Question about battery chargers

[John Doecliff]

I'm in the middle of a new build and I will be using 6S batteries. The charger I have now will not put out enough power to charge a 6S battery in a reasonable amount of time. Looking to buy a new charger and I see that the DC input types have the most choices. My question is if I get a charger that only takes DC input does that voltage have to match or exceed the voltage of a 6S battery? In other words If I have say 12VDc input will it step up the voltage to >25VDC to charge a 6S battery?

 

[Ti@goo]

Yes it will. Of course it will all depend on the maximum Watts your charger will give.

I had a Imax B6 that only gives 50w. So to charge a 6S battery, I could only put 2.1 amps.

With that new charger you will need to buy a Power Supply.

 

[John Doecliff]

Thanks, One of the pitfalls of going to a larger UAV. Batteries cost more and I have to upgrade my charger as well. Since I will be running dual batteries I am going to get a dual charger too. I'm going to look at converting an old computer power supply first before I buy a new power supply.

 

[fltundra]

. I'm going to look at converting an old computer power supply first before I buy a new power supply.

http://www.tjinguytech.com/my-projects/server-ps

 

[violetwolf]

I have one of these under a different brand name. Built in 120/220 power supply and up to 4 batts at once. VERY good units. Will run off DC as well. Large and sturdy.. about the size of a small laptop but thicker.

 

[fengshuidrone]

I'm going to look at converting an old computer power supply first before I buy a new power supply.

Can it balance while it charges? Fast charging without balancing can lead to dead cells.

 

[John Doecliff]

Can it balance while it charges? Fast charging without balancing can lead to dead cells.

That would just be the DC power supply to the actual battery charger.

 

[fengshuidrone]

Whew! I should have known you knew that. Sorry. I feel so stupid now

 

[cootertwo]

violetwolf, I have one of those chargers also. Works great, I'm running mine off of a big 20 amp power supply. Charge 4 batteries at a time, no problem. Does balance charge too.

 

[John Doecliff]

Whats the watt output per channel? I need at least 5 amps on a 6S battery. So that would be about 125 watts.

 

[violetwolf]

Mine is 80 watts per channel. (320 watts total) I charge four 6s batts 5 amp each at a time with no problems at all. it will run all day with that load. It takes about 40 mins to charge all 4 iirc

Cooter mine has a built-in power supply so no need for external power unit.. Simply plug it into the wall.. (Or a car battery etc.)

I just looked at it. The one I have is a "Vista Power" Q6320AC ... But a quick web search shows they have a 400 as well.. presumably 400 watts total.. But as I say the 320 will charge 5 amp 6s batts all day without a sweat.

 

[moonpie57108]

Mine is 80 watts per channel. (320 watts total) I charge four 6s batts 5 amp each at a time with no problems at all. it will run all day with that load. It takes about 40 mins to charge all 4 iirc

That math does not work for 80 watt channel at 5 amps. It might let you set 5 amps but at 80 watt per channel you are short watts.

4 batteries at even the nominal 3.7 volts would need 444 watts, at 4.0 volts per cell your power is up to 480 watts out of a 320 watt charger?

 

[moonpie57108]

I'm in the middle of a new build and I will be using 6S batteries. The charger I have now will not put out enough power to charge a 6S battery in a reasonable amount of time. Looking to buy a new charger and I see that the DC input types have the most choices. My question is if I get a charger that only takes DC input does that voltage have to match or exceed the voltage of a 6S battery? In other words If I have say 12VDc input will it step up the voltage to >25VDC to charge a 6S battery?

To answer your original question on 12 volt supply to a 25.2 volt battery, no problem. The only downside is that it may reduce max watts of chargers. A 1000 watt charger might have a hard limit of 400 watts if you can only provide 12v from say a car battery.

In another battery thread, I posted a small table of charge times on a 6s 10,000 mah battery. Might be of interest.

http://www.dronevibes.com/forums/threads/battery-charger.34142/

 

[Petr Hejl]

I had the same dilemma when I started running large 6S batteries. I've been using Revolectrix Cellpro Dual Charger with their 24 VDC 55A Power Station and Parallel Boards, and LOVE this setup. While not the cheapest, it can charge a single 6S 16000 mah battery in about 12 minutes (at 35Amps), for two batteries I need to stay around 20Amps. This lowers the number of batteries I need to lug around to three (as long as I have an access to power supply or a generator), which makes this expensive setup a great value.

http://www.usastore.revolectrix.com/Products_2/Cellpro-Dual-PowerLab_2/Cellpro-Dual-PowerLab_373

 

[moonpie57108]

And that is how I ended up with a Honda EU2000 generator. Just multi purpose the generator to back up for the house sump pump and you can get it through without the wife saying another drone part!

 

[violetwolf]

Your guys' batteries must not last long! I found I double to triple the lifespan by staying to 1c charge rates, regardless of what the battery manufacturer says about rates.

 

[moonpie57108]

Your guys' batteries must not last long! I found I double to triple the lifespan by staying to 1c charge rates, regardless of what the battery manufacturer says about rates.

Maybe one of these days, I will get enough time to try and do a test that is controlled to say that the charge rate is actually affecting the life of the battery. There are quite a few other things that go into battery life: cell quality, discharge rates, discharge temperate, over discharge, storage voltage, storage temperature, and crashing, to name a few. I have charged up to 5C and have never noticed a temperature change of the cells. Heat, outside of physical damage is my gauge for what is bad for my battery.

I need say 6 new volunteer batteries(same brand, same batch, a good size might be 2200, cannot go to big as the charger needs to handle 5C), two identical chargers, and two identical loads. Charge 3 of them at 1C and other 3 at 5C (or whatever they are rated for), find a consistent load as flying won't work due to variables. Probably around 10-15C because you cannot stress the cells from discharge. Then the question would be what do we call dead? Dead cell, loss of capacity, fire?

I don't know much about battery chemistry but I did hear someone pose the question, how is a 5C charge rate going to destroy a battery that can handle discharge rates of 45-75C.

High charge amps doesn't necessarily mean high C rates. In the case of a 12 minute charged noted above, yes you are 4-5C depending on discharge state, possibly only 2C if the lipo was at storage capacity if Petr is talking about 1 battery. Once you start parallel charging, you can push a lot of amps into quite a few batteries at one time and maintain 1C per battery. While it make take you 60 minutes to complete a charge, you just charged 6 batteries, equivalent of 1 per 10 minutes.

I have some of my original turnigy and spyder batteries that are in age from 3-5 years old. Not used heavily maybe, not cared for well (not based on my current standards) and I have only ever lost a battery to crash damage.