That Wacky Previa and How it Needs Relays

[Alaric Darconville]

Or at least, I think it does:

Engine State	Off*			On, @idle	
	          Reading	 Loss		Reading	Loss
Battery	             11.86	0	        12.59    0
Battery + to High	11.03	0.83		11.92	0.67
Battery + to Low	11	0.86		11.88	0.71
Battery - to High	10.89	0.97		11.77	0.82
Battery - to Low	11.13	0.73		12.06	0.53
		Total Loss High Beam [B]1.8[/B]	Total Loss High Beam [B]1.49[/B]
		Total Loss Low Beam [B]1.59[/B]	Total Loss Low Beam [B]1.24[/B]
			
	*Key in ON position				
	In both cases, the heater fan was set to maximum

Key: Battery + to High meant I had the red probe on the battery positive terminal, and the black probe on the bulb leg for the high beam feed.
Battery - to High meant the black probe on the negative terminal, and the red probe on the bulb's ground.

I had an awesome spreadsheet to do the output difference calculations, but suffice to say a low beam at 11.35V is going to be pretty poor...

Maybe I did the whole thing wrong... I thought for some reason I should be seeing readings like -1.2 or something like that. I suppose it would help if I knew the pinout of the 9003 (which should be simple to test with the ohmmeter, you'd think).

I did find this pinout of the socket: http://i51.photobucket.com/albums/f369/bbottomley/Forester/H4pinout.gif

I think I may have been doing it wrong, but now it's too hot outside to go and mess with it again.

 

[Kuryakin]

Yeah, relays will help, they just about always do!

Or at least, I think it does:

Engine State    Off*            On, @idle    
              Reading     Loss        Reading    Loss
Battery                 11.86    0            12.59    0
Battery + to High    11.03    0.83        11.92    0.67
Battery + to Low    11    0.86        11.88    0.71
Battery - to High    10.89    0.97        11.77    0.82
Battery - to Low    11.13    0.73        12.06    0.53
        Total Loss High Beam [B]1.8[/B]    Total Loss High Beam [B]1.49[/B]
        Total Loss Low Beam [B]1.59[/B]    Total Loss Low Beam [B]1.24[/B]
            
    *Key in ON position                
    In both cases, the heater fan was set to maximum

Key: Battery + to High meant I had the red probe on the battery positive terminal, and the black probe on the bulb leg for the high beam feed.
Battery - to High meant the black probe on the negative terminal, and the red probe on the bulb's ground.

I had an awesome spreadsheet to do the output difference calculations, but suffice to say a low beam at 11.35V is going to be pretty poor...

Maybe I did the whole thing wrong... I thought for some reason I should be seeing readings like -1.2 or something like that. I suppose it would help if I knew the pinout of the 9003 (which should be simple to test with the ohmmeter, you'd think).

I did find this pinout of the socket: http://i51.photobucket.com/albums/f369/bbottomley/Forester/H4pinout.gif

I think I may have been doing it wrong, but now it's too hot outside to go and mess with it again.

 

[Diesel_Bomber]

If your engine running voltage was 12.59v then your charging system has failed.

Why not just measure the voltage at the battery, then the voltage at the headlights themselves, and subtract one from the other? Going by your figures, yes you most definitely need relays. 10% drop in voltage = 46% drop in light.

 

[Alaric Darconville]

Why not just measure the voltage at the battery, then the voltage at the headlights themselves, and subtract one from the other? Going by your figures, yes you most definitely need relays. 10% drop in voltage = 46% drop in light.

Was mostly making sure I did the battery/bulb leg connections right, I suppose.

I did measure voltage at the battery, both at idle and with the engine off, and in each case with the heater fan set to maximum, and with the lights on (of course).

Going down the road, the SGII reports upwards of about 14.2V (read from the computer, haven't had the VOM hooked up to the battery while on the road).

 

[Alaric Darconville]

(quoted text removed by AlaricD)

You don't have to quote the entire message, especially when you're the first reply in the thread. You do that quite a lot.

Think you might could go back in that post and unquote me to help keep the thread readable?

 

[Random Guy]

If your engine running voltage was 12.59v then your charging system has failed.

Why not just measure the voltage at the battery, then the voltage at the headlights themselves, and subtract one from the other? Going by your figures, yes you most definitely need relays. 10% drop in voltage = 46% drop in light.

I think there is some validity here. I just went and checked my truck ('86 S10 pickup), and the voltages at the battery were:
Engine off, headlights off: 12.05 V
Engine off, headlights on: 11.80 V
Engine on, headlights off: 14.00 V
Engine on, headlights on: 13.50 V

 

[Alaric Darconville]

It's an old battery, and I created additional load with that heater fan. The engine idles at 750 in neutral, well below the alternator's preferred operating speed.

Why not just measure the voltage at the battery, then the voltage at the headlights themselves, and subtract one from the other?

Daniel Stern has a procedure that is supposed to check both sides for their own losses, since it is more accurate then just checking right at the bulb. I guess it is just all the more accurate.

Now I just have to scrimp and save a bit to get some relays (I'll do it the Daniel Stern way, no "SUVLights.com" for me).

 

[Kuryakin]

I don't want to lose any references. And you're welcome!

You don't have to quote the entire message, especially when you're the first reply in the thread. You do that quite a lot.

Think you might could go back in that post and unquote me to help keep the thread readable?

 

[Alaric Darconville]

I don't want to lose any references.

How would you lose any references? And I'm welcome for what?

Again, quoting entire messages, especially those with complicated formatting, is not very kind to your fellow CPFers.

 

[Diesel_Bomber]

It's an old battery, and I created additional load with that heater fan. The engine idles at 750 in neutral, well below the alternator's preferred operating speed.


Daniel Stern has a procedure that is supposed to check both sides for their own losses, since it is more accurate then just checking right at the bulb. I guess it is just all the more accurate.

Now I just have to scrimp and save a bit to get some relays (I'll do it the Daniel Stern way, no "SUVLights.com" for me).

Two routes to the same destination. I feel my way is jumping on the highway while yours(and Mr. Stern's) is taking side streets, but whatever floats your boat.

 

[Kuryakin]

In the end, measuring the voltage drop from the source to the load is what matters, and it doesn't make a huge difference as long as the loads in the load path are all there. Clearly he's identified a large voltage loss through the factory wiring, and outside of using relays and a dedicated harness, there's not a lot he can do about that. In the end, the solution is the same, and in the beginning the diagnosis is quite valid.

Two routes to the same destination. I feel my way is jumping on the highway while yours(and Mr. Stern's) is taking side streets, but whatever floats your boat.

 

[Diesel_Bomber]

In the end, measuring the voltage drop from the source to the load is what matters, and it doesn't make a huge difference as long as the loads in the load path are all there. Clearly he's identified a large voltage loss through the factory wiring, and outside of using relays and a dedicated harness, there's not a lot he can do about that. In the end, the solution is the same, and in the beginning the diagnosis is quite valid.

Put another way.............two routes to the same destination.

 

[-Virgil-]

In the end, measuring the voltage drop from the source to the load is what matters

That's half of what matters. The other half is voltage drop from load to ground! The advantage of doing it Stern's way is that you get to see how much drop is occurring on each leg of the circuit.

 

[Kuryakin]

Yes, I know, and given that the ground is part of the load path, yes, that matters, obviously, and in his spreadsheet, he measured that as well. Whenever I add relays, it's a given the grounds will be replaced as well.

That's half of what matters. The other half is voltage drop from load to ground! The advantage of doing it Stern's way is that you get to see how much drop is occurring on each leg of the circuit.

 

[Kuryakin]

Yep! And in the end, there's one good solution. Relays and better wiring!

Put another way.............two routes to the same destination.

 

[Alaric Darconville]

That's half of what matters. The other half is voltage drop from load to ground! The advantage of doing it Stern's way is that you get to see how much drop is occurring on each leg of the circuit.

I knew there was a method to his madness...

So, does it look like I did it correctly, then?

I thought I'd get a "direct reading of the voltage drop" and see readings like "-.83" or ".83", instead of "11.03"... (Not exactly sure WHY I expected such readings, but the wording in the "relays" article seemed to indicate that.)

 

[was.lost.but.now.found]

I'm not sure why you consider your idling voltage to be a valid measure of the performance of your lighting. I'll bet you a dollar (as I have confirmed with my ScanGaugeII) that the voltage goes up to AT LEAST 13 V when you have a load on your engine (and thereby a load on your alternator) while driving down the road.

 

[Alaric Darconville]

I'm not sure why you consider your idling voltage to be a valid measure of the performance of your lighting. I'll bet you a dollar (as I have confirmed with my ScanGaugeII) that the voltage goes up to AT LEAST 13 V when you have a load on your engine (and thereby a load on your alternator) while driving down the road.

The Scangauge voltage disagrees with the VOM; but the SC is reading it from elsewhere (like what the computer reads from the alternator or whatever).

There's a load on the alternator: The lights and the heater fan are on.

However, the alternator doesn't really start kicking out the juice until about 2000rpm or so.

I tested it at idle because I didn't want to have to try to keep the engine above a certain speed (and couldn't test while driving), and basically just wanted to establish a baseline.

 

[was.lost.but.now.found]

The Scangauge voltage disagrees with the VOM; but the SC is reading it from elsewhere (like what the computer reads from the alternator or whatever).

There's a load on the alternator: The lights and the heater fan are on.

I tested it at idle because I didn't want to have to try to keep the engine above a certain speed (and couldn't test while driving), and basically just wanted to establish a baseline.

Ok, my confusion. So where in your spreadsheet is the comparison between DMM and SGII readings for a given constant (say, idling)?

 

[Alaric Darconville]

Ok, my confusion. So where in your spreadsheet is the comparison between DMM and SGII readings for a given constant (say, idling)?

I didn't include it because it didn't seem germane to the problem at hand. I just wanted to get the voltages as read at the battery itself (and maybe there's some shorting in the battery if it reads that low in either engine state, but I'm not yet ready to replace it).