Low battery icon adjustment???
Posted by: farmtech
Low battery icon adjustment??? - 27/03/2006 02:55
Hello,
Just wondering if there was any way to disable or change the low voltage icon threshold? Every time I turn my engine off with the system on the player mutes and the icon shows up within 10 - 15 seconds. It seems to me like the voltage threshold is a little too high. I wish there was a way to disable it completely.
Thanks for any help.
Posted by: matthew_k
Re: Low battery icon adjustment??? - 27/03/2006 03:41
Have you tried a new battery in the car? I've never heard of it behaving like that for anyone. Do you have large amps installed?
Matthew
Posted by: n2toh
Re: Low battery icon adjustment??? - 27/03/2006 04:04
Quote:
Hello,
Just wondering if there was any way to disable or change the low voltage icon threshold? Every time I turn my engine off with the system on the player mutes and the icon shows up within 10 - 15 seconds. It seems to me like the voltage threshold is a little too high. I wish there was a way to disable it completely.
Thanks for any help.
I had a similar problem when I had my empeg installed in my Jeep, in my case the problem was a bad ground connection.
Posted by: Robotic
Re: Low battery icon adjustment??? - 27/03/2006 05:40
I get the battery icon to come up when I'm driving with my headlights on and then step on the brake or switch on the turn signal.
It's annoying, to say the least, but I haven't yet exhausted my possible problem areas- such as grounding issues (as mentioned above).
I also have a nasty 'alternator whine', which usually points directly to grounding issues.
It makes me wonder, though... would a capacitor in the power circuit smooth out such voltage fluctuations?
Posted by: n2toh
Re: Low battery icon adjustment??? - 27/03/2006 06:00
Quote:
I get the battery icon to come up when I'm driving with my headlights on and then step on the brake or switch on the turn signal.
It's annoying, to say the least, but I haven't yet exhausted my possible problem areas- such as grounding issues (as mentioned above).
I also have a nasty 'alternator whine', which usually points directly to grounding issues.
It makes me wonder, though... would a capacitor in the power circuit smooth out such voltage fluctuations?
I should have been more specific before, I cheated when doing my Jeep install and used the grounding bolt for the door switch. I later attached the black wire for the player power to the steel dash sub frame. (as a side note in my VW it has a cool star thing for quick connects in the same basic location as the Jeeps ground bolt for the same thing plus about 20 other things, but without the battery warning issues.) On the subject of alternator whine, I have a strange digital squealing on startup most times that eventualy goes away.
Alternator whine can also be caused by a leaky or bad rectifier diode in the alternator.
Posted by: schofiel
Re: Low battery icon adjustment??? - 27/03/2006 09:15
Errr... a battery, built of many parallel plates with an electrolyte - is effectively a capacitor.
Posted by: schofiel
Re: Low battery icon adjustment??? - 27/03/2006 09:19
I would suspect stuff other than the player:
- is the battery good?
- is the charging system good?
- what is the local temperature?
- what voltage is arriving at the sled through your wiring?
- what is the gauge of the wire (end to end) supplying, and earthing your sled?
- is the gauge of the wire on the sled earth the same or larger than the power feed?
- how many hard disks in your player?
Why does having this icon come on irritate you? It does have a useful function.
Posted by: Roger
Re: Low battery icon adjustment??? - 27/03/2006 09:24
Quote:
I get the battery icon to come up when I'm driving with my headlights on and then step on the brake or switch on the turn signal.
I also get the battery icon when I press the brake pedal. On the other hand, I have to have the A/C, the headlights, the heated front and rear screens and the heater on.
Get a newer battery?
Posted by: farmtech
Re: Low battery icon adjustment??? - 27/03/2006 12:59
Hello,
My install is just fine, I have this in a Chevy Tahoe and it is a 2 year old factory battery. The battery is not great and I think the voltage drops quite a bit when the key is on, engine off. It always starts good so I don't want to buy a new one just yet. The problem that bothers me is the fact the Empeg cuts out for 2-3 seconds before coming back up with the icon. It is kind of like a reboot. I know the Empeg should be able to safely run down to 9 volts or so, that is why I wish I could change the sensitivity level. When I shut my engine off the factory radio and Empeg stay on until I open a door, I love this feature but it always cuts out within 10 seconds of doing so. Sometimes it will do it more than once also.
Posted by: tfabris
Re: Low battery icon adjustment??? - 27/03/2006 14:36
Agreed that Farmtech needs to check and see what's wrong with his car's electrical system, BUT...
I'd still like to know the answer to his specific question: Is the low voltage threshold controlled in the player software or the kernel? Or is it hard-coded into a PIC somewhere?
Posted by: schofiel
Re: Low battery icon adjustment??? - 27/03/2006 15:07
If the battery is older than about 3-4 years, then It May Be Time.
However, first, do the usual - check the connectors are clean and greased, that the cells are topped up (assuming you can). If you have not got one of the no-discharge types, you could try the total discharge trick (H4 bulb wired across the terminals, outside the car, discharge till flat, re-charge). However, not all batteries will allow this. Mike Tempsch is our battery man. Mike?
Posted by: schofiel
Re: Low battery icon adjustment??? - 27/03/2006 15:17
There's an op-amp driving a GPIO pin on the CPU. The actual voltage at which it flips is measured relative to the processor's 3V supply line: this is set to be roughly 3/5 of your car battery voltage.
Assuming your battery is healthy and being charged, it's voltage should be about 14.4V. Off charge, it should be about 12.6V.
Hence, if your engine is off and your battery is good, you should only see the icon come on if the battery is loaded (fan? amplifier?) sufficiently to bring the voltage down to 7.6V. I would say, if you can do that to a battery then either the battery is sick, your wiring between the battery is causing too big a voltage drop or your amp is
TOO B***** BIG 
Posted by: tfabris
Re: Low battery icon adjustment??? - 27/03/2006 16:16
Quote:
There's an op-amp driving a GPIO pin on the CPU. The actual voltage at which it flips is measured relative to the processor's 3V supply line: this is set to be roughly 3/5 of your car battery voltage.
In other words: It's set in hardware and cannot be altered by a software modification. Thanks!
Too bad, but, thanks! 
In my case, I get the battery icon because my amp is too f'ing big. Only when the car is idling and there's lots of bass thumping does the problem occur for me. I had once solved the problem by putting some capacitors on the power line to the empeg. But once when troubleshooting some noise issues, I removed the capacitors so I no longer have that advantage.
Posted by: wfaulk
Re: Low battery icon adjustment??? - 27/03/2006 16:20
I could be wrong, but it seems like capacitors on the amp would solve that problem, too.
Posted by: tfabris
Re: Low battery icon adjustment??? - 27/03/2006 16:56
Quote:
I could be wrong, but it seems like capacitors on the amp would solve that problem, too.
Yeah, but I'd need bigger capacitors for the amp than for the empeg.
Posted by: farmtech
Re: Low battery icon adjustment??? - 27/03/2006 17:04
Is this the same op-amp that senses absolute low voltage and tells the Empeg to write to flash and shut off? I am the guy that had that weird broken resistor problem that did not let my Empeg save on power down. I was losing all my settings when power was removed because that op-amp circuit did not work correctly and was not able to signal the processor upon power loss. This problem seems to me more code related, does the Empeg read battery voltage through an A/D anywhere? I thought the low battery icon was activated in the 10V - 11V range through software? My battery is not the greatest but I know I am well above the 8V range with the key on, probably in the 11V range. I will hook it up to a lab supply tonight and figure out the exact voltage where this "icon" condition occurs.
Posted by: Roger
Re: Low battery icon adjustment??? - 27/03/2006 18:03
Quote:
Is this the same op-amp that senses absolute low voltage and tells the Empeg to write to flash and shut off?
Rob's explained the hardware side; here's how it works in the software:
Every now and then, the player writes the contents of the flash area to kernel space. Rather than write it to flash immediately (which would wear out the flash too quickly), it's cached in kernel space.
When the op-amp sees the voltage drop, it signals the CPU, which prompts the kernel to write this cached data into the real flash device. There's usually enough juice in the on-board capacitors that this succeeds before the power drops out completely. This is why the display is turned off at this point -- it leaves more runtime from the juice in the caps.
In case it doesn't succeed, the block written to the flash has a checksum in it. This means that when the player starts up, it can avoid loading a half-written flash block.
The player cycles through several flash blocks, which means that it can always get a 'last known good' block, even if the last one was corrupt.
If, after flushing to flash memory, the power comes back, and the player is still running, then the player displays the low battery icon. Thus, it's not actually telling you that the voltage is low at that point. It's telling you that the voltage dropped out just now, and you should maybe check your installation.
It doesn't actually tell the empeg to 'shut off'. The power going away is all the 'off' that the player needs.
Posted by: schofiel
Re: Low battery icon adjustment??? - 27/03/2006 19:11
This, and the hardware explanation, really should go into the FAQ. Tony? You up for that?
Posted by: tfabris
Re: Low battery icon adjustment??? - 27/03/2006 20:02
done.
Posted by: wfaulk
Re: Low battery icon adjustment??? - 27/03/2006 20:19
FAQ update ported to Wiki FAQ copy.
Posted by: farmtech
Re: Low battery icon adjustment??? - 28/03/2006 01:01
Guys,
Thanks for the explanations. I thought the op amp that Rob talked about was just for low power dropout set to around 7.6V or so. I checked the output of my op amp and it drives high (thus signaling the processor) at 10.51V or less. At the same time the player resets and then shows the low battery icon. I will now monitor my battery voltage at the sled and see if it is in fact 10.51V I still wish the voltage threshold was less, I may (at my own risk) change the reference voltage divider so the threshold is closer to 10.0V. I'm sure if I had a big new battery this problem would not be as bad though. The player seems to run happily down to less than 7.0V so I would not think the op amp would have to be 10.51V.
Thanks for eveyone's help.
Posted by: altman
Re: Low battery icon adjustment??? - 02/04/2006 13:07
ISTR 10.5v is about what we set it to. It's annoying for me too, as when the Noble's cooling fans (hovercraft impersonators, more like) kick in I get the screen off/etc behaviour.
The switch-mode PSUs in the player running the HDDs, CPU, etc will run down much lower, 7v would be fine. The only issue is that the 9v (?) analogue linear regulators will also drop out - however, these will only cause - at the worst - momentary distortion, not any sort of CPU upset.
You can change the resistive divider split to set the threshold lower if you want - or just disable the behaviour in the kernel (Mark?
)...
Hugo
Posted by: mlord
Re: Low battery icon adjustment??? - 02/04/2006 14:11
Quote:
You can change the resistive divider split to set the threshold lower if you want - or just disable the behaviour in the kernel (Mark? )...
It's just the little battery icon that we're discussing here, right? Not much point in disabling *that* (what would it accomplish?).
Cheers
Posted by: Shonky
Re: Low battery icon adjustment??? - 03/04/2006 06:01
Quote:
Quote:
You can change the resistive divider split to set the threshold lower if you want - or just disable the behaviour in the kernel (Mark? )...
It's just the little battery icon that we're discussing here, right? Not much point in disabling *that* (what would it accomplish?).
Cheers
I assume the player accesses the interface through the kernel. i.e. Hugo is saying if Hijack intercepted it in kernel space, it could easily disable it or at least provide a bit of a delay before it passes it through to the player. A delay would provide a solution to the majority of peoples problems since it's the initial spike that causes the temporary dropout from what I've seen.
Posted by: mlord
Re: Low battery icon adjustment??? - 03/04/2006 09:15
Quote:
Quote:
It's just the little battery icon that we're discussing here, right? Not much point in disabling *that* (what would it accomplish?).
A delay would provide a solution to the majority of peoples problems since it's the initial spike that causes the temporary dropout from what I've seen.
Again, my original question stands.. what would that accomplish, other than not displaying the little battery icon?
Posted by: peter
Re: Low battery icon adjustment??? - 03/04/2006 11:02
Quote:
Again, my original question stands.. what would that accomplish, other than not displaying the little battery icon?
Yeah, quite; the thing that would need changing is the hardware component. Any delay on the software side would stop it working properly in the cases where it does need to happen.
Peter
Posted by: Robotic
Re: Low battery icon adjustment??? - 03/04/2006 20:41
Quote:
Again, my original question stands.. what would that accomplish, other than not displaying the little battery icon?
When the problem occurs for me, the screen goes blank and all sounds stops for a couple of seconds. When the player comes back, the battery icon is displayed.
It's not the icon that's a worry, it's the interruption in the playback.
It's very similar to normal cut-out for radios and accessories during cranking of the motor, for example; just that it occurs with combination of lighter loads (headlight and blinker/brakes).
I've got to sort out a better grounding strategy on my installation, though, and perhaps that will solve my individual problem.
Hmm- maybe my amp is powering down for that interval...?
Posted by: mlord
Re: Low battery icon adjustment??? - 03/04/2006 23:10
Quote:
When the problem occurs for me, the screen goes blank and all sounds stops for a couple of seconds. When the player comes back, the battery icon is displayed.
It's not the icon that's a worry, it's the interruption in the playback.
Well, not much to do about that. The blanking etc.. are quite necessary for proper operation. Go for the hardware tweak instead.
Cheers
Posted by: Roger
Re: Low battery icon adjustment??? - 04/04/2006 07:59
Quote:
Hmm- maybe my amp is powering down for that interval...?
Yes, it is. The amp remote line is directly connected to the empeg display. When the display is turned off, the amp is turned off.
As Mark says, the display/amp off behaviour is the correct behaviour -- otherwise the empeg won't be able to save the flash area when you pull it out.
If you want to adjust the voltage at which it happens, it'll have to be done in hardware.
Posted by: Robotic
Re: Low battery icon adjustment??? - 04/04/2006 12:15
Thanks Mark and Roger!
Posted by: farmtech
Re: Low battery icon adjustment??? - 05/04/2006 13:54
Guys,
I changed the value of the 3.3V reference divider and now the Empeg runs to a lower voltage before it signals the processor. The battery icon was never the problem, just the audio cutting out. It now seems to run down to @ 10.0V or so before reporting low voltage. This will help me greatly. The biggest problem with the op amp signalling circuit is that it has almost no hysteresis, therefore it senses low battery, cuts out, comes back on, then the voltage rises slightly and the icon goes away. Then with a good bass note or even pushing a front panel button the voltage dips again and the condition repeats. So in other words, just listening, the Empeg can cut out several times a minute if the battery is sitting on the 10.5V threshold. With the divider modification it will still cut in and out multiple times but just at a lower overall voltage which will be just fine for me.
Thanks for all the help.
Nick
Posted by: tanstaafl.
Re: Low battery icon adjustment??? - 05/04/2006 14:43
It now seems to run down to @ 10.0V or so before reporting low voltage.
But isn't this along the lines of getting a bigger can to bail out your leaking rowboat, instead of fixing the leak?
There should be no circumstance (except maybe when actually starting the engine) that your voltage drops much below 12 volts. You have a problem in your car's electrical system (specifically in the charging circuit) that you need to address, otherwise you are likely to find yourself stranded with not only a non-functioning empeg, but a non-functioning car.
tanstaafl.
Posted by: schofiel
Re: Low battery icon adjustment??? - 05/04/2006 16:00
I agree, a battery dropping to less than 10.5V under load has lost a cell, or has a high-impedance cell.
I would have thought it more practical to sort out the battery/charging circuit than operate on your empeg
Posted by: tanstaafl.
Re: Low battery icon adjustment??? - 05/04/2006 19:01
I agree, a battery dropping to less than 10.5V under load has lost a cell, or has a high-impedance cell.
Or a slipping alternator belt... or a bad diode in the alternator... or a faulty voltage regulator... or worn/sticking brushes in the alternator... or low fluid [acid] in the battery... or dirty/corroded connections on the battery... or a poorly crimped battery cable... or a bad connection on the ground strap... or excessive sulfation on the battery plates... or... well, you get the idea.
Lots of things it could be, almost all of them easy to find, cheap to fix.
tanstaafl.
Posted by: Robotic
Re: Low battery icon adjustment??? - 05/04/2006 19:41
Quote:
... Lots of things it could be, almost all of them easy to find, cheap to fix.
tanstaafl.
Agreed. In my case, however, I think the first place I have to start looking is the grounding of my empeg and amp. I need a direct line to the negative terminal of the battery instead of going through the sheetmetal. I've been reading in the FAQ about ground loops and refreshing my memory concerning the typical install problems and solutions.
Hopefully that will fix the whine as well as stabilize the voltage seen by the player.
If that doesn't do the trick I would then look at the positive supply from the factory harness- maybe routing something more direct.
After that I'd go looking at charging system issues as you've suggested. The thing is that the car is quite happy and I don't have any reason to suspect the alternator or battery at this time.
Farmtech seems to have found a solution for his problem, but I'm going to go looking around under the hood and dash before I try mods to the player. I've got to start looking tonight- I've got a long drive to Las Vegas this weekend!
Posted by: Robotic
Re: Low battery icon adjustment??? - 06/04/2006 02:15
It seems that the direct ground lead solved the player dropping out. At least that's what 10 minutes of testing shows so far.
I checked the charging system voltage with the motor at various rpm- all nice and happy- so I doubt I've got any alternator or battery problems.
But now the problem is that my ground-loop whine is louder than ever.
Before, I could reduce the whine by pushing on the face of the player (on the bolt heads - don't hate me). Now there is no 'wiggle solution'. Can't say why pushing used to help.
I tried holding my new negative terminal lead onto the sled and empeg housing- it did alleviate the whine by about 80%. I'll have to find a screw to fit that threaded hole at the back of the sled.
If I can't find a screw or that doesn't solve the whine I'll have to re-install my old head unit for entertainment on the drive. Out would come the empeg for now.
Feel my pain.
Grrr.
Posted by: schofiel
Re: Low battery icon adjustment??? - 06/04/2006 10:01
I would:
- check shield continuity on each audio channel at the sled
- likewise at the amp
- check the RCA leads
- remove the rolloff caps in your player.
Posted by: Robotic
Re: Low battery icon adjustment??? - 06/04/2006 14:47
Quote:
I would:
- check shield continuity on each audio channel at the sled
- likewise at the amp
Shield as in shielded wires? They're just straight up normal insulated wires. Should I shield them?
Or is there some shielding on the player that you're referring to?
Quote:
- check the RCA leads
I swapped in a different sled (and sled harness) but that didn't help.
The RCA leads from empeg to amp are new, albeit cheap-o, as is the amp. Fiddled with all connections with no luck.
The whine disappears when I remove *all* four RCA's from the amp, so the problem is definately inbetween the car, player and the amp.
Quote:
- remove the rolloff caps in your player.
Gonna have to search the FAQ for that one!
Thanks for the suggestions, Rob! I'll have another look tonight.
Posted by: schofiel
Re: Low battery icon adjustment??? - 06/04/2006 17:33
Quote:
The RCA leads from empeg to amp are new, albeit cheap-o, as is the amp.
RED Alert! Danger! Warning!
I would check the grounding of your amp straight away, don't bother with the rest. You should ensure a short DC ground wire, VERY heavy gauge, grounded to bare metal on the car chassis.
I'm willing to put money on you having a puny ground wire that is grounded onto paintwork.
Posted by: Robotic
Re: Low battery icon adjustment??? - 06/04/2006 18:18
Quote:
You should ensure a short DC ground wire, VERY heavy gauge, grounded to bare metal on the car chassis.
I'll change the ground to the amp. The run to the battery is only a couple of feet, so my new lead for the empeg goes directly to the battery and skips the sheet metal altogether. I'll run the amp ground in the same way. BTW, while under the hood I checked the battery terminals and cable connections for cleanliness and godliness- the factory ground strap goes to painted sheetmetal, but the threads of the nut welded to the sheetmetal are bare metal, so I guess the ground path is through the bolt/nut. I cleaned it all and gave it some grease to fight oxide build-up.
This is a very basic install- no heavy hitting speakers, so the amp is low grade; just to boost the four channels. All I have is the four stock 6" positions, the empeg, and the amp. I'm using the stock harness to connect the empeg to the car and the amp to the speakers. Even with the relative simplicity of this setup it's still the most complex I've ever put together- and the most finicky.
Once I manage to get it fitted right, it will be the most rewarding music system. More later-
Posted by: schofiel
Re: Low battery icon adjustment??? - 06/04/2006 19:49
Good man: very similar to my setup. Got surprisingly good results from it as well: it has finally been made to sound superb (in my humble opinion, of course) by using John Graley's Auto EQ in V3A11. Worth trying when you have the install in order, but you will need a mic of course.
Don't forget (if possible) to earth the empeg at the same point as the amp, again with heavy gauge wire.
Posted by: Robotic
Re: Low battery icon adjustment??? - 07/04/2006 00:58
Ah!
It's wonderful what a good ground does!!
Thanks, Rob!
Posted by: schofiel
Re: Low battery icon adjustment??? - 07/04/2006 07:58
So you got rid of the whine then?
Posted by: Robotic
Re: Low battery icon adjustment??? - 07/04/2006 09:01
Quote:
So you got rid of the whine then?
WE did it!
The whine is gone!
The dropping out is gone!
Hurrah!
Posted by: schofiel
Re: Low battery icon adjustment??? - 07/04/2006 09:33
Glad to be of service, sir!
Posted by: schofiel
Re: Low battery icon adjustment??? - 07/04/2006 09:34
I'm getting quite good at this, aren't I?
Posted by: schofiel
Re: Low battery icon adjustment??? - 07/04/2006 17:07
Tony, how about a distillation of this thread for the FAQ? Or anyone fancy turning it into a Wiki article?
Posted by: tfabris
Re: Low battery icon adjustment??? - 07/04/2006 17:39
There's a Low Battery Icon article in the FAQ already, and there's a section on ground loops in the FAQ already. Everything he did to solve the problem was already covered in both of those places, save for a few touch-ups to the low-battery icon entry that I made as a result of this thread. What specifically would you want me to write?