battery chargers

[steve shaw 3]

i regularly read RCM&E and am amazed that people consider a 200 watt charger as being big . I personally don't own a charger of less than 1000 watts . I can go flying with one plane and two batteries and get in fourteen flights in a morning . I have been using these chargers for about two years now.

[Biggles' Elder Brother - Moderator]

Steve, what are you powering this charger with at the field?

BEB

PS And what size batteries are you charging?

Edited By Biggles' Elder Brother - Moderator on 11/11/2012 20:09:23

[Myron Beaumont]

Wow ! That is 1,000,000 mWatts!in modellers language

Edited By Myron Beaumont on 11/11/2012 20:31:00

Edited By Myron Beaumont on 11/11/2012 20:32:46

[Former Member]

[This posting has been removed]

[steve shaw 3]

brother of biggles- we were using to truck batteries in series but found these batteries failing after about six months .we are now using a generator to run six x 1kw chargers. i charge everything from small 2200ma 3 cell up to 5000ma 6 cell . i charge my 3000ma 6 cell batteries two in parralel at 30 amps . i dont like to wait too long for a charged battery.So tom do you take a ship load of batteries to the field.

[Chris Bott - Moderator]

No idea why you're amazed Steve, 200W is plenty for some people.

I use a 350W charger and charge batteries for .40 - .50 I/C sized panes in 15 minutes, so I too use two plane batteries and fly continuously.

For smaller models I find it much easier to take half a dozen lipos for a flying session, rather than cart a big charger battery and charger to the field.

Bear in mind that we have to walk a good way from the car park to the pits area too. So we don't want to be carrying too much.

It's horses for courses. Each of us does what suits us.

[steve jones 7]

Hi - I'm new to this forum and I don't know if this will come up as a new thread - I have a couple of questions about the IMAX B6AC charger, so if it comes up as a response to someone ele's thread it will be a bit off message. Still, nothing ventured.... so here goes. I'd be grateful for anyone's help.

I have a B6AC charger and am trying to decipher the instructions, which I find imprecise at best. Several basic questions:

1) Do I plug the battery into the charger first and then then follow with hooking up the mains or 12v car battery lead?

2) If I am doing a 'Balanced Charge' on a LiPo, when I connect the flight battery do I insert the balance plug in first or the main (flight) battery lead?

3) If I am doing anything other than a 'Balanced Charge@ i.e. a fast charge, a discharge or a storage charge, do I have to leave the balance lead un connected?

4) If the answer to 3) is 'leave the balance lead un-connected' then will this mean the battery is unprotected against going unbalanced and therefore face instability and thermal runaway?

5) Finally, the ESC I have has no provision to plug in a balancing lead.... Is this a problem? the ESC is part of an ARTF kit called (wait for it...) the GreenR/C Model Airplanes 'Pretty'

Any help would be great - if anyone knows of a properly written manual for the B6AC, (I have downloaded three versions of the manufacturer's manual, plus I have the original paper one, and they are all mostly gobbldeygook and might just as well have been written in the original Chinese) then I'd like to have details of its whereabouts.

Many thanks in advance

Steve

[John Privett]

Steve, I have an IMAX B6 (not sure if the B6AC is any different) and yes, the instructions with mine were not particularly clear either. Like most goods originating from China the instructions are written in something often jokingly referred to as "Chinglish" - a strange language that bears a passing resemblance to English as long as you don't try and make any sense of it!

Anyway, I'll offer my answers, based more on what I do than what the instructions say and anybody else who thinks otherwise can chip in and please say so!

1) I always have the charger connected to the power supply before connecting any battery to be charged, but I can't imagine it making any difference.

2) Can't see it making any difference, I think I probably plug the balance lead in last, but not out of any concious decision.

3) I always connect the balance lead on a LiPo, but have no idea whether or not it makes any difference when not doing a balance charge. What I do works...

4) Don't know. As mentioned above I always connect mine, and I've never had a battery become unbalanced when charging.

5) None of my ESCs do either. Do any have one?

[Dave Bran]

1. There are extremely minor pros and cons, i.e. it really does not matter. I usually connect the power first so as I connect battery the alarm circuitry is already active.

2. There are extremely minor pros and cons, i.e. it really does not matter. I usually connect the balance lead next after power so as I connect battery the alarm circuitry is already active.

3. Answered in above

4. If you leave the balancing lead disconnected the charger cannot possibly check cell over voltage, e.g., you might have on a 3S two low and one going dangerously over voltage, if of course it has that facility, though most do.

5. ESC's with a balance lead connection (I have only two out of very many and have not bought one of that type for years) check discharging for each cell and go into whatever shutdown mode is set if a single cell transgresses the settings. Those without (the vast majority) can only look at total cell voltage. While marginally better to have balance connection, the extra connections often get in the way.

[Dave Bran]

Going back to the OP, I usually take enough flight batteries to cover whatever I am flying, though I always take a small car battery I use for engine starting and a charger.

If I charge at the field it is usually only to save time on my return, not to re-use that battery then and there.

At home I use the longest charge time that is practical, rarely pushing cells to the max charge rate stated possible, purely on the basis that manufacturers claims are usually a trifle over zealous.

[Paul Marsh]

I see this scenario:

To avoid using heavy. messy fuel-burning engines, electric seems a viable option.

Then to get the power, people take large, heavy batteries across a field and supplement with large genearators that run on fossel-fuels, to charge the flight batteries.

Isn't it easier, just to stick an engine in there and fill and go...?

[Greybeard]

Posted by Paul Marsh on 24/02/2013 08:02:37:

I see this scenario:

To avoid using heavy. messy fuel-burning engines, electric seems a viable option.

Then to get the power, people take large, heavy batteries across a field and supplement with large genearators that run on fossel-fuels, to charge the flight batteries.

Isn't it easier, just to stick an engine in there and fill and go...?

Do you enjoy poking wasp's nests with a stick?

[John Olsen 1]

I have a 65Ah deep cycle battery and a Turnigy Fat Boy charger, the latter can do up to 1344 Watts, although only if I connect to a 24 to 30 Volt supply...I do have two of the batteries but so far haven't needed that much capacity or wanted to carry them both the 100 or so yards from the parking to the pits. One is enough, it lets me charge a 6S 4200mAh Lipo in about quarter of an hour, a charge being the 3000mAh that the timer is letting me use on a typical flight. This seems about right, leaves a bit for an extra circuit or two if the strip is blocked, and avoids fully discharging the Lipos. I'm charging at 2.5C on batteries that are rated for 6C so should be well within what they can stand. Alternating two Lipo packs and the usual standing around talking gives the batteries time for a rest between times too. I'd rather have two Lipos and charge at the field in these larger sizes, as the capital cost of more gets a bit high.

I wouldn't want to go much bigger with electric, the main limitation being the size of the ground equipment needed to charge them, eg bigger lead acid cells. I don't really want a generator hammering away in the background all the time. Now if we could cover the roof of the shed with solar cells and put a good size bank of batteries in there it would be nice.

I do own chargers smaller than this, the one for my Ember indoor model takes four AA cells and charges the 1S 70mAh lipo in about ten minutes or so. The Fat Boy can in theory charge those OK, if I could be bothered organising the leads. I also fly IC, but will try to avoid poking any wasps nests.

John

[steve jones 7]

John & Dave. Thanks for your replies. Dave - I love your icon - makes me feel right at home! many's the time I have felt like head bvutting my keyboard.

I'm just waiting for some Deans connectors to come so I can take the plunge and charge my first LiPo. This is an interesting thread. I have much to learn... taxes the ol' grey matter a bit.

Thanks again, guys.

Steve

[Tony Smith 7]

Posted by Chris Bott - Moderator on 12/11/2012 08:49:21:

No idea why you're amazed Steve, 200W is plenty for some people.

200W is much more than many people need, I don't need anything bigger than my 50W charger and most of the time I would do just as well using smaller still. My batteries wouldn't charge any quicker on the original poster's 1000W charger. Size isn't everything!

[steve jones 7]

Just an update to all who replied and helped me out with my Imax B6AC charger. I have now completed my aircraft, itself a new experience because for the first time I used fibreglass to glass in a false floor to strap the battery to with velcro. All went well.

I have flown many times now, sadly there is a warp in the wing which requires a significant amount of trim to fly straight. Oddly it doesn't seem to affect the set trim of the aircraft. In previous experience trimming out a warp was only good for one airspeed. Faster and it would go one way, slower and it would go the other. This one seems to be quite steady regardless of speed.

Caught a few thermals and am enjoying flying again. gaining experience with the electrics and am now up to 16 minutes on the tranny timer. At that I'm still on 11.34 v on landing. should get better with better weather and thermal activity, should be able to throttle right back for longer flights.

Have written up a full set of instructions for charging lipo batteries eiththe imax in what I consider to be proper english. If anyone is interested, let me have some contact details and I'll send.

So, thanks again, guys.

Steve