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HomeAircraftHelicopterMain Discussion › Why do lipo chargers balance a pack? that is so dumb...
04-06-2010 11:09 PM  8 years agoPost 21
jackheli

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Vancouver - Canada

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The idea is that by using a "balancing" approach, complex software prone to defects and mistakes is needed. That is the "dumb" part. My 1010 has gone through some 5 different software revisions and still does many dumb things.

By creating a very simple CC/CV, one cell charger and cloning it to the number of cells required makes much better sense. Any child can program that!

It's easy to find an excuse to do wrong. Hard is not to find an excuse to do right.

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04-06-2010 11:52 PM  8 years agoPost 22
hootowl

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Garnet Valley, Pa.

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I love my 10S. FMA calls it full power balance charging.

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04-07-2010 03:36 AM  8 years agoPost 23
aceisback

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Terre Haute, IN

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By creating a very simple CC/CV, one cell charger and cloning it to the number of cells required makes much better sense. Any child can program that!
This what what I had set out to do last winter (simple and cheap). I did not want to spend hundreds on a decent charger. What should be simple, I found would be too costly and inefficient for our hobby.

It has already been done, but $18-$25 per charger (no power supply, control circuitry, voltage monitoring, etc) it is not very cost effective. You could buy a bunch of 1S AC chargers (nothing available with much over an amp of charge current) but you would have no charge monitoring other than the simple intelligence of a standard wall wort charger which. What you are asking is by all means possible, just not good for our application. For the money we spend on our helis, I WANT to know that my battery is charged and charging properly.

a few years back, I had a NiCad pack that was charged using a JR wall charger over night, and the charge light was on. Next day, I found out the hard way that the pack had a bad cell. Since that day, I check every pack after every charge and after every couple of flights to make sure everything is ok. I will never trust a wall wort again.

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04-07-2010 03:54 AM  8 years agoPost 24
Anthony.L

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Seattle, WA

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The problem is.. No one makes an affordable 24v, 50 amp power supply to power the next generation of chargers.
This is very true, 24V will be the future power supply need. The cheapest I've found so far after spending 5 minutes on Google is this.

24V, 42AMP $210

That's very reasonable and I would gladly pay around $200.

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04-07-2010 05:58 AM  8 years agoPost 25
jackheli

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Vancouver - Canada

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Here is a 20A http://cgi.ebay.com/24V-power-suppl...=item3a5980f3d8

It's easy to find an excuse to do wrong. Hard is not to find an excuse to do right.

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04-07-2010 03:53 PM  8 years agoPost 26
Aaron29

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USA

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That's because the balance connectors are only capable of carrying 3A.
The easiest way to do what the OP was talking about would be to disconnect the cells from one another, charge separately through a larger wire, then after charging reconnect in series (or series and parallel for 5S2P).

But that's a pain and what would we gain in going through that? Really the balance charging we do now only has minor disadvantages I can think of...

First, we are consuming energy to charge the battery and then the balancer discharges individual cells. Essentially you're filling a bucket with a small hole in the bottom. This means charging takes more mAH than it should and of course there is the minor increase in time to charge since

But really, even that isn't a big deal. The mAH we're talking about isn't big and charging times are coming DOWN due to high C charge rates. i.e. we have a big hose and the hole in the bucket is small.

We don't lose much using the balance lead.

By the way, that's my charger. I'm not sure if other chargers work different. I suppose there could be a charger that provides charge through the MAIN lead but has a supplementary current through the balance lead to balance. (a hose filling the buckets through the bottom, too, essentially).

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04-07-2010 04:02 PM  8 years agoPost 27
cudaboy_71

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sacramento, ca, u.s.

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balance taps are still only wired in series. there's not an individual + & - tap to each cell.

you'd not only have to run thicker wires, but you'd have to run additional wires in a completely new circuit. then, the pack would ONLY be good for individual chargers, as no current balancer would be able to work with that schematic.

even that is not a solution though. the cells are still wired in series to the main leads that you'd plug in to the ESC/BEC...so, voltage would/could leak out from one cell to the other if there is voltage differential between cells.

nope, back to square one. not so dumb after all, is it?

if it ain't broke, break it.

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04-07-2010 04:08 PM  8 years agoPost 28
Aaron29

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USA

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balance taps are still only wired in series. there's not an individual + & - tap to each cell.
Check that statement?

As I understand it, the balance taps are separately wired to each cell. That's why you have 4 wires on a 3 cell balancer lead. One for each cell plus the common ground.

Otherwise there is no way to balance.

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04-07-2010 04:13 PM  8 years agoPost 29
cudaboy_71

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sacramento, ca, u.s.

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here's a completely typical tap layout.

if you still don't believe it, grab a VOM and try taking the voltage of the cells through the taps. their voltages are additive. only the first cell will read 4.2v...the next will be 8.4, 12.6, etc., etc.

if it ain't broke, break it.

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04-07-2010 04:16 PM  8 years agoPost 30
Aaron29

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USA

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OK I see what you mean.

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04-07-2010 04:19 PM  8 years agoPost 31
Aaron29

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USA

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You'd have to disconnect them all everytime you charged.

Not worth it.

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04-07-2010 04:25 PM  8 years agoPost 32
Aaron29

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USA

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You're right, it isn't so dumb after all.

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04-07-2010 05:18 PM  8 years agoPost 33
jackheli

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Vancouver - Canada

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balance taps are still only wired in series. there's not an individual + & - tap to each cell.
if you still don't believe it, grab a VOM and try taking the voltage of the cells through the taps. their voltages are additive. only the first cell will read 4.2v...the next will be 8.4, 12.6, etc., etc.
Oh please, give me a break!

Just get the voltage from the previous tap and not always from the first tap.

Each cell has a wire in the balancer connector for each of it poles. You can isolate each cell as you please.
You're right, it isn't so dumb after all.
Oh my...

It's easy to find an excuse to do wrong. Hard is not to find an excuse to do right.

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04-07-2010 05:51 PM  8 years agoPost 34
synodontis

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United Kingdom

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but then all this comes down to a recommendation that the balancing wired to be thicker for the prospect of being able to charge through them?

Is that what the OP was asking? And are we countering that with the fact that it's not worth doing and that the present arrangement we have is fine, so we're splitting hairs over nothing?

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04-07-2010 05:55 PM  8 years agoPost 35
Aaron29

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USA

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Yes my point is that it is fine as is.

Couldn't hurt to have thicker wiring in the balance lead to enable higher rates for those chargers that charge through it.

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04-07-2010 05:58 PM  8 years agoPost 36
Aaron29

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USA

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Each cell has a wire in the balancer connector for each of it poles. You can isolate each cell as you please.
They still share the common ground.

You will see the voltage exactly as he stated, even though you effectively move electrons in an isolated fashion when balancing.

And in the end that's all we care about.

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04-07-2010 06:04 PM  8 years agoPost 37
hootowl

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Garnet Valley, Pa.

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Instead of charging from the discharge connector, why aren't there chargers that charge from the balancing connector? Then no balancing is necessary: just charge each cell independently to 4.2 volts.

So if you are charging a 6S you would need 6 independent simple chargers instead of a complicated but dumb single charger...

What gives?
I think this question was answered?

Wolves don't lose sleep over the opinions of sheep

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04-07-2010 06:15 PM  8 years agoPost 38
Aaron29

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USA

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Well someone stated we already have chargers that charge through the balance lead.

But that is different than having multiple SIMPLE chargers which was the OP's point.

The chargers that charge through the balance lead are probably similar in complexity to those that charge and balance. And they don't charge in the way the OP said. As I understand it there aren't 6 separate chargers inside the box. It likely varies resistance and thus potential across each wire which is not the same as what he asked.

Which is why I chimed in with it wouldn't be worth it to have to disconnect the series cells every time you charge. The connect/reconnect every time you charged wouldn't be worth it. I'd rather pay the money for the high dollar complex chargers we have.

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04-07-2010 06:22 PM  8 years agoPost 39
hootowl

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Garnet Valley, Pa.

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OK so what would the advantage be to having a multi-cell charger with descrete charge elements/circuits? Sounds like a high end charger for the snob crowd that has no "measurable" advantage but lot's of WOW.
The end result is the same.... fully charged and balanced pack.

Wolves don't lose sleep over the opinions of sheep

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04-07-2010 06:25 PM  8 years agoPost 40
Aaron29

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USA

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Essentially the hose and bucket illustration, I guess.

It wouldn't be without SOME worth. You'd still shave a tad off charge time and wouldn't be wasting electrons.

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