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Evo GeneralDiscuss any generalized technical Evo related topics that may not fit into the other forums.
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Looks like I have work to do. I would hate to shell out $300 for an alternator and that not be it. That’s for an oem alternator. Imagine the cost on an upgraded one.
Okay wait. Lets say the alternator puts out 14v when cold, right
13.8 warming up
13.5 warm
13.2 with the fans on
13.0 with the a/c on
12.8 with the lights on
12.75 at idle with all that stuff on
So what we are noticing is that, the alternator has been putting out 14v the whole time, but because of all these things running, we are only seeing 12.whatever at the battery. I suppose you could think of it as 'leftover water' from the level where pour in 14height water and only 12height is left after all the water driven accessories take their flow. To help with the example, opening a flood gate and letting all the water dump out would be like connecting a ground cable to the water voltage flow. It would just instantly allow all the water to exit. So the water is the 'voltage' is sort of like 'hydrostatic pressure' i.e. 14volts is 14 volts worth of 'water pressure' and if you have water flowing through all those devices the leftover 12 volts of 'water pressure' is all that the 'pump' can provide. Exactly as if you had 45psi of fuel pressure at idle and 65psi during 20psi of boost, except that fuel pressure drops to around 60, you lost 5psi because of the pump flow insufficiency. But it still 'makes it there' it still 'fuels the engine'
Which brings me to the point of that terrible example. If the engine still runs fine, the battery isn't undercharging (It carries a surface charge over 12.64 volts after shutting off, usually 12.8v or more) and you are seeing no ill-effects from this 'reported voltage issue'. Then the alternator is literally doing its job and everything is fine despite what you are seeing, is 'normal' as long as the voltage stays kinda above what would maintain a fully charged battery.
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After re-reading the first post. it sounds like a battery cable issue. That you had corrected at least partially (it may need more work). However because it drew your attention to the charging system now you are suspecting all these other readings. When in fact everything is pretty much normal that you are seeing.
I would say, make sure the cables are proper. Then, make sure the alt keeps the battery fully charged. If nothing else seems wrong, then its good right?
Well technically speaking, OP's 13.5 volt reading would meet the criteria of minimally acceptable, IF he took the reading at 140 degrees F Even then though, is bare minimum really what we are shooting for here with our cars? Here is the Voltage regulation test from the FSM
Okay wait. Lets say the alternator puts out 14v when cold, right
13.8 warming up
13.5 warm
13.2 with the fans on
13.0 with the a/c on
12.8 with the lights on
12.75 at idle with all that stuff on
So what we are noticing is that, the alternator has been putting out 14v the whole time, but because of all these things running, we are only seeing 12.whatever at the battery. I suppose you could think of it as 'leftover water' from the level where pour in 14height water and only 12height is left after all the water driven accessories take their flow. To help with the example, opening a flood gate and letting all the water dump out would be like connecting a ground cable to the water voltage flow. It would just instantly allow all the water to exit. So the water is the 'voltage' is sort of like 'hydrostatic pressure' i.e. 14volts is 14 volts worth of 'water pressure' and if you have water flowing through all those devices the leftover 12 volts of 'water pressure' is all that the 'pump' can provide. Exactly as if you had 45psi of fuel pressure at idle and 65psi during 20psi of boost, except that fuel pressure drops to around 60, you lost 5psi because of the pump flow insufficiency. But it still 'makes it there' it still 'fuels the engine'
Which brings me to the point of that terrible example. If the engine still runs fine, the battery isn't undercharging (It carries a surface charge over 12.64 volts after shutting off, usually 12.8v or more) and you are seeing no ill-effects from this 'reported voltage issue'. Then the alternator is literally doing its job and everything is fine despite what you are seeing, is 'normal' as long as the voltage stays kinda above what would maintain a fully charged battery.
---
After re-reading the first post. it sounds like a battery cable issue. That you had corrected at least partially (it may need more work). However because it drew your attention to the charging system now you are suspecting all these other readings. When in fact everything is pretty much normal that you are seeing.
I would say, make sure the cables are proper. Then, make sure the alt keeps the battery fully charged. If nothing else seems wrong, then its good right?
Water analogies can be helpful. In your example its the pipes that need to be enlarged to reduce the pressure drop. What hasn't been established yet though is there enough water being generated by the alternator or are the pipes too narrow.
What made me focus my attention on voltage is that when fans or headlights turn on the engine idle changes. Also, the one day just decided to go one full point lean everywhere. Idle/cruise/wot. Something similar seems to happen every summer when it’s hot outside. Then out of nowhere it’ll go back to being normal. I’ve replaced about 3 walbros thinking they were the issue. Also new grommet, plastic piece at the pump and double checked. Also different fpr etc. The other day when flashing the car on the street it wouldn’t turn on. It would just click. Put jumper cables on and car started right up. Battery wasn’t drained, sounded strong when started. But this happened when the lean issue was going on. My thinking is maybe something happened there where there wasn’t enough voltage to engage starter. I have replaced the ignition switch part that goes bad on these etc. Also makes me think about some type of ground. This one is hard to explain but lately sometimes I try to start the car and sounds lazy and in the middle of cranking while I’m still holding the key in on position it’ll go from lazy cranking/turning over, to clicking on that same cycle and lights start dimming and turning on and off. I have to let go of the key and right away I’ll turn the key again and it will crank right up. No lazy turning over or anything it just starts up like a champ. It’s hard to explain without catching the phenomenon on camera. Unfortunately I’ve never looked at the voltage while this was happening. I believe while cranking it shouldn’t drop under 10v? Does the alternator have anything to do with cranking or is it strictly off battery?
Just battery. The issues you are describing with poor cranking have everything to do with the connection between starter and battery. Cables, or battery itself.
Or the size of the cable / length of cable (typical for rear mount battery installs). The alternator does nothing until the engine is running.
I had similar situations. In one case, I re-routed power from the ignition switch into a separate relay to handle the current load of the solenoid on the starter, rather than forcing it to go through the ign switch, then the fuse box, then to the solenoid.
In another case, I've seen a ford "starter" solenoid to drive current both through the main starter power wire and solenoid wire simultaneously. This allows the main battery power wire to remain dead in a relocation while the engine isn't cranking.
What hasn't been established yet though is there enough water being generated by the alternator or are the pipes too narrow.
If he wants to see whether the 'pipes' need to be larger or the 'pump' output is low, all he has do is measure the voltage at the alternator lug. If the alt lug voltage matches the battery voltage (low) then it isn't the size of the pipes, because there would be more 'water pressure' on the lug coming off the alternator.
In other words, "voltage drop" = small 'water' plumbing, "low voltage everywhere" = low alternator output 'pressure'
Last edited by KingTal0n; Jun 3, 2019 at 01:38 PM.
What made me focus my attention on voltage is that when fans or headlights turn on the engine idle changes. Also, the one day just decided to go one full point lean everywhere. Idle/cruise/wot. Something similar seems to happen every summer when it’s hot outside. Then out of nowhere it’ll go back to being normal. I’ve replaced about 3 walbros thinking they were the issue. Also new grommet, plastic piece at the pump and double checked. Also different fpr etc. The other day when flashing the car on the street it wouldn’t turn on. It would just click. Put jumper cables on and car started right up. Battery wasn’t drained, sounded strong when started. But this happened when the lean issue was going on. My thinking is maybe something happened there where there wasn’t enough voltage to engage starter. I have replaced the ignition switch part that goes bad on these etc. Also makes me think about some type of ground. This one is hard to explain but lately sometimes I try to start the car and sounds lazy and in the middle of cranking while I’m still holding the key in on position it’ll go from lazy cranking/turning over, to clicking on that same cycle and lights start dimming and turning on and off. I have to let go of the key and right away I’ll turn the key again and it will crank right up. No lazy turning over or anything it just starts up like a champ. It’s hard to explain without catching the phenomenon on camera. Unfortunately I’ve never looked at the voltage while this was happening. I believe while cranking it shouldn’t drop under 10v? Does the alternator have anything to do with cranking or is it strictly off battery?
Do a search for the "Big 3" electrical upgrade. I think because of your battery relocation the concepts of that upgrade are going to apply to you. The engine normally has a ground straight to the battery negative terminal. Now it has to go through chassis to the battery. If the engine to chassis, chassis to battery, and alternator to battery cables haven't been upgraded then your going to have issues. By upgraded I mean that the factory gauge cables work because of the length. When you make that cable a whole lot longer to reach the trunk the cable also has to become thicker to reduce the resistance. Electricity, unlike water, has to make a round trip to complete a circuit. So the engine to Chassis ground (and the whole chassis) now has to transport all the power to crank the starter, where before there was a cable going straight from battery negative to the transmission case.
Just battery. The issues you are describing with poor cranking have everything to do with the connection between starter and battery. Cables, or battery itself.
Or the size of the cable / length of cable (typical for rear mount battery installs). The alternator does nothing until the engine is running.
I had similar situations. In one case, I re-routed power from the ignition switch into a separate relay to handle the current load of the solenoid on the starter, rather than forcing it to go through the ign switch, then the fuse box, then to the solenoid.
In another case, I've seen a ford "starter" solenoid to drive current both through the main starter power wire and solenoid wire simultaneously. This allows the main battery power wire to remain dead in a relocation while the engine isn't cranking.
If he wants to see whether the 'pipes' need to be larger or the 'pump' output is low, all he has do is measure the voltage at the alternator lug. If the alt lug voltage matches the battery voltage (low) then it isn't the size of the pipes, because there would be more 'water pressure' on the lug coming off the alternator.
In other words, "voltage drop" = small 'water' plumbing, "low voltage everywhere" = low alternator output 'pressure'
That's the last thing I advised him to do. See post #27
I will get to checking voltage at alternator to rule out the alternator. It would be red from meter to positive lug on alt and black to case or do I have to run a wire all the way from the trunk on the battery negative to the front so I can check the meter?
I will get to checking voltage at alternator to rule out the alternator. It would be red from meter to positive lug on alt and black to case or do I have to run a wire all the way from the trunk on the battery negative to the front so I can check the meter?
Just from Lug to Alternator case and then get a measurement at the battery. Also a measurement from the power wire into the under hood fuse panel to chassis would be good. Again with the system under load.
Ok so a measurement from alt, power wire at fuse box and bat. All of this with ac, lights, etc turned on. Got it I’ll do it tomorrow. I’ll report results here.
This is the wire that was used for the battery relocation kit. It is not 100% copper. Not sure if it should be or not. You can also see the negative side wire which is thinner but 100% copper. I haven’t been able to get the readings because this pos doesn’t want to start today. I can hear the starter clicking. I tried smacking it to see if it was the starter but nothing. But jumper cables on battery and still didn’t start. Starter would just click. After leaving jumper cables hooked up a while the battery reading with car off was in the 12.60s. Before jumper wires it read 12.11. Battery is from 2018. Wtf is going on with this thing.
This is the wire that was used for the battery relocation kit. It is not 100% copper. Not sure if it should be or not. You can also see the negative side wire which is thinner but 100% copper. I haven’t been able to get the readings because this pos doesn’t want to start today. I can hear the starter clicking. I tried smacking it to see if it was the starter but nothing. But jumper cables on battery and still didn’t start. Starter would just click. After leaving jumper cables hooked up a while the battery reading with car off was in the 12.60s. Before jumper wires it read 12.11. Battery is from 2018. Wtf is going on with this thing.
That looks like an aluminum 4 gauge wire from a cheap amp kit or something. So effectively its a 6 gauge copper wire. You should replace it with at least a 4 gauge copper wire. My advice would be to run a 2 gauge wire.
Use to be you could get it from them cheaper on ebay. Not sure if that's still the case. I think they sell on Amazon too. You can also check local stereo shops to see if they will sell it off the roll. Then you want to make sure to properly terminate the wire. The
for any wire of an appropriate gauge is ~50 bucks on the low side. This might also be a good time to hit up a stereo shop and see if they can terminate the wire for you.
I just took battery and starter to advanced and battery was a little low but still wouldn’t need a charge according to them. Starter works fine. Damn it. Yeah I plan on changing the wire. Only thing I can think of now is a ground somewhere? I mean the starter clicks. I got under the car and had someone turn the key and I can hear it clicking. Maybe starter not getting enough juice?
I just took battery and starter to advanced and battery was a little low but still wouldn’t need a charge according to them. Starter works fine. Damn it. Yeah I plan on changing the wire. Only thing I can think of now is a ground somewhere? I mean the starter clicks. I got under the car and had someone turn the key and I can hear it clicking. Maybe starter not getting enough juice?
Thats usually what just clicking means. What does the engine to chassis ground look like? As I was saying, that should be a pretty big cable.
Jun 3, 2019, 12:18 PM
Even then though, is bare minimum really what we are shooting for here with our cars? Here is the Voltage regulation test from the FSM
