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Midland Helicopters . HeliProz . ZoomsHobbies

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e-Electric Batteries & Chargers > Low run time batteries
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

Why can't I discharge my Batteries any farther than3.85 Volts? Here's my setup.

HDX450 with

JGF400DH on a 9t pinion
Align 25A ESC
2250 3s 20C G-Force lipos and
ABF 2100 3S 20C Lipos

I can fly just fine for about 3-4 minutes and then my power drops off suddenly and I can't spin up enough to lift off.
I'm not sure of the battery setting on the ESC but would that make that much of a difference? Nothing "feels" hot. Not the motor, ESC or battery. When I check the voltage left in the battery, I'm showing 3.85-3.88 volts. When I charge the batteries, they're showing 4.18-4.21 volts.

I'd think it was the cheap batteries but it's two different brands and I also tried a JGF450TH motor with the same results. Also changed out the ESC to a CC 25A.

Any ideas?

Thanks
Tag
09-13-2008 12:37 AM
 
 
dave75d
Veteran
Location: Jacksonville, FL

when you set up your esc, what voltage cutoff did you set? probably high. may need to reprogram.

ten grand in helis and all i can do is hover
09-13-2008 12:47 AM
 
 
Heli 770
Elite Veteran
Location: Lemon Grove, Ca. USA.

I think your batt packs are bad. Even if it shows full voltage that does not mean you have full capacity in the packs.
09-13-2008 12:48 AM
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

Is that the battery protection mode? What should I set that to? I think it might be set to 70%.
09-13-2008 12:52 AM
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

Im replacing less that 1000MaH when I recharge them. Could they still be bad? I would think if they were bad, I would be putting a lot more in them when I re-charge them, wouldn't I?

Plus these are all new batteries. about ten cycles each on all of them.
09-13-2008 12:54 AM
 
 
Heli 770
Elite Veteran
Location: Lemon Grove, Ca. USA.

If your putting 1amp back in all the time. that means your batt is only giving you 1amp all the time.
09-13-2008 12:58 AM
 
 
dave75d
Veteran
Location: Jacksonville, FL

yeah, battery protection. esc will also limit the amount of discharge the battery allows. double check that too, as you may have bad batts also.

ten grand in helis and all i can do is hover
09-13-2008 01:03 AM
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

I'm not sure that I'm following you on that. Are you saying the true capacity of all of the packs are only about 1000-1300. Remember, I said that I am using two different brands of batteries ( 4 batteries all together). That's one reason I can't "believe" that it's my packs. I never rule out anything but again, it's two different brands.
09-13-2008 01:04 AM
 
 
dave75d
Veteran
Location: Jacksonville, FL

id start with the esc. double check, or reprogram to make sure, use mid level cutoff protection. thats mid stick on the last beep i think.

ten grand in helis and all i can do is hover
09-13-2008 01:06 AM
 
 
Heli 770
Elite Veteran
Location: Lemon Grove, Ca. USA.

Tag1260
Ok, you have two batt packs. 2100mah and 2250mah and you say when you charge them they only take about 1000mah on the recharge, Right?
09-13-2008 01:12 AM
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

Yes. I'm only putting about 1000 Mah in them when I re-charge them. I have used two different chargers to try to check to see if my charger could be bad.
09-13-2008 01:19 AM
 
 
Heli 770
Elite Veteran
Location: Lemon Grove, Ca. USA.

Tag1260
Try the other charger.
09-13-2008 01:23 AM
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

Already tried it with the same results. THis has got me baffled as I'm not an electronic genius by no means (Of course it's been said "I'm about a real rocket scientist"!! LOL.) Could I need to try a bigger pinion gear? I'm reading up right now about some sort of thermal protection that shuts down the ESC at 80 degrees C. Maybe my ESC "IS" getting too hot and shutting down.
09-13-2008 01:27 AM
 
 
Heli 770
Elite Veteran
Location: Lemon Grove, Ca. USA.

The Esc has nothing to do with your batt being charged. When you first got the packs, were you only discharging them to 80% before recharging?
09-13-2008 01:34 AM
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

NO because I've been having this problem from day one, so I've only been discharging them about 50%.
09-13-2008 01:42 AM
 
 
Heli 770
Elite Veteran
Location: Lemon Grove, Ca. USA.

I hate to say this but you should have return them that day.
09-13-2008 01:46 AM
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

OK. Might be my ESC. I just spun it up until it shut down and Used a temp gun on it. I'm running about 150 degrees F . I'm going to let it all cool down and try it again without charging the Battery. If it runs up ok, I'll try to find a 35A ESC and see if it runs any cooler and any longer.
09-13-2008 02:35 AM
 
 
fenderstrat
Elite Veteran
Location: Aston,Pa

anything over the 140 deg F area is bad news,and really 120-130 is the most you ever want to see,either the esc is dying or the set up needs fine tuning but either way thats much too hot,especially if you just spun it up to see temps and there was a light load on it

PerformancePlusRC field rep
COMPASS helis field rep
Mini Titan/SE
HBK2
Futaba FASST
09-13-2008 02:12 PM
 
 
Tag1260
Senior Heliman
Location: Eastern Ohio USA

OK. Ran it up and it looks like what I have is thermal and not the batteries. I also read up on thermal shutdown and it appears that my problem might be the JGF400dh motor. It likes a high throttle curve
(0,50,85,85,100)or it overheats the ESC . I can't do this TC change with the radio I'm using right now as my Royal EVO is in the shop getting repaired. When it gets back I'll try changing the curve to higher rates and see if that helps.

Thanks
Tag
09-13-2008 03:58 PM
 
 
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e-Electric Batteries & Chargers > Low run time batteries
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