Nodd

I'm likely dragging up an old topic here so my apologies if so. I'm looking for current advice on current tech (most relevant threads I found were several years old).



I'm trying to get a feel for how most folks maintain their LiPo batteries. We all know its bad to keep them fully charged between flying sessions. We're supposed to maintain them at "storage voltage" (approximately 3.8v per cell) while they're not in use. I have a couple of problems with this though...

[*]I fly several times a week. That's a lot of work to charge/discharge all my batteries between flying sessions. Time consuming & labor intensive.[/list]
[*]Keeping the batteries at storage voltage means I can't go fly at the drop of a hat. I have to plan ahead if I want to fly.[/list]So like many, I've been abusing my LiPos by keeping them fully charged, all the time. Most have started to puff & now fail to balance properly. As a result I'm also seeing greatly reduced flight times, not good. So what to do?..

First off, I've invested in some new batteries. I'm considering buying a "quad charger" that can deal with as many as four batteries at once. There's several fairly cheap four-in-one chargers I'm looking at (I'm between jobs so need to do things on the cheap). My current plan is to do one of the following...

Pre-Charge
The night before I fly I'll bring all my batteries up from storage voltage to full. That way when I get to the field the next morning I'm ready to roll.

Charge-on-demand
The problem with pre-charging is I don't necessarily use all my batteries when I fly. So some inevitably end up being unnecessarily cycled. So maybe I should charge my packs at the field, only as required? My new nano-tech LiPos can be charged at a high C rating, so theoretically once I get to the field, I can decide what I want to fly then fast-charge up a pack or two & start flying.

So I think for either of these methods to work efficiently, I'm going to need the ability to charge multiple packs at once. My question is, what do you folks do?

Goldenduff

Pre charge.

guver

My Feedback: (325)

I charge on demand and almost NEVER charge or discharge to a storage value.

Theoretically this is what I shoot for: packs I use regularly.

Pack sets at 3.7 volts/cell until I decide to use it. Charge as fast as possible and use it immediately.

Nodd

Thanks for the feedback, much appreciated.

3.7v is more or less storage voltage although 3.8v is more common but close enough. So yeah that's how I aim to store mine from now on. No more letting my LiPos sit around for days on end busting at the seams with energy.

I also posted this over at RC groups & it was suggested that I look into parallel charging instead of using a cheap low powered quad-charger. I may need to invest in a more powerful charger to pull off a parallel fast charge though, not sure my current "four button" charger is up to the task.

There was also talk of regenerative charging/discharging where a fully charged pack is hooked up to a discharged pack via a resister. The idea being, once you're done flying you dump the power in your unused packs into the spent packs until both arrive at around storage voltage. I think that's friggin brilliant! Info on that can be found here... http://www.rcgroups.com/forums/showthread.php?t=1255751

Goldenduff

That device would still result in storage type voltage so doesnt solve the problem of OMG it isn't raining ....

Nodd

Yeah I'm going to build a couple of regenerative dischargers, looks like a great way to place batteries in storage mode.

As for the "OMG it isn't raining" scenarios I'm still undecided. I think I'm leaning more towards using a quad-charger Vs parallel charging but we'll see.

trax de max

quad chargers are generally low powered, maybe about 50W per port. You may regret buying one.

Nodd

I agree, generally that's true but not all of them are whimpy. Just looking at what HobbyKing has to offer, they have a few 100-200W per port multi chargers available for around $100. I'll do some shopping around & see what's what.

Goldenduff

Hobbyking also have an 400w per (2) port. The only problem is the max amps is something like 20amps per port. A more expensive charger that has similar watts generally has higher amp output, say 40amps for the one channel. This then means if you have a large capacity battery you can charge at a high c rate. Something the multinports cannot do. Not a problem of you never intend to use medium size batteries.

trax de max

what are the battery specs? if it's all same cell count a high power single charger with para board is where it's at. If they are different cell counts the dual would do. But i still think quad chargers aren't up to the task with Lipo's getting higher capacity, it's best to have overkill than something that;s just ok for now.

I'm with the power lab 8, just waiting for it to be in stock at lhs. There is also the fatboy 8 at hobbyking, made at same factory by the same people as the pl8, the only difference is the lack of quality firmware updates.

richrd

Yea me too never know when i can fly or even get to the field an it's to windy can'nt win [:@]

Always storage or cheat at 3.9V then fast charge at 2C or higher while packing car etc.
If no fly at field then play with plane to discharge to high side...
It's the only way i can do it cause full charge, just is a settup for bad things to happen.
Same with my glow starter charge high side of 3.95V then recharge at 3.8V couple years now an still good shape.
Rich

Scota4570

I just found out about storing charged LIPOS. Most of mine are ruined. I found a solution. I am switching over to A123 cells. Done deal, no more muss or fuss. And no more worry about burning my house down.

Nodd

Okay the good news is I've stopped abusing my LiPos. They're sitting happy upstairs right now at a comfortable 3.8v per cell. I fast-charged one battery while packing my car for the trip to the field yesterday. It was fully charged by the time I had everything in the car. Then at the field I charged a second pack while I flew. Worked out pretty well.

The bad news is I'd like the ability to fast-charge multiple packs at once & I don't think my current 80w charger is up to the task. So I'm shopping for a new charger...

PARALLELVSMULI-PORT
Its possible I'm starting to get a clue here (maybe). I've been mulling over my options, multi-port charger Vs parallel. So far the biggest batteries I've been using are 2200mah 3S nano-tech with a 5C max charge rate. Based on that here's a few fairly economical options...

PARALLEL CHARGING
Use a parallel wire harness that'd let me charge multiple batteries from a single-port charger.

Turnigy MEGA 400W V2


Price $71.73
1 x 400w
Parallel fast charge four 2200mah 3S LiPos at around 4C in approximately 18 minutes.
Great price, lots of power, fully featured.

Hyperion EOS 1420i NET3


Price $129.95
1 x 550w
Parallel fast charge four 2200mah 3S LiPos at around 5C in approximately 14 minutes.
Quite a bit more money but lots of power. Quality brand, comes highly recommended from clubmates.

MULTI-PORT CHARGERS
Separate controls for charging up to four batteries at once.

HobbyKing 4B6


Price $77.29
4 x 50w
Fast charge four 2200mah 3S LiPos at around 2C in approximately 36 minutes.
Great price, fully featured. Lacks ability to charge at high C ratings.

Turnigy 4x6S 400W


Price $116.99
4 x 100w
Fast charge four 2200mah 3S LiPos at around 4C in approximately 18 minutes.
Good power per port, fully featured.

The charge times are based on a charge calculator I found here, not on real world numbers. No clue how accurate that is.

CONCLUSION
At this price range, using the packs sizes I'm currently using, I'm having a hard time seeing the advantage of parallel charging Vs a full-function 100w/port quad-charger. Using the Turnigy 4x6 400W charger I could charge my 2200 3S packs at up to 4C. That's pretty respectable plus I don't have to mess about making/buying parallel wiring harnesses. I'd have complete control over each pack's charging and when I'm not in a hurry I could also do bulk balance charging to keep the packs in good shape.

Now if I start to fly larger aircraft & need to use bigger packs I can see where parallel charging comes into play. Instead of being limited to 100w per port I'd have the flexibility to use up to 400-500w. For example I could fast charge at high C ratings, say a pair of 5000mah 4S in a short time.

The question is how important is it to me to be future proof? A cheap 100w/port quad charger would more than satisfy my current needs. If & when I move on to bigger & better batteries its not a huge investment to pick up a high wattage single-port charger & do the parallel thing. So for now I'm leaning towards getting the Turnigy 4x6 400W quad-charger.

Last chance to talk me out of this.

guver

My Feedback: (325)

The top two will not do the job you've described. They will both be limited to 20 amps and will do an equal job since it is this 20 amp max that will be found first. The bottom one will do the job the fastest. Sorry I can;t answer your question though. (lot of help, right?)

I like your idea, buy the 4 port now and then buy the top one later.

Nodd

No kidding, good catch, I didn't factor in the 20 amp limitation. I suppose something like the iCharger 306B 1000W which caps out at 30 amps would be a better choice. If & when I get into bigger packs I'll likely get something like that to do parallel charging. That's assuming of course there aren't high capacity multi-port chargers available by then.

guver

My Feedback: (325)

I like my 306B and leave it set to 30 amps all the time. I've also had my eye on the 100x4 since it's the biggestbest 4 port charger, 10 amps and 100 watts isn't too shabby for most 3sx2.2 packs. I've also had my eye on the HK 380 wattx20 amp charger.

I don't quite think we will see a higher power 4 port charger very soon , but there are a number of much higher 2 port ones. I've been wanting for a long time for a charger that can "share" the power between 4 ports. Inotherwords 500 watts and 20 amps max would be a nice spec , but with the ability to share that 400 watts between ports. Using all of it on one port if desired.

I think what's import for you to make the decision whether to parallel or to use multi-port charger is this: Are most/all of your packs 3sx2.2 ? and will you be charging them all at the same time? If both answers are yes, the parallel is a good idea. If you needed to place a pack on at different times because someone just got done flying it then the multi-port would probably be best. (starting at different times)