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Old Feb 09, 2011, 12:40 PM
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Help!
imax B6AC charger question

Dear forum,
I just received today my Imax charger and I have some questions for you.

1. Do I have to set the end of charging time or it stops automatically?

2. The NiMh / NiCd menu it is suppose to have a manual and auto function but the screen shows only manual. Do I have to press anything to switch to auto?

3. I set it up and charge a 2200 mah NiCD 7.2 v battery with 0.8 amps but after 1-2 minutes I got the message INPUT VOLUME ERROR. According to manual this is ''erroneous selection of voltage of lithium pack, please check the voltage of battery pack''.

I have to note here that the power supply comes from a 1 amp 12 volt transformer set to 11.6 volt. Do you think that the input is to low and thatís why im getting this error? Unfortunately the AC cord came with wrong plug (from the chargers side and I canít connect it until I found a new wire).

I think ill come up with more questions later but letís start from here.
Thomas
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Last edited by gordinir8; Feb 09, 2011 at 12:46 PM. Reason: switch to help
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Old Feb 09, 2011, 02:30 PM
God of Gravity Poisoning
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Hi Gordinir8 I think I can answer some of your questions.

1) The timer and temp probe functions are a secondary safety feature your charger should automatically shut off as long as you have the correct battery settings for whatever battery type you are charging. Ni_xx chemistry batteries use what is called "Delta Peak" detection. As your Ni battery comes to full capacity its internal resistance to taking further charge goes up as this resistance goes up the battery starts to get warm as the temperature goes up the battery's voltage drops very slightly the charger detects this "Delta Peak" voltage drop and shuts off the charger. (Note the temp probe isn't necessary for Delta Peak detection). The trigger voltage for detection is automatically set but it can be changed manually with the "Sensitivity" setting. I wouldn't change the defaults unless your battery manufacturer recommends it. If the sensitivity is set too high it can damage your batt. or cause a fire, if it is set too low your battery will never reach full charge.

Lipo batteries detect charge state through the balance tap you must always connect the balance tap regardless of whether you are "Balance Charging" or not.

That being said never leave you charger unattended while charging or rely on the safety features of your charger alone to avoid mishaps. Chargers sometimes fail and cause fires. As for a fire never charge where you would mind having one because they can happen. Sand is a great thing to use it isn't as messy as a fire extinguisher and it's cheap, 2-3 gallons of sand should smother most fires.

2) You can change the Maunal/Auto charge setting for Ni_xx batteries go to the "Ni_xx Charge" menu and press "Enter". Now the current setting should be blinking press and hold both "Status" buttons for a couple of seconds and the Manual/auto setting should change.

3)You need an input current of 5 amps or greater for your charger to function properly 1 amp isn't going to cut it there is a lot of current loss involved in charging 1 amp of input doesn't = 1 amp of output. You can use a large capacity lead acid 12vdc battery for a power source a car battery should deliver well enough current and capacity. Just keep in mind car starting batteries aren't designed for deep discharge so don't deplete it more than 20% of it capacity. If you can use a deep cycle lead acid battery you can take up to 80% of its capacity without damaging it.

4) If you are charging Ni_xx type batteries you should do a "formation" charge at 1/10 C to condition the pack. (for a 2200 mAh pack .2 amps). This charge will take 16-18 hours to complete but it will fill your pack to the fullest capacity it can take. It will "remember" this full capacity for subsequent 1C fast charges. If your Ni_xx pack isn't taking a full charge sometimes a formation charge can help if it doesn't your battery may be going bad. Once a battery loses 20% of it's rated capacity it isn't good for flying anymore use it for a bench test power source or a ground vehicle. Another thing to keep in mind when using NiHM pack is they have a very high self discharge rate. They lose about 15% of their charge per day so they are more powerful hot off the charger then if they sit for half a day to a day before use. Unlike NiCd's NiMh pack can be topped off on the charger without getting a short charge memory. NiCd should be fully discharged before recharging while NiMH packs don't care.
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Old Feb 10, 2011, 03:31 AM
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Thank you very much for the interesting informations and your time. I bought the correct AC cord and now it works fine with 220v and no cut offs. Up until now i was charging all of my batteries niCd or NiMh with the same simple 60-500 mah output charger, no buttons screens so this is a small step to the moon for me.

Thomas
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Old Feb 10, 2011, 04:51 AM
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Hi All,
I have one some question i have start charging ZIPPY Flightmax 500mAh 3S1P 15C with imax B6AC charger and set the charger to auto with 0.5A but i don't know how i can know if the battery is fully charge each cell show 3.99 volt is there any way to let the imax to auto cut off if the battery charge is full ?

sorry for my bad english

Thanks
jaf
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Old Feb 10, 2011, 06:44 PM
God of Gravity Poisoning
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Hello ooaa welcome to the forums! Don't worry about you English I'm not so good at it and it is my native language

Your charger should automatically shutoff when the lipo pack is fully charged be sure you plug in the battery's balance tap (small wires) as well as the main power connector (two big wires). Even though it is called a 11.1v battery a fully charged 3s pack should read very close to 12.6v (4.2v per cell). 3.7 volts is the nominal charge for lipo cells but their in their fully charged state it is actually 4.2v per cell. If your charger is stopping at 3.99v per cell it isn't fully charging the battery if your battery came at that voltage that's normal they don't come fully charged (see below).

Also don't store your lipos fully charged it can increase the batteries internal resistance and it won't last as long. I wouldn't leave them fully charged for more than a few days to a week. Your charger has a "Storage" setting it will charge or discharge your battery to 3.85v per cell. In this storage state it can hold a charge for a month or two maybe more. Keep you packs in a cool dry place heat is bad for them.

(Thomas you're welcome glad I could help.)
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Old Feb 11, 2011, 03:28 AM
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Ok here is another.

I charged yesterday a 3300 NiMH, I set the charger at 05A, 5mv delta peak voltage and 3300 capacity.
The charger stopped at 4.5 hours 8.72v and the capacity was at 02127
Is this battery charged? How important is the setting of the capacity number on the charger and why in my case it didn’t reed 3300 but 2127?

Also today I put a 2300 NiCd, set it at 05A etc. etc, the charger complete it after 3 minutes.
I watched the display and around 3 minutes voltage went to 9.7 volts and then start drop to 9.11, then is stopped. What happened? (This battery is not new, id say tired)

Also is the auto mode better than the manual?


Thomas
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Old Feb 11, 2011, 12:14 PM
God of Gravity Poisoning
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I said you shouldn't change the default sensitivity setting you probably have set it too low and the battery isn't reaching full charge use the defaults settings or you will ruin your battery. By 05amps do you mean 5 amps? If you mean 5 amps that is way too high of a current setting for the batteries you are charging you should never charge a pack at more than 1C unless the manufacturer specifically says you can. Your 3300 pack should only be charged at 3.3 amps and your 2300 at 2.3 amps max. I use automatic for all my charging and it seems to work fine.

Your charger only displays the amount of charge your battery accepts. If your 3300 mAh only took 2127mAh it probably had 1173mAh before the charge. Since you changed the default sensitivity setting it is hard to say what happened but I'd bet it is undercharging I think the NiMH default is 7mv. I'd try using the battery until it was dead and then charge the pack at the default sensitivity setting and see what you get. If the battery is new it may need a few charge cycles before it take full capacity.

Your 2300 pack sounds like it might be on the way out, charging it at over 2C isn't helping it either. Does the charge last as long as when it was new? I'd try a 1/10C (200mAh) formation charge to see if it can be brought back but I wouldn't hold out much hope. Keep in mind the slower you can stand to charge your packs the more charge cycles they'll give over their lifetime fast charging is hard on your packs.


You might want to spend some time reading about batteries over at battery university they have a lot of good info over there.

http://batteryuniversity.com/learn/
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Old Feb 11, 2011, 06:06 PM
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Hello again,

When i say 05A i mean 500 mah so i quess it is ok.
I set the sensitivity of the charger according to the battery manufacturer instructions. In my case 20Mv per pack, thats 3.3 mv per cell but the lower set at Imax is 5 mv, default is 7mv

It is possible that the battery had some energy before so today i discharge it and ill give it a new charge at automatic mode.

When using automatic mode is it also gets the default delta peak settings?

I will give a try at my 2300 pack at 200 mah and see what will happen but this pack is old.
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Old Feb 11, 2011, 10:06 PM
God of Gravity Poisoning
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Yes the automatic Ni_xx setting uses delta peak detection. As for the sensitivity I don't think they mean per cell I'm pretty sure they mean per pack the charger doesn't have the ability to determine the charge state of individual cells in a Ni_xx battery. That being said 20mv seems pretty high since the default is 7mv. Did the manufacturer recommend dividing the 20mv by the cell count to derive sensitivity? If your battery doesn't take a full charge I'd try the default setting if you find the pack is still charging low I'd slowly raise the sensitivity but be careful you don't want the battery to get too hot I'd use the temp probe to shut it off at about 120f.
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Old Feb 12, 2011, 04:23 AM
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LRP suggests 20mV per pack dividing by 6 is my thought since i thought that imax calculates per cell but you are right how it can determine the charge state of individual cells? Anyway i will raise it a little (delta peak) and see what will happen.
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Old Feb 12, 2011, 02:57 PM
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For your info, after i discharge my 3.3 pack i recharge it again at 300mah. After 11.5 hrs the battery received 3243 mha. so i quess now i have a fully charged battery.
For now on i will use default settings and auto mode to charge my packs.
Besides up untill now i was charging my NiCad/NiMH packs with a cheap NiCAD charger without monitoring of anything.

Thomas
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Old Feb 12, 2011, 05:06 PM
God of Gravity Poisoning
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That is good to hear hopefully your new charger will help your packs last a long time.

Here's another common question asked by people who own 50w (5amp) 1-6s chargers. This is mainly a lipo issue but it is good to know anyway. When charging batteries everything is fine until you try to fast charge (1C) large volume packs above 3s (11.1V). You'll find that a 5000 mAh 6s pack will only charge at about 1/2 c this is because it requires 111 watts to charge at 1C (6s=22.2vx 5amp batt. capacity = 111watts) so your charger can charge large volume packs above 3s it just can't do it as fast as smaller packs.
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Old Feb 13, 2011, 07:19 PM
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Thanks Arkansas for your answers they were very helpful for me.

Thanks
jaf
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Old Feb 14, 2011, 01:25 PM
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Yes, thank you very much Arkansas for your time and your helpful info.

Thomas
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Old Feb 14, 2011, 02:24 PM
God of Gravity Poisoning
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No problem guys I'm glad the forums could help.
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