Inverter powered by a 12vdc alternator ?

[veggie]

Can inverters use high frequency DC power (eg: from an automotive alternator) or do they need a constant (+)/(-) flow ?
I was thinking of using a 104 amp Leese 12vdc alternator to power a system and have an inverter to bring the power up to 120 vac.
Perhaps if a battery bank is present in the system, the batteries would smooth out the pulsing DC ??
The batteries would also be available for emergency power.

see sketch...

[mbryner]

Perhaps if a battery bank is present in the system, the batteries would smooth out the pulsing DC ??

As long as you have a way to regulate charge current and voltage.

[mobile_bob]

do use the battery as a buffer, otherwise the very real issue related to dump load will run the risk of damaging the inverter.

if you use the standard oem regulator that the leece neville comes with it will work well enough for your needs, provided you are running the alternator while you are drawing a load from the inverter, which is likely the only way to do it using a single battery as a buffer.

no reason why it won't work

bob g

[LowGear]

Hmmmmmm,

1000 Watts + 500 Watts = 1500 Watts Load

12 Volts @ 100 Amps = 1200 Watts Line

There's something wrong here.  You're going to rely on the batteries to make up the 300 Watts?

Casey

1500 Watts / 12 Volts = 125 Amps

[veggie]

Hi Casey,
The system is fairly flexible. I can speed up the engine or alternator to match the load that I eventually end up with.
My concern at this stage was the pulsing DC from the alternator.
Veggie

[LowGear]

Hi Veggie,

I often project my own short-comings onto others.  The old saying "Not seeing the trees for the forest."

I too dream of pulling 1000 to 1500 watts off a 12 Volt inverter but those are some big Amps.

Casey

[veggie]

Hi Veggie,
I often project my own short-comings onto others.  The old saying "Not seeing the trees for the forest."
I too dream of pulling 1000 to 1500 watts off a 12 Volt inverter but those are some big Amps.
Casey

Hi Casey,
My system has 4 X 6volt Trojan 225 amp batteries wired in series/parallel to provide 12vdc @ 550amp.
The Inverter is a 5000w, 12 volt mod-sine unit which is limited (by my circuit breakers) to 2500 watts.
(I agree that 5000w is beyond the workable limits of a 12vdc system, hence my current limiting breakers)
My cables, DC breaker, and fuses are sized accordingly.
When pulling 1500 watts, the electrics won't even break a sweat and the engine (at 1300rpm) will be loaded to 75%.
The Leese alternator puts out 100 amps at 2500 rpm and 140 amps at 3500 rpm.
My reason for considering the Leese instead of a fixed speed generator head is to have the flexibility of running slow most of the time to charge the bank, and run faster when I want to drive bigger loads. Can't do that with a synchronous unit.

cheers,
veggie

[Lloyd]

Hi Veggie,

Yes you can do it...the bat bank acts as a big buffer...I have been running a Trace 2500 watt modified sign wave inverter, off three pair of Trojan T-125's since 2003, backed up by a pair of 150 amp alts, with Balmar 612 max charge regulators, and a Balmar Centerfielder. The max load I have put on it was 2400 watts on a run from Seattle to Orcas Island 6hr trip, typically I run about 1,000 watts but after six hour cruise at 2400 watts, we had full bats when we arrived at Orcas island.

Lloyd

[veggie]

Thanks Lloyd,
It always helps to have a real life example.
I suppose the larger the battery bank, the better it takes out the pulses.
(Until it's fully charged).

veggie

[LowGear]

Hi Lloyd,

Wow!  I realize you're probably running three sets of wire to the inverter but that still is a lot of current to supply 2400 watts.  What sized wire are you using?

Casey

[bschwartz]

Looks OK except for the engine that fell over on it's side 

[veggie]

Looks OK except for the engine that fell over on it's side 

Aaaaah! That explains why the dipper is not working anymore !!   

[Lloyd]

Hi Lloyd,

Wow!  I realize you're probably running three sets of wire to the inverter but that still is a lot of current to supply 2400 watts.  What sized wire are you using?

Casey

Hi Case,

I'm Running 4/0 on the dc side including the series jumpers, and the parallel jumpers, and number 8 on the AC side.

You never run three sets of cables, you always series the 6volt pos to neg, then parallel each series, then take the pos off one end of the string, and the neg off the other end of the string. Each series cable pos and neg are the exact same length, and each parallel cable are the exact same length.

Lloyd

Lloyd 

[squarebob]

This web page makes a lot of sense for connecting batteries together

http://www.smartgauge.co.uk/batt_con.html

[Lloyd]

    
HI [_] Bob,

3 & 4 don't work, and waste cable, as well as increase cable distance which increases voltage drop. Because the bank preforms to the weakest bat in the bank.

In ver. 3 all bats will perform to the which ever of the bats is the weak sister. I have seen a couple of clients who had their boat set up like 3 and complain that the bats must be bad, and eventually they will be bad. One gets over charged and all the rest get under charged resulting in sulfating. Which will make the bats bad.

While version 4 looks like a nice design it stops there. If bat 1 and 2 are the weak sisters then 3 and 4 will be over-charged, until they become the weak sisters, then 1 and 2 will be over charged. It goes on until the bats are either boiled or sulfated.

Ver. 2 is the correct way. It's important to make each jumper, series/parallel the exact same length. Next don't stack the cable lugs on top of each other, use heavy duty lugs that allow you to load one cable on one side of the lead post, and the other on the other side, that forces all current to flow through the path of least resistance, which becomes the plates of the bats. When you stack the cable lugs the path of least resistance is lug to lug.

Lloyd