Yippee! Charging The Lithium Polymer Beast

[njswede]

Dennis is a forum buddy of mine. He flies giant scale cubs and that kind of stuff and has a lot of experience with very large (up to 5kW) power systems. I may drop him a note and ask if he's interested in sharing some of his knowledge with us. He's a retired high-voltage switching expert, so he knows a few things about electrics... Let me see if he's interested in posting something about his experiences from flying electric planes for 30 years!

 

[dth7]

Ok guys, all great input but I'm getting scattered a bit. Let me put it into "me" mode for a second to try to better understand.

I have two AC 680 Thunder chargers (from Nitro) with built in AC/DC supply and a cooling fan. It charges at a max of 6A and I have been doing fine with parallel boards on both at home and off the car battery (12-14Vdc at battery, note for those using an accessory jack as I did at first, you'll get a couple more volts at the Batt. I was getting low input voltage errors too Doc). I'm getting 6 3cells (usually adding up over 6000mAh done in a little less than an hour. 4s a little more. At the field I will usually throw on a couple at a time while flying and BS ing and get one or two charged. I'm moving into a 6 cell 3300 airframe and will likely want to "pump up the volume". I assume I'll need a new charger AND the power supply. Or, will the new power supply be able to work with my AC680?
I'm trying to stay on a budget so the options I see based on this thread are:
-Keep what I have and get more batts or talk more at the field!
-Use a new power supply with my AC680? if able
-Get a new power supply and charger. Recommendations? the 24+ sounds like a winner. Charger to use with the parallel board that won't break bank ? (I know a budget or money conversation has no place in this hobby but I do want to stay happily married!)
-Is an investment in a deep cycle battery (recommendations for size/ rating) a good idea if I'm pumping up the size of the batteries to charge? Although, if there is flying to be had getting "stranded" at the field with a dead car battery would make for a good excuse!
Thanks for clearing this up guys, I'm sure you will.
Daren

 

[Santi8]

I have solar panels charging large deep cycle batts that I can hook up in series to make a 24v power source.. Very convenient...

 

[SnowDog]

Ok guys, all great input but I'm getting scattered a bit. Let me put it into "me" mode for a second to try to better understand.

I have two AC 680 Thunder chargers (from Nitro) with built in AC/DC supply and a cooling fan. It charges at a max of 6A and I have been doing fine with parallel boards on both at home and off the car battery (12-14Vdc at battery, note for those using an accessory jack as I did at first, you'll get a couple more volts at the Batt. I was getting low input voltage errors too Doc). I'm getting 6 3cells (usually adding up over 6000mAh done in a little less than an hour. 4s a little more. At the field I will usually throw on a couple at a time while flying and BS ing and get one or two charged. I'm moving into a 6 cell 3300 airframe and will likely want to "pump up the volume". I assume I'll need a new charger AND the power supply. Or, will the new power supply be able to work with my AC680?
I'm trying to stay on a budget so the options I see based on this thread are:
-Keep what I have and get more batts or talk more at the field!
-Use a new power supply with my AC680? if able
-Get a new power supply and charger. Recommendations? the 24+ sounds like a winner. Charger to use with the parallel board that won't break bank ? (I know a budget or money conversation has no place in this hobby but I do want to stay happily married!)
-Is an investment in a deep cycle battery (recommendations for size/ rating) a good idea if I'm pumping up the size of the batteries to charge? Although, if there is flying to be had getting "stranded" at the field with a dead car battery would make for a good excuse!
Thanks for clearing this up guys, I'm sure you will.
Daren

Daren,
I have one of those AC680 chargers...that was my first purchase of an electric charger...it still works great today and I use it for charging little things like glow plug nicads (what are those! ) as well as ignition and servo life batteries. I purchased an iCharger and 24V power supply and paraboard from a fellow 3D'er (thanks again Ray! [Ohio AV8TOR]). Wow...what a difference. I had a paraboard for my AC680 and it took me quite a while to charge 4s3000 packs...now with the iCharger it only takes 20 mins!
At the field, I got a deep cycle marine battery (for about $70) that has been working well so far. I won't charge from my car battery because I can't imagine that phone call to the wife "hi honey, I'm at the field and my car won't start...would you come out and rescue me?" :O
You can get higher capacity equipment for not too much money from the advertisers on this site!

EPBuddy.com - iCharger 306B - $160 (comes with a free paraboard!) - well worth the money....don't skimp here
SolidHobby.com - 24+ Power Supply - $125
Local WalMart - EverStart 24DC Marine Battery - $70

You could use a new power supply with your AC680 but it won't be worth it...the AC680 can't output enough amps to make use of what the 24+ can provide.

Also, I think money conversations do have a place on this site, and I'm not afraid to have them...exactly for the reason you stated! Also, I have kids in college and soon to be in college, so I'm spread pretty thin!

Hopefully this helps.

 

[Steve_B]

Ok guys, all great input but I'm getting scattered a bit. Let me put it into "me" mode for a second to try to better understand.

Daren,

Regardless of how you power it the AC 680 is limited to a maximum 6A current or 80W power. When you charge a 6s battery the power limit will really slow you down a lot. 80W on a 6s battery means charge current will be down around 3A, so you will take upward of an hour to charge a single 6s 3300mAh battery, parallel charge two and it's two hours. If you want to fly, say, six times in a outing it starts to get prohibitive. Even if you buy six batteries (expensive!) you still need to have the charger running all day to charge your batteries and field charging is hardly practical.

There are lots of high power chargers out there. The Cellpro PowerLab range are probably the cream of the current crop but they are not cheap. The iCharger range is also really good (I've got the iCharger 3010b) and is a bit cheaper. I'd say that you should be looking for something with at least 350W of charge power, but the more the better if your aim is to parallel charge big batteries. You can get cheaper high'ish power supplies from the likes of Hobbyking, I've not tried one myself but they probably get the job done ok: http://www.hobbyking.com/hobbyking/...EGA_400W_Lithium_Polymer_Battery_Charger.html

For a power supply, converted server PSU's like the one in this thread are the best bang for buck. You can build one for next to nothing if you pick up some ex-server power supplies . Go to eBay and search on DPS-600PB and you will find loads of them. The one shown in this thread is about the tidiest conversion I've seen so far and is great value, but if money is tight it is possible to do it a lot cheaper if you can solder (like for maybe $15-$30). Bear in mind that many chargers are limited to about 18V input, so you could only use a single 12v server supply on them, which would be enough power to max out your charger unless you were over 350w output.

I've never used deep cycle lead acid batteries but for 100% sure you couldn't think of using your car battery to charge big LiPos at high rates (unless you like the thought of walking home). Even charging one 6s 3300mAh lipo from an average car battery would shorten the car battery life dramatically. Charge three or four and chances are you are walking home, though in practice the charger would probably trip out on low voltage. I know of some reports that the sort of amps that the most powerful chargers pull will kill even a big deep cycle battery quite quickly.

 

[njswede]

You mean 80W of power, right?

 

[gyro]

You can get cheaper high'ish power supplies from the likes of Hobbyking, I've not tried one myself but they probably get the job done ok: http://www.hobbyking.com/hobbyking/...EGA_400W_Lithium_Polymer_Battery_Charger.html

Don't really agree with this recommendation, as their products have proved troublesome in the past with many documented screen failures, and other internal component failures. Also, by the time you pay for the high shipping costs, (and then wait forever) you could have a better quality charger from a reputable company.

When it comes to something that could malfunction and burn down my house, I would rather squeeze out a few more dollars and buy a quality product that has passed through some sort of failure testing and safety checks, such as UL (Underwriters Laboratories), or an equivalent.

 

[Steve_B]

Gary,
I'm not sure I recommended one? As I said I've not used one of the high power HK chargers, I decided to spend the money and get an icharger, and if you can afford it that is what i would recommend. But not everyone has the money to do that. I do have one of the cheapo Turnigy Accucell chargers and it works perfectly ok, it's never burned my house down even once Obviously isn't a fraction of the charger that the iCharger is, but I still use it occasionally to charge smaller batteries if the icharger is busy with the bigger stuff.

For what it's worth the HK one does carry a 'CE' mark which is supposed to mean that it meets all relevant European safety standards, and FWIW#2, it is available from the USA warehouse. I was using HK as an example, I'm sure you can pick up pretty cheap Chinese chargers from other lots of other retailers, many of which no doubt have better customer service than HK..

 

[gyro]

Gary,
I'm not sure I recommended one? As I said I've not used one of the high power HK chargers, I decided to spend the money and get an icharger, and if you can afford it that is what i would recommend. But not everyone has the money to do that. I do have one of the cheapo Turnigy Accucell chargers and it works perfectly ok, it's never burned my house down even once Obviously isn't a fraction of the charger that the iCharger is, but I still use it occasionally to charge smaller batteries if the icharger is busy with the bigger stuff.

For what it's worth the HK one does carry a 'CE' mark which is supposed to mean that it meets all relevant European safety standards, and FWIW#2, it is available from the USA warehouse. I was using HK as an example, I'm sure you can pick up pretty cheap Chinese chargers from other lots of other retailers, many of which no doubt have better customer service than HK..

Fair enough.

 

[Steve_B]

You mean 80W of power, right?

Yep, well spotted!.. corrected

The limit on Watts is often not made clear on many chargers. They make claims of being able to charge as 6A, 10A, 20A or whatever, but very often they can only actually achieve that if they are charging a 2s liPo. Anything higher cell count and they can no longer do their claimed amps because power becomes the bottleneck.