New to electric questions

BCRandy schrieb:

Let's consider you may not discharge a single cell below 2.5 Volts and you may not charge it higher than 4.2 Volts. As soon as more than one cell is in a pack not all cells discharge at the same rate. Your ESC will try to protect your lipos by switching off the motor when all cells provide a multiple of 2.5 Volts e.g. 5V for a 2S pack. But in fact it might be that one cell dropped already to 2.4V while the other still has

2.6V If you charge the pack without a balancer the charger will stop charging at 8.4V But one cell was already at 2.6V when charging started. So the charger will most propably stop charging when one cell ist at 4.3V and the other at 4.1V If you would repeat this often one cell will always get discharged too much and the other one will get charged too much resulting in both cells being destroyed after a while. This is why some people tend to use balancers even in their models to prevent stupid esc's from damaging the pack. Some smart esc's already have an inbuilt balancer.

Great explanation - thanks! My ESC protects against discharging below 2.5 volts. I should be OK if I only charge/discharge them once without the balancer I just now ordered.

Youu will save the cost of a balancer

I have never used one. My packs are fine.

Balancing is a more or less religious issue. Some people say you should always use one and the sky will fall if you don't. Others never use one and say it's fine without one.

The reality is probably in between. Good matched packs might never need one. Slightly mismatched packs might need one.

Personally, I've got one charger I use at the field and one at home. The field charger has no balancer. The one at home only has a balancing charge lead. So what happens is that I charge my packs without balancers at the field and with a balancer at home. For years I've charged without using a balancer. Worked just as well.

So, balancer is probably the safe route. Using no balancer seems to work fine though.

J

It's my understanding that ALL LiPo battery packs are NOT wired for using a balancer. Check before buying the balancer or the pack.

Earl AMA 40329 Website:

--------------------- BCRandy wrote: > I'm just getting into electric models. Beyond basic house wiring, I know nothing about electricity, so please bear with me... >

2200mah) once or twice directly?

---------------------

Balancing is a more or less religious issue. Some people say you should always use one and the sky will fall if you don't. Others never use one and say it's fine without one.

The reality is probably in between. Good matched packs might never need one. Slightly mismatched packs might need one.

Personally, I've got one charger I use at the field and one at home. The field charger has no balancer. The one at home only has a balancing charge lead. So what happens is that I charge my packs without balancers at the field and with a balancer at home. For years I've charged without using a balancer. Worked just as well.

So, balancer is probably the safe route. Using no balancer seems to work fine though.

Jennifer

You men "not all", right? Because mine are.

Jen

Earl Scherz> It's my understanding that ALL LiPo battery packs are NOT wired for

| > I bought a Triton Jr. charger and I just got my first LiPos. The | > Triton instructions say to ALWAYS use a balancer when charging | > LiPos. Until I pick one up, what will happen If I charge the | > packs (3 cells, 2200mah) once or twice directly?

Pure CYA. If they really meant it, the Triton would be a balancing charger -- or wouldn't charge LiPos at all.

Using a balancer occasionally will extend the life of your packs, and will reduce somewhat the chance of ruining your packs accidently. But you don't need to do it every time.

(But it doesn't hurt things, either.)

My opinion for what its worth, is that a balancer will stop the pack you juts ruined by running it too hard from exploding on the charger.

Solution? buy a bigger pack to start with, and don't fly so long!

This whole discussion has some paralles to the discussions held on smoking cigarettes (and other similiar topics)

Fact is: smoking causes cancer in many cases. The people do not die from smoking a single cigarette but their life would propably be longer if they did not smoke. But there are many people smoking anyway. The better your health is the less it will kill you. And some people live a long life smoking without any problems at all.

Fact is: Not using a balancer destroys lipos in many cases. They will not explode any first time you do not use a balancer but their capacity will decrease each time a little bit. There are many people not using a blancer at all and their packs last a long time. This might leave the impression that they do not need a balancer and - this is the onyl truth that was told in other postings in this thread - very expensive well balanced packs might really not need a balancer because all cells discharge and charge at the same rate. Funny thing is - those who have enough money to buy expensive packs tend to buy a balancer just to be on the safe side. If you buy cheap packs you should spend the money you saved to buy a balancer.

Not fact.

Opinion only.

Not fact. Opinion.

At last, a fact.

I guess you add antiknock to your fuel injected cars too ;-)

A pack that is seriously out of balance is *already damaged*. That's how it GOT out of balance.

Balancing it is throwing bad money after good.

I see your point. Poor analogy IMHO in that with smoking you do take in toxins ect..... Not using a balancer may not hurt the pack. That being said, use a balancer once in awhile. mk

Obviously from someone who thoroughly understands the nature of charging and discharge cells in series and believes that all cells are identical in charge acceptance, capacity, etc. NOT!

In any system where constant potential charging is employed the probability for cells becoming unbalanced is directly proportional to the number of cells in a string. Not all cells will reach the terminal cut off voltage at the same time, therefore some will see more than recommended voltage while others will be a bit lower such that the sum of all equals n X 4.2 volts in the case of Lithium Ion, n being the number of cells in a string. Example when the terminal voltage of 12.6 volts, individual cell voltages could be

4.1, 4.05 and 4.45, with the cell seeing 4.45 being damaged such that the next charge cycle sees it hitting the recommended cut off voltage earlier which accelerates unbalance on the next charge and drives that cell deeper on the discharge as its capacity is compromised by the overcharge.

It is not what people know that gets us in trouble, it is what they think they know that simply isn't true.

Red Scholefield schrieb:

Sigh. So true! And already said in my first post. Thank you!

You have missed a point.

If they start in balance, and discharge to out of balance because one has less capacity, on recharge, they go back exactly into balance again. The mah taken out of each cell MUST be the same, and so must teh mAh put back equal the mAh taken out in every case.

Only if a cell has been damaged so it self discharges will they go out of balance at full charge.

Its not that important how they are in part discharge. Voltage wise. As long as you don't run the pack to the ends tops they won't be damaged.

The ONLY way they can get dangerously out of balance is if they are ruin totally too flat and one cell is damaged.

Of course if you are silly enough to either believe the manufacturers specs and/or use an LVC too low, (because thats the only way you can run the pack at the manufactures specs) then in time you will f*ck the pack, and the balancer will at least stop you from having a fire.

It won't protect the pack whatsoever. Unless the pack is already damaged you won't damage it at charge time. Its discharge time where the damage is done.

Indeed, and the above is a classic example of just that.

I've never balanced a single pack,. I checked one with a meter recently. Nothing untoward.

You WILL get an out of balance pack if the cells aren't matched when it pretty discharged. Wow! Panic! If however you charge it up. Gosh golly. Its back in balance, How did *that* happen?

Ive been running Lips fior 3 years now. Never go near manufacturers peak ratings on discharge ever since I sw what it did to the pack volts.., never empty the packs more than 80%. Guess what,. No problems at all, ever.

Whereas according to the zealots I should have wrecked every pack i have.

I guess I somehow missed your web site on batteries or your Curriculum Vitale on the discipline. I don't have access to British patents either to see what you have done. Faulty interpretation of anecdotal evidence has crashed a lot of models, but then you have never had that problem obviously, or attribute your incidents to other's carelessness.

Red S. Red's R/C Battery Clinic

us out for "revolting" information.

----- Original Message ----- From: "The Natural Philosopher" Newsgroups: rec.models.rc.air Sent: Sunday, June 24, 2007 6:15 PM Subject: Re: New to electric questions

You are right there. I don't have a reputation to defend.

Or any commercial connections with any manufacturer of 'balancing equipment'

And my experience of LIPOS is as long as yours is, brother.

"Curriculum Vitae", Red. If you want to appear erudite, a course in English and Latin is a must, don't you think?

*shrug* more than you think, but that's my business.

Actually, you could have if you wanted. Not that having a patent filed is any indication of anything. Other than the ability to file a patent and enough money to do it.

Actually, most of mine crash from pure pilot error.

Hardly, since I seldom fly in company.