Lipo 1 big or 2 small

[rupP]

Need some advice regarding purchase of more batteries for my Tarot 810 with gH3/z15.
I purchased it s/h with 1 nearly new 16000 Tattu and 2 pairs of well used 5000 haiyin 30/40c.
From a full charge with i308duo (mini led voltage alarm set to 3.7v & naza is also set to 22.2v) I get just 8.5 mins flight from the Tattu and 11.5 mins from the Haiyin pair. I am surprised by this and wonder if the rig is over its weight capacity with the heavier Tattu or that the voltage drop off happens more quickly and with less charge left in the Haiyins, they are certainly more responsive.
Is it obvious that I should get more Haiyin batteries (a pair of 5000 cost nearly half the 16000) or is there an issue with the Tattu that I may be overlooking?15c inadequate?
Batts weigh 1950g and 1650(pair).
Can I run to a much lower voltage with the Tattu as 3.7v occurs at 35% remaining compared to 20% with the Haiyins.
Help appreciated

 

[Benjamin Kenobi]

It's the difference between sharing the load between two lipos or just one. I would always recommend using a dual lipo setup. Each lipo is then being used at a fraction of it's peak discharge which should increase it's lifespan.

 

[rupP]

Yes, I appreciate dual batts make a lot of sense and for a variety of reasons, I'm just a bit surprised at the extent that two 5000 batts outperform the 16000. Wondering why too.... So I'm comparing 16000@15c with 10000@80c
Are there any disadvantages to running way higher"c" rating than required? Other than weight/cost.

 

[Benjamin Kenobi]

Going back to your original post. I think your cutoff (3.7V) is too high. You will always get voltage drop under load, with a single lipo the drop will be more.

The 20% rule applies to the amount of mah you put back in. The best way to determine that you are using your lipos to the fullest is simply to measure the mah you put back in on the charger and adjust your voltage cutoff accordingly. For your 16000 lipos you should be putting back in 12800mah.

Ideally you want the lipos back up to 3.7v per cell 15 minutes after a flight. In-flight you can go down to 3.5V if you like.

 

[rupP]

Interesting.
Being new to this game I'm probably being over cautious, I think I'll get more 5000 batteries to run as pairs. I can't be doing with watching for different voltages on a variety of batts.
The Tattu has been taking around 10.5ah on each charge. I'm off out to fly it now, I'll keep a closer eye on how the voltage dips under load and run it down to 3.5v.

 

[Benjamin Kenobi]

Well that sounds pretty good. 10.5ah is nearly there. Maybe try 3.6V.

New lipo brands take a while to get an understanding of. Each setup is different so just keep flying and monitoring those batts and you'll work out the sweet spot.

I do recommend a dual lipo setup! Why have everything dependant on just one little lipo connector not failing?

 

[Pumpkinguy]

There are many added benefits of a dual setup. Smaller connectors and main conductors to the PDB. Balance, being able to have your gps puck in the center and a battery on either side vs one battery in the center and the puck and imu offset etc.

 

[John Doecliff]

Seems to me like all of the larger (more expensive) craft tend to use 2 batts in parallel rather than just one. If you are running 2 batts and one of them has a cell failure it won't be a disaster.