Battery Voltage Levels

[Marky Mark]

Afternoon All
i have recently got my F450 buils up and running. Back of the net! lol

How do i work out the values for the Low Battery voltage alarm setting on Naza assist?

I am usng a Overlander 30C, 200mha , 11.1v, 3S Battery.
I am using a Overlander RC6-VSP Battery charger.

Is there any important points which are displayed when charging on the screen which provide me with info which i should take note of?

Cheers

Obviously i want the longest flight times available without discharging it to much.

 

[holtneil]

Hi mate no lipo can be taken below 3.7v a cell or battery will be trash, so i set my alarm for 3.8 and this gives me time to land before it drops below 3.7v
So its 3.7 x the number of cells this gives you the volts for the alarm

 

[NCFRC]

Hi holtneil ,

Not trying to be a wise ass here but you can discharge a lipo to 3.30 with zero problems.
When a battery is rated for mah from the manufacturer , thats their cut off voltage.
Thats what I have my bench units set for when I post the tested mah.

As far as a flight warning voltage , I'd want a 3.6 - 3.7v notice as that would still give you a
minute or two at partial throttle to land.

If your not going to use that battery for a few weeks , charge it to a storage charge of
roughly 3.85 volts per cell. A full charge stored is also not a good thing.

 

[holtneil]

Hi mate I was always told 3.7v less than this and the battery can loose the memory state it need to recharge , I have batteries that are over 2 years old and are as good as new , I know you can go as low as 3.0v , but then you have to store charge back to 3.8v , so by flying to 3.7v you can just put lipos away and know they are at storage charge already

 

[NCFRC]

I agree 100 % that if you terminate your charge voltage on the low side , like 4.10 to 4.15
AND cut off your discharge voltage at 3.60 to 3.70 volts , your lipo's should last an incredibly long time.

I guess I've always been more of a performance person and may sacrifice some battery life.
A lipo can easily cycle from 3.30volts to 4.30 volts and vise versa for 100's of cycles.

What happens below 3.0 volts is the lipo loses big time in the capacity aspect.
A 1200 battery will turn into a 900 in no time.
It's not memory like the old round cell days , it's a chemical reaction that happens.

Some battery manufactures have raised their discharge cut off to 3.5 volts to show a flatter
curve and a higher average discharge voltage.

Sorry to ramble but the other major factor is to buy good quality lipo's in the first place,
a cheap one is going to puff and perform lousy no matter how you treat it.

" I havn't watched the video yet "

 

[NCFRC]

Many , many times , the C rating is strictly a marketing number , not a real world number.

Yes , you usually get a better battery when it's C number is higher but no where what the
numbers factor out to.

For example , take a 5000mah battery that has a 100c burst rating .

Your talking 500 amps !! That's what your automobile battery has for amps.
Does your Lipo battery have wires as big as your automobile ones ??
No , and couldn't produce 500 amps for a micro sec.

That's where the marketing of batteries comes in. Anybody can print a label.

They print what you want to hear.

I'm sure either of the battery manufacturers in the video make a good battery ,
just take the C ratings with a little knowledge of marketing.

 

[Marky Mark]

Thanks for the video link holtneil thats all my questions answered thanks.
cheers

 

[holtneil]

Hi mate I try to keep thing simple for the newbies , some one coming into this hobby from a non rc back ground will get over powered by all the tech info , So by keeping it simple so they can learn to fly and then start to ask questions ,is much better for them , so i tell them easy things to remember so 3.7v flight and store is easier than 3.0v flight , 3,7v store plus what c rate is, charger rates ,cell counts balance charging ,
If you fly to 3.0v and then go home and forget to charge or store , when you do remember the battery may had gone bad so will have to buy new ones , so while they learn i get them to play safe so its one less thing to worry about

 

[holtneil]

Hi mate there is so much to learn a video helps , easier to learn if you watch

 

[Marky Mark]

Pictures paint a thousand words.
Keep it simple keep it stupid.

Happy days

 

[NCFRC]

Hi mate I try to keep thing simple for the newbies , some one coming into this hobby from a non rc back ground will get over powered by all the tech info , So by keeping it simple so they can learn to fly and then start to ask questions ,is much better for them , so i tell them easy things to remember so 3.7v flight and store is easier than 3.0v flight , 3,7v store plus what c rate is, charger rates ,cell counts balance charging ,
If you fly to 3.0v and then go home and forget to charge or store , when you do remember the battery may had gone bad so will have to buy new ones , so while they learn i get them to play safe so its one less thing to worry about

I agree 100% with this approach as it is a lot to grasp for a newbie. It's actually ," Keep it simple stupid "

I let my engineering background loose sometimes ,,,, ha ha

 

[holtneil]

Its nice to have you here to help with the real nitty gritty of the job thanks

 

[trailhead]

Good thread guys, I've been wondering about this kind of information.

One other question I have about charging is safety. The manuals for my charger make it sound like you need to build a steel reinforced concrete bunker to put your batteries in while charging because of the chance of explosion. I figure that's the lawyers talking, not necessarily the reality of the situation. But I could easily see increased hazard if you're fast charging, like 5.0C (assuming your charger can handle it).

But I digress. The question is, is there really much of a hazard to charging batteries at 0.5C to 1.0C? For example, can I charge my 2200 mAh at 1 amp with low probability of a problem?

 

[NCFRC]

Most of the time your perfectly fine with a 1c charge.
Up to a certain C I wouldn't reccomend unless there were very rare circumstances.

I'm going to take the cautious side here as no lipo should be left unattended while charging.
The biggest factor there is what if the charger does not shut off ?? Then there's a major problem !

I'd guess ALL lipo battery manufacturers reccomend using a lipo charging bag/sack to cover their butt
and we probably all should use them.
The problem with a lipo fire is that it's a chemical fire and CAN NOT easily be put out.
Even if you were in theory to throw it out into the snow bank , it would burn for a long time.

If it accured in a lipo bag , I believe you could quickly get it out of the house as it would try and
contain the lipo explosion. You here of more fires charging than explosions.

Sorry for such a political answer but safety can't be strived enough when using any batteries.
I'd hate to see anyone loose their house over charging a toy 500 mah lipo , but it can happen.

Charge your 2200 at what the manufacturer reccomends

 

[trailhead]

Thank you NCFRC. I'd never heard of a LiPo bag, I'll have to look it up.

I definitely agree, never leave a battery unattended while charging. I've never had a problem but I know that doesn't mean it won't ever happen.

Thanks for the feedback!

 

[holtneil]

Hi trailhead ,when you say fast charge its not what you mean Ok fast charge on a lipo charger means it charges battery at the rate you set which should be C1 to 80% which is enough for a flight , Charge or balance charge will charge to 100% it takes longer due to the amps drop off as the battery starts to get full , You can charge faster if you want by upping the C rate I have a 2200mah I charge at C1 = 2.2amps , but I can charge faster as the battery will take C2 so I can charge at 4.4amps so will take half the time but every time i do this the life of the battery will be reduced
I use lipo sacks 1 for charging and a bigger one for storing the batteries in
http://www.hobbyking.com/hobbyking/..._Charge_Bag_23_x_30cm.html?strSearch=lipo bag