Multirotor, multicopter and quadcopter discussion - The Drone thread

Tackle_Berry · 16 Jan 2015 at 14:08

I got an idea from someone on RC Groups, instead of discharging batteries through the charger which usually takes over an hour as most are limited to a 5w drain also doing it through a charger puts more wear and tear on it.

Anyway he suggested using a 12v device to quickly discharge a battery I ended up going for 55w headlight bulbs. I can now drain a battery in minutes if it rains or for whatever reason I can't fly and need to store them. Just to mention they get hot so I either put them on a glass dish or do it outside on the slabs.

*EDIT* after testing it took 8min 20sec to drain a 1500mah down to 50%, now thinking about soldering both bulbs to one XT60.

DJMK4 · 16 Jan 2015 at 14:14

Useful idea, is there any negative effects caused by discharging batteries quickly, as opposed to discharging them at a slower rate?

howler · 16 Jan 2015 at 14:14

We used to do that back in my RC car racing days. They were obviously NiCad batteries back then though

howler · 16 Jan 2015 at 14:16

DJMK4 said:
Useful idea, is there any negative effects caused by discharging batteries quickly, as opposed to discharging them at a slower rate?

I can't imagine that you'd discharge them anywhere close to the speed you would if you were flying

Tackle_Berry · 16 Jan 2015 at 14:16

DJMK4 said:
Useful idea, is there any negative effects caused by discharging batteries quickly, as opposed to discharging them at a slower rate?

I don't think so as long as they are balanced charged and also not drained too much.

There is a discharger sold in the US which does it at 150w I think it's made by Emax but they don't ship that's why I went with this.

Tackle_Berry · 16 Jan 2015 at 14:17

howler said:
I can't imagine that you'd discharge them anywhere close to the speed you would if you were flying

No but then you would just fly this is if you charge them up for a flying and then can't and need to store them.

I just done a quick test, it took 8min 20sec to drain 50% of a fully charged 1500mah (thinking I might solder two bulbs to one XT60)

Col_M · 16 Jan 2015 at 14:47

Just a bit of advice, put a suitable inline fuse as close to the XT60 as possible on the positive lead.

The exposed spade connectors are asking for something to short them out.

5A should be fine (55/12.6 = 4.37A)

edit: nope, ignore that, when the voltage drops the current will increase so go for ~6A or just a bit over.

Russinating · 16 Jan 2015 at 14:51

Worth nothing you should be storing LiPos at around 60% charge, not empty.

Tackle_Berry · 16 Jan 2015 at 14:55

Russinating said:
Worth nothing you should be storing LiPos at around 60% charge, not empty.

Thanks I know that, but worth mentioning for anyone that doesn't that might use it.

Col_M said:
Just a bit of advice, put a suitable inline fuse as close to the XT60 as possible on the positive lead.

The exposed spade connectors are asking for something to short them out.

5A should be fine (55/12.6 = 4.37A)

edit: nope, ignore that, when the voltage drops the current will increase so go for ~6A or just a bit over.

Thanks, I was just going to tape them but might do that.

Russinating · 16 Jan 2015 at 14:56

*thumbs up*

booyaka · 16 Jan 2015 at 16:06

When people talk about "storing" - how long do you mean.

I charged my 4s's last weekend hoping to fly but high winds etc means no flying - hopefully get out this weekend but what is the "storing" time?? How long can I leave them fully charged?

Tackle_Berry · 16 Jan 2015 at 16:24

I personally only leave a battery fully charged for 3 days max.

booyaka · 16 Jan 2015 at 16:33

Ash2097 said:
I personally only leave a battery fully charged for 3 days max.

really??

Rilot · 16 Jan 2015 at 16:53

I leave it a week on occasion but usually when I get back from flying I discharge any batteries to a storage charge as soon as I get home.

Genoma · 16 Jan 2015 at 17:19

Ash2097 said:
I got an idea from someone on RC Groups, instead of discharging batteries through the charger which usually takes over an hour as most are limited to a 5w drain also doing it through a charger puts more wear and tear on it.

Anyway he suggested using a 12v device to quickly discharge a battery I ended up going for 55w headlight bulbs. I can now drain a battery in minutes if it rains or for whatever reason I can't fly and need to store them. Just to mention they get hot so I either put them on a glass dish or do it outside on the slabs.

*EDIT* after testing it took 8min 20sec to drain a 1500mah down to 50%, now thinking about soldering both bulbs to one XT60.

Good idea, but I will probably forget something like that on and take the battery down to the point of no return

Already happened with a couple of zippy's in my Tx after forgetting the Tx on by mistake they had to go to the LiPo cemetery.

opstrat · 16 Jan 2015 at 17:54

does no one do the storage charge option on their chargers?

Flukester · 16 Jan 2015 at 18:03

I used to leave my old Phantom batterys fully charged, but after a year they had lost a good 20-30% capacity. I think I remember reading they lose 20% or so a year if full.

I always storage charge now... only down side is I can never just go out flying, have to plan ahead, and if I don't get around to flying I have to discharge them all again which is painful on my current charger as so slow.

A fully charged lipo is under a lot of chemical 'stress'... which is why you never buy a lipo with 100% in it generally.

I might invest in a quick method like the bulbs mentioned here, or some kind of nicely cooled power resistor of some kind

edit: thinking about this more, with Lipos getting so cheap... you could just leave full charge, get a season out of them then buy new for next season

Flukester · 16 Jan 2015 at 18:08

Nearly dropped £270 on a 250 quad today but resisted. Found a lovely little OSD for it..

http://www.ebay.co.uk/itm/RC-Mini-OSD-System-GPS-Module-for-FPV-Transmitter-Camera-Fatshark-Quad-Hex-UK-/331138225495?pt=UK_ToysGames_RadioControlled_JN&hash=item4d19605557

EMAX Nighthawk 250 CF 103.33 FPV
(12A SimonK Escs, 6030 CF Props, 2204 Motors, CC3D FC)
Strobon Nav Light 8.32 FPV
Mini OSD with GPS (voltage / GPS / height / speed / RSSI etc) 29.99 EBAY
700TVL Mini FPV Camera W/1/3"CMOS SUPER HAD CCD II CCTV FPV Camera 2.1mm Len 11.85 EBAY
Power Dist Board 5.75 EBAY
ImmersionRC Fatshark 600mW 5.8GHz TX (using 250mw from F550) 55.79 QUADCOPTERS
ZIPPY Compact 1500mAh 3S 25C Lipo Pack * 2 13.46 HK
XT60s / Wire 3.48 HK
Frsky X8R 24.83 T9
Gemfan 5030 Props 9.95 EBAY
Servo Leads 4.49 EBAY

TOTAL 271.24

Tackle_Berry · 16 Jan 2015 at 18:20

opstrat said:
does no one do the storage charge option on their chargers?

My typical cycle is balance charge to 100, fly down to 3.75 per cell (11% roughly) and then use the storage charge feature to store them at 60%.

When I charge up then can't fly I take the full charged battery and just drain it with the bulbs to 60% for storage and then when I need them I will balance charge.

Lisapete · 16 Jan 2015 at 21:37

ImmersionRC 5.8GHz Circular Polarized SpiroNet Antenna V2's arrived today. Looks the part I think.

Going to try a directly line of sight test see how far I can go off my GoPro Hero 3 Black. Have a 4 mile stretch of road