Astroflight 109 HELP

it's finally nice out, so i put connectors on my 5s1p packs and my two 109 chargers..

i plugged both packs into each charger, and they started charging just fine.
while adjusting the amps to 4, i bumped it up to 6 for a second, and the charger instantly gave an error:
volts <10.5 (not sure if it was .5, but it was right around 10.5)
so I unpluged the battery and instantly the second charger gave an over voltage error.

i unplugged the psu, plugged it back in, and hooked one pack up again. started charging at 4amps. plug the second pack in, and get an over voltage error. everytime I plug that pack into that charger it gives an over voltage error.
so I left it unplugged, and watched the first pack that was still charging at 4amps.

the charger said:
5C2
3:11
.104ah
19.2volts

I watched it till the volts went up to 19.66v, then unplugged it and came on here. what voltage do these packs hold when charging? and i'm assuming the 19.66v is the battery's voltage?

the psu is an Elco 12v13a.
i'm guessing i need a psu that can do 20v and 8a at the minimum?
i'm still extremely cautious around lipo, having never used them before, so I'll await a reply.. hopefully the suns still out when this is resolved :(

[BrianG]

OK, first of all, the "volts<10.5" error probably meant the 12v power supply dipped to under 10.5v. Trying to charge two 5s1p at 4A can require almost 200W on the power supply (including charger losses). That's at least 16A at 12v - but since the voltage was dropping to 10.5v, the current was higher at about 19A. Sounds like you need a bigger powersupply, or maybe one for each charger.

A 5s pack will charge constant-current mode up to 4.2v/cell, which is 21v. So the battery voltage will steadily increase until the pack gets to 21v. Then, the voltage is "locked" and the current steadily falls until the charge stops. That said, I don't know why the charger is stopping. I would use one charger at a time on the power supply to eliminate input voltage issues.

You don't need a 20v power supply, you need a 12v power supply that can supply about 25A. Or you can just get another one like you have now and run one charger on each power supply.

thanks brian. I actually just checked true-rc's site, and saw that it can charge at 21v. so I'm going to continue charging one pack at a time, and hopefully i'll be able to go run it today.
it's gonna take 2 hours to charge one at a time.. maybe i'll have my sister watch the packs, and go pick up another psu..
i know you're always supposed to monitor the chargers.. but if a cell blew up, what could i do anyways? i've got it in a lipo-sack sitting on a big piece of metal..

[BrianG]

Originally Posted by A4DTM

...i know you're always supposed to monitor the chargers.. but if a cell blew up, what could i do anyways? i've got it in a lipo-sack sitting on a big piece of metal..

Well, you're right; if it's gonna puff, it's gonna puff and there's not much you can do about that. But if you're there monitoring them, you can stop the charge before the cells go from puff to flame. Using a lipo sack and on top of something non-flammable simply mitigates the risk, it doesn't eliminate it.

If charge time is important, then I would either get a single supply capable of about 25A, or two supplies each capable of 12-15A. You don't want to pull the max current a supply can supposedly generate because:
1) It reduces the life of the devices running at their max.
2) Power supplies are rated to supply a certain current at usually 25*C - but the inside of a PS is rarely 25*C and there is a derating curve.
3) When drawing the max current (or close) a supply can provide will cause the output voltage to drop. When this happens, the current has to increase to compensate which then causes the voltage to drop further.

You can make the power supply a little more stable on the 12v line by loading the 5v and/or 3.3v line(s) with about 1-2A. All supplies are switching units and the circuitry usually measures the current on one of these other lines to provide feedback for the regulator to adjust the voltage on all the lines accordingly. The reason for this is because these power supplies are meant to be used in computers where all lines are bing used in a somewhat equal proportion. So, the circuit assumes that heavier current on one line will most likely be drawn on the other lines. Since you aren't using the other lines, the circuit thinks you aren't using much power on the 12v line either. And since it doesn't measure the 12v line specifically, it has no way of knowing. I hope all that made sense and I didn't give you useless info. :)

oh, also, the one pack was up to .104ah..
when i plugged it in this time, it started from .000 again.. will it figure out it already had some charge in it, as it goes along?

and, any idea what 5C2 means? i'm guessing 5 is for 5s, and C2 is..... ? - never mind, about that.. http://astroflight.com/store/pdffiles/109.pdf has the info

ok, one last question.. right now, the voltage goes from 21v to around 21.2v, in the 3rd stage of charging, which the manual says if normal.
the amps shows 0.00 and the mah is SLOWLY increasing.. like 1mah per 10 seconds.

i know it's almost completely charged, so i can take it off the charger...
now if I do the other pack, and take it off around the same time, the mah won't be the same as the first pack. i'm running these in parallel, so can I take one off with say 3950mah, and the other's at 4000mah, will they balance each other when running? i've also got 2 505guard balancers, that i'm doing to each pack after charging.. but i don't have a meter, to see how much they're different..

brian, the psu i have isn't a modified computer psu. it's this one: http://www.rcgroups.com/forums/showthread.php?t=646923
(best link i could find sorry)

both packs are charged, and when the first one finished, i put the 505 guard on it, and cells 2-4 are discharging.. well the second pack finished, and the first pack is still flashing cells 2-4..
this was the first time ever charging the packs, so is that maybe the reason it's taking so long to balance? how long should it take to balance 5 4000mah cells? i think i might try a parking lot tonight, as the sun has set.. but i don't want to run them till they're balanced.. what a waiting game :(

[BrianG]

Oops. That's what I get when I make assumptions.

You should be able to balance while you charge so by the end of the charge, the cells are already balanced. You're right though; I'd wait until the pack is balanced before running them, or you might discharge one or more cells too deeply.

nope, the 109 charges differently than most other chargers, so you can't use balancers while charging.
I got the two 109's, three polly quest 2s packs, a pq balancer, AND 2 reedy quasar pro chargers for about $250, so i couldn't pass it up.. after the fact i learned the 109's can't balance while charging =\

ok, the second pack finished charging, and is completely balanced.

the first pack i had charged is STILL balancing. that's around 3.5 HOURS. cells 2-5 are all continuously blinking. while cell 1 stays off.. so i'm guessing that could be a bad cell or something? voltage showed 21v when charging, and it also detected it as a 5s pack. WHY is this taking over 3.5 hours?

[BrianG]

Not necessarily. A balancer works by applying a small load, typically between 50mA and 150mA, on the higher voltage cells. This slowly discharges those cells. If you have 5Ah cells, it could take a loooooong time to discharge the high voltage cell(s) since you are discharging high capacity cells with a very small current. The greater the difference in voltage, the longer it will take.

Simply charging can cause a small imbalance. If you charged a pack that already had an imbalance, it could only get worse after then end of the charge. That's why it's a good idea to balance while charging.

BTW: Why can't you balance while charging on the 109? Do you have a link that explains why? I'm quite curious.

To get the pack back to full balance quicker, you could charge each individual cell at 2A or less through the balancer leads. This will make each cell 4.2v. Then let the pack sit for a while for the cells to settle down, and then attach the balancer. This process may require some special adaptor cables or something and requires that you know exactly what you are doing.

[QUOTE=BrianG]
BTW: Why can't you balance while charging on the 109? Do you have a link that explains why? I'm quite curious.[QUOTE]

from this thread:
http://www.rc-monster.com/forum/show...&highlight=109

Originally Posted by MetalMan

The Astro Flight charger is good for the price (9 cells and 8amps). But, it isn't a CC/CV charger, it is a pulse charger. Most balancers assume that you will be using a CC/CV charger, as the is the standard charge method. They will get confused with the pulsing of the AF109 and could kick in at the wrong time (and potentially make the charge take longer).

i'm updating my project thread w/ some pictures.
http://www.rc-monster.com/forum/show...t=3489&page=12

[BrianG]

Ahhh, makes sense now.