Fun, Learning, Friendship and Mutual Respect START  HERE


Unregistered
Go Back   HeliFreak > R/C Electronics Support > JR and Spektrum Radios and Electronics > 2.4G Spektrum Radios


2.4G Spektrum Radios Spektrum 2.4 Gigahertz Radios and Technology


Reply
 
LinkBack Thread Tools Display Modes
Old 07-26-2010, 10:37 PM   #1 (permalink)
Registered Users
 
Posts: 999
 

Join Date: Mar 2010
Default DX7 voltage issues

Recently my DX7 has been displaying different voltages depending on what model I select. After an overnight charge, models 1-8 will show about 11.2 volts. Models 9-20 show 8.4 - 8.7. If I power on the radio with any model in the 9-20 range selected, I get the low voltage alarm.

At the moment, only model spots 1-8 have anything bound to them. I had 2 helis on 9 & 10, but after this problem cropped up I moved everything to spots 1-8 to see if anything changed. I have an e-mail into Horizon, but thought I would ask here as well.

Does anyone know why the displayed voltage would vary so much?

Last edited by GT86; 07-27-2010 at 01:13 PM..
GT86 is offline        Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 07-27-2010, 12:58 PM   #2 (permalink)
Registered Users
 

Join Date: Sep 2008
Default

Hmmm....

I've heard of this exact problem before but don't remeber the solution exactly, I'm thinking it's a bad tx battery.

Horizon is kind of slow on e-mail response, suggest you call 'em and expect to be on hold for a bit, or if you leave a call back number which is what I usually do, they're really good about calling you back in a relatively short period of time.
zeb29 is offline        Reply With Quote Quick reply to this message
Old 07-28-2010, 06:15 AM   #3 (permalink)
Registered Users
 
Posts: 1,079
 

Join Date: Jul 2009
Default

My recollection was that there was a difference in Tx current drain between DSM & DSM2 modes resulting in a lower operating voltage being displayed. Here it seems the difference is between assigned and unassigned model memory locations so it is likely the same issue.
N017RW is offline        Reply With Quote Quick reply to this message
Old 07-28-2010, 09:41 AM   #4 (permalink)
Registered Users
 

Join Date: Sep 2008
Default

Quote:
Originally Posted by N017RW View Post
My recollection was that there was a difference in Tx current drain between DSM & DSM2 modes resulting in a lower operating voltage being displayed. Here it seems the difference is between assigned and unassigned model memory locations so it is likely the same issue.
Ah yessss!

You've come to the rescue of my failing memory again....

Guys had both types of models and yes the DSM mode uses a bunch more battery power than the DSM2 resulting in a lower tx battery voltage showing. Not sure if that's the OP's problem, but that is the one I was thinking about.
zeb29 is offline        Reply With Quote Quick reply to this message
Old 03-19-2011, 08:46 PM   #5 (permalink)
Registered Users
 

Join Date: Feb 2010
Default

I'm having the same problem. Is it because of the Tx batt?

I thought that the DX7 is a DSM2 transmitter. I am not sure that you are able to switch between DSM and DSM2. Does anyone have any ideas?
abacus is offline        Reply With Quote Quick reply to this message
Old 03-20-2011, 01:49 AM   #6 (permalink)
Registered Users
 
Posts: 4,545
 

Join Date: Jun 2008
Default

The radio will automatically switch to the appropriate mode when binding.When you select a blank memory slot the radio is by default in DSM thus the higher curent draw on the battery and associated lower voltage.But if you are in DSM and its pulling a fairly well charged pack down to the alarm voltage I would say that the pack is weak,has a bad cell or possibly the connector where it plugs into the radio is dirty.The increased current draw of DSM may make it discharge faster or show a slightly lower voltage from DSM2 but should not be enough to pull the voltage down far enough to trigger LV alarm so soon.
__________________
Too many helis & Too many planks
Lots of DX radios & A couple Futaba 72mhz radios
AMA member & Full scale plank driver
HELIFREAK !!!
aerocal is offline        Reply With Quote Quick reply to this message
Old 03-20-2011, 08:04 PM   #7 (permalink)
Registered Users
 
Posts: 999
Thread Starter Thread Starter
 

Join Date: Mar 2010
Default

My problem turned out to be a weak tx battery pack.
GT86 is offline        Reply With Quote Quick reply to this message
Old 03-20-2011, 08:16 PM   #8 (permalink)
Registered Users
 

Join Date: Feb 2010
Default

My tx pack is pretty old... Do you know of any good source for a replacement? Spektrum stock 1500mah NiMH are $30. A little too expensive if you ask me.
abacus is offline        Reply With Quote Quick reply to this message
Old 03-20-2011, 09:49 PM   #9 (permalink)
Registered Users
 
Posts: 4,545
 

Join Date: Jun 2008
Default

Buy cheap and you will get cheap though.
I build all of my own packs.For almost a year now Ive been using 2000mah Sanyo eneloop cells.They are 3 bucks a piece.A little less if you buy a quanity of them but they still arent cheap.2 bucks for the lead unless you reuse the old one.And 25 cents for the shrinkwrap.So it costs me 26-27 bucks to build an 8 cell Tx pack.My LHS has some Eneloop Tx packs for I think its 32 bucks.Im pretty sure they come from Cermark.Im sold on the Eneloop(LSD) type cells.They may not be cheap but in the case of cells you do get what you pay for.Plus if you put them away for 6 months or more they will have pretty much the same charge as when you stored them.They do last alot longer than cells that will self discharge in storage.
Letting them sit and go dead doesnt completely kill a NiMh like it would a LiPo but it does take the life out of them.I havent used them long enough to say for certain but Sanyo claims 5 good years and 1000 cycles.Ive found that others last 2 or 3 years tops and they are getting wimpy.
__________________
Too many helis & Too many planks
Lots of DX radios & A couple Futaba 72mhz radios
AMA member & Full scale plank driver
HELIFREAK !!!
aerocal is offline        Reply With Quote Quick reply to this message
Old 03-20-2011, 09:56 PM   #10 (permalink)
Registered Users
 
Posts: 999
Thread Starter Thread Starter
 

Join Date: Mar 2010
Default

I bought a replacement pack that used Sanyo Eneloops instead. Easier than going with a lipo, and the charge lasts a lot longer than the stock one. You can still use the wall-wart charger, and you don't have to modify anything in the tx.

I forget where I got it, but you can also just buy the Eneloops, then pick up an 8-cell AA size battery holder at Radio Shack and solder on the plug.
GT86 is offline        Reply With Quote Quick reply to this message
Old 03-20-2011, 10:36 PM   #11 (permalink)
Registered Users
 
Posts: 4,545
 

Join Date: Jun 2008
Default

Quote:
Originally Posted by GT86 View Post
I bought a replacement pack that used Sanyo Eneloops instead. Easier than going with a lipo, and the charge lasts a lot longer than the stock one. You can still use the wall-wart charger, and you don't have to modify anything in the tx.

I forget where I got it, but you can also just buy the Eneloops, then pick up an 8-cell AA size battery holder at Radio Shack and solder on the plug.
Good move.I prefer them over LiPos anyday.You wont be disappointed.
Im not a big fan of the spring clip type battery holders.Every one of the contacts is a point of failure.Plus if you bump them in the right direction the cells can move towards and compress the spring allowing loss of contact on the other end.For something that important I would always opt for soldered or hard connected cells.
__________________
Too many helis & Too many planks
Lots of DX radios & A couple Futaba 72mhz radios
AMA member & Full scale plank driver
HELIFREAK !!!
aerocal is offline        Reply With Quote Quick reply to this message
Old 03-20-2011, 10:41 PM   #12 (permalink)
Registered Users
 

Join Date: Feb 2010
Default

Thanks guys, Eneloop sounds good, I'll go that route.
abacus is offline        Reply With Quote Quick reply to this message
Reply




Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the HeliFreak forums, you must first register.
Please enter your desired user name, your REAL and WORKING email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself. Use a real email address or you will not be granted access to the site. Thank you.
Email Address:
Location
Where do you live? ie: Country, State, City or General Geographic Location please.
Name and Lastname
Enter name and last name here. (This information is not shown to the general public. Optional)
Helicopter #1
Enter Helicopter #1 type and equipment.
Helicopter #2
Enter Helicopter #2 type and equipment.
Helicopter #3
Enter Helicopter #3 type and equipment.
Helicopter #4
Enter Helicopter #4 type and equipment.

Log-in


Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On




Copyright © Website Acquisitions Inc. All rights reserved.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.

SEO by vBSEO 3.6.1