Lipo Pack for Gwiz HCX

[a9a1c1]

Hey, just picked up a new Gwiz, and wanted to know about getting a Lipo for it. I have emailed Giwz already for Lipo info and its been about 2 weeks and no response, so I figured Id ask here. I was checking out a few of them and found a few that could fit the bill:

https://hobbyking.com/hobbyking/sto...00mah_3S_35_70C_Lipo_Pack_USA_Warehouse_.html
https://hobbyking.com/hobbyking/sto...180mah_3S_25_40C_Lipo_Pack_US_Warehouse_.html
https://hobbyking.com/hobbyking/sto...50mAh_3S_45_90C_Lipo_Pack_USA_Warehouse_.html


Now Looking at the Gwiz specs it shows only able to go to 7.5v -- 12v for the CPU and 7.5v -- 15v for the pyro chanel. Any recomendations for a 2 battery setup and a 1 battery setup beyond what I found?

 

[tsai]

I think any of those will work.

The first one is BIG. I have those for some helicopters. If you need something that will power your electronics for an entire week, though, it will do the job.

The second is just fine. I use 180mah batteries on one of my alts. Since I replace batteries every flight, these are more than sufficient. The 20C discharge rate may seem low, but that's still 3.6A or so, which should be plenty for e-matches.

The third just falls in between the two.

The only concern I would have is that the 11.1v is actually 12.6v at full charge. (Lipos are 3.7v nominal, 4.2v full per cell)

Any of these would be sufficient for a single battery setup with the HCX.

Hey, just picked up a new Gwiz, and wanted to know about getting a Lipo for it. I have emailed Giwz already for Lipo info and its been about 2 weeks and no response, so I figured Id ask here. I was checking out a few of them and found a few that could fit the bill:

https://hobbyking.com/hobbyking/sto...00mah_3S_35_70C_Lipo_Pack_USA_Warehouse_.html
https://hobbyking.com/hobbyking/sto...180mah_3S_25_40C_Lipo_Pack_US_Warehouse_.html
https://hobbyking.com/hobbyking/sto...50mAh_3S_45_90C_Lipo_Pack_USA_Warehouse_.html


Now Looking at the Gwiz specs it shows only able to go to 7.5v -- 12v for the CPU and 7.5v -- 15v for the pyro chanel. Any recomendations for a 2 battery setup and a 1 battery setup beyond what I found?

 

[bobkrech]

The 180 maH 3s battery pack is the proper choice for both single and dual battery setups.

This altimeter draws 65 ma, so you have just under 3 hours of run time on the 180 maH battery pack. Most altimeters draw less than 10 ma and would run all day on a 180 maH battery pack, but this altimeter will not, so make sure you have spare fully charged battery packs when you launch as you will have to swap out the batteries several times a day if you have any substantial pad time.

The maximum allowable FET current is 8 amps (or 7 amps). The cell is rated a 40 C burst (5 second pulse) so 0.18 amps x 40 = 7.2 amps is fine and just under the max current you want to provide so you won't blow the FET an a short. A higher capacity battery pack is not recommended as it could supply more than 8 amps on a short and destroy the pyro FETs.

Bob

 

[Adrian A]

The 180 maH 3s battery pack is the proper choice for both single and dual battery setups.

This altimeter draws 65 ma, so you have just under 3 hours of run time on the 180 maH battery pack. Most altimeters draw less than 10 ma and would run all day on a 180 maH battery pack, but this altimeter will not, so make sure you have spare fully charged battery packs when you launch as you will have to swap out the batteries several times a day if you have any substantial pad time.

The maximum allowable FET current is 8 amps (or 7 amps). The cell is rated a 40 C burst (5 second pulse) so 0.18 amps x 40 = 7.2 amps is fine and just under the max current you want to provide so you won't blow the FET an a short. A higher capacity battery pack is not recommended as it could supply more than 8 amps on a short and destroy the pyro FETs.

Bob

Just a reminder that the current described by a lipo battery C rating, even in burst mode, is generally significantly lower than the current that would be produced in a short circuit. I would be surprised if the 180 mAhr, 3-series pack described above would feed a hard short with less than 15-20 Amps. The 130mAhr, 10C battery cell I use with the Featherweight products has a short-circuit current of about 8-10 Amps. If you're using it with a regular ematch and deployment charge, you're not likely to get a hard short that could damage an output FET. But if you're doing an airstart, the hot plasma inside the motor after ignition is a great conductor and hard shorts are common. If you do damage a FET from overcurrent, what typically happens is that it will be stuck always-on after the event, so always check the health of FETs used for airstarts before you connect them to something dangerous, particularly another motor.

 

[a9a1c1]

Ok so If I go with a lower burst 30c and under (keeping the amps below 8) I should be fine. I do see needing a battery that will run for more then 3 hours on a min diameter bird, since I do not have a gps unit yet and just RFD. So I guess having 2 batteries per flight would help, one for the Pyro channel and one for the CPU channel, should ensure longer run times. If I stick with 180maH packs.

I did some more digging and found these:
450maH pack at a max of 6.75A total, so it might be good too. Just below it they have a 350maH pack for a max of 5A. So they might give a longer run time. Not sure if they have protection circuit installed to limit them.

https://home.comcast.net/~truerc/ready_pack/readypack.htm#450mAh Not sure they are decent since ive never heard of them before.

 

[bobkrech]

No. That's not what Adrian is saying.

What the battery pack is rated for, and what it will put out on a short, are 2 different things. The ratings are for what the battery pack will source without anly significant voltage drop. It is possible to draw significantly more than the burst current rating on short, which I also alluded to, but you are somewhat restricted to what LiPo you can use since the G-Wiz is designed to be powered by 9 volt alkaline batteries which self limit to 5 amps, and not LiPos. You definitely do not want to go any larger capacity than 185 maH with the LiPos. You can get external current limiters, but that adds to the complexity, and will confuse someone who is new to LiPo batteries.

Bob

 

[a9a1c1]

Great, thanks. I haven't worked much with lipos and will stay within your recommendations for the lipos for flights. To test them Ill start with one lipo for the Pyro channel and a 9v for the CPU to make sure there are no issue for the first flight as a backup to my rrc2/rrc3 (if it come up for sale when I need to fly). Then Try just one for both the CPU and pyro. If all goes well hopefully ditch the 9v, and retire my rrc2/lc 800 for the rrc3/hcx.