does anyone make

[Mobilesport]

I don't mess with the alternator at all. Systems are 100% isolated. So my question means he just uses an alternator not a generator.

And are running alternator straight into battery or through a charger?

Yes , straight into battery

 

[Mobilesport]

Right but that can be a whole lot of $$ in idle time. We'd be talking many hours a day. Not to mention isn't it significantly less efficient to run off an alternator than a generator?

You only charge while your driving  , not when you're idling.
The alternator is more efficient

 

[Mobilesport]

Right but that can be a whole lot of $$ in idle time. We'd be talking many hours a day. Not to mention isn't it significantly less efficient to run off an alternator than a generator?

You only charge while your driving  , not when you're idling.
The alternator is more efficient

 

[jonsun]

wait how is that? You saying the output is too low at idle to charge? wouldn't that depend on pulley ratio and rated output? alternators are constant voltage, no?

if not that makes it a definite no-go for me. I need a daily bulk boost.

I cannot fathom how a DC run off a V8 is more efficient than a lawnmower engine pushing AC, though. care to elaborate?

 

[Mobilesport]

wait how is that? You saying the output is too low at idle to charge? wouldn't that depend on pulley ratio and rated output? alternators are constant voltage, no?

if not that makes it a definite no-go for me. I need a daily bulk boost.

I cannot fathom how a DC run off a V8 is more efficient than a lawnmower engine pushing AC, though. care to elaborate?

A alternator will charge while idling but it will charge slower then when driving and
plus you'll be wasting gas because your burning fuel but not going anywhere , plus it's not 
good on your engine  to do excessive idling if you  can avoid it

 

[Mobilesport]

Are you planning to boondock in one place with very little driving?

 

[Mobilesport]

Bardo wrote
"I cannot fathom how a DC run off a V8 is more efficient than a lawnmower engine pushing AC, though. care to elaborate?"
Because you'd be driving anyway , you don't charge while idling

 

[jonsun]

Are you planning to boondock in one place with very little driving?

yes...maybe 5-10 days at a time

Im also anticipating the draw from a 12v compressor fridge in the winter and assuming I will need regular bulk "bumps" to help the panels cause of it.

 

[jonsun]

Bardo wrote
"I cannot fathom how a DC run off a V8 is more efficient than a lawnmower engine pushing AC, though. care to elaborate?"
Because you'd be driving anyway , you don't charge while idling

I would wager a bet that you use more gas doing that than you would running a generator on a hitch tray driving down the road. especially on my carburated 8ft hightop van.

 

[Mobilesport]

I would wager a bet that you use more gas doing that than you would running a generator on a hitch tray driving down the road. especially on my carburated 8ft hightop van.

When you wager that bet account for all the gas the generator used to charge , vs
the little bit of Xtra gas the carburated van used because of the added 
load you put on the alternator. 
You don't count the gas used to propel the van , you only account for
the gas used to charge.

 

[jonsun]

right

a cheap 2k peak generator uses about .1g per hour @ 50% load

any v8 will use more than that pulling 50-100A extra off the generator above its usual usage

 

[SternWake]

There is no need to disconnect automatic  charging sources, they can all work together until the battery reaches the absorption max voltage on one charging source, then it drops out and the other continues.


At this point the battery can only accept a small amount of current and two sources are not required anyway.




I can get 72 amps at idle cold, and 42 when hot. -8.2 amps  for ignition and fuel pump.

The issue Idling hot maxed out with depleted battery is alternator temperature.  Mine rises quickly when maxed out and not moving.  About 12 or 15  minutes after a cold start, the maxed out alternator is in the danger zone.

 

[jonsun]

alternator deletes usually get tested around 10% increases in MPG....and that's on typical operation, not pulling an extra 70A

a high top van going 60mph @ 12mpg would use 5 gallons an hour
IF we assume a 10% increase with a maxed out alternator, which is likely conservative
we get 10.8mpg over 60 miles = 5.55

for an increase of .55 gallons per hour vs .1-.13

if we do this for 2hrs daily we use ~30 gallons a month over a generator

easily get into the thousands a year if gas up any more

 

[Mobilesport]

I've also have heard it's bad to idle because overtime coolant seeps down into
your crank case and gets to your bearings , so if you idle alot you might want
to do oil changes more often .
I've also have heard the army does alot of idling but come time they do a engine swap.
How true this is I don't know.