What batteries am I supposed to get to and what happens if I don't sign up for batch 2?


#1

Hi!

Looking to sign up for Batch 2 but have some question,
What batteries should I get?

And what If I don’t sign up for batch 2 (Weather here is awful for a few more weeks…), How long will take until Batch 3 is ready?

Thanks!"


#2

Batch 2 won’t be shipping out right away so you should be ok with batch 2. As far as recommended batteries go a good cheaper option is the

I also like these, they’re another good option
http://www.bonkapower.com/a/Multicopter/20150825/11.html

Any 10c or the more 6s battery will work.


#3

How many can I use?
Is it just plug and play or do I need to modify the batteries to place them somewhere?
Do I need a special connector for multiple batteries?
Can I use 10 batteries at once and what flight time would that give me (How many did you test to get the ~40min)?


#4

HobbyKing out of stock! :frowning:

If we were to try source elsewhere, what’s the key criteria we should make sure it has? These names/numbers/symbols mean nothing to me!


#5

Disclaimer: I’m human, I make mistakes. Make sure you fact check with others before making purchases based on this post. Anyone reading this who already knows all of this: please consider reading through this post to fact check me. We really should have a go-to guide for this.

You can buy the Multistar online from other vendors, but it looks like we’re quickly buying up the available online stock, so here’s an example of how to look up alternatives.

First I go to HobbyKing, because it’s a good site for this kind of thing. Then I search for Lithium Batteries because they’re light, cheap, and energy dense. I filter my search by selecting 6 Cells. Finally I filter for only batteries above a 10 ampere-hour capacity, with a discharge rate of at least 10C. Here’s one of the batteries that I like:

Turnigy Graphene Professional 12000mAh 6S15C LiPo Pack w/ XT90

How do I know that it will work?

  1. It uses the XT-90 connector, which is what OpenPPG uses.
  2. It can output enough current for our needs. 12 ampere-hour capacity multiplied by the 15 “C” rating equals a maximum output current of 180 amperes. So with two of these batteries you should have enough output current (360 amperes) to run OpenPPG at max throttle (300 amperes).
  3. It’s also a “6s LiPo” battery. That means that it has 6 cells. Since LiPo batteries normally give out around 3.7 volts, that means a 6 cell battery provides around 22.2 volts normally. That’s what OpenPPG takes in, so that’s what will work.

Pros: They’re more energy dense. They provide 8.333Ah/kg, better than the 7.453Ah/kg density of the Multistar. They also claim to be able to handle more cycles than the Multistar as well.
Cons: They are lighter and have only 75% of the capacity of the Multistar. So you’ll either have a shorter flight time, or would need to put on more batteries. They’re also more expensive.

Here’s a good battery charger that will charge LiPos with any number of cells.


How about 18650 Li-Ion battery pack over the Li-Po packs?
#7

Could I mix 4 of these graphene batteries with 4 of the Multistar lipo batteries?


#8

No way! We’re running LiPo batteries in parallel. When LiPos are plugged in in parallel they have to be at the same or a similar voltage, otherwise they can catch fire. Since the Multistar and graphene batteries have different capacities, one will discharge faster than the other, causing a large difference in voltage, and potentially causing a fire toward the end of your flight.

Don’t mix batteries. Don’t use batteries at different levels of charge.


#9

[edit: I’ll make a new post]


#10

Based on the 51 lbs with bigger battery, that’s 30lbs of batteries.

Multistar:
16 Ah, 6S, 2.044 kg

The closest estimate is 6 which would weigh 27 lbs.

16Ah * 6S * 3.7V * 6 Packs = 2.1 kWh

Depending on the amount of power the system demands, you could in theory get 2, 4, 6, 8…as long as you have the room.