# Charge controller and battery charging question!



## Big Dreamer (Aug 6, 2010)

I just installed a charge controller and made a panel to mount everything. 

Today was a great solar day and direct sunlight. The charge controller I installed is a EPIP20-H I bought off ebay. I know you get what you pay for but I have a tight budget right now. I have put the manual on my website at http://www.sci.projectgm.com/html/epip20-h.html
Just below the picture of the manual is a link to the PDF if you want to see that and below that is a picture of the setup I have. A work in progress! 

Okay now for the question

When charging the battery with a solar panel and charge controller what should the max voltage at the battery be? 

I am assuming that the controller should regulate it around 14.4 volts per the manual. This had the battery voltage up around 15.5 volts and at that point the charging current was around .86 ma but had been as high as 3.46 at one point at 13.00 volts. I am sure that is too high and could destroy the battery if I keep using that. The other charge controller I was using kept the battery voltage around 13.9 â 14.00 during direct sun light which I think is about right. 

I wired this as follows. Solar panel to the disconnect box to the charge controller and then to the battery. There is a shunt between the charge controller and the battery so I can monitor the voltage and current. 

This charge controller supposedly has a 2 year warranty but I want to make sure I have everything correct before I try and get a hold of them. 

Any advice or suggestions would be appreciated.
Thanks
Gerald


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## 12vman (Feb 17, 2004)

Maybe you got a bad one. 15 volts is a bit high but the current was low. I might question the battery!


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## Big Dreamer (Aug 6, 2010)

I hope it is not the battery! it is less than a month old.


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## wy_white_wolf (Oct 14, 2004)

15.5VDC measured at the battery. I'd say the charge controller is bad if the voltmeter is accurate. Can you get/use a second one to check?

Like the manual states "regulation point - 14.4V" That should be the highest voltage on the battery side of the CC you see.


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## Big Dreamer (Aug 6, 2010)

I found this what do you think about it? 


Battery Charging

Battery charging takes place in 3 basic stages: Bulk, Absorption, and Float.

Bulk Charge - The first stage of 3-stage battery charging. Current is sent to batteries at the maximum safe rate they will accept until voltage rises to near (80-90%) full charge level. Voltages at this stage typically range from 10.5 volts to 15 volts. There is no "correct" voltage for bulk charging, but there may be limits on the maximum current that the battery and/or wiring can take.

Absorption Charge: The 2nd stage of 3-stage battery charging. Voltage remains constant and current gradually tapers off as internal resistance increases during charging. It is during this stage that the charger puts out maximum voltage. Voltages at this stage are typically around 14.2 to 15.5 volts.

Float Charge: The 3rd stage of 3-stage battery charging. After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since it's main purpose is to keep an already charged battery from discharging. PWM, or "pulse width modulation" accomplishes the same thing. In PWM, the controller or charger senses tiny voltage drops in the battery and sends very short charging cycles (pulses) to the battery. This may occur several hundred times per minute. It is called "pulse width" because the width of the pulses may vary from a few microseconds to several seconds. Note that for long term float service, such as backup power systems that are seldom discharged, the float voltage should be around 13.02 to 13.20 volts.


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## 12vman (Feb 17, 2004)

I allow mine to rise to 14.2 then float at 13.6. 15 volts really makes them boil, let me tell ya..


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## wy_white_wolf (Oct 14, 2004)

From another site



> Type of Charging
> 4 Stages: PWM, Equalization, Boost and Float, temperature compensated charging


Is it in equalization mode? That would be around 15-15.5 volts


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## Big Dreamer (Aug 6, 2010)

I am not sure if you can change the mode of operation on this unit. Maybe it goes through the motions the first time. And at 15.5 it did boil not to the point of boiling over but when you pulled off a cap you could see some bubbles. Now it was not like having a charger on a car battery at 20 amps or nothing but there were some bubbles. I am just afraid to screw something up.


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## mightybooboo (Feb 10, 2004)

Yeah,you blew it this time. .

For small system its hard to beat Morningstar and look at the sizes and amp ratings,plus the price has dropped as the new ones have come out.These are bulletproof rock steady controllers and reasonably priced.Shop for price,there are super deals out there on em.

This is the product.Another nice thing about them is they are stackable,as your system grows just add more,dont have to trash what you have,NICE! So in my case,using the 20 amp ones,I can just add 20 amps more when I want. 

http://www.ecodirect.com/MorningSta...-12-Volt-p/morningstar-sunsaver-ss-20l-12.htm

BTW,AFAIK,bubbles arent a problem at all,but keep up on the water


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## mightybooboo (Feb 10, 2004)

Read HandyBob for a primer on charging,then take it or leave it whether to follow his advice or not,he makes claims and claims to be able to back em up.

Something Bob says that may make you feel good....
I see as high as 15.2V on my meter on cold days and that is what it takes for correct charging. Setting it low all the time is what most installers do, and that keeps your batteries from getting full and is very bad for them. 

Me,I like Bob,he is outside the box and backs up his claims on systems he has worked with,I think he is spot on.

http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/


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## Big Dreamer (Aug 6, 2010)

Well from reading that article and from reading about battery charging it might have been working correctly. It is a temperature compensating unit according to the manual and it was about 25Â°F (-4Â°C) so that might be about right. I did not let it go very long so I donât know if it would have dropped back. I do think I will invest in a better charge controller just to make sure.


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## idahodave (Jan 20, 2005)

Was the current .86ma or 86ma or .86 amps?

.86 ma will not harm the battery!

I'd try a few more days and watch the current and voltage to see what happens. The documentation doesn't describe how the charge modes are determined. If it stated out with an EQ cycle the voltage wasn't that high. Check the SG and watch the liquid levels.


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## Energy Rebel (Jan 22, 2011)

Can you install another shunt, battery or even a dumping device like to a water heater, light, etc?
Just a suggestion if it seems like the power is getting too high.
Also, check out the voltage coming directly from your panels. As noted, on a cold day, they will really crank, that's why you pick the inverters, charge controllers, etc,. based on the record coldest day for your area - then add another 10%, to be sure.
Probably as time goes on and the panels get older and a little dirty, it'll go down a little.

Update, if you find out something...good or bad. We can never learn too much.


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## Big Dreamer (Aug 6, 2010)

It was 860ma or .86 amps sorry about that I was not thinking when I typed it wrong the first time.


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## mightybooboo (Feb 10, 2004)

idahodave said:


> Was the current .86ma or 86ma or .86 amps?
> 
> .86 ma will not harm the battery!
> 
> I'd try a few more days and watch the current and voltage to see what happens. The documentation doesn't describe how the charge modes are determined. If it stated out with an EQ cycle the voltage wasn't that high. Check the SG and watch the liquid levels.


I would try that.You do have an obvious learning curve with that controller and I dont see anyone here familiar with it.

Along with what HandyBob has to say just go and keep an eye on em and measure lots of numbers so the Pro's here know what to tell you,that isnt me,Im a hobbiest.

But I like Bob,indeed I do,he gets full production out of systems he works on,and his KEY is the 15 volt charging,he calls 14.8 MINIMUM for lead acid batts.

I like how he takes people using back up gennies constantly with their systems,kicks UP the voltage and has them OFF the genny,theory being you are wasting charging power during peak hours at the 14.2,14.4 set points.

Says Trojan actually recommends 14.8 (IIRC,just glanced over this time) and claims his systems have very healthy batteries at higher voltages.Also like his wiring rants and to exceed recommended sizes by 1 or 2 on the wiring charts.

It sounds to me like the industry has made lower charging points the 'norm' to keep the system needing less work on battery maintenance (watering/cleaning) at the expense of higher production,kinda dumbing down the system for the convenience of the masses.IF Im reading Bob correctly.


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## mightybooboo (Feb 10, 2004)

Big Dreamer said:


> Well from reading that article and from reading about battery charging it might have been working correctly. It is a temperature compensating unit according to the manual and it was about 25Â°F (-4Â°C) so that might be about right. I did not let it go very long so I donât know if it would have dropped back. I do think I will invest in a better charge controller just to make sure.


Before you change out charge controller let it do some running,you may be good actually.Lets see what it does when batt is in discharged state ,different temps.See what mode its in.....etc etc.
----------------
Something Bob sent to a friend of mine about controllers and his takes...

Holy cow! Your panels add up to 2180 watts & somewhere over 60 amps at 24V. That means you would need at least three 3024âs. Maybe it is time to start over. I have no experience with any system this big. Then again, all the basics are the same. I donât know what you are trying to run, but you should have enough power to run virtually anything you want. Like I said before, you cannot parallel different controllers. Actually, many controllers cannot be paralleled even with exactly the same model with their lousy electronics that will fight with each other. Paralleled controllers must be exactly the same if you want then to work together and not have one shutting the other one off. Blue Skyâs master/slave idea is a good one, just donât fall for their over rating philosophy.



Outback says their 60 amp controller will handle up to 1600 watts at 24V (about 46 amps). They realize that you need to be conservative. 46 x 1.3 = 60, right about where it should be. The Blue Sky folks are way too optimistic about what their equipment will handle. I have a friend who melted the input terminals on a Blue Sky 50 with about 42 amps of charging (42 x 1.3 = 54.6). They tried to tell him that he was the first person they had ever heard from with this problem and that the controller would protect itself. Just like me; he said âyea, rightâ.



Large systems do get enough boost to pay for the extra cost in MPPT controllers. However; do you need the extra 10% or so on top of the panels that you have? Maybe you should consider buying a very good charge controller that works very well & doesnât cost an arm and a leg. You have over 7% of your amp hours storage in charging amps, so you have a very good balance (more charging than needed). Think about two Morningstar Tristar 45âs, both with temp compensation (identical). They add up to $400 total. That is a lot less than two SB50âs or MX-60âs. I have been using a Tristar for over two years (and have installed several for customers). I believe it to be the best buy available. They do a very poor job of marketing. I had to drag out of them the facts about how it works. It has a brain & changes the charge time automatically depending on the discharge it sees during the previous 24 hours. You can get the Tristar instructions on line. Pay attention to the need for both input & output fusing. This is a code requirement, but it is also needed to make the Tristar work correctly.



You just need to make sure that the controller will receive more than it needs for charging, since its biggest job is to shut the volts off before overcharging. With gel batteries you donât need the 15.5V for equalizing, so you could shoot for 15V to controller & be safe. IF you decide to go MPPT, you can wire the panels in series & reduce the voltage drop so the controllers get the extra volts for boosting the amps. The outback will accept up to 140V open circuit voltage, which really does away with voltage drop, and then put out whatever the batteries need. However, they do lie about efficiency. (98% is a pipe dream). You need to put fuses or breakers at the panels and combine the feeds there. If you want to meet code you need a separate breaker for each feed from the panels to the combiner. Who cares, but it does simplify maintenance in the future.


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## wy_white_wolf (Oct 14, 2004)

Big Dreamer said:


> Well from reading that article and from reading about battery charging it might have been working correctly. It is a temperature compensating unit according to the manual and it was about 25Â°F (-4Â°C) so that might be about right. I did not let it go very long so I donât know if it would have dropped back. I do think I will invest in a better charge controller just to make sure.


I didn't think voltage would vary that much at 25F. But thuis chart confirms that it would.'

Temperature F/C Absorption Voltage 
122/50 13.80 
104/40 13.98 
86/30 14.19 
77/25 14.34 
68/20 14.49 
50/10 14.82 
32/0 15.24 
14/(-10) 15.90 
(-4)/(-20) 17.82 

http://www.amplepower.com/primer/temp/index.html

at 25Â°F voltage regulation point should have been ~15.6V


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## mightybooboo (Feb 10, 2004)

WOW!!! Thats a lot of controller for 135 bucks!!!

http://www.ecodirect.com/Morningstar-TS-45-12-24-p/morningstar-tristar-ts-45.htm

try here and click on users manual,I liked the dip switch power regulation,nice for the price!
http://www.morningstarcorp.com/en/tristar


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## Big Dreamer (Aug 6, 2010)

Well finally a good sunny day here in Ohio and I got off work a little early. When I got home the green battery light was flashing indicating a full charge and the voltage was at 14.2 volts. I am assuming that it was in the float mode. So I think so far it seems to be working. I am working on making a data logger to hookup and so I can monitor the current and voltages while I am away or at least review them when I get home. Also got my inverter today and mounted it. Still need to make the cables and get it wired in. Another picture of the setup at the bottom of this page http://www.sci.projectgm.com/html/epip20-h.html


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## mightybooboo (Feb 10, 2004)

Sounding good but 14.2 seems a little high for float,dont forget SG readings when batteries are rested.And volt readings after a small load put on batteries.

Like your pics,thats a nice little system youve got going on!


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