Possible to run without an alternator?
- Thread starter mcleansc
- Start date
I wouldn't do it. Could you? Maybe. The alternator provides a nice steady voltage which keeps things happy.
I have had to sit in the lanes for a long time waiting to go for a run. Now you have very little amperage draw which is good, I would clamp a meter on and see exactly how much it is drawing.
When the voltage gets low the electronics do weird things. Not what you want when WOT in the 1/4.
You save a couple of pounds for the alt and obviously a small bit of power is 'gained' by not having the losses of the engine when connected to the alt via the pulley but it is sooo small I don't see how it would matter.
I would keep the alt and go with a lightweight battery.
What is your reason for wanting to do this? It sounds like more of a hassle, even if it did work fine.
I have had to sit in the lanes for a long time waiting to go for a run. Now you have very little amperage draw which is good, I would clamp a meter on and see exactly how much it is drawing.
When the voltage gets low the electronics do weird things. Not what you want when WOT in the 1/4.
You save a couple of pounds for the alt and obviously a small bit of power is 'gained' by not having the losses of the engine when connected to the alt via the pulley but it is sooo small I don't see how it would matter.
I would keep the alt and go with a lightweight battery.
What is your reason for wanting to do this? It sounds like more of a hassle, even if it did work fine.
When you say big battery you mean a lot of amp hours of capacity right? If it is close to the OEM battery weight this seems like a no go.
I agree on a li iOn battery as it will keep the voltage higher and not drop to 12.4 basically instantly like a normal SLA.
Again, I don't see the advantage of running the car without the alternator? Seems like more negatives than positives.
Reason is just me being me mate
I'm looking to lose as much weight as possible so thought it could be an idea. I removed the oil cooler, AC and about to ditch the PS and liked the idea of the engine bay looking tidier as well.But yeah voltage drops at WOT wouldn't be great, and I'd always intended on putting a lightweight battery in. That would take more weight out than ditching the alternator most likely as well. I'm just doing things for the sake of doing them at the moment it seems
Right. So. Circling back to this, I've done more digging. I've found a 'reasonably' priced 16v Lithium Battery that only weighs 9lb. Without an alternator it should provide a steady 14.8v-15.8v.
According to the internet (we all know the internet is always correct) 12v systems can run 16v but you can buy a step down box for more sensitive parts. However, that's with an alternator. As I'll be running without do we think I should be ok and not fry the DME etc?
I know it's a pain, adds to the hassle of going to the track etc but I'm trying to eek everything I can out this stock turbo build. It also won't be any time soon and may never happen, I'm just letting my mental mind wander while Im at work.
According to the internet (we all know the internet is always correct) 12v systems can run 16v but you can buy a step down box for more sensitive parts. However, that's with an alternator. As I'll be running without do we think I should be ok and not fry the DME etc?
I know it's a pain, adds to the hassle of going to the track etc but I'm trying to eek everything I can out this stock turbo build. It also won't be any time soon and may never happen, I'm just letting my mental mind wander while Im at work.
Voltage is one thing. Important ofcourse but now comes your amperage draw. I believe stock coils already draw up to 7amps a piece at full send. Thats why you have a 80amp battery in the back and an alternator that adds another 90 amps at the very least.
Now compare that to the specs of your 9lbs lithium battery
Now compare that to the specs of your 9lbs lithium battery
Nope. Why does it?
It will still have a parasitic physical load on the engine from the belt/pulley right? There is no clutch on the pulley or something to that effect?
Simple answer, because you're requesting maximum power.
Same reason the A/C shuts down on WOT. Cut down on things that eat up power.
Pull the belt and spin the alternator. Yes there's some drag. But it's not enough to loose sleep over. There's far better ways to get more power than making more work for yourself at the track ... dragging more shit with, charger, generator, fans, fuel, ice, jump pack, spare battery, ... ... ... and then you get beat by a car that drove there.
And IIRC the options for the alternator are on the coding side.
It doesn't on my car. But I have by IBS disconnected to make sure I always have good voltage when sending it.
Still cannot imagine why it would. It has a voltage regulator to regulate its load/resistance.
Is there documentation that shows the alt turns off at WOT? It does not seem to make any sense why they would do it. The AC? I guess it makes some sense, but again the losses much be so small.
@Sausage what are the implications of removing/disconnecting the IBS? I assume you need to code it out?
Somehow I have misfires at WOT when I keep my IBS connected. Something in the IBS system is causing the car not to have the amount of power required. Didnt figure out yet why.
When disconnected, the car/alternator is always charging (14v+) causing higher alternator wear and increased resistance/consumption. I think it triggers a code somewhere but nothing noticable on dash/idrive.
Interesting...in theory you could use a switch or relay and turn off the IBS when you go WOT. Even as simple as a pedal switch, if you know what I mean vs having it disconnected 24/7(which is obviously easier).
I assume with a healthy battery the car sits at around 13.2v? I never checked...If you can get it up to 14.2 your coils will make more power, better ignition, less chance of knock/misfires at WOT.
If @iminhell1 is right and the alt turns off at WOT(which makes no sense to me) the battery voltage will drop and sit right a ~12.4 before dropping even lower with loads. Not great for your coils. If you look at the coil pack studies they usually use a power supply set at 14V: https://www.spoolstreet.com/threads...rk-energy-comparison-n54-n55-b58-and-pr.7169/
Those coil pack numbers will drop significantly at 12VDC vs 14VDC.
Please pardon the ignorant question, but when you guys are talking about misfires, are you talking about limp mode/half engine light misfires where you have to restart the car? Or are you simply checking codes after a pull and seeing misfire codes listed?
That depends. If you lift of quickly enough upon misfireing, it might not even trigger a code. But if you keep pushing it or you're not quick enough then, in my case, it shuts down the cilinder and you need to clear codes (while driving) or restart to restore it.
Its been a while since ive looked at the issue but I noticed alot of high 11's while driving/cruising. Also seeying high 11 when turning on ignition. Dropping to 10.x shortly when starting.
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