555-JHO Regulator vs Charge controller question

[dkeav]

Looking to make an off grid 48v bank charger for mobile applications (utility/golf cart type banks) when coupling a 555-JHO to a small engine like a gx series honda, It has been advised to use one of the marine voltage regulators for soft start and ramping up.  Question is, in this setup do also need to use an MPPT charge controller?

[mobile_bob]

aside from other issues, the short answer to your question is this

no you will not need an mppt controller, the marine controllers are programmable and will do everything you will need to get the job done.

mppt only really comes into its own when you have a significantly higher dc bus voltage over that of the battery bank, mppt takes this higher voltage and converts it to higher amperage and thus more effective power vs simply clamping down a higher voltage to the battery buss voltage.

with the marine controller the alternator voltage is set to the proper charge voltage (regime) for the battery technology used and state of charge of the battery... therefore there is no gains to be made by going through a mppt controller.

the issue you will run into however is how you intend to get a 555jho to charge up to ~58vdc needed for most battery technologies to properly charge, without modification/upgrade to the rectifier bridge.... even then the efficiency is not going to be all that good.

the 555jho does very well into a 24v bank, charging at 28.8volts, here the efficiency is quite good, provided you connect things correctly as the 555jho requires a 12v field and controller, rather than a 24volt controller. 

you could do a couple of things to simplify matters.

run dual 555jho alternators, split the battery bank and charge at 24v nominal into each bank, even then you have to have a source for 12v excitation.  or...

you could have your 555jho alternators, built with 24volt rotors, and then you could use a 24v controller, provided it is like the balmar and can handle two field rotors.

it all depends on what your goals are, if you simply need it as a backup to a solar pv installation, maybe you could do it with one alternator with the rectifier upgraded to 200piv diodes and a single controller, the efficiency might be acceptable even if not spectacular as i would expect it to be somewhere in the 55-60% range. 

l settled on a split system myself, as i have a large capacity of pure sine wave inverter installed and the ability to drive dual 555jho alternators, with this system getting upwards of 80% efficiency is possible and has proven so in testing.

maybe more than you asked? 

fwiw

bob g

[dkeav]

Not too much that is great information, I guess I didn't understand MPPT all that well (or any of this really).  I suppose with some clever wiring to split the bank on the golf carts for charging in halves could work, only fear there would be have imbalanced bank maybe.  Don't currently have a method besides full oversized AC generator running full blast to power the AC/DC golf cart charger, this works but obviously isn't efficient at all and not as portable.  Was just trying to come up with a smaller more portable method to charge 48v banks directly regardless of location (woods, pasture, wilderness).  Will have to research further.

A thought occurs since you mention breaking the banks down for charging.  I wonder if I couldn't use a battery isolator like for RV use to charge the bank in 24v segments.

https://www.emarineinc.com/categories/Battery-Isolators

[dkeav]

Another thought occurs.  The DC version of the Honda EU gensets the AlphaGen models produce 48-52VDC output.  This is ok for maintaining and somewhat charging a bank, but won't equalize it.  They have an AVR on them just like the AC model, why couldn't someone replace the AVR with something that can get the voltage up to 60vdc or so?  Has anyone replace the AVR's on the AC model?

http://www.ebay.com/itm/ALPHAGEN-DCX3000-36-48V-DC-GENERATOR-NEW-WITH-ACCESSORIES-041-028-10-/321772512458?hash=item4aeb22e4ca