn't be too bad. The kinder you are to them, the longer they'll last.

 

 

[Guest ozzie]

How hot is the starter getting. Most can only handle short cranking times. hopefully it is only taking a few seconds to bring the presure up. I've seen some starters cranked so hard they start to melt the solder connections.

 

how many batteries do you get for 10 grand?

 

Ozzie

 

 

[Spin]

Spin,Doesn't seem a problem. Do you suggest this is not good practice?

 

I am pretty paranoid re starting a dry engine. I love to know the oil pump is bringing something to the party before she fires. Perhaps you know something I don't and I should.

 

All ears.

 

Mark.

Mate, I don't pretend any specialised knowledge, but I probably err in the other direction, if the engine doesn't fire after a second or two's cranking, I stop and rethink the procedure, choke on, choke off, whatever. Both starter and battery tend to take a bit of a caning and get very hot after prolonged cranking. I see your point about oil pressure, but particularly where the engine has run recently, the residual oil film should be sufficient until the pressure comes up. My 2c (Zimbabwe:big_grin:) anyhow.

 

 

[Thalass]

Ozzie: at a rough guess ten thousand dollars would get you 12kWh of battery capacity, which would get you approximately 50km in a decent small car. Can't remember what that pack would weigh, though. I was budgeting for 18kWh, which with my car should get me about 60 or 70km, though there's alot of fudge factor in that so it could be better. That pack would cost me $14,000.

 

It sounds expensive, but this pack would last for possibly 3000 discharge/charge cycles, which would be around 140,000km. It's like buying petrol in advance, and still cheaper because 140,000km worth of petrol would cost me around $17,000! - and that's assuming petrol doesn't go up again. :P

 

But I don't have the price list in front of me, and most of my numbers for the EV are guestimations with a large error built in. Hopefully it will work out better (less than 200wh per km, rather than the 300wh/km that I'm estimating)

 

Anyway, your cranking pack should last quite a while, if you treat it kindly.

 

 

[Guest ozzie]

I have been following the progress of 'E Power" for Aircraft for some time now as i would love to take the Lazair that way. Off the shelf components that will work without major modification are not to far away. Battery weight and cost are the real drawbacks. But same as you i consider them to buying fuel in addvance. the recharging cost is minimal and i view it as one would a fee to 'open the bowser'.

 

the fact is fuel cost will rise a lot and the price of bateries will drop as long as demand does not start exceeding supply. although i think as they improve in performance and weight they may stay close to todays prices. But in the long run be cheaper to operate than 'ICE' power. Interesting future ahead.

 

ozzie

 

 

[Guest Andys@coffs]

The problem with this approach is that the batteries are a mere storage facility for the energy and as such comparing their cost with the cost of petrol is not the same thing. To have a valid comparison you need to compare the cost of the ICE petrol tank and the energy content. (ie $0, cause you already have the tank plus the cost of the fuel) vs the cost of batteries (over the same lifetime as you do for the fuel and tank) and the cost of electricity to recharge them.

 

When that is done I'll be amazed if you can even get close to the cost of the ICE solution (assuming in this case that cost is constrained to pure $ alone. When we introduce damage to the planet in an environmental context then of course it is much more complex and I haven't a clue if it would be cheaper or not especially when the costs in both $ and environmental impact is factored for the manufacturing and ultimate disposal of both solutions..... Being a cynical and suspicious sorta guy I semi suspect that in the battery scenario we are simply moving the polluting parts of the equation to areas that the consumer doesn't see so much of and as such wonder if it is simply a more complex form of the 3 coconut trick...

 

I'm sure its this level of complexity that is the reason why most are confused about climate change and what we should ultimately do about it.

 

Andy

 

 

[Thalass]

Haha I won't get into the whole spiel here, it'll seem like I'm evangelising. But in a car you ought to come close to breaking even vs petrol car costs over the life of the pack. Aircraft are different, though. But while you'll get less range for a given size of pack, in a decently designed aircraft you could soar for a great distance given the right conditions. So an electric self-launching glider will be where things start to happen, i think.

 

(for more info see diyelectriccar.com or the "fossil fuel free" part of the ecomodder.com forums, or of course you can ask around the Australian Electric Vehicle Association's forums (Australian Electric Vehicle Association))

 

Evangelising over :P

 

 

[Tracktop]

more complex form of the 3 coconut trick...

Andy

:thumb_up::thumb_up::thumb_up:

 

 

[Bruce Tuncks]

lithium batteries, cranking and self-launching gliders

 

Thanks Mark for the report on how the lithium batteries are going.

 

I too crank to get oil pressure up before starting. Sure its harder on the battery and starter, but you are saving the con rods and crankshaft from combustion forces while they have no hydrodynamic lubrication.

 

 

[Bruce Tuncks]

self-launch gliders

 

oops I sent the last post before finishing.....

 

I'd really like to do an electric self-launch for my Libelle, but lithium POLYMER is too dangerous I reckon. There is nothing new about the idea, you can buy commercial electric gliders. I think they use lithium ion .

 

These lithium phosphate batteries that Mark has tried are safe but don't have a good enough power-weight for a self-launch glider, but they are heaps better than a lead-acid.

 

Bruce

 

 

[Bruce Tuncks]

I've just sent off for two LiFePo4 batteries from Hobbyking. They are 13.2 volt, 8.4 amp-hour and weigh 1026 gm each.

 

They are planned for working the radio etc in my glider. The price was $75 each, with about $30 freight.

 

But they are sold as " 30C , which I think means 30 times 8.4 amps or 252 amps, with 40C burst whatever that means.

 

Well two of these in parallel should in theory give 504 amps, more than enough to start a Jabiru.

 

Too good to be true? Anyone think its worth a try?

 

Bruce

 

 

[turboplanner]

Hi Bruce, I'm not completely up with battery technology,but this may help.

 

The first check should be for any thermal runaway characteristic. ANY tendency, and I'd forget it because it's not going to extinguish on the way to the forced landing.

 

A key factor if a starter motor is to be used, is to have deep cycle capacity. (This might be why previous experiments failed)

 

The amp hour capacity should also be compared to the standard Jab battery, and equal or greater used.

 

 

[Tex]

Anti-gravity batteries http://antigravitybatteries.com/ use them.

 

Not as cheap as yours though you want very good quality batteries. They do not like being discharged and will be damaged if they go to low.

 

Yes you will have 16amp with a discharge (charge) capacity x 30... but it delivers lots of its charge at that capacity (very efficiently) and once voltage drops it will drain the battery very fast. Ideally you don't want it to do much work at high discharge though to get best result and life.