Hey Veeky Forums

dong

12-14 volts of amp boost in America
Euro cucks use metric boost

having a bad day there son?

>some sort of DC-DC converter in between

Yes, I believe they're called "wires"

I would have expected some higher quality trolling

>Do you guys know if there is a list of alternator voltages (actual measured) for various cars?

The slight differences in alternators don't matter because they work in tandem with a voltage regulator. Alternators produce AC, not DC. So their outputs have to be rectified and voltage regulated before use. So, your comment is really about the output of voltage regulars and of course all those will have the same output voltage.

Ah my bad

Don't worry about the alternator type so much. With B+ connected to the Sense input, it should be right on 14.5 to 14.8

The issue with a Calcium battery and for some wet cell AGM's is that they cannot handle constant high amperage charging without damaging the plates or grid. C-TEK has made DC-DC charging converters for a long time and I have never been let down by one yet.

Make sure you pick up a model that has switchable FLA/ALK/AGM charging patterns as the patterns for an AGM are very different in the bulk charge stage to an Alkaline battery.

Electronics summary: alternators generate AC. The voltage can vary a little bit depending on a lot of things, but it ultimately doesn't matter because everything is standardized. The output goes through rectifying diodes which convert it to DC. Specifically, around 13.8 to 14ish volts.

DC to DC converters *are* things that exist: buck converters, boost converters, ect, but they aren't things consumers are generally concerned about.

Just worry about heat and fire hazards. You're not trying to do anything particularly squirrely.

Newer model cars (build this decade, really) usually have 'smart charging', which means the ECU will change the alternator output based on engine load, battery charge level, electrical load on the system, and a variety of other variables.

If you're adding a second battery, you may need to do some research specific to your vehicle - it might need recalibration for the extra electrical load, or it might require some kind of charging circuit (most use a simple relay, but they're for older vehicles) that accounts for the varying alternator output.

If you've got a 4WD, you shouldn't have any problems finding information on dual battery systems - people install them all the time - but if it's something that doesn't usually see a second battery, do some research specific to your particular vehicle.

Some cars will even throw an engine code or have charging issues if you stick the wrong battery type in them, so you'll need to find out what your system is capable of handling.

tl;dr New cars are complicated and it's fucking hard to give any kind of generalization, google/aftermarket suppliers are your friend

If you have a lot of devices drawing power, and an idling alternator is not turning fast enough to create enough current to maintain a necessary voltage level, then you might install a 2nd alternator. Those custom audio shops do things like that particularly if they work on cars for IASCA or other car audio competitions.

>if I am fine with just connecting the alternator voltage directly onto the 2nd battery
As others have said, modern cars use smart charging because a lot of new cars now use AGM type batteries. It's not just to eliminate the chore of adding distilled water to batteries, but to make use of the improved features of AGM over the older batteries.

Unfortunately, AGM is lot pickier about how they are charged and need smart charging. Otherwise their lifespan is severely reduced. So you cannot simply connect them up with a relay for charging unless you simply don't care about lifespan.

But let's say all batteries have perfect lifespan. So what happens if you simply connect multiple batteries up with relays? Each battery is slightly different in terms of charge, charge rate, and condition. If one battery has a higher charge than the other, it could end up discharging into the lower-charged batteries. That is not good. You also have the other problem of batteries going dead when a cell shorts out. If you simply have relays connecting that bad battery with the other good ones, you will short out the other batteries. Is that a potential fire condition? Possibly but probably not. Regardless, it is not a good thing and will cause the other batteries to go bad.

There are devices that let you connect the outputs of multiple car batteries together. Use those.

Not sure if theres a list somewhere, my cars vary between 13.2 to 14.7 each car varies .5 or so depending on temps. Ive seen as low as 10.2 under load and as high as 14.9

Pretty sure OP wants to know about amperage.
In which case old cars (60's) were in the 60-70 range
Slowly they increased as electronics in the vehicle increased.
80's were up to 85 amps
90's, with the introduction of efi was 100+
You can get aftermarket's that are 180 for cheap.

What gets me is that old alts have large wires but lower amperage ratings than new china made alts with thin wire windings. Did china improve copper wire technology somehow to make wires carry more amps?

more windings.

Thanks for the info everyone :D

>Did china improve copper wire technology somehow to make wires carry more amps?
No, although it is tempting for people to blame china for simply claiming 18awg wires can carry 200 amperes since chinese companies are often dishonest. What happened is that those chinese are simply copying a patent-expired european innovation of using smaller wires in parallel to eliminate waste space.

The passageways of an alternator are tight and limited in space and number. Alternators also have various standardized sizes and mount points. Thus, the use of large diameter wires results in wasted space between the large bending wires due to the large circular diameter of the wires. But the use of small wires results in much less wasted space.

They actually compensate for more then temp, but that is their main factor. My old 2002 Mitsubishi lancer would compensate for temp and also engine load. Ive seen it go from 13.5ish on hot summer days, to 15.3ish on sub zero starts. My newer ford fusion compensates similarly, i think it also compensates for engine run time (to turn down the voltage and trickle charge after the battery has had significant time to charge)

joke never gets old

4 turbos
beats an ecoboost which has only one turbo

That would look mean as on a tattoo ;^)