When to charge and when to balance?

[Andrewl]

Hi there, Sorry to be a pain and not knowing anything.

I just finish building up my heli (with Bob's helpful videos). and what i got:

- Trex 450Se (come with align motor and esc 35a).
- lipo 3s 11.1V 2200mah 20-30C with Align balancing lead
- E-station BC6 from Bantam (charger and balancer)

I set my estation BC6 charging at 2.2C and (i calculate: 2200/2.2= 1000/11.9 = 84minutes of charging) at normal charge. can i set the fast charge at 2.6 or more?

My biggest question is when do i balance my battery? is it my estation bc6 automatically balancing it while charging?
do i fully charge my lipo battery then balance it? Im completely blank out when reading the intrustion manual, i only understand how the rate and stuff work, but not telling much about when to use or how to use!!

Sorry if this question is kinda dumb. :dontknow

[spork]

I'm not familiar with the BC6, but I'm concerned you might not be completely clear on "the rate and stuff". If you charge at 1C it takes 1 hour to charge (by definition). If you charge at 2C it takes 1/2 hour to charge. I think you may be confusing 2.2C (C for "capacity") with 2.2A (A for "amps").

In any event. I personally balance during charging every time. I imagine the BC6 probably does that (does it charge through the balance tap?). If not, you certainly can balance during charging with a separate balancer.

Finally, 2.2C is a bit of a stout charge for a LiPo. We generally don't go above 1C, although some do 2C when they're in a hurry to fly again.

[markk]

LiPo charging can be done in either "charge", "balance", or "fast" mode.

The BC6 has separate ports for balancing and charging. In order to charge in Balance mode, the battery must be connected to both ports. The balancing port is connected by using an adapter board with the proper connectors for your type of battery. Charge and Fast modes only require the main charging cable.

I've only had my BC6 for a couple of days but I've been using "fast" mode while flying and "balance" mode at home. I've only charged my 3S 2170mAH batteries at 1C (2.2A). BTW, as I understand it, Charge and Balance modes terminate when the charging current is 1/10 C and fast mode terminates when it's 1/5C.

markk

[kgfly]

Andrewl - Not sure of your arithmetic there as pointed out above.

For maximum safety and longevity of your lipos you should balance charge at no more than 1C (2200/1000 = 2.2A).

As mentioned, the BC6 "fast" charge does not charge at a higer rate, rather it terminates the charger earlier to give you a ~90% charged pack. The last 10% can often take 30% of the total charge time.

While in theory, charging a 2200mAh battery at 2.2A will only take 1 hour, in practice it is more complex and balance charging an 80% dicharged pack will take anywhere from 60 to 90 minutes depending upon how well the cells are matched and the overall health of the pack.

If you really want to charge at above 1C (not recommended but is allowed for some packs, at the cost of reducing their lifetime) then get the temperature probe for the BC6 and use it every time. This is an important fire safety measure and could save not only your batteries, but your house and family.

[spork]

While in theory, charging a 2200mAh battery at 2.2A will only take 1 hour, in practice it is more complex and balance charging an 80% dicharged pack will take anywhere from 60 to 90 minutes depending upon how well the cells are matched and the overall health of the pack.

Good point. I didn't account for the ramp down time and charge lost to balancing.

[Pinecone]

Also I notice that my Triton takes longer to get to 1C rate than my TP 1010C, so the Triton takes longer. About 3 minutes right there.

Also due to the CC/CV of lipo charging, it take smore than 1 hour, since you only charge at a true 1C for part of the time, then you charge at a constant voltage with a steadily reducing charge rate (amps).

IMO< you should balance before or during charging, NOT after. Why? Say your pack starts out of balance with the cells at 3.5 - 3.6 - 3.7 volts. You charge and get to a pack voltage of 12.6 volts, but you are now at 4.1 - 4.2 - 4.3 volts per cell. So cell 3 is now overcharged. NOT good.

[kgfly]

I'm with you on that one Pinecone. Balancing after charging makes little sense. Standalone balancing beforehand is of some use but balance charging is the most important step for maximum safety and pack life.

[Andrewl]

Thanks for the info guys. Really insteresting

Lets not worry about the fast charge. So mean if i charge it normally, it shouldn't be more than 30mins. i get that. Can i use the BALANCE CHARGING on my e-Station BC6 at 2.2A ?
Or is it better to charge normally and balance it after the charge done?'


Thanks
Andrew

[spork]

As kgfly says, it's best to balance during charging (best for the batteries, and safest). A normal (1C) charge will be at 2.2A (for a 2200 mAH pack), and will take 1 hour (plus the overhead time of current ramping up and down etc.).

[RC Accessory]

The built in balancer does not function by itself like an external balancer. So you cannot balance the pack after the charge is competed.

Simply just use the balance charge function every time you charge and you should never have a charger related damage your battery packs.

As far as amperage goes, charging beyond 1C when using the balance charging program is fine. The built in balancer can keep up with the higher charge rates to maintain the cell balance.

[spork]

As far as amperage goes, charging beyond 1C when using the balance charging program is fine. The built in balancer can keep up with the higher charge rates to maintain the cell balance.

I believe the built in balancer can keep up, but I thought charging at higher than 1C inherrently stressed the batteries. :dontknow

[kgfly]

Andrew - I don't think you have quite got it yet. A normal 1C charge cycle will take more like an hour than 30mins. Yes, you can balance charge on the BC6 at 1C (2.2A). Not much point charging then balancing since the main goal is to prevent one cell in a pack being overcharged. Hence your safest approach is to always balance charge.

[Andrewl]

:noteworthy :noteworthy :noteworthy Thank guys, Now i am charging my battery while do some research.

Another question regarding to my DX7, when i bought it there's also another battery for Rx. and in TREX 450SE book didn't show where to mount the reciever battery.

Let me show u what i have done, I have install all my servos HS56s and plug them all in right position (rudder, pitch, eval).
The motor plug to ESC and ESC plug to battery, and connecter go to Throttle.
I have alook at many pic of trex 450 (people on here and other forum, there no pic that has 2 batteries pack). But if there is no reciever battery, how can the reciever AR7000 power the servos? :dontknow

Can someone please explain to me? :arggg: :arggg:

Thanks

[kgfly]

You don't need an Rx battery in most electric aircraft (well not smaller ones anyway). The ESC includes a Battery Eliminator Circuit (BEC) which is simply a voltage regulator that provides 5V to the Rx via the throttle cable.

You can keep the Rx pack for bench work or sell it.

[Andrewl]

Awsome, thank for the quick answer. :noteworthy :noteworthy

I guess from here on, i am on my own and its where the fun start!!


Thank a million guys!!.... I try to do my best.

Helifreak rocks!!

[spork]

I guess from here on, i am on my own and its where the fun start!!!

Unless they yank your internet connection or break all your fingers, there's no reason to be on your own. Plenty left to learn and contribute.

[RC Accessory]

I believe the built in balancer can keep up, but I thought charging at higher than 1C inherrently stressed the batteries. :dontknow

Personal opionion here....

I beleive that it does only if there is an imbalance in the cells to start with. If you use a balancer consistantly AND the balancer can truely keep up with the higher charge rates, then they should be fine.

For example, the balancers in the BC-x series of e-Station chargers as well as the external e-Station chargers have a discharge rate of 500 mah. As far as I know, this is the highest discharge mah of any balancer.

Being able to maintain the cells balance, the higher charge amperage should not make that much difference. I am referring to a 2C charge rate versus higher amounts.

As an experiment, I used an e-Station 902 with the e-Station PB-6 balancer, connected to my laptop for graphing.

I charged and discharged a 4S A123 pack at 9.9 amps! Graphed the curves and watched the process the whole time including the individual cells voltages on the screen.

The PB-6 balancer was able to maitain the cell balancers perfectly even working against a 9.9 amps charge rate.

The A123 cells were new, just built the pack so the imbalance was minimal to start with. The external temp of the pack at the highest at 105 degrees F.

I did the same thing on the cycle. Cycled the pack at the highest rate the 902 would allow and kept the balancer connected as well.

Not real model data as the draw would be higher on the discharge and there balancer would not be connected during flight but the experiment ot see how these A123 cells performed was amazing.

Here is the link:

http://image.rcuniverse.com/forum/upfiles/15157/Zx71435.jpg
http://image.rcuniverse.com/forum/upfiles/15157/Us53359.jpg

http://image.rcuniverse.com/forum/upfiles/15157/Nh11278.jpg
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