### 1 battery vs 2 batteries that equal the same mah?

G'day DIY Drones,

I have a question about batteries, yes, I know this has been done to death, but I would like some real world experiences rather than the math.

I have used the search bar but I guess I am not using the right keywords, hence the reason for this post.

I am considering using 1 10000mah 4s instead of 2 5000mah 4s batteries to get more flight time from my 690mm photography rig.

A bigger battery of the same C rating or close to it.

Here is the math (feel free to correct me if I'm wrong)

2 x 5000mah 4s at 25 C = 125 max amp draw and has 10000mah. Weight, approx 1300g

1 x 10000mah 4s at 25 C = 250 max amp draw and has 10000mah. Weight, approx 800-850g

I only need about 115 max amps so both will do the job.

My question is about flight time and battery voltage sag.

I don't want theory but real world experience please.

Will the 10A, lighter battery give me more flight time because of the weight saving or will the voltage drop off sooner because it is only a single battery?

Another way to put it would be, would the 2 5A batteries hold the voltage longer than the 1 10A battery given the same flight situations?

Another way to put it is, are two batteries that equal the one in MAh, better?

I hope I am making sense here

Cheers

Aussie

#### Replies

• Developer

The biggest factor for flight times is weight. So everything else being similar or good enough, the one with less weight will always win.

• So really, there is a choice between redundancy and max flight time and a bit of a trade off.

1 battery (should) = more flight time due to weight saving

2 batteries (should) = slightly less flight time but redundancy in case of a cell failure

Yes?

Aussie

• I've run both single and dual battery (Parallel) setup on 3 air frames.  While weight is critical, I chose the dual for the redundancy factor much the way 2 of my 3 air frames have coaxial motor designs.  Cost to rebuild or replace was becoming a big factor for me, so after testing batteries, I found 2x matching mAH batteries was the best way to go.  The trick is to find the right mAH and C rated batteries for the amount of flight time you desire and performance demands (ie., hover, cruise, acro, or high speed) vs weight.  With my copters, I built them with strong motor/propeller configurations to where the GW is at approximately 40-45% throttle, and cruises around 25-30 kph.  Using 5A batteries rated around 35C, I found my sweet spot (12-14 minutes).  I try to not push full throttle with these as they will cook the batteries, but my main objective it hover and cruise modes.  As long as I do not push max throttle for too long, I will not destroy my batteries by puffing them.

• Doug,
Thank you for your perspective and reason. That's what I'm after
Cheers
Aussie
• This discussion really sheds a light to me.

Currently i'm rebuilding my quad from a serious crash.

I'm using a 6000 mah 6s lipo and now considering of using 2 x 6000 mah 3s lipo in series.

Would it be better in term of amperage draw on each batteries as well?

The reason i'm asking is because things discussed is in parallel configuration and i want to apply a series configuration.

Thanks

• beware, if one of the batteries has a voltage drop, you are dead while in parallel not.
So be shure to use fresh and good quality batteries.
Always stay far from voltage limit of the battery.
Amperage draw correspond to the battery lowest Ampère rating , it will not add as for parallel.
So in series, if a battery as 3A and the other has 10A , you will have a 3A system.

• Personally my experience is "lower cost" multiple batteries in series/parallel has two fold benefit. If a cell in a pack goes bad, your only out 1/2 the pack (unless you know how to assemble packs with a simple spot welding technique, 99% don't). I have used the Turnigy hardcase 4S-5000 packs (at \$21/ea on sale shipped) for my AP 600mm deadcat quad and electric bikes for years now (I buy them for her bike, but mostly get used for my quad, lol), I have not found a better bang for buck yet, if you find something please post, tia.

Here is the pack I get for \$21 shipped when on sale

http://www.hobbyking.com/hobbyking/store/__18631__Turnigy_5000mAh_4...

• Thanks for your replay Alasdair,

I am using Zippy 30C 5000mah High Discharge "Flightmax" LiPo batteries.  I use 2 at a time and get about 13 to 14 minutes before I hit 13.7v (my personal get the hell home voltage)

Maybe that is a good time and I am just being greedy wanting more?  I still think, from the comments here and my gut feeling, that 2 is better than one larger battery.

Zippy do have an 8000mah 30c.  Two of those might get me the extra I need.

Cheers

Aussie

• What is the weight of your copter ?
What props are you using ?

Without this information it is hard to help you to increase flightime.

A quad with average efficiency and no payload will fly 60 minutes with one 5000 mah 4S battery while only 69 minutes with two 5000mah 4s batteries.

• Moderator

Spot on

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