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  1. #1
    James c harrell's Avatar
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    A123 life charge?

    My A123 batteries have two futaba leads. One to the switch, two wire, and one for the balance, three wire. My question is how many times can I charge with just the two wire, Non-balance? I have to take the plane apart to access the balance plug but the main switch has a charge port.

  2. #2
    nonstoprc's Avatar
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    RE: A123 life charge?

    If you install a Himax switch with the charge port, you can wire the three balance wires to the charge side of the switch and balance charge the A123 through the port. You need to cut the white wire from the switch to the receiver side.

    Balance charge A123s is preferred.
    Where facts are few, experts are many.
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  3. #3
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    RE: A123 life charge?

    +1,
    Pete
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    RE: A123 life charge?

    Go to www.hangtimes.com and look at the Ultra Switch II. This is an excellent switch for A123 batteries. You should also see on this site the wiring diagram for your system.

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    RE: A123 life charge?

    You can also get a 2S balancer from Fromeco for around $8.00 that stays plugged in to the battery all of the time. Much like a Lipo "Blinky", it maintains cell balance while charging, and any charge switch will work. I have charged my batteries multiple times with no problems. Seem like a good option. These balancers can be had with either a 3-pin or JST style connector. They have two blue LED's to show discharge for balancing and a red LED that comes on if you plug the battery in with the polarity reversed.


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  6. #6
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    RE: A123 life charge?

    I have those Fromeco Balancers; I don't leave them plugged in all the time, I plug them in the Day or Night before I charge the batteries to go flying; my thought is to get the packs balanced before charging, maybe my approach is wrong, should plug them in after charging; either way I think works well.
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  7. #7

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    RE: A123 life charge?


    ORIGINAL: dasintex

    I have those Fromeco Balancers; I don't leave them plugged in all the time, I plug them in the Day or Night before I charge the batteries to go flying; my thought is to get the packs balanced before charging, maybe my approach is wrong, should plug them in after charging; either way I think works well.
    Shouldn't the approach be to balance while charging?

    If you do it after you may have already overchagred a cell and damaged it.

    The whole point of balancing is to prevent any cell from an overcharge or overdischarge.

    So you need all cells the same when on are using them, not after you have discharged them by flying.



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    RE: A123 life charge?

    That's why I leave them plugged in. They only are active during charging, or if one cell is higher than the other. Same principal as the "Blinky" balancers for Lipos. You can charge with the "Blinky" connected with a non-balancing charger to maintain cell balance. I have done this many times with my Lipos before buying a better charger. I am using the batteries in a scale 25% Cub where they are mounted behind the interior, PITA to disassemble and remove every time. Also in 60 size planes converted to GAS, where batteries are mounted for best CG. Most cannot be easily accessed. Both ways are maintianing the cell balance by leaving the boards plugged in. That is the purpose of having them. During charging the balancer applies a small load to the higher cell to bring it into balance as both cells charge together as a pack.

    I verified this tonight after a mishap today required stripping down the interior of my Super Skybolt for damage assessment and repair access. I have (8) charge cycles on a 2100mA LiFE Source 2S pack with the balance board left connected and charged via a standard charge jack at the documented 2.1A rate using my Hitec X4 in LiFE mode. Both cells are almost identical. Tested the cell balance by removing the balancer and connecting the balance plug to the X4 for a voltage check.

    Just another charging option for LiFE. Works well for me so far.


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    RE: A123 life charge?

    Balancing before charging is good if there is a pretty big imbalance. It gets the cells closer to the same before you even start the charge. If you try to charge and balance a badly out-of-balance pack, one or more cells may get to the CC/CV threshold (3.6v for A123 cells) before the balancer has a chance to equalize the cells. This is more true for external "blinky" type balancers. Balancers built into the charger don't have this problem because there is communication between the charger and balance circuits, and if the CC/CV threshold is reached before the cells are balanced, the charge rate is automatically reduced or stopped until they balance.
    For packs in good condition with minimal imbalance, it's ok to just balance while charging.
    If you leave any kind of circuit attached to the battery at all times, make sure it has VERY low quiescent drain - something under 100uA (micro-amp). Devices that draw currents of even a low 10mA can totally drain a cell over time. For instance, a fully-charged 2.3Ah A123 pack hooked to a device drawing just 10mA of standby current will be discharged COMPLETELY in under 10 days. But this same pack hooked to a device with 100uA of standby current will be discharged in a little over 2.5 years.
    http://scriptasylum.com/rc_speed/

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    RE: A123 life charge?

    "If you try to charge and balance a badly out-of-balance pack, one or more cells may get to 3.6v (limit for A123) before the balancer has a chance to equalize the cells."

    I don't understand this.

    In balance charging the charger will limit the charge going to the higher cells till the lower cell catches up.

    It will not lower the higher cells voltage to match the lowest one.

    At least that is how I have seen it in the chargers I own.

    So I still say balancing and charging at the same time is still the best way to do.
    Not balancing before or after charging.



  11. #11

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    RE: A123 life charge?


    ORIGINAL: TheWoodCrafter

    ''If you try to charge and balance a badly out-of-balance pack, one or more cells may get to 3.6v (limit for A123) before the balancer has a chance to equalize the cells.''

    I don't understand this.

    In balance charging the charger will limit the charge going to the higher cells till the lower cell catches up.

    It will not lower the higher cells voltage to match the lowest one.

    At least that is how I have seen it in the chargers I own.

    So I still say balancing and charging at the same time is still the best way to do.
    Not balancing before or after charging.


    Sorry, I guess I wasn't clear. I agree with you. If you read the part of my post after the section you quoted, I say this is only a problem with blinky style external balancers. For balance chargers, this isn't a problem.
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  12. #12
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    RE: A123 life charge?

    A Blinky balancer discharges the higher voltage cell(s) to match their voltages to those of the lower voltage cells. You can use the Blinky balancer during the charge cycle to limit the voltage of any cells within the safe range. Since the charger and Blinky balancer do not talk to each other, balanced charge with a blinky is of lower efficiency.

    Other chargers work differently by slowing down the charge of the higher voltage cell(s) to allow the lower voltage ones to catch up.
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  13. #13
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    RE: A123 life charge?

    Blinky's can't in any way shape or form keep up with the charge rate that you can charge A123 batteries at. If separate balancing is your only option, do it before charging in non-balance mode.
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  14. #14
    James c harrell's Avatar
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    RE: A123 life charge?

    So to answer my origional question. If I take my planes apart and balance every third or fourth charge, do you think I would be O.K. ? I don't charge fast . Usually about 1.5 A on a 2300 6.6V pack.

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    nonstoprc's Avatar
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    RE: A123 life charge?


    ORIGINAL: BarracudaHockey

    Blinky's can't in any way shape or form keep up with the charge rate that you can charge A123 batteries at. If separate balancing is your only option, do it before charging in non-balance mode.
    I do it frequently with the charging current set at 1.3A, a safe and very conservative value for himax charging switch. The blinky does the balance job well during charge.
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  16. #16

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    RE: A123 life charge?

    Barracuda,

    I think the key word in your post is "Can" Not everyone charges LiFe or any other battery chemistry at the max rate possible.

    I charge my 2100mA LiFE packs at 2.1A with the on board balancers in line, and see little difference in charge time. I have verified with my balanging charger (Hitec X4) that the cells are in fact in balance with the onboard balancers in use. the same holds true for balance charging Lipo's with an external balancer and a non-balancing charger. With the manufacturers recommended rate, and properly maintained packs, there is absolutely no problem charging with an external balancer.

    Now, if you wanted to charge a 6S 35C Lipo that has been abused and not balanced at an extremely high current, there is no external balancer out there that could correct the problem or even keep up. Eventually, the pack will puff and fail.

    Likewise, I charge my NiMH packs at half the higest recommended rate, with field chargers in the trailer. I believe the more consistant you are with your charge and discharge cycles, the more reliable and longer life you will get from your packs. I have manu cheap-o Turnigy 2200 3S 20C packs that have had numerous cycles without puffing or showing signs of significant degridation.

    I think the point of the original poster is to determine a way that will work best for his application. There are obviously several qualified and workable solutions presented here, and no one solution is necessarily the absolute best for all applicaitons.

    I don't think it is accurate to state absolutley that outboard balancers cannot properly balance multi-cell packs, because they are performing essentially the same function as a balanceing charger. I do agree there is some effiency lost, but I believe it is negligeable when you have to spend 45 minutes disassembling a plane to remove the batteries, if there is another equally workable way.

    Like I said earlier, it work s for me. If balancing at the charger works well for you, I say great!

    bgosselin,

    I'm not sure how a balance charger is any different for an external balancer other that the reduced rate at balance if the cells are way off. You are applying the charge current and voltage to the main high amperage connector of the pack. the charger monitors the individual cell voltages during charging at the balance connector, and limits the individual cell volatge them by applying a resistive load to the highest individual cell to maintain it;s voltage level as the other cell voltages increase while the pack charges. While the capacity of the resistive load contained withing a balancing charger may be larger, in the end it is still a constant voltage/constant current process. That is why I disagree with the notion that external or "Blinky " chargers cannot be used to balance charge. In essence, they are performing the same function (Monitoring the individual cell voltages electronically) and apply a resistive load automatically to limit individual cell voltage during the charge process. The only difference is the balancing charger has the balance function integrated into it's electronics, and in the case of badly balanced packs, the ability to automatically correct for the balance issue.

    It's just an integrated vs external process. My opinion is that if you maintain your packs, the likelyhood of a major imbalance is minimized. In my case, I am always monitoring and maintaing cell balance automatically, both during charging and discharging, and while in storage. I agree, there is a going to be a miniscule parasitic load, but look how long it would take to become a problem, if ever.

    But all suggestions here are great. Just keep them balanced!


  17. #17

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    RE: A123 life charge?

    Hmm. I'm beginning to think I should have not posted at all because I don't think people are reading my post correctly...

    ORIGINAL: BGCombs
    I'm not sure how a balance charger is any different for an external balancer other that the reduced rate at balance if the cells are way off. You are applying the charge current and voltage to the main high amperage connector of the pack. the charger monitors the individual cell voltages during charging at the balance connector, and limits the individual cell volatge them by applyingΒ* a resistive load to the highest individual cell to maintain it;s voltage level as the other cell voltages increase while the pack charges. While the capacity of the resistive load contained withing a balancing charger may be larger, in the end it is still a constant voltage/constant current process. That is why I disagree with the notion that external or ''Blinky '' chargers cannot be used to balance charge. In essence, they are performing the same function (Monitoring the individual cell voltages electronically) and apply a resistive load automatically to limit individual cell voltage during the charge process. The only difference is the balancing charger has the balance function integrated into it's electronics, and in the case of badly balanced packs, the ability to automatically correct for the balance issue.
    "I'm not sure how a balance charger is any different for an external balancer other that the reduced rate at balance if the cells are way off" -> That's exactly what I'm saying. I am not saying external balancers shouldn't be used; just not when pack imbalance is great because they lack that charger to balancer communication that integrated units have. For newer hobbyists who don't know (or don't want to know) how/when to set separate chargers/balancers up right, an integrated system is just a better solution for safety. Particularly when charging high-capacity cells at higher than 1C rates since most external balancers bleed off capacity at a relatively low 100-300mA; the charger could get to the CC/CV threshold before the balancer has had a chance to equalize the cells. If, for example, you have a 3s pack sitting at 4.3v, 4.1v, 4.1v, the charger will still be in CC mode even though cell 1 is already over-charged because the charger sees only the overall 12.5v. With an integrated charger/balancer setup, the charger knows the individual cell condition and wouldn't let that scenario happen. Granted, that scenario is an exaggerated example and would only happen with severely imbalanced packs, but you get the point.

    With the exception of a fairly new charger (Hyperion EOS 0615 duo3+), all my chargers and balancers are separate. Also, I am fully aware of how external and integrated balancers work.
    http://scriptasylum.com/rc_speed/

  18. #18

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    RE: A123 life charge?

    bgosselin

    I understand and agree.

    Given the original posters question, I think he woudl be fine with either option. In this case he has a charge switch, it would seem easier to go the Fromeco route, especially since we are talking 2S packs here.

    I think my issue was with another poster's statement made that external balancers cannnot be used for charging. I've done it with Lipo's, Li-Ions, and now LiFE with no problems. Integrated balance is best, but if not able, I'm saying external balancers will work fine too. (Let me qualify that with "In this instance"- RX packs).

    I appreciate the info and discussion. It's folks like yourself who are willing to explain that make this site the resource it is. I'm glad you followed up!

    Thanks!

    James c harrell

    I think the answers are:

    A) Balance charge whenever able. It's the best way. In your case, the balance charge jack option would be the best
    B) It's okay to charge without balance as long as you check and balance the cells from time to time with an external balancer. Use reasonable rates when you charge. Keep an eye on the condition of the pack.
    C) If your batteries are not readily accessible, the onboard balancers can be another option for your RX pack if you choose to go that way. Use reasonable rates when you charge.




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