Jetdesign

My Feedback: (8)

I went to charge my first set of batteries - was practicing with my 2S lipos charging in series as I would with my larger 5S sets. I was sure I hooked everything up right, the charger went through it's paces and let me start charging. Within a few seconds the charger was smoking from inside.

I stopped everything. Charger appears to be working OK, but the batteries differ quite a bit in internal resistance, although I never checked them before the charge. Sometimes both batteries will tell me there is a voltage problem at the balance port.

Here are pics of the setup. The charger is capable of up to 6S charging/balancing (this was only 4). The batteries appear to be properly connected to the balancer as my other charger was able to read all the cells as one 4S battery. I hooked one red battery lead up to the other black lead, then plugged the free ends into the corresponding colors on the charger.

Not sure what I did wrong but I'm afraid to do this with my 10S setup.

petec

My Feedback: (58)

Sent you a PM. On my charger I need to have the balance tap from the battery with it's negative power lead going to the charger plugged in as the, for lack of a better term, "most negative" on the balance board. If not you are putting a short on the pack...your charger may be different.

can773

My Feedback: (1)

Pete's right, and the way you have it wired makes it impossible to tell which pack is #1 when viewed from the balancing circuit.

As Pete said, the pack who's negative lead is connected to the charger must be plugged into the A or first connection on the balancer board, otherwise you short it out. This is the same for every type of charger I have used, I don't think yours would be any different.

I would suggest wiring it different so you can clearly see which pack negative lead is going to the charger.

I have done it a few times, never really seemed to hurt anything though.

Velco

Cell count is done from the side of the negative that goes into the charger. The same is valid for the balance plug negative.

I did make a mistake once but the only thing damaged was the balance split cable. Some friends reported damaging Accucell 6 charger if not connecting the balance cables in the right order.

Jetdesign

My Feedback: (8)

You guys got it, had no idea...

Thanks Pete for the phone call!

So, my IR for the cells are: (55 60) (123 78) - is that a problem, or am I still OK??

Looks like I shorted something out in the charger, hopefully the EE guys at school will help me out

petec

My Feedback: (58)

Glad I could help.

now get one of the EE students to fix your charger for you...I bet once you tell them what you do as a hobby you'll make new friends.

Jetdesign

My Feedback: (8)

So the setup seems to be working properly.

Right now I have my two 5S batteries hooked up in series and on the balance port. The charger is set to balance at 3A, but it's only working at 0.09A. After 1.2 hours it's only charged 120ma. They are brand new batteries and the voltages were within 0.2V of each other. I am using the iCharger 1010B+

I also hooked up my 3S batteries in series on my other charger and had pretty much the same thing - hours and hours on "Balance" and still not charged.

Is this normal, and is this what I should expect in the field?

Chris Moon

My Feedback: (8)

Joe, what is the total pack voltage? If the packs are nearly fully charged, you will get a low tapering charge rate although I don't know why it would take so long unless the cells were way out of balance.

Jetdesign

My Feedback: (8)

Currently 38.5V.

I don't even know what the voltage range is for these packs. Probably need to figure that out[&o] I thought it should go up to 42V or something.

petec

My Feedback: (58)

Joe,

Check here:

http://www.rcgroups.com/forums/showthread.php?t=839657

The manufacturer monitors that thread.

Pete

Jetdesign

My Feedback: (8)

Ok, first problems solved - it was the power supply


So what is proper battery care and maintenance? I've been hearing about 'breaking in' a lipo power pack, of course after I've started flying my plane. I've got 3 more sets of packs on the way and want them to last, and to give me power throughout the duration of the flight.

-How do you 'break in' a battery pack?

-Do you always charge at 1C, and do you give the battery a break between flying and charging?

bedowinn

Joe,
I was told by a wise sage to fly a new batt 5 times using 1/2 capacity and no or little full throttle.
Rotate the batteries through and log each flight.
Let the battery cool off before recharging.
Pre-warm the batts before use (I'm still trying to figure out a practical method).
I charge at 1C thru the balance port of a procell 10S charger.

DaveL322

Joe,

"Ideal" battery care/maintenance for lipos is not something that is practical for our applications as motor batteries (high discharge rates).

Practically -

Break-in will not hurt the packs, and will likely improve their longevity (I no of no specific amount of increase). For break-in, it is best done on a test stand at full throttle, using the prop to control the peak amp load. Part throttle does not control the peak amp load, only the average amp load. The ESC is a high frequency switch that simply decreases "on" time as throttle is reduced. Inline ampmeters (or Eagletree) are reflective of averaging. I typically break-in lipos over the course of 5 bench runs....starting at about 3C and 30% discharged, and gradually working up to 5C and 60% discharged. I charge at 1C during break-in. If I notice any hotspots or cell imbalance, I break them in more slowly (only needed to do this with 1 pack). And then I go a little easy on them the first couple flights (no extended full throttle).

For routine care/use -
- leave discharged at ~3.8 volts per cell at cool temps (but not freezing)
- charge (1C) just before flying
- allow them to cool to ambient before charging again
- never exceed 130F
- the shallower the discharge, the better. My personal opinion/experience is that <70% discharge is quite safe and limiting to 60% will not likely show much benefit for our application.
- prop to keep a minimum of 3.5 volts per cell at full throttle at the start of a flight (higher voltage is better)
- if unused for more than 1 month, don't expect maximum performance

You are not likely to "toast" a pack just because you charge it when it is still warm, or you stored it fully charged, or it got to 140F during discharge. However, all these things are relative, and the harder you run the packs, the shorter the life will be. A bad scenario is to charge a pack, let it sit for 3 months, then use it in a high discharge application with high ambient heat, discharging to 90% - that is far more likely to puff a pack then using the same pack reguarly, charging before the flight, and discharging to 70%. Newer lipos are far more tolerant of abuse than prior generations (especially high rate charging and discharging), but "abuse" is stil relative.

Regards,

iflyrctoo

Dave,
Do you carry your batteries in some kind of container or have some way to keep them cool in your vehicle? I usually carry my planes and all of my equipment in the back of my pickup. During the Summer months the temperatures in my truck probably approach 130° F. I'm sure this can't be good for the batteries. Any recommendations?

Thanks Dave

Joe Dunnaway

DaveL322

Joe D,

My white van with tinted windows (left open a bit for ventilation) when parked in the shade doesn't get too hot in the summer....but on very hot days, I do try to take the lipos into the office with me to keep them from getting cooked. Again, I can't say that his definitely extends their life, but it can't hurt.

Regards,