|bouncebounce crunch||18/08/2012 03:21:34|
1173 forum posts
Any chance of a charging rate chart, with peak detect (i don't know how to interperate that one.)and cycling rates, added to one edition of the mag, very helpful for people like me that bought a charger but the instruction are rubbish. I might be a few sandwiches short of a picnic basket but a chart would make this electric stuff easier to understand.
|bouncebounce crunch||18/08/2012 08:05:53|
1173 forum posts
I am sure a few newcomers would like a manual of charging batteries to be understandable.
|bouncebounce crunch||18/08/2012 09:13:19|
1173 forum posts
Do I need to pay for this/
|Peter Beeney||18/08/2012 15:26:49|
|1211 forum posts|
bbc, - I think the charging, and also very importantly, the care procedures for batteries have been covered in these pages a few times, I’ve chronicled them more than once myself, but I have to confess that I’ve no idea how easy, or perhaps difficult, the posts are to find.
For starters, what sort of cells are you talking about, you mention peak detect, so this must at least include nickel types, most likely Ni-MH nowadays, nickel metal hydride, and as such I suspect this then will simply be receiver and transmitter batteries. I’m not sure a chart, as such, would tell you very much, and it’s possible it might not tie up exactly to your kit anyway! Again, I’m presuming your charger must be a fast charger. I’d have thought that a better way would be to get a bit of a handle on the procedures and then simply calculate your own charging rate. The system is very flexible. Then I’m sure the charger instructions will make much more sense, too.
Regarding cycling, I’ve always tampered with batteries, my own and many other folks, and I’ve never bothered with cycling anyway. But I would say the very first starting point in battery maintenance is to check your packs for capacity on a regular basis, say at least once a year, or preferably twice, and that also includes from brand new, before you even put it in a model. Many models have crashed over the years, everyone will know of at least one, in circumstances where the battery has suddenly gone flat. But it’s most likely because it’s simply gone faulty, over time, all on it’s own, and no one has noticed. Regular capacity checks would have prevented all of these. I consider that because of the easy life they have, tx and rx batteries do not suddenly fail out of the blue. There are also other reasons for flat packs, forgotten to charge etc., but it invariably all comes down to the pilot again. Transmitter batteries are safer, these days I think just about every tx has a low volt alarm, which has saved the day on a few occasions.
One point to consider, any crash involving a flat battery is an out of anyone’s control type crash. It can come down anywhere, and it certainty does!
If the system is flexible, some batteries are very bendy indeed, in some cases it would be difficult to elevate them up to a second class rubbish status. You cannot be too careful!
Hope there are some starter clues in there for now, and this information will cost you the grand sum of four shillings and sixpence, please…
|Mike Wabe||18/08/2012 21:40:37|
37 forum posts
Four shillings and sixpence!! Good grief man, it is good information but not worth more than 3 shillings and 4 pence 3 farthings.
|bouncebounce crunch||18/08/2012 23:56:12|
1173 forum posts
thank goodness for that i thought it might have to pay two bob.
Thanks PB, I'll chase down some of your posts and go from there. My charger is badged Swallow AC/DC 2, equal to the Sigma brand in GB. the problem is rubbish instructions and my lack of battery understanding, but i will eventually get it. I have some batteries from ye olde days, NiCd, also NiMh, 2s and 3s LiPos, so a fair mix, all came with their own charger so as any sane person would do, find an affordable charger that can charge the lot. I have been using the charger but i doubt i have ben using it to its full potential.
|Peter Beeney||19/08/2012 18:27:21|
|1211 forum posts|
Thank for the reply, bbc, and I can easily still remember Mike’s farthings, too. Ceased to be legal tender sometime late fifties, at a guess. It’s remembering what the value of today’s money is supposed to be is what I have trouble with……
Nickel cells, that’s lumping nicads and nihms together, are the most difficult types to charge, lead acid are more accommodating and lithiums are the easiest. A constant current, that’s a steady unchanging current irrespective of the battery voltage is used for nickel charging. The charging and discharging voltage curves are very flat, and it’s therefore it’s quite difficult and extremely unreliable to try and judge the SoC, (State of Charge), by checking the open circuit voltage. It needs to be on some level of discharge to get an accurate reading. Nickel cells, when charged at a low rate, at a 10% level of capacity, or less say, can withstand a degree of overcharging, that’s an excess beyond the full charge. This just turns into heat, which at this low rate, can be dispersed as it's generated. Also when they are charged at a faster rate they exhibit a characteristic that when they become fully charged the voltage starts to fall instead of continuing to rise, this is known as the delta peak, the charger recognises this and terminates the charge. One little snag is that should the charger miss this for whatever reason, the current just continues into the battery at a rate of knots, the heat then starts to build up and can't escape quickly enough and things can eventually get very warm indeed on occasions. A normal battery in good condition will have a low impedance, that’s the resistance that the charger ‘sees’ when looking in the terminals, but sometimes if they have been left unused for a time this resistance rises and confuses the charger. Even brand new batteries can, on the odd occasion, suffer from this, too. But never fear, there are ways round this. The low internal resistance is also the reason why the battery is able to deliver the amps in quantity when called upon to do so.
Lead acid batteries are usually charged by a constant voltage source, the alternator on your car for instance can supply a great many amps if necessary at a steady theoretical 13. 8 volts, in practise around 14, mine is 14.2. They can also withstand a degree of overcharging as well.
Lithiums are different, they cannot accept any overcharge at all, so they always use a constant voltage charger, 4.2 volts per cell or multiples thereof. However, if we connected this to a discharged pack with no restrictions it might charge too quickly, so within the charger there is a current limiting device, which is adjustable to suit various sizes of packs. So I might describe it as ‘constant voltage with current limiting’ charging. The difference in voltage between the battery and the charger is taken up by the current limiter, but the battery voltage will gradually rise until it equals the charger output, the limiter then drops out and the battery will gradually get the final little finish to the charge.
The overcharging has the very beneficial effect of equalising the charged levels of the individual cells in a pack, exactly what we want, but unfortunately we can’t do this with lithium batteries so this explains the reason for balancing, to keep all the cells at the same level of charge.
So now you need to pick the bones out of this, and gen. up on the details. Starting with the nickel wire corrosion perhaps. Look carefully for any signs, even just tarnishing on the pins in the plug is a start, if it’s there open the pack and unsolder the wires, then check the pack to make sure it’s up to speed and if ok solder on a new plug. Gives it a whole new lease of life. I’ve always tried to be a bit Green with batteries, so I only throw them away unless I really really have to. With the proper care and attention, many packs will go on for years.
All Good Luck with it.
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