on field charging?

[Clifford Stone]

I'm looking at the practicality of 'on field charging' rather than having 6-8 batteries charged and ready to go?

I have an Etronix or Turnigy quad charger in mind, it will be charging up to 4 batteries in one hit, 4s 2200mah 14.8v 35c, just the once, ie. taking 4 fully charged batteries, they will all need one recharge over lunch.

I wondering what sort 12v battery, type, size etc would be 'adequate' for the job? ie, I dont want to strugle humping a large car battery if a more modest sealed gell type would do?

CJS

[Frank Skilbeck]

You can work it out, a discharged 2200 mah battery will take say 2,000 mah ( 2ah for simplicity) and the votage input to the battery will need to be 16.8v, or about 34 Wh, assuming the charger is about 80% efficient (it has to step up the voltage), then the battery has to supply 42 Wh, which with a 12 v battery is around 3.5ah, so to charge up 4 batteries you need a battery with a capacity of more than 14 ah.

[Plummet]

Dual Purpose...

Have you got, or should you get one of those car emergency starter things. I have one from Machine Mart. It is good for starting the car if the battery is flat, but it also has a light - not especially useful - and a cigarette lighter type socket. It will take the usual connector, and you can run your chargers from that.

It is a heavy but carryable unit. I presume the weight is a lead-acid battery.

I have seen similar things in Aldi or Lidl, but they were very light weight, and I am not sure how much capacity the batteries in them might have.

Last year my unit was in great demand by our neighbours on cold mornings.

Plummet

[Biggles' Elder Brother - Moderator]

I use a 70Ah leisure battery - probably overkill, but its what I have available. On that I can charge a set of four 6s 3000mAh and numerous 3a 2200mAh batteries sufficient times to fly as much as I want all day (10am till dusk!) and not see any appreciable drop off in battery performance!

BEB

PS Its very heavy though!

[Myron Beaumont]

Plummet

I use one of those as well sometimes .It's a Yuashu (or something like that from memory 17 Ah ) inside .Living on and running a campsite ,you wouldn't believe how many idiots run their car batteries down over night .A couple of weeks ago ,I lent the thing to a camper who snapped off the valve thingy for pumping up tyres (the main reason I bought it by the way)

Question--Where can I buy a new valve to compressor thingy with that little lever ? Can't find one anywhere .

[Chris Bott - Moderator]

Myron how about this replacement hose from Halfords ? Or probably cheaper, search ebay for "foot pump hose"

[Peter Beeney]

It’s always seemed to me that battery capacity is directly related to weight, in terms of lead batteries, there is apparently no easy way out that I’ve ever discovered. To maintain the the watts in copious supply you need to apply the same proportions to the muscles, perhaps?

I’ve always carried jump leads as a matter of course, and back in the days when the powered gliders first started to become popular they were used quite a bit, we found it does not take long to reduce the sometimes smaller capacity car battery to a heap of lifeless lead; and we soon had developed an understanding that no one was left on their own, too, or at least not without starting the car, on one occasion the last man leaving found his battery flat. No mobile phones in those days, and it was a very long walk……

I said ‘apparently’, I’m slowly getting to the point where I also need a new auxiliary battery for the field. I’m very seriously considering a 12V LiFe battery, they are obtainable in larger sizes. I calculate the voltage will be spot on for connecting in parallel to the car battery for charging. The advantage is that the weight is about one third of the equivalent capacity lead acid, the disadvantage is the cost is about two thirds more! Or more! They are very expensive! But if I also take the expected longevity into account, then maybe it’s not quite so bad. They are expected to have a long life; 2000 cycles as standard. Also less than half the size of the same capacity lead acid; and they are already getting a reputation for taking punishment with no after effects.

I think that LiFe batteries are being produced as standard replacements for some motor cycles, maybe they will eventually appear for cars, perhaps then the price may become more realistic.

PB

[Frank Skilbeck]

Or bit left field **LINK**

Maybe even lighter than a 70ah leisure battery

[Plummet]

Posted by Frank Skilbeck on 20/09/2012 14:18:37:

Or bit left field **LINK**

Maybe even lighter than a 70ah leisure battery

But I would be cautious about connecting a genny directly to a battery charger. I suspect that the waveform from the genny might not be too smooth - it might be used to charge a smaller battery which you could use for the charger.

Plummet

[Clifford Stone]

Posted by Frank Skilbeck on 20/09/2012 14:18:37:

Or bit left field **LINK**

Maybe even lighter than a 70ah leisure battery

Made me smile, tying to reduce noise with leccy models . . . .

CJS

[Simon Chambers]

I've got one of these: **LINK** - I bought it last year when it was on offer for £50.

Fits perfectly in an small blue Ikea bag! A fliers down our field uses one of those stacking crate boxes (the ones that are often use to put all the junk up in the loft in) and mounted his charger on a wooden sheet on top of the box.

However it is heavy! I'd say its around 20-25kg. Those with a weak back, etc may consider getting a trolley of some description to move it about.

Don't use a Jump start box to charge your batteries. Those batteries are designed like car batteries, in that they give huge current over a very short period. Where as charging batteries is a small current over a long period. Basically if you deep discharge a battery, the lead plates break down/corrode. So using one of these to charge batteries will give it a short life.

Main types of Lead Acid batteries:

Starting batteries - Huge currents, short period i.e. starting an engine. The lead plates in the batteries are very thin but large. This allows large currents to pass, but hence can break down and corrode quickly if deep discharged

Leisure batteries - Low currents, long periods i.e. powering a caravan. The lead plates are thick and withstand deep discharging much better. However the thicker plates have a lower surface area, and hence less able to deliver large currents.

Hybrid battery - A compromise of both above. All sort of names for these. Generally used on boats and motor homes where you want to power your fridge and lights, but also start the engine.

You also get different cell styles - such as flooded, gel cell, AGM. Flooded is like your car battery - the electrolyte is liquid and floating in the cell. Gel cell the electrolyte is a gel, commonly used on wheelchairs, etc - can be mounted in any orientation without risk of leaking. AGM (Absorbed Glass Mat) has the electrolyte suspended in a woven glass matt - good power/weight ratio, good deep discharge characteristics, good current capability. Flooded cheapest, then Gel cell and finally AGM are expensive (but the best).

Even with a Leisure battery, don't discharge it more than 50% for long life. I.e. a 75Ah battery, don't take more than 37.5Ah out of it. However for most, that is more than a days flying season anyway.

Cheers,
Si.

[Clifford Stone]

Thanks for the replies people. My curent thinking is slightly confused?? go for somthing like this:

**LINK**

or maybe something a litle lighter:

**LINK**

Frank's calculation seems to indicate that 40ah will do the job, also considering Simons advise not to discharge more than 50% . . . although, as my partner and I are mobility scooter users, we do push the discharge bounderies on ocasions it seems?

My thinking is 'weigh', and 'walking distance', weight I can cope with at present, but walking with weight any distance is hard! It is not going to get better, so I have to look ahead.

I have the 'charge on field' option or buy 8-10? 2200mah 4S 14.8v Lipo's. Ten lipos will set me back £350 + £100 for a quad charger, there is no way I can recharge them one at a time! The on field charging looks like £70 battery, £100 quad charger and £140 for 4 lipo's. Either way, I need a 'service/charging trolly' . . . make that out of bits and pices, based on an old fishing trolly or a fold up sack barrow, say £25?

8-10 lipos is the most convenient, but the most expensive, I could manage with 8 lipos, but that leves only a margin of 'one' battery going down, and no test flight facility?

So to taking the question on a little further, will a 40ah battery be enough or is the sealed 86ah the better bet, albeit slightly larger and heavier? (by the way, are these larger 'sealed' batteries, gell based?).

Any sugestions on 'quad chargers', Turnigy seem to have two or three on offer, Etronix have one, looking at the construction, I would wagger they are all based on the same electronics???

Thanks for your help, CJS

[Simon Chambers]

You may be better off with a pair of smaller batteries for ease of carrying. Use one, when the voltage gets a bit low (i.e. discharged), put it back in the car and get the other out.

Do you have any older batteries from your Mobility Scooter? Maybe you could put new batteries in your scooter and use the old ones for field charging?

You can of course go below 50%, infact you can go as low as 80% discharged. But the lower you go, the shorter the life of the battery. For me, I expect my Leisure Battery to last 3-4 years - hence why I don't go below 50% discharge.

In terms of charging the LiPo batteries, a lot of modern packs can be charged at a rate more than 1C. Check the label, some can go as high as 5C. I.e. a 5C Charge, 2200mAh pack can be charged at 11A. Of course the higher the charge rate, the shorter the life of packs. 2C charge rate is a safe rate (if the pack is rated to of course) for a long pack life. At 2C charge rate, expect it to be charged in around half hour. You'd need to get a charger that can handle the current - i.e. a charger that is bigger than 50W. For example a base iCharger 106B can charge at 250W. So that's a 6S pack at 10A.

To save time too, you can get Parallel charge boards that allow you to charge multiple packs (that are the same capacity) at the same time - in one go.

Si.

[Simon Chambers]

Posted by Clifford Stone on 21/09/2012 12:47:46:

So to taking the question on a little further, will a 40ah battery be enough or is the sealed 86ah the better bet, albeit slightly larger and heavier? (by the way, are these larger 'sealed' batteries, gell based?).

The 86Ah looks like a flooded, the 40Ah looks like a sealed gel cell.

Posted by Clifford Stone on 21/09/2012 12:47:46:

Any sugestions on 'quad chargers', Turnigy seem to have two or three on offer, Etronix have one, looking at the construction, I would wagger they are all based on the same electronics???

I'd personally recommend a higher wattage charger (250W or greater) than a quad charger. Most quad chargers are only 50W per channel, and you'll find as you get to the bigger packs, that becomes very limiting. So on a 50W charger a 3S LiPo, your looking at a maximum charge current of ~4A - a 4S Lipo a maximum charge current of ~3A. Hence a 4S >3000mAh pack will take longer than an hour to charge. Thus making it not very useful for field charging.

Si.

[Simon Chambers]

Just re-read the 86Ah battery. That is a hybrid leisure/starter battery - Numax calls them Marine batteries. The big give away is "Significantly enhanced cold cranking ability" - i.e. its capability to crank over a cold engine in cold environments. As I described above, you can use them for both starting and deep discharge - hence a compromise. I would recommend for field charging to get a proper leisure and/or a deep discharge/deep cycle (both mean similar things) battery.

Gel cell and AGM cell will be lighter for equivalent capacity than a flooded cell. Be aware that the Gel cell and AGM cell require special chargers - like the ones you will use for your mobility scooters.

Si.

[PatMc]

Posted by Clifford Stone on 21/09/2012 12:47:46:

I have the 'charge on field' option or buy 8-10? 2200mah 4S 14.8v Lipo's. Ten lipos will set me back £350 + £100 for a quad charger, there is no way I can recharge them one at a time! The on field charging looks like £70 battery, £100 quad charger and £140 for 4 lipo's. Either way, I need a 'service/charging trolly' . . . make that out of bits and pices, based on an old fishing trolly or a fold up sack barrow, say £25?

8-10 lipos is the most convenient, but the most expensive, I could manage with 8 lipos, but that leves only a margin of 'one' battery going down, and no test flight facility?

Clifford 10 4s 2200mAH batteries can be bought for £150 - £200.

IMO pre-charging is the best option. I haven't charged at the field for a few years now as I always take enough batteries to the field for a day's flying. I re-charge the used ones from the time I get home then as convenient until they are all ready for my next flying session. Although I have a couple of chargers but usually only re-charge one battery at a time.

[Clifford Stone]

Posted by PatMc on 21/09/2012 13:40:23:

Posted by Clifford Stone on 21/09/2012 12:47:46:

Clifford 10 4s 2200mAH batteries can be bought for £150 - £200.

Mmmm . . . The batteries I use are 35c with a hi boost rate, 'racing batteries, so I am told?', standard output 35c is stated in the rules. Turnigy do a 4S Nano-tec 45c-90c at $26.00 but that is not allowed in e2K racing . . . at the moment . . . a bit vague, I will have to ask the question? They also do a 4S 35c-50c @ $21.00 . . . might be worth a look, especialy when HK gets its act together on the UK warehouse, which is only 15 minuites away from my home!

Pat, I would be very pleased if you have any sugestions or pointers?

CJS

[Clifford Stone]

Posted by Simon Chambers on 21/09/2012 13:05:46:

You may be better off with a pair of smaller batteries for ease of carrying. Use one, when the voltage gets a bit low (i.e. discharged), put it back in the car and get the other out.

Do you have any older batteries from your Mobility Scooter? Maybe you could put new batteries in your scooter and use the old ones for field charging?

You can of course go below 50%, infact you can go as low as 80% discharged. But the lower you go, the shorter the life of the battery. For me, I expect my Leisure Battery to last 3-4 years - hence why I don't go below 50% discharge.

In terms of charging the LiPo batteries, a lot of modern packs can be charged at a rate more than 1C. Check the label, some can go as high as 5C. I.e. a 5C Charge, 2200mAh pack can be charged at 11A. Of course the higher the charge rate, the shorter the life of packs. 2C charge rate is a safe rate (if the pack is rated to of course) for a long pack life. At 2C charge rate, expect it to be charged in around half hour. You'd need to get a charger that can handle the current - i.e. a charger that is bigger than 50W. For example a base iCharger 106B can charge at 250W. So that's a 6S pack at 10A.

To save time too, you can get Parallel charge boards that allow you to charge multiple packs (that are the same capacity) at the same time - in one go.

Si.

Appologies for my dumbness Simon. The charger I have at present is a single Etronix 'Power Pal', max charge, 0.1a-5.0a (50w max). Will a paralell Charging board work with this OK at home, will it slow the charge time of mutipul batteries? And does it do the job as efficiently?

Using the Parallel board with the 'iCharge 106B' . . . better charge time, or no different?

In other words, using a single charger with a higher W capacity and a parallel board, is it a better idea? . . . at home or on field?

The mind asks the question . . . 'single hi capacity charger + plus Parallel board on the field'? is it a practical option. Can batteries be added during the cycle, ie, start with two, then half an hour later add another two?

By the way, 4 batteries will give me a charging window on the field of about 2 hours, if I can start with two and add as used?

The above are important questions overal for 'e2k racing'. I see it as a great entry to the adrenalin rush of pylon racing, in club and social terms. However, the sticking point is the outlay of batteries and/or on field charging. It is an argument I have heard from the other side of the fence many time in just a few months.

What is ignored by the 'ic, we will never change fraternity', most competitors are awash with engines, only this last Sunday; "I have 12 engines and only one goes well" . . . another coment, "I buy 10 engines at a time, blue print them by mixing parts, end up with one or two decent motors, sell the rest off".  The ic lads see the Leccy models as a threat, they can be faster, but suffer battery lag after 6 or 7 laps, when the ic power claws back . . . a good leccy pilot might just pip the ic model, but its so close, its realy exciting!!!

The Leccy motors we use, Turnigy 3536 1400kv, either go or not!! . . . If not the supplier replaces it! By comparison, the battery issue is, IMHO minor, but it is used as a big stick . . . if you see what I mean?

CJS

Edited By Clifford Stone on 21/09/2012 14:53:46

[PatMc]

Clifford, there are some Loong Max Tipple 2300s & Gens Ace 2200s in this page that are good quality & in the price range. I've used (still use) both of these types but have no experience of the Gens Eco.

IMO it's not worth going over 25C for sports flying & I've found the Tipple 20C to be as good as some other brands rated at 25-30C.

BTW I make a point of only charging at 1C rate.

Edited By PatMc on 21/09/2012 15:06:32

[Clifford Stone]

Posted by PatMc on 21/09/2012 15:05:39:

Clifford, there are some Loong Max Tipple 2300s & Gens Ace 2200s in this page that are good quality & in the price range. I've used (still use) both of these types but have no experience of the Gens Eco.

IMO it's not worth going over 25C for sports flying & I've found the Tipple 20C to be as good as some other brands rated at 25-30C.

BTW I make a point of only charging at 1C rate.

Edited By PatMc on 21/09/2012 15:06:32

Have to stick to 4s 2200mah its the rules . . . 'in this page' I presume there was a link, not now? . . .

I don dissagree with you on sport flying . . . but believe me Pat . . . 2000/e2k is serious stuff, sport flying it is not. . .

CJS

Edited By Clifford Stone on 21/09/2012 15:37:11

[PatMc]

Sorry forgot to insert the link - it was a Giantshark page. I didn't realise that it was for comp flying, so won't be relevant to your needs.

[Steve Hargreaves - Moderator]

Cliff has been bitten by the e2k pylon racing bug Pat.......

As a left field suggestion might a smallish petrol Genny do the job for you Cliff....you could run your mains charger from that.....just a thought....

[Dave Bran]

With six years plus experience of Loong-Max and Tipple batteries from their first availability in the UK, and owning about 75 currently, there is no advantage to be gained in charging Tipple batteries at low C values. All it achieves is a longer wait! They are fine at 5C, but I usually charge them at 3C or so, fast enough.

I went to my local car battery place and blagged an "exchanged in" car Battery type 805. Reasonably small and not too heavy, with a decent carry handle (I was told its the size used on a Nissan Micra) this is used to start all my engines inc my Heli blackhead competiton OS91 which has ridiculously high compression, and all my TT 53 powered helis, a 26cc petrol, fixed wing glows up to 91 (as that is the biggest I have) and field charge if needed up LiPos to 6S and at 3-4C.

Other people with the stupid little gel things borrow it frequently (in fact it was borrowed twice today to start a couple of big four strokes!!).

It sits 24/7 when at home on a small solid state auto cycle/auto reconditioning/trickle/high current burst charger made by CTEK.

I have had it since 2007. Cost me nothing........................

Really must go and blag another..................

[Clifford Stone]

Posted by Dave Bran on 21/09/2012 16:46:41:

With six years plus experience of Loong-Max and Tipple batteries from their first availability in the UK, and owning about 75 currently, there is no advantage to be gained in charging Tipple batteries at low C values. All it achieves is a longer wait! They are fine at 5C, but I usually charge them at 3C or so, fast enough.

Another dum question Dave, when you charge at these higher 'C' rates is that ballanced or unballanced . . . ?

CJS

[Clifford Stone]

 

Posted by Steve Hargreaves - Moderator on 21/09/2012 16:16:24:

Cliff has been bitten by the e2k pylon racing bug Pat.......

As a left field suggestion might a smallish petrol Genny do the job for you Cliff....you could run your mains charger from that.....just a thought....

Here I am Steve, trying to keep things quiet . . . by racing electric . . .

In truth I think I have worked it out now, it aint cheap which ever way one looks at it. However, a quad charger:

**LINK**

100w per chanell will do the job, give me flexability over the whole range of batteries I will use for fun fly as well as the spacifics for pylon. I need to tie this high 'C' rate thing down a bit more, but I think I'm looking in the right direction?

12v supply will be a compromised, 86ah sealed leasure battery, dont want any acid sloping around:

**LINK**

Four lipos, 2200mah 4S 35c, this I see as a practical settup for all my future flying, competition or for fun. Its the flexabuility I like . . . a charger/service trolly, with all tools, spares, batteries, each item in or will have its place, rather than the higaldy-pigaldy way things are don normaly, boxs every where:

This is my ideal, I like organised and tidy . . . will it happen?

CJS

 

Edited By Clifford Stone on 21/09/2012 19:15:33