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Old Jan 16, 2011, 06:26 PM
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Melbourne, Australia
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Balancing is needed in any multi-cell battery but is achieved in different ways for different chemistries. It is needed to ensure that some cells do not get discharged dangerously low while others are still OK. The difference comes about because cells do not all hold an identical amount of charge. Imagine you bought three 1 litre bottles of water. Nominally they all hold 1 litre. However in reality, one is 900ml, one is 1000ml and one is 1100ml. Now let's drain the bottles at the rate of 100ml per minute. After 8 minutes the bottles now hold 100ml, 200ml and 300ml. This is what happens with the cells in a battery. The voltages on the cells are all different at the end of the discharge since the remaining charge is different. If we charge up based only on the total pack voltage, we will overcharge some cells while waiting for others to fill up.

You are correct that always having the balance lead connected is the secret to safe charging. This ensures that regardless of the charge mode used, the charger can monitor the per-cell voltages and ensure that no single cell is ever over charged.

Balance charging will take longer than non-balance charging but for healthy packs with well matched cells the difference will be small. For unhealthy packs the difference will be larger but they are the ones that need it the most. Many people tend to use non-balance charging at the field and then do a final balance charge at the end of the day. For those that storage charge at the end of one day, then do a balance charge as the first charge before flying.

Balancing ONLY makes sense when the cells are near to full since imbalance can only usefully be addressed when near full. Hence there is no point to balancing in Storage mode or Discharge mode.

Imbalance of 0.04V in a fully charged pack is considered large and worth worrying about. Some folk like to balance to 0.001V, which I think is pointless. I am usually happy when cells match to within 0.01V.
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Old Jan 16, 2011, 06:27 PM
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thank you.

So far my understanding then of using Lipo's in a sensible way (from what i have read):

* do not charge unattended and use your LiPo bag.
* start charge with Lipo batt at room temp
* use temp sensor of charger
* charge with one C
* always connect the balance leads
* use balanced if you can
* use unbalanced if you need fast charge but do not overdue it (aka after like 5 charges use balance)
* if one becomes "buldged" (bubbled) - dispose

to keep them working/alive some time:
* do no discharge to under 3.3v (3.3v under load like 10c drain)
* do not discharge them faster than the lower rated discharge C aka if you have a "20-30 C discharge pack", best thing is staying at/under 20C
.
and something I found but i'm not sure if it's (still) true for current battery's or makes really economical sense (lipo's are not that expensive) : charge not up to 4.20 but to a lower voltage will also greatly expand the life of the battery's.

edit out silly Q that is answered in above excellent post !

thank you very much, i'll see if I can get a decent voltmeter and (if needed) calibrate the charger to stay in like 0.01 v when using balancing
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Old Jan 16, 2011, 07:07 PM
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Melbourne, Australia
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Quote:
* start charge with Lipo batt at room temp
Not vital, they will charge better warm. I wouldn't charge them if they feel hot, but warm is OK.
Quote:
* use temp sensor of charger
Most don't bother. I don't. It certainly won't hurt to use it.
Quote:
* charge with one C
Most packs can be safely charged at 2C or 3C so long as the balance lead is connected to allow monitoring of per-cell voltages. Many today are rated for 3C up to 10C charging. With a decent charger I wouldn't be wasting my time charging below 2C.

to keep them working/alive some time:
Quote:
to keep them working/alive some time:
* do no discharge to under 3.3v (3.3v under load like 10c drain)
Should not be below 3.7V/cell within 5 minutes of sitting idle after use.
Quote:
charge not up to 4.20 but to a lower voltage
Yes, I charge mine to 4.18V and do not notice the difference in flight time. Lipos are much, much cheaper than they used to be, but if they last an extra season or two then this is a painless way to save money over time.
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Old Jan 17, 2011, 09:59 AM
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Hi,
I received my iCharger from Hobbyking and I am not sure if it is not a copy of it.
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Old Jan 17, 2011, 10:17 AM
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Knoxville, TN
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Quote:
Originally Posted by holda29 View Post
Hi,
I received my iCharger from Hobbyking and I am not sure if it is not a copy of it.
My 208B doesn't have those typos on it, but it's not a 206B, and it's just over a year old. I would be SHOCKED if it's a copy. Hobby King is known for selling products that are clones, or compatibles, but I don't know them to sell copies of products that are passed off as the original. Remember, Junsi is not a huge company, and English isn't their first language. Although you'd hope that someone would have caught that mistake before production.
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Old Jan 17, 2011, 10:27 AM
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Originally Posted by holda29 View Post
Hi,
I received my iCharger from Hobbyking and I am not sure if it is not a copy of it.
i have the 106b+ from HK and I have the same "Menory" typo. I wonder the same....
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Old Jan 17, 2011, 10:52 AM
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The images in the 206B manual from Junsi have the same typos.
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Old Jan 17, 2011, 11:46 AM
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Well I am still unsure, see my log. On 3s the overall voltage exceeded 12,6 V a lot.
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Old Jan 17, 2011, 11:55 AM
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Originally Posted by holda29 View Post
Well I am still unsure, see my log. On 3s the overall voltage exceeded 12,6 V a lot.
That's totally normal, and has been discussed extensively in this thread. That is what the output voltage is from the charger, not what the voltage in the pack. You have voltage loss across the wires and connectors, at no time did any of your cells go higher than .007 over 4.2v, and were then balanced out to nothing more than .001-.005v over 4.2v, and I'm sure after resting for a few minutes they settled to well under 4.2v.

Don't sweat it, it's real, and it's doing what it's supposed to do.
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Old Jan 17, 2011, 12:05 PM
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Okay, I wanted to be sure. I hope you can understand, that it takes some time to read all this huge topic
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Old Jan 17, 2011, 01:09 PM
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Part of the problem is that most charger threads also become how to charge battery threads.

When a thread covers 12 different models,97 revesions and 12 different battery types then the same questions get asked and answered about 103 times each.

Many charger questions could be answered by web searches on how to charge X type of battery. The icharger manual does not provide much how to charge X type battery at all but it does provide a lot of user setting which most seem to find very confusing.

Common knowledge is that LiPo should be charged to only 4.2V per cell. Very few are aware that 4.325 is the actual maxinum safe charge to voltage. No I am not saying that tyou should charge past 4.2 per cell.

As pointed out the cells volatges as measured thrugh the balancing leads and the total pack voltage as measured on the main power leads are not the same measurements.



Charles
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Old Jan 17, 2011, 01:26 PM
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Quote:
Originally Posted by holda29 View Post
Hi,
I received my iCharger from Hobbyking and I am not sure if it is not a copy of it.
FWIW, my 206B bought from Progressive RC has the same typos.
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Old Jan 17, 2011, 01:31 PM
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Quote:
Originally Posted by holda29 View Post
Hi,
I received my iCharger from Hobbyking and I am not sure if it is not a copy of it.
Quote:
Originally Posted by EricJ320 View Post
My 208B doesn't have those typos on it, but it's not a 206B, and it's just over a year old. I would be SHOCKED if it's a copy. Hobby King is known for selling products that are clones, or compatibles, but I don't know them to sell copies of products that are passed off as the original. Remember, Junsi is not a huge company, and English isn't their first language. Although you'd hope that someone would have caught that mistake before production.
Quote:
Originally Posted by mtc777 View Post
i have the 106b+ from HK and I have the same "Menory" typo. I wonder the same....
My 208B that I bought from HobbyKing does NOT have any typos. It would be a real shame if your 206 is a copy. Please check with Junsi. If it is an Junsi original then they would change the printing immediately. Misspelled texts looks cheap...
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Old Jan 17, 2011, 01:52 PM
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Originally Posted by mackee View Post
My 208B that I bought from HobbyKing does NOT have any typos. It would be a real shame if your 206 is a copy. Please check with Junsi. If it is an Junsi original then they would change the printing immediately. Misspelled texts looks cheap...
Have you read the last 7 posts?
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Old Jan 17, 2011, 02:09 PM
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Poland
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Originally Posted by everydayflyer View Post
Very few are aware that 4.325 is the actual maxinum safe charge to voltage. No I am not saying that tyou should charge past 4.2 per cell.
Charles, you shouldn't post such informations.
Even when we know you're correct.
You've just burned a few houses...
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