Dx7 Battery lasts 30mins

[elcarter1]

I've had my Dx7 for a while and I've got the feeling somethings wrong. I'm getting around 20-25mins before my battery low warning comes on from a full charge.
It's the 1500mah 9.6 volt pack and charges a few volts above 9.6 but rapidly drops.

So fist question is this normal? If not can I do anything to fix it or do I take it in to get replaced?

Thanks for any help.

[CompuFoil]

It should charge up to around 11 volts if I remember.
Eric

[Raydee]

Sounds like either the charger isn't working right or the batt is bad. Try a different charger and see if that does the trick. My DX7 Battery seems to work forever.

[0636]

DX7 has 1500mAh battery. It suppose to work at least 6 hours on full charge.

How do you charge it? With new stock 110mA charger?

Try to cycle it. Discharge it below 8V and then charge it with 110mA for 20 hours. Then repeat it couple more times.
If this cycling does not give you more time then your battery is bad.

[derekschultz]

Just an idea about your battery issues. not sure if you figured it out yet or not but maybe this will help. i read this on spektrums website

DX7 Charger Update
Wednesday, February 21, 2007

The Spektrum team realizes that the charger included in the DX7 is not optimal for charging the Tx battery in a convenient, overnight fashion. Although the current charger works adequately with additional charge time, future production will include the higher rate charger as referenced in the instruction manual. If you intend to use the 50mah charger, please increase the charge time to 30hrs for the Tx and 22hrs for the Rx.

My battery last for a really long time. somewhere around 8 hrs and it fully charges over night. i would look into your charger and make sure its not the older one. the output ratings on mine are 11.6 @ 110mA for the TX.
good luck

[elcarter1]

Thank you for the info guys, looks like I might have the old charger it's 11.6v at 60mA.
So do I just make up a charge lead and charge it on my swallow charger?
Or if i put this thing on charge for about a week non-stop it will eventually get there?

I reckon they should replace my charger if this things not able to get my tx charged then I figure that warrants a replacement.

[derekschultz]

if your swallow charger is a peak detection type i would use that. your batt will last a lot longer if its properly maintained. its pretty hard to tell whats going on with these wall chargers.

[elcarter1]

Gave it a cycle in the swallow, mis calculated the charge amprage and she got a little hot but charged alot better than that wall charger. I've cycled it twice now last time with a few less amps and she's taking a few more Mah each time she took 1100 last time so I think i'll just keep cycling it a few more times.

Unfortunately the weather down here's been crap so haven't had a chance to test it but i have worked out for some reason having the battery plugged in to the tx draws on the battery so I now disconnect it while not in use.

Can someone explain to me what C/10 actually means. I took that C = Mah so i charged my 1500Mah at 1.5A. I believe i made 2 mistakes first C is the rating of a battery not the Mah and second if you divide 1500mah by 10 you get .150 not 1.50. Please correct my stupidness :)

My overall conclusion is that the "old" charger is rat shit and can probably only be used as a trickle charger if you leave the battery connected to the Tx once you've manually charged it. Not to mention being able to break the battery in with the old charger would probably be impossible and take forever.

I hope I'm the last guy that gets sold the crap charger but I brought mine 2 months ago?
Thanks for you guys help without it I would still be at a loss.

[vetterick]

I too have the "crap charger", it works fine if you don't go much below 10V, it will charge up again overnight.

[Libelle]

I think I have a bad pack too!

My pack holds up to 5 hours but when charging with my delta peak charger at 300mA the 1500mA pack swallows more than 2500mA and does not atomatically switch off :confused:.
When I manually stop charging the V indicator on the DX7 shows that the battery is not full charged ???

The pack gets warm (not hot) after 1500mA are loaded.

I also tried first uncharging under 8V and then charging but the charger never stopps automatically.

The charger is OK because it stopps on other packs when charged.

Do you think my battery back is bad?

Thanks
Martin

[elcarter1]

Your not going to get much over 11.2 volts so the bar on your tx wont show full, unless you go for a larger battery.

Your getting 4 hrs more out of my battery at the moment so I cant really say if your's is bad. I am concerned that your able to put more than 1500mah into it and it's getting hot at 300ma charge rate. Mines cool at 600mah.

I found cycling my battery down to 4 volts and then back up helped it but i don't recommend you do it that low cause I'm just experimenting.

I also got in contact with horizon hobby's product support and they were trying to be helpful but not with the information i asked from them.

For some reason they wont give me the average time the battery should last only that after the initial 33hrs charge a subsequent overnight charge should be enough for a days flying.

They just wanted me to send the battery and charger in to test it. Which leaves me without a battery :( even if it does only last a hour or so now it's better than not being able to fly,

[0636]

NiMH battery usually charged by 0.1C for 15 hours.
In case of DX7 1500mAh battery that would be 150 mA for 15 hours which gives us 2250 mAh. You have to top off NiMH battery for 150%.

With 300 mA you should charge it for 7.5 hours. Timing charge for NiMH is most reliable way of charging. There are other two methods how to determine if it full by rising temperature and/or by monitoring delta V. But if you will charge it with 300 mAh for 7 hours, there is nothing to worry about.

Fully discharged battery should read around 8V (1V per cell). Fully charged around 11.2V (1.4V per cell).
DX7 voltage bar is calibrated for something like 12.6V to show full so it's Ok to see it at 80%.

[0636]

If it's cold that means you did not give it full charge. At the end of charge NiMH will get warm/hot because of the nature of this chemistry.

At 0.5C you have to put a bit more then 150% of capacity and battery definitely will get hot at the end.


I am concerned that your able to put more than 1500mah into it and it's getting hot at 300ma charge rate. Mines cool at 600mah.

[elcarter1]

Thanks for the info guys, like i said I'm just stabbing in the dark with this one. it may seem my battery's the borked one not yours lol.