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Topic: Brain Teaser (Electrical) (Read 2726 times) previous topic - next topic

Re: Brain Teaser (Electrical)

Reply #20 –
Quote from: Barry & Cindy –
We use a variable voltage regulator in our Leece Neville alternator. Since the alternator does not use temperature compensated voltages, we lower the output voltage in summer to not over volt charge battery banks. We really don't count on the alternator to charge batteries at maximum voltages. To us, the alternator's main job is to supply electricity for a running coach, like keeping inverter, engine, lights, dash heater motor and other 12-volt loads.
The engine-driven alternator charger systems in most motor homes is based on 1920s technology and seriously needs to be re-engineered. Originally it was designed to give a big charge to the battery immediately after starting in order to replace the power withdrawn in the starting process and then provide enough for lights, engine, etc. as the vehicle moves down the road. Now, with 170-amp alternators it's supposed to be able to handle a big load while under way. But if you're not running a big load, then it's possible that your alternator is not helping your battery life.

Unfortunately, the built in regulators - and most of the add-on regulators - for them have not kept up with the pace of technology and lag considerably behind the regulators for the newer charger/converters most of us have switched to when connected to shore power or run our generators. And in comparison with some of the solar panel charging controllers they are downright antedeluvian!

I stumbled across this link for a do-it-yourselve adjustable alternator regulator but it's completely manual... not the ideal solution, I don't think. But close.

Self build adjustable alternator controler

What we really need is an accurate method of putting in a voltage setpoint so that solar panels and engine alternator can work together to keep the batteries in good shape.

Or just have the engine alternator charge the start batteries and be done with it. Maybe just a reverse-boost switch... one that when "off" only charges the engine batteries and when "on" will also charge house batteries.

Craig

Re: Brain Teaser (Electrical)

Reply #21 –
Craig,

Quote from: wa_desert_rat –
Or just have the engine alternator charge the start batteries and be done with it. Maybe just a reverse-boost switch... one that when "off" only charges the engine batteries and when "on" will also charge house batteries.

You already have that exact capability built in to your coach.  It would only require a small "adjustment" to your existing wiring harness.  While waiting for my coach to thaw out, I was analyzing my "Bubba-wired" alternator setup.  I realized that I now have a standard "2-wire" alternator in place.  All it requires to operate as designed is one post (NEG) hooked to ground, and the other (POS) connected to the positive (+) terminal of the batteries you wish to charge.  I could eliminate the existing "sense" wire from the charging system by simply disconnecting it at both ends.  If I then moved the alternator output lead from the ALT post on the isolator over to the ENG BATT post on the isolator, I would have accomplished what you are describing.  Because the two battery systems are "isolated" from each other, the alternator would only "see" the engine start batteries, and would charge them just like in any motor vehicle.  If you wanted to ALSO charge the coach (house) batteries with the alternator, you could activate the existing "BOOST" switch on your instrument panel.  This would tie both sets of batteries together, and both would be charged by the "dumb" alternator.  OR, you could wait until you were parked and connected to shore power, and then let the "smart" AC powered charger/converter do the job of charging the coach (house) batteries (the job for which it is specifically designed).  You would have complete (but manual) control over the whole process!  It would, however, require some thought on the part of the operator.

I think I've read that early motor homes were set up exactly like this.  The isolator was later added to protect the brain-dead coach owners from leaving the two sets of batteries tied together, and then running the batteries (both coach and chassis) down so far that they could not start the engine.

Re: Brain Teaser (Electrical)

Reply #22 –
Quote from: cajk –
You already have that exact capability built in to your coach. 

Yes... but then, if you want to charge both banks, you have to energize the "BOOST" solenoid. That's not a "bad thing" by itself but I'd rather see something a little more clever. It does solve the problem of an alternator boiling out the start battery; but not boiling out the house batteries if the driver mismanages the system.

Craig

Re: Brain Teaser (Electrical)

Reply #23 –
I think Brett Wolfe already mentioned this outfit in another thread.  Might be the same thing as Barry is talking about.  Perhaps they offer something that would meet your needs?

Balmar Voltage Regulators

Re: Brain Teaser (Electrical)

Reply #24 –
That would do it... the 614 looks like the one... but over $300. Seems over-priced in comparison to the Midnight Solar Classic 150 which does so much more for $600.

Craig
 

Re: Brain Teaser (Electrical)

Reply #25 –
I regularly charge house battery bank with impunity using the alternator, figure if a 160 amp alternator can't handle a hundred amp charge then I'd rather it go ahead and die.  Generator run time is too long to charge my lead acid batteriy bank.

The Balmar regulator is interesting but really expensive for what it is.  If you want an easy way to control the voltage output of your alternator just come up with a simple device to set the bias on your sense wire (disconnected from isolator of course.)  You can make it output any voltage you wish this way, it's merely removing the control of the alternator from the dumb isolator to the smart operator.