Just suppose,...

[Amy]

Ive done some reading and unlike a regular AC generator which needs preset stable engine revs to produce 50 hz, the travel power has a capacitor to iron out and compensate, but im still wondering if a one good 200 amp 12v alternator for $150 is the way to go?

[Justme]

Twin alternators?

Build some resilience into the system

[Lincsoldbird]

Travelpowers cost the best part off 2 grand! Alternators are 50 quid from the breakers

[billi]

Amy perhaps this one is something for you ( ok its AC  ) but a good "German" make 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&Item=370365051610&Category=46412&_trkparms=algo%3DLVI%26its%3DI%26otn%3D2

but its called Zeise not Zelse 

Should be this one http://www.set-zeise.de/UserFiles/File/MPW/Ben%20MPW5%2093-2006%20eng.pdf

Generator and engine watercooled so provides your heating as well

Unfortunately the seller does not know if its working  , but i reckon worth to find out 

those units are generally over 4000 pounds plus

Billi

[Amy]

Thanks Billi

I dont know whether I should take the chance and buy them. 
Are spares readily available?
Whats likely to be wrong with them, if there is something wrong.

[Amy]

Travelpowers cost the best part off 2 grand! Alternators are 50 quid from the breakers

Am i right in thinking that alternators take longer to charge the more the battery is charged, ...ie, half the distance takes you twice as long (eagles)

I was originally intending to put a pair of 120amp on through one regulator, but it will still take ages to charge batts.

Also, i will still need a lot of batts to fuel my large inverter. Looking at 2k worth and they dont even live forever. Top of the range Trojan 6v only have a 1200 cycle life span

[Amy]

On the other hand

down on the farm, there is an ex water board LDV/sherpa van with a travel power and compressor on board.

Its all being scrapped and could be had for 150 quid. If I had the PTO driven travel power from that, and it was tarted up, it might do. I dont know the output and the guages and wiring is slightly trashed. But it has an electronic engine speed guvnor fitted.

Maybe it can be pully driven.  Worth a grovel in the dirt underneath to see?

[Billy]

Hi Ames,

With a smart regulator (Stirling for instance) the alternator turns into a 4 stage battery charger and will continue to pump in 120 amps for as long as is needed for the bulk of the charge.  It will only ramp down when reaching close to fully charged.  As long as you use flooded batteries you can even up the voltage to make it happen quicker, you need to keep an eye on the fluid levels mind.

Sounds like a good deal and a compressor would be handy too.

Billy

 

[Justme]

Yeh but the last 10-20% will still take as long (actually longer if you use a higher amp charge) as the bulk phase.

You need a "system" of bat use & charging where you off set bat life for sensible charge times & fuel costs. If you are moving lots then the charging is basically free but if you need to run the engine every other day for 12 hours just to charge the bats thats a lot of cost.

During the winter we charge for 3 to 6 hours ish every 3 or 4 days & then do a full charge (about 8 hours plus) once per week or two (whilst doing the laundry) & do an EQ charge (think 12 hours) roughly monthly(on BIG laundry washing day). In summer we dont need to run the charger at all as the solar covers it all with some to spare.

[Amy]

Hi Ames,

With a smart regulator (Stirling for instance) the alternator turns into a 4 stage battery charger and will continue to pump in 120 amps for as long as is needed for the bulk of the charge.  It will only ramp down when reaching close to fully charged.  As long as you use flooded batteries you can even up the voltage to make it happen quicker, you need to keep an eye on the fluid levels mind.

Sounds like a good deal and a compressor would be handy too.

Billy

So i dont use an auto motive type regulator but an inverter type and let that do the work and worrying over how much and when to charge?
 

[Amy]

Yeh but the last 10-20% will still take as long (actually longer if you use a higher amp charge) as the bulk phase.

You need a "system" of bat use & charging where you off set bat life for sensible charge times & fuel costs. If you are moving lots then the charging is basically free but if you need to run the engine every other day for 12 hours just to charge the bats thats a lot of cost.

During the winter we charge for 3 to 6 hours ish every 3 or 4 days & then do a full charge (about 8 hours plus) once per week or two (whilst doing the laundry) & do an EQ charge (think 12 hours) roughly monthly(on BIG laundry washing day). In summer we dont need to run the charger at all as the solar covers it all with some to spare.

Monkeys can be trained so I guess theres hope for me

[Billy]

Ames,

The smart regulator is a little box that is wired up to the alternator and is a bit more advanced than the alternator one hence the wizzy functions.  The original regulator is kept as a back up and cuts in should the smart one fail (unlikely).  That way you don't have all your eggs in one basket and can still charge the start batteries or keep things going should the posh stuff have a day off.

Justme,

I don't worry putting the last bit in when using the DC generator as I nearly always have a power draw when it's on.  The windy thing floats during the day when I'm not around and if I must I turn the Victron charger on overnight.  Like you say it would keep the neighbours up for a few hours!  I don't know about taking longer with higher amps, I don't know the science but my in/out (NASA monitor) meter says less time with more amps.

Billy


 

[EccentricAnomaly]

Yeh but the last 10-20% will still take as long (actually longer if you use a higher amp charge) as the bulk phase.

Is that just because high bulk charge currents will mean you'll get to the specified voltage to switch from bulk to absorption when the battery is still at a lower state of charge or is there a more subtle reason for this?

[Justme]

Yeh but the last 10-20% will still take as long (actually longer if you use a higher amp charge) as the bulk phase.

Is that just because high bulk charge currents will mean you'll get to the specified voltage to switch from bulk to absorption when the battery is still at a lower state of charge or is there a more subtle reason for this?

That about sums it up. Basically think of the often quoted "surface" charge. Charge hard & fast & the chemical reaction can not / has not penetrated the cells plates. So it looks full (IE high volts) but after a while it will lower.

If I do a fast charge & dont follow it with a full absorb cycle I would get 2 days use, if I do the full charge I get 3 or 4 days.

Billi that NASA monitor just counts amps in & out with an adjustment for pukerts/charging losses. In use it gets further & further out of sync with the bank. You need to do a full EQ charge & then tell it that the bank is full to reset it.

It does not tell you how full the bat really is. When it says its full how many amps do you still have going into your bank & how big is the bank?

[Billy]

Justme,

When it says the battery is full the charge rate goes down to zero with the alternator floating any load.  The bank on the little boat is only 2x100C20.  The 24hr rest voltage is 13.2 and stays there for a couple of weeks.

When I spoke with NASA they said it does not just count amps but takes rest voltage into account to make up for amps in/out anomalies.  I thought it was quite clever for the price.

Are you saying that you can get a surface charge on the plates that will give the appearance (voltage) of full charge but not really without a good boil, as it were?  I think I'm learning here.

Billy