Solar panel charger/ regulator for Alternator

Submitted: Thursday, Dec 16, 2004 at 20:32
ThreadID: 18640 Views:7345 Replies:11 FollowUps:25
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Hi all,

Wondering if you could connect a 3 stage smart charger / regulator (such as Plasmatronics) used on solar panels to a vehicles alternator output to control charge to main and aux batteries in cars / campers?

I cannot read anywhere an input voltage range for the units but if it could be done it would give a fantastic charger capable of charging your batteries to 100% capacity instead of the 75% that the alternator does.

Any ideas?

Regards
David

GU Patrol currently being converted.....
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Reply By: Eric Experience. - Thursday, Dec 16, 2004 at 22:02

Thursday, Dec 16, 2004 at 22:02
David.
The solar regulator is a series regulator so it must have at least 1volt drop across it so it wont help your auxilaly batteries at all. If you wont to get 100% charge into your 2nd battery just charge it via a relay from your alternator output terminal. The modern charging systems have a small resistance between the alternator and the battery so the alternator output is a little higher than the starting battery, this is enough to fully charge your battery. obviously you must check with a meter that you dont go over 14.8V. Eric.
AnswerID: 89160

Follow Up By: Member - David C (QLD) - Thursday, Dec 16, 2004 at 22:10

Thursday, Dec 16, 2004 at 22:10
Hi Eric.

Many thanks on the voltage drop - something I didn't find in my searches however a cars alternator never charges a wet lead acid battery past 75% capacity. It can charge gel and AGM batteries to 100% due to their different design and voltage characteristics but a 3 stage charger is needed to charge wet lead acid to 100% and I was hoping that this type of charger could be utilised to do this for me.

Regards
David
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FollowupID: 348067

Follow Up By: Eric Experience. - Thursday, Dec 16, 2004 at 23:06

Thursday, Dec 16, 2004 at 23:06
David
That is the purpose of going directly to the alternator output, it has that little extra voltage you need to get a full charge, check it with a meter, full speed with your lights on will give almost 15 volts. Eric.
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Follow Up By: David Au - Friday, Dec 17, 2004 at 07:31

Friday, Dec 17, 2004 at 07:31
David C "cars alternator never charges a wet lead acid battery past 75% capacity" is not a correct statement. If you check vehicle batteries is the alternator regulator is correctly set or manufactured, the battery will always be in the order of 95% to 100%. If the battery is only charged 75% the regulator needs adjustment or replacing.
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Follow Up By: Glenno - Saturday, Dec 18, 2004 at 11:05

Saturday, Dec 18, 2004 at 11:05
Im with David.

If I drop my 3.5A/hr 3 stage charger on my Hilux starting battery it only take about 30mins of charging before its 100% charged.
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Reply By: brett - Thursday, Dec 16, 2004 at 22:25

Thursday, Dec 16, 2004 at 22:25
There is no reason an alternator will NEVER charge to 100%, it's a high current source regulated to approx 14.2 ~ 14.4V, just like your battery charger. The problem is that last 20% of charge takes time, as the battery charges the current drawn drops off. So it's unlikely you'll drive for 24 hours to get that last 20%. The AGM type batteries will draw a higher charge current so tend to charge quicker, but it will probably still take a while to get that last bit in.
AnswerID: 89165

Reply By: Wok - Thursday, Dec 16, 2004 at 22:34

Thursday, Dec 16, 2004 at 22:34
David C,

I have gone through the same pain, if you do a search it is here [somewhere]?!

To answer your question about Plasmatronics, I have a cit from them outlining the connection from alternator, battery charger + solar panel to the controller + battery for their model PL20.

1. This model is PWM.
2. It cannot give you more voltage then the alternator output.
3. It requires [a.] the DC Shunt [b] PLS2 Shunt adapter = $$$

The conclusion I came to is that this unit would not fully charge a wet-cell aux battery from the alternator IF your alternator's output is below 14.7V.

Rgds
AnswerID: 89166

Reply By: drivesafe - Friday, Dec 17, 2004 at 00:10

Friday, Dec 17, 2004 at 00:10
Hi David C, unless you have some bad connections or wrong cable or what ever, in most cases you can easily get better that 90% charge off your alternator.
After you have been for a decent drive some time. Leave the vehicle for a few hours and then check the voltage level in the batteries and compere them with a conversion list. This is NOT an accurate way to check the battery charge but it will give you some idea of the state of charge that has been applied to the battery by the alternator.
Cheers.
PS. If someone knows a web site with a list of voltage verses % of charge please post it.
AnswerID: 89175

Follow Up By: Member - Sand Man (SA) - Friday, Dec 17, 2004 at 01:30

Friday, Dec 17, 2004 at 01:30
Here you go drivesafe.

Battery FAQ

To get to it quick:-
Click - Battery Voltages - then scroll down to State Of Charge

Bill


I'm diagonally parked in a parallel Universe!

Member
My Profile  My Blog  My Position  Send Message

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FollowupID: 348084

Follow Up By: drivesafe - Friday, Dec 17, 2004 at 08:27

Friday, Dec 17, 2004 at 08:27
Hi Sand Man, thats a good site.
It explains it in layman’s terms, making it easier for someone to arrive at as near a correct finding as can be expected without going in to heaps of tests and calculations.
Thanks again.
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Follow Up By: Member - Ross P (NSW) - Friday, Dec 17, 2004 at 08:52

Friday, Dec 17, 2004 at 08:52
Here's another one;-
http://www.uuhome.de/william.darden/index.htm
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Follow Up By: Member - Ross P (NSW) - Friday, Dec 17, 2004 at 08:58

Friday, Dec 17, 2004 at 08:58
drivesafe,

This is my experience.

Drive for 8 hours wth caravan battery connected via heavy duty cable (>10 mm sq). Disconnect battery and connect mains powered "smart" 3-stage charger. It takes a couple of days before the charger switches to "maintenance-fully charged"mode.
It's a deepcycle wet cell battery, though!
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FollowupID: 348104

Follow Up By: Member - Jeff M (WA) - Friday, Dec 17, 2004 at 15:33

Friday, Dec 17, 2004 at 15:33
Great site, here I was being not 100% happy with my charging setup because I didn't think I was getting close to 100% but in reality both my battery are a 12.6 first thing in the morning before I start the truck, that's pretty good considering it's only doing short trips at the mo.
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FollowupID: 348159

Follow Up By: drivesafe - Friday, Dec 17, 2004 at 19:44

Friday, Dec 17, 2004 at 19:44
Hi Ross P, I don’t use battery chargers much so I don’t have all that much experience with them so your posting is interesting.
There are a number of reasons that might cause such a long delay.
The battery may have been overdue for a good top up charge.
The charger itself might be set to such a high point where the battery has to get to before the charger changes ( note I am not saying this is a problem just an observation )
The charger may be a SMART type charger and may have a deliberate delay programmed into it to do just what it did.
Anyway it is still interesting.
Cheers.
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FollowupID: 348186

Reply By: fourplayfull - Friday, Dec 17, 2004 at 00:17

Friday, Dec 17, 2004 at 00:17
Hi David , very simple , we have a set up running on several diesel powered houseboats with a smart reg. which charges similar to 3 stage batt. charger - made by BV Engineering - SAR -20 Cruz Pro reg . Check details on www.cruzpro.com The VAH 30 is a great gauge for monitoring volts, amps in &out & amp hours remaining .
Happy CHARGINGGGGGGGG!!!!
John
AnswerID: 89176

Reply By: Member - David C (QLD) - Friday, Dec 17, 2004 at 09:16

Friday, Dec 17, 2004 at 09:16
Hi all

My system has been designed for optimum performance using the the alternator as the charge source by using good quality connectors, 6 B&S cable throughout and electrnoic isolator. However it is common knowledge in the auto electrical industry that to charge a wet celled battery to 100% you would need to drive continuously for 24-48 hours because of the tapered off charged that the alternator produces when it comes up to 70-80% battery capacity.

This is one of the main reasons why people experience poor performance in their dual battery setups because they only have around 30AHr usable from a 100AHr battery (working on the manufacturers recommendations of not discharging past the 50% level which will damage the batteries longterm).

A way around this is to manually control the alternators field to "trick it" into thinking that the battery is at a lower state of charge, however you have to be very careful with this and switch it back to standard after a couple of hours or you will overcharge the battery.

I have done a lot of research on the problem and have found smart regulators (like the cruzpro and xantrex) which take alternator output and turns it into a 3 stage smart charging system that will charge all batteries to 100%. These however are quite expensive (around $500) but if a solar 3 stage smart charger operates the same then I can buy one of these for around $150 - $250 which I could use.

The problem is finding out if the input voltage is enough to enable me to do this. The link that sandman provided is a good explanation of all this and describes why standard alternators and chargers only get your batteries up to 75% - 80%.

I read a lot of people saying that this is not true but a search on the internet and books sold (such as those by Colin Rivers) will prove that it is. I think people are just not wanting to accept this fact for fear that their system is not actually performing as good as it could but I have done my research and can back up all facts.

I welcome all posts though and am happy to post links to sites with great explanations of vehicle charging systems and 3 stage mart chargers.

Regards
David
AnswerID: 89199

Follow Up By: drivesafe - Friday, Dec 17, 2004 at 12:44

Friday, Dec 17, 2004 at 12:44
Hi David C, your result is correct but what causes that result is actually back to front.
An alternator just produces current determined by the current load present to it, it has no way of knowing if the battery is charged or not.
When a battery is low there will be a larger than normal voltage difference between the battery voltage and the regulator voltage.
The current being produced is the current that the battery requires and as long as the alternator is turning fast enough then it will produce the current the battery will needs.
As the battery charges and it’s voltage approaches the regulator voltage, the current requirements of the battery reduces.
If you had a battery full charged by the vehicle’s charge system at as example ONLY, the battery was about 85% charged and the you increased the vehicle’s voltage regulator from 14.2 to 14.9 and the went for a good drive. You would find that at the end of the drive battery would be close to 100% but if you measured the current coming from the alternator, you would find that at the instant you increased the voltage level of the regulator, the current coming from the alternator increased.
This has nothing to do with the alternator “knowing” how if the battery is charged or not.
Facts are that the battery itself determines how much current it wants, the alternator only knows that there is a demand for current.
The greater the voltage difference between the batteries voltage and the power sources voltage, the greater the current will be going into the battery.
There is another way this could be demonstrated. If you had 50 batteries all fully charged and you connected one battery to the vehicles charge system and that battery pulled 1 amp when fully charged as you connected each new battery to the charge, the alternator would increase it’s out put by one amp for each additional battery.
Also if you have a battery that is pulling 10 amps at a given voltage, It won’t matter if the alternator is capable of producing 10 amps or 1,000 amps, the battery will only pull 10 amps.
Put quiet simply, you have to increase the voltage applied to the battery to increase the battery's charge level.
Cheers
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FollowupID: 348135

Follow Up By: Member - David C (QLD) - Friday, Dec 17, 2004 at 20:40

Friday, Dec 17, 2004 at 20:40
Thanks for this great discussion drivesafe. I believe that we are all learning something from this.

Regarding your post above - Yes and no....

Yes an alternator produces current according to the voltage on the voltage sense line. Any high current device connected to the circuit drags the voltage down which tells the alternator to produce more current. A battery may however need 50 amps to bring it back to 100% (which won't happen because of the safeguards) but an alternator won't produce 50 amps just cause the battery wants it. It may produce only a fraction of this as it is designed to charge a lead acid battery according to a C-rate (for example C/8) which corresponds to battery capacity divided by rate (8 in the example). This is usually how an alternator and battery is matched to standard vehicles.

But with battery charging the charging voltage is critical - not current. Current determines the length of time it charges for but voltage determines at what capacity. According to this site (go to heading near bottom called "Battery Charging Voltages and Currents:") "Charging at 15.5 volts will give you a 100% charge on Lead-Acid batteries" Therefore because an alternator can only output a max 14.5 volts (no load), a battery will never be charged to capacity.

Regards
David
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FollowupID: 348190

Follow Up By: drivesafe - Friday, Dec 17, 2004 at 21:24

Friday, Dec 17, 2004 at 21:24
Hi David C, I posted some details relating the charge voltage in an earlier, down further in this posting so I won’t go there again.
As for take battery voltage up to 15.5 volts, this MY opinion not text, so take it or leave it but I would not like to take a battery up to that voltage level. Although only marginally lower, I still would not go above 15 volts and even then only for a matter of about 2 hours once every 30 days.
14.5 is the highest operating voltage that I would maintain and again this only my opinion, keeping a battery at higher voltages is not good housekeeping.
One more point, few batteries could ever hope to take 50 amps. AGMs and the like, yes. But as the vast majority of batteries are standard wet cell cranking batteries and deep cycle batteries and these batteries may take a very short burst of 40 amps for a few seconds and even this is unlikely and more likely to be in the order of no more than 25 amps and that is for a relatively flat battery.
I make a 40 amp battery charge controller and that works for 95% of auxiliary battery charge controls set ups.
Cheers
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FollowupID: 348200

Reply By: Member - David C (QLD) - Friday, Dec 17, 2004 at 10:20

Friday, Dec 17, 2004 at 10:20
Hi All,

Maybe an explanation of the alternator may help the situation.

An alternator adjusts it output according to a sense line connected to the battery. As the battery voltage increases, the alternator output decreases.

To prevent overcharging batteries, the alternator reduces current output to only a couple of amps (or less) as you cannot accurately determine a batteries state of charge by its voltage (hence why output is minimal when battery is at around 80% state of charge) This is the key point and is the safe guard that the manufacturers have built in to the system so we don't overcharge, kill and/or blow up batteries.

The alternators primary task is to run the vehicles electricals and secondly to recharge the battery so the voltage sense line is continually changing depending on engine revs, what ancillary devices are drawing current etc. Also with nearly every dual battery system I have seen there is also a mismatch in battery capacities which further adds to the problem.

I hope this helps in trying to explain why I am looking into other systems.

Regards
David
AnswerID: 89208

Follow Up By: Austravel - Friday, Dec 17, 2004 at 10:41

Friday, Dec 17, 2004 at 10:41
I thought the unregulated voltage output of an alternator was quite high, depending on speed it can be up to 100volts. If this is so it could be reduced and then put through a plasmatronics unit. I guess this is the reason for the shunts you talk of, is it?
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Follow Up By: Mainey... - Friday, Dec 17, 2004 at 10:56

Friday, Dec 17, 2004 at 10:56
David,
Re; your post further above where you talk about "tricking" the alternator into thinking the ………......

I had my vehicle’s regulator replaced with a "different" one that gives that same result.

Cost was about $60 and was fitted in minutes by a qualified Auto electrician as part of the dual battery/solar system installation.

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FollowupID: 348118

Follow Up By: Member - David C (QLD) - Friday, Dec 17, 2004 at 12:49

Friday, Dec 17, 2004 at 12:49
Now this is great! I did'nt even think of searching for companies with modified regulators. A hell of a lot cheaper too.

You could also have 2 regulated outputs - one standard (for vehicle electrics) and one modified to supply a solar 3 stage charger / regulator to charge batteries.

Regarding shunts, I believe these are mainly used for accurately reading current and amp hours used (with the appropriate meter). I think all smart solar regulators use them but will have to delve into it a bit more. Also you could regulate the raw alternator output to any voltage required.

Thanks guys
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FollowupID: 348136

Follow Up By: Austravel - Friday, Dec 17, 2004 at 13:25

Friday, Dec 17, 2004 at 13:25
Hi David,

Can you let me know were your travels with this issue takes you. I'm interested in doing the same thing if the cost is reasonable.
Thanks
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FollowupID: 348145

Follow Up By: Wok - Friday, Dec 17, 2004 at 14:07

Friday, Dec 17, 2004 at 14:07
David,

How do you propose to get 2 different regulated o/ps from 1 alt? I have heard of twin alt setups to do this?

Following on from your explanation of the Sense wire...would it help if I used as many electrical accesories, lights highbeam etc...... would that 'fool' the regulator into giving more current for the battery..and hence fully charge it?

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FollowupID: 348149

Follow Up By: Rod - Friday, Dec 17, 2004 at 15:16

Friday, Dec 17, 2004 at 15:16
Mainey

Interested in your $60 regulator swap. Was your original regulator a internal type ? What brand of alt did u have ? Do you have any more details on the swap (eg reg brand)

Thanks

Rod
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Follow Up By: drivesafe - Friday, Dec 17, 2004 at 16:06

Friday, Dec 17, 2004 at 16:06
Hi Wok, the only way to get a greater % of charge in the battery is to raise the charging voltage. It makes no difference how much current you make available to the battery, the battery itself rules how much current it is going to accept. You could have an alternator that can produce 1,000 amps but if the battery will only take 10 amps thats it 10 amps. Simply put the high the voltage the better the charge, again, the current is limited by the battery itself.
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FollowupID: 348161

Follow Up By: Wok - Friday, Dec 17, 2004 at 17:57

Friday, Dec 17, 2004 at 17:57
How are you going Drivesafe?

I agree with your analysis. I think David's 'trick' is a voltage divider on the sense line to change the reference voltage?...thus giving a higher output VOLTAGE across the battery >> more charge.

Too many questions...............

Gave TRADIXX [sp] a plug somewhere........Merry Christmas to you & family.

Cheers..................hic...........hic.........
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FollowupID: 348176

Follow Up By: drivesafe - Friday, Dec 17, 2004 at 18:20

Friday, Dec 17, 2004 at 18:20
And the same to you and yours Wok and everyboby else
Cheers all.
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FollowupID: 348180

Follow Up By: Member - David C (QLD) - Friday, Dec 17, 2004 at 20:53

Friday, Dec 17, 2004 at 20:53
Hi Wok,

Regarding the 2 different outputs from one alternator - you just parallel another regulator with the standard one but of a different voltage. Obviously current will not be as much (shared between the two) but you can achieve the desired voltage you want while maintaining the existing system. Where it becomes tricky is the voltage sense line and determining which output has priority over the system.

A better way would be to adjust the voltage sense line using a switch and resitor to produce a voltage drop which would make the alternator think that the voltage was low (current requirement high) so that its output is raised. I think that making an adjustement to the voltage regulator would also be required.

Regards
David
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FollowupID: 348192

Follow Up By: Glenno - Saturday, Dec 18, 2004 at 16:02

Saturday, Dec 18, 2004 at 16:02
Hi David C,

If what you are saying is right, then when the voltage sense line on the alternator detects the main battery is fully charged and the alternator current drops off, does this mean that the dual battery controller will at best be only feeding through a few amps, as thats all the volate sense line on the main battery is telling the alternator to do.

Or do the dual battery controllers play with the voltage sense line?

Or am i confused? :)

Cheers,

Glenn.
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FollowupID: 348239

Reply By: Rigor - Friday, Dec 17, 2004 at 13:50

Friday, Dec 17, 2004 at 13:50
Just my 2 cents worth , an alternator does not have a"raw" output without a regulator , the reg pumps current back into the rotor coils at a rate determined by the output load ,eg battery state of charge . It is easy enough to make your own reg with a variable reference voltage that one can vary the charge rate to suit your needs . I agree that the battery is not generally "full" even after a couple of hours of driving , this is why I trickle charge my batts at 1 or 2 amps overnight every week or so . I believe the industry calls this a conditioning charge and keeps the batts in the best state possible.

Cheers Dave L
AnswerID: 89234

Follow Up By: Member - David C (QLD) - Friday, Dec 17, 2004 at 19:20

Friday, Dec 17, 2004 at 19:20
Hi Dave,

When I saw "Raw" I mean the 3 phase AC voltage that is a direct result of the action inside the alternator. This raw output is rectified and the regulator determines the voltage. An alternator is just an AC generator with additional components to provide a regulated DC output.

Regards
David
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FollowupID: 348184

Reply By: Mainey... - Friday, Dec 17, 2004 at 21:39

Friday, Dec 17, 2004 at 21:39
Rod

In reply......

The regulator is an Ex-ternal type
The brand of alt I DID have -> Toyota original
Do you have any more details on the swap (eg reg brand) -> I will get the brand and model numbers for you early next week, not home till then.

Mainey...
AnswerID: 89289

Reply By: Eric Experience. - Saturday, Dec 18, 2004 at 22:34

Saturday, Dec 18, 2004 at 22:34
David.
You are nearly correct with your discription of the charging system. The bit about parallel regulators is completetely wrong. The way an alternator works is to supply a constant voltage to a bus bar or common piont in the fuse and fusable link box, this is acheived by sampling the voltage on the bus bar. The alternator does not know or care about the battery charge it just keeps pumping out a constant voltage and the battery is charged by a wire to the bus bar, it is the resistance of this wire and the fusable link in series with it that limit the charge rate,as the battery voltage increases the current drops off. The reason you can get more charge by connecting directly to the alternator output is because the resistance between the alternator output and the bus bar where the voltage is constant has a voltage drop across it that is proportional to current, if the current is high as it is when you first start up then this voltage can be .5 volt above the regulated voltage this is about the extra voltage you reqiure to fully charge your your 2nd battery, as the current drops this extra voltage drops and all is in control, as you can see if you draw out the cct as described if you connect any load to the battery terminals it will be robbing the vehicle battery of charge that is where the commercial so called smart regulators fall down. Eric.
AnswerID: 89408

Reply By: Mainey... - Thursday, Dec 23, 2004 at 22:33

Thursday, Dec 23, 2004 at 22:33
Rod

sorry for the delay, the Regulator I have is as follows ->

Written on the case is the following;

INGRAM

"831231 ?

TEMP/COMPENSATED ADJUSTABLE made in Australia by Ingram Corporation"

Not 100% totally positive as to the number as paint has faded

Hope this assists you

Mainey...

.
AnswerID: 90142

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