# Thoughts and a solar power question



## Chiefster23 (Feb 5, 2016)

With the NOKO situation, I have been thinking about my solar set up. If I were to lose my charge controller, do you think I could strip a voltage regulator out of a car alternator and use it as a charge controller? Yes, I understand that alternators may be destroyed by emp. But there are millions of them out there. Surely some will survive. I can't really think of any reason why this wouldn't work. It may be more crude than my fancy controller, but anything is better than nothing. And if alternator voltage regulators ARE suitable, they certainly provide a much cheaper alternative than commercially available charge controllers because junk yards are full if them. And alt regulators are rated much higher than charge controllers (amperage).


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## dwight55 (Nov 9, 2012)

Chiefster23, . . . I like your idea, . . . and while I am an electrician by trade, . . . not much into the interior workings of low voltage setups / auto stuff, . . . unless you go back to a '68 Mustang, . . . that electric I can handle.

OTOH, . . . I like your idea, . . . do not know why it won't work.

My backup to the backup to the backup is a Pepboys self contained alternator, . . . one of those one wire things that is an alternator and voltage regulator all in one. I have done nothing to make it work so far, . . . but the idea in the back of my head is to put it on some kind of windmill thingy or rig it up to a stationary bicycle, . . . 

BUT, . . . I might just have to go see about one of those junk yard alternators, . . . post it up here if you try it.

May God bless,
Dwight


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## sideKahr (Oct 15, 2014)

An alternator's voltage regulator is solid state. Probably wouldn't survive an EMP. But if one did, make sure to strip out the rectifier; it's not needed as your solar panels already produce DC.

You would have to manually monitor the charge, and disconnect it when your batteries top up, or they could boil dry. I can't think of any other reason that it wouldn't work. The regulator should supply 14 volts, which is close enough for lead acid or AGM batteries.

Have you ever bought a junk one and tried it?


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## Chiefster23 (Feb 5, 2016)

No. Never tried it. But if I can scrounge up an alternator I want to give it a try. The idea just recently occured to me due to the doom and gloom on the news channels. I honestly don't see any way Trump can avoid an armed conflict, assuming of course he has the stomach for it. So I am fine tuning my situation and spending a lot of time thinking about things I may have missed or can improve on.


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## dwight55 (Nov 9, 2012)

Chiefster23 said:


> No. Never tried it. But if I can scrounge up an alternator I want to give it a try. The idea just recently occured to me due to the doom and gloom on the news channels. I honestly don't see any way Trump can avoid an armed conflict, assuming of course he has the stomach for it. So I am fine tuning my situation and spending a lot of time thinking about things I may have missed or can improve on.


There are a lot of us thinking in those terms..........

May God bless,
Dwight


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## Mad Trapper (Feb 12, 2014)

I've used a small 12V panel straight to charge my 12V deep cycle battery. The panel is only a few amps. Labor intensive as I need to disconnect at night and monitor charge with my multimeter. 

Why not use a simple cutout regulator or analog voltage regulator found on early tractors? Those won't care about a EMP.

P.S. 

Why don't we just remove the NOKO nutjob? His weapons were all procured with Willie Clintoons stamp of approval. Aren't you glad H-Beast is not POTUS!


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## Back Pack Hack (Sep 15, 2016)

Why not just purchase a second controller and store it in a faraday cage?


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## SOCOM42 (Nov 9, 2012)

You could use an old electro-mechanical one from the 60's when DC generators were common in cars and trucks.


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## Chiefster23 (Feb 5, 2016)

Back Pack Hack said:


> Why not just purchase a second controller and store it in a faraday cage?


I have a small cheap one stored. But many can't afford to do this so looking for logical alternate solutions. My primary controller cost over $300. So it is cost prohibitive for me to store a duplicate. But I appreciate all your suggestions.

I don't think it would be necessary to strip out the rectifier. Yes it isn't necessary due to the DC output from the solar panels. But the rectifier would pass the DC right thru with no problems.

As far as boiling the batteries after they are fully charged......not sure that would happen. Cars and trucks run for hours with their alternators putting out 14 volts into fully charged 12 volt batteries without damaging the batteries.

I have a car I rarely drive and never drive at all in the winter. I purchased a small COLEMAN solar panel that puts out around 13 volts if memory serves me correctly. I have this direct connected to the car battery without a controller. 13 volts charging into a fully charged 12 volt battery results basically in zero charging current. I've been doing this for years now without any damage to the battery.

But again, I appreciate the replies and this thread certainly supplies ideas and food for thought.


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## Back Pack Hack (Sep 15, 2016)

Chiefster23 said:


> I have a small cheap one stored. But many can't afford to do this so looking for logical alternate solutions. My primary controller cost over $300. So it is cost prohibitive for me to store a duplicate. But I appreciate all your suggestions.............


Your second controller doesn't have to be the exact same make & model as your $300 unit. Look around on ebay, Craigslist, maybe inquire within your network. You might find a usable back-up for far less.


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## sideKahr (Oct 15, 2014)

Chiefster23 said:


> ...I don't think it would be necessary to strip out the rectifier. Yes it isn't necessary due to the DC output from the solar panels. But the rectifier would pass the DC right thru with no problems.
> 
> As far as boiling the batteries after they are fully charged......not sure that would happen. Cars and trucks run for hours with their alternators putting out 14 volts into fully charged 12 volt batteries without damaging the batteries...


1. The rectifier requires a minimum forward voltage before it will pass any current. I believe it's around 3 volts, I'm not certain. In partial sun, your panel may only be producing 2-3 volts, so with the rectifier in circuit, that energy would be wasted.

2. I run an AGM battery bank. Specs require 14.8 volts tapering to 14.2 volts while charging, and no more than 13.6 volts maintenance. So I have to be careful not to overcharge, and 14+ volts would be walking the line for me. Lead acids may be different.

Do you find you need to add a lot of water to that car battery you're charging with the Coleman panel?


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## Chiefster23 (Feb 5, 2016)

Good info to know! I love this forum. Lots of folks with different backrounds and tons of good info.
No, I never added water. I have used this panel on 3 different cars but all were sealed batteries. The COLEMAN panel is small. About 16 inches square. And full output is 6 watts so it is more of a battery maintainer than a charger. I was very hesitant initially about using the panel without a controller. Who wants to ruin a battery costing between $100 to $150? But it has worked out as advertised so no problem.

Now, about the rectifier. I realize there is a minimum forward voltage to overcome the diode. But most/all solar panels have a blocking diode factory installed on the panel to prevent nightime discharge. So the panel has to produce a minimum voltage to overcome this blocking diode anyway. Am I missing something?

Now maybe someone with auto tech knowledge can chime in here. My understanding is that auto voltage regulators are set to produce a certain fixed voltage output, 14 volts. I don't believe they taper down as the battery charge approaches 100%. Am I correct? So if the engine is at a certain minimum rpm, there is 14 volts charging into the battery. Of course if the car is running there is always some load on the battery, too. So I guess my question is why doesn't the constant 14 volt overcharging damage a car battery?

Maybe I'm getting pretty far into the weeds on this subject but I think knowing how to jury rig a voltage regulator might be a very useful bit of knowledge someday.


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## modfan (Feb 18, 2016)

My understanding is the alternator regulator is a switching regulator. So it's either on or off. When the battery reaches around 14 volts it will shut off and turn back on when drops to around 12volts. It uses the vehicle battery to filter this switching from the vehicle electronics.

It does this by turning the field on and off on the alternator. So, you will need to add a heavy duty transistor to switch the current from your solar panel off and on. You can also purchase an electronic regulator out of an alternator separately. Just pick your alternator and order a replacement regulator. Napa can get these for you.


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## sideKahr (Oct 15, 2014)

Chiefster23 said:


> ...Now, about the rectifier. I realize there is a minimum forward voltage to overcome the diode. But most/all solar panels have a blocking diode factory installed on the panel to prevent nightime discharge. So the panel has to produce a minimum voltage to overcome this blocking diode anyway. Am I missing something?...


You're right. But there are different kinds of diodes. Schottky diodes have very low forward voltages, around 0.8 volts, whereas normal diodes are much higher. I have no idea what types of diodes PV panels or alternators use.

Now you've gone and done it! I guess I'll be on the electronics forums for the next few hours.


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## Chiefster23 (Feb 5, 2016)

So from modfan it sounds like just using an auto voltage regulator by itself won't work. OK. It was just a thought and it certainly got us all thinking. I like socom's idea of an old 60's tractor voltage regulator. I know just where to get one if push comes to shove.

Bye the way, I purchased spare schottky diodes for my solar panels. They were very cheap on ebay.

News this morning about fatboy moving another rocket and prepping for a launch. I wish Trump would just quit shitting around and hit the rocket on the lauch pad with a cruise missle. Kim isn't going to do anything about it. He's not suicidal. He knows any strike by his troops would result in his personal total destruction. China and Russia will bluster and moan But do nothing about it. No one is going to risk nuclear war over a fat petulant child.


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## Kauboy (May 12, 2014)

I respect the ingenuity of this entire discussion, but have reservations about implementing such a set up.
Not from a technical standpoint, but from a practical one.

We all hope an EMP never hits, but if it does, do we really want to be the guy on the street with full power and huge panels on the roof?
For comfort during a blackout? Sure.
For a long lasting situation where the grid isn't coming back for a few months, minimum?
Personally, I don't want that target on me.

If you have a full set up, and live away from civilization, this could make perfect sense.
For those like myself who find themselves in suburban hell during SHTF, this is playing with fire.
I have a grand total of 2 solar panels. Their wattage nears 100w total if run together. Their purpose is only to charge small 12v batteries, which will in turn charge other lower voltage items and *maybe* run a small DC lighting set up for a few hours. (this is my portable power box from a thread long ago, I'll link it if I can find it)
My thinking is, when the world goes dark, try not to let others know you've got the only light.

I'm still interested to know if this would work though.


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## 8301 (Nov 29, 2014)

The answer to the OP is no. Basic PMW controllers slowly reduce or cut off all charging when needed but only work well when the panel voltage Voc is roughly 170% the battery bank voltage. Modern automotive regulators instead close a switch to send current to the cars alternator creating an electromagnetic field when the controller senses that battery voltage is low; kind of the opposite of what you'd want the switch to do.

On the older 1 wire alternators the controller probably would work but you wouldn't get a good battery absorb cycle so the cells on the battery would probably get out of balance. In addition with higher string voltages (two of my strings run at 316v) the mechanical gap in the older alternator switches probably isn't wide enough to prevent the spark from jumping which would quickly burn out the contacts.


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## sideKahr (Oct 15, 2014)

Thank you, John Galt.


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