Travis A's posts

Jon, This is actually beyond my wildest expectations.  I think the relationship between the battery and the capacitors is like the relationship between concrete and steel. 

Neither the battery nor the capacitor is perfect by itself.  The capacitors have limited (compared to a large battery) power storage however can provide nearly unlimited amounts of surge amps.  The battery holds a lot of power yet cannot provide any surge amps without a nasty sharp reduction in amp hour capacity along with destroying the plates inside the battery.  Together they produce a "super battery".

That is a good call on the fusing.  I appreciate your friendly reminder.  I hadn't even considered protection and was focused on trying to minimize losses of any kind.  I never even thought about fusing this because its tied to the batteries directly.  After reading your post and giving it some thought I really should have some type of fusing installed.

I'm not sure how I would fuse cell to cell in the capacitor bank.  If I use a lead acid battery as an example there is no fusing between the individual cells inside the battery itself.  Is fusing between cells necessary?  A friend suggested that I alter the aluminum I have currently hooked up to make it thin in the center.  Then the capacitor to capacitor links would physically melt/blow and should provide some level of protection.  The question would be how thin should they be made in the centers.

I don't know what the proper value would be to select for a fuse between the capacitor bank and the battery.  This capacitor bank is able to provide insane levels of current however I never expect to draw those levels of power.

Since I am getting 100amp shunts I guess 100amps would be the proper value for my testing.  I would have to replace these fuses once I attach more batteries and loads in excess of 100amps however.  I am open to any input on proper values for the fusing.

Please everyone keep in mind that I'm very new at this.  As I stated before I'm just an average person with a screwdriver and a multimeter.  If anyone sees anything I am doing wrong please let me know.  Chances are I honestly don't know the proper way.  This is especially true if you notice anything that is a fire hazard or a personal safety concern.

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Some people have questioned why I am doing this at all.  I have had lots of people tell me that simply adding another battery (or batteries) would do the same thing.  The reason I am doing this experiment comes down to something called Peukert's Law.

http://en.wikipedia.org/wiki/Peukert%27s_law

This law defines the relationship between current draw and overall capacity of the battery.  It would be impossible (impractical) to design a battery bank around the 20 hour rate that most battery manufactures use.  My battery is a 100AH battery so the example given on wikipedia works perfectly for my system.

I am attempting to violate this law and produce a practically sized battery that can be charged completely daily for maximum battery health yet can provide all the power that I need.

I was doing some math on this last night and currently I'm seeing approximately a 40% increase in battery capacity.  This cannot be due entirely to the capacity of the capacitors and must have more to do with the peukert effect. 

Keep in mind that the capacitors are constantly charging and discharging as the battery voltage changes.  The capacitors don't work like a battery and only respond to changes in voltage.  The more the voltage sags (or increases) the more current the capacitors produce or accept.  I key up the radio and the voltage sags which causes the capacitors to discharge.  When I quit transmitting the battery attempts to return to its unloaded voltage and in the process of doing so it recharges the capacitors for the next blast.  Unlike a battery these capacitors can do this millions of times at nearly 100% efficiency.

Version 3 of my capacitor bank.  I decided I needed to beef up the connections between the caps.  I used some aluminum stock that I picked up at home depot.  I also used a sheet of plexiglass to hold the cells together.  This seems to work wonderfully.



I still haven't gotten my shunts so I still don't have any scientific testing done however at the end of the night my voltage is much higher than previously.  These are making a huge difference from what I can see so far.

I have 12 more of these caps on order and I'm going to be testing 24 also.  I am going to see what capacity creates the greatest increase.

(I hope I'm not boring anyone with my posts)

Please see my posts on ultra capacitors.  I think ultracaps are the answer I was looking for.

http://www.altestore.com/forums/index.php/topic,2402.new.html#new

New and Improved Version 2

http://imageshack.us/photo/my-images/856/img20110730172155.jpg/

http://imageshack.us/photo/my-images/189/img20110730172209.jpg/

I have all 12 caps wired in series parallel.  See pictures above.  I will be doing some further testing and I'll post some results here when I get my test gear.

So far this seems to be twice as good (makes sense)

I cannot resist posting again.  There are DEFINITE increases in the abilities of the solar system.  I am currently sitting at 14.45 volts.  If I key up the radio on high power previously the voltage would do a nose dive all the way to 13.2'ish.  The capacitors are doing their job and during short transmissions the voltage isn't dropping.  This means a few things.

1> The battery is still charging even while I transmit

2> The solar panels are going to put out more since they are closer to their Vmp rating.  I have a PWM charge controller so this brings me a little closer to MPPT efficiency.  Actually I think I am over MPPT efficiency because the battery is still seeing nearly the same charge during short cloud cover.  Lead acid batteries seem to resist charging and capacitors don't.

3> The battery will last longer (more daily capacity).  Lite usage while the sun is out isn't going to discharge the battery.  I will be able to make transmissions without my batteries even knowing I'm doing it.  They are even still charging while I transmit.

4> It seems to make the charging more efficient.  I don't have any scientific proof however when the sun goes behind a cloud the voltage is lingering high almost staying flat during short cloud cover. The battery is still getting a charge even with dropping solar voltages.  The caps are holding the voltage higher.

Obviously a capacitor isn't going to help with steady continuous loads to this degree.  But for my application I can already see a HUGE benefit.

My radio draws 114 watts during a high power transmission.  My panel is a 110 watt panel.  To me this is the true test of how well this is all working.  Previously on transmit the voltage would fall to the batteries working voltage and I would bleed off the surface charge almost instantly.

Now if the capacitors can stay balanced without maintenance then this is the PERFECT setup. (So far they are staying balanced)

A photo for anyone interested in the project:
http://imageshack.us/photo/my-images/843/img20110729133025.jpg/

For size reference that is a Group 27 Battery. Notice how the caps are nearly as large. Yes I know a lead acid battery inside isn't smart. Yes I also know my interconnects are too weak. Yes I know my wiring is a mess.  Notice the discolored interconnect from the wrench incident.  That happened in a fraction of a second.

Jon C,

Thanks for the reply. I didn't realize the worst case scenario. I am going to be watching these really close. What I'm going to have to do is design a emergency disconnect circuit that monitors the voltage of each cell and disconnects the pack at say 2.49 volts. The manufacturer left a 10% surge voltage designed in. They can be used at 2.75 volts per cell however that is the absolute max before bad things can happen. They de-rated them for safety. I am going to have to put some serious thought into this before I can leave them unattended.

Last night before I went to bed I went through and equalized them using that same light bulb that I charged them with. I brought them all to within a .01 volts of each other.

They have been charging all day and the cell voltages are as follows.

Cell 1 - 2.17
Cell 2 - 2.17
Cell 3 - 2.18
Cell 4 - 2.17
Cell 5 - 2.18
Cell 6 - 2.18

Yesterday when I charged them I don't think I got them close enough to being at the same voltage. I was pretty close but discharging them (individually) with the bulb to get them exact seems to have been the trick.

I can tell these are adding capacity to the system because now when the sun passes in and out of clouds the voltage doesn't swing up nearly instantly as it did. In fact typically I would be at 14.2'ish volts right now. I am currently at 13.8 so there is a big difference. I am curious to know if these will help with the charging of the lead acid battery. I'll have to do some testing on that also.

The exciting thing is that overnight they didn't fall out of balance. If I can continue this for an extended period of time without them falling out of equalization I'll feel a lot better.

I am going to start building the other pack of caps today. I cannot wait to see what happens with 2 of these packs connected.

I will make another post tonight with any new findings.

(I hope these types of posts are acceptable)

Disclaimer: As Jon pointed out this can be VERY dangerous. I am not responsible for anyone duplicating my setup. I am just an average person with a multimeter and a screwdriver. I have no formal electrical experience/education (Computer/Network Technician). If anyone is crazy enough to try this please post your findings here.

Tom,

These capacitors are very new technology.  Capacitors in this capacity were typically out of reach of everyone (except insanely rich).  New they were insanely expensive.  I bought these used from a Hybrid Bus application.  They provided the current needed to move an entire bus.  These are not your typical capacitors. 

Jon C,

I need your help with picking the correct resistors for this project.  I'm new to electronics and currently I have them running without any balancing circuitry.  I will report all my findings in the most scientific way I can.  I have a computer driven scope and a shunt on order.  I am going to record total amps drawn and also battery voltage.  If I can achieve anything close to the quoted increases for a forklift in a renewable project this is very big news.

Random First Night Operating Notes.

End of night voltages @ 12.53 pack voltage

Cap 1 - 2.05
Cap 2 - 2.10
Cap 3 - 2.07
Cap 4 - 2.07
Cap 5 - 2.08
Cap 6 - 2.11

I have made and connected a pack.

I have been testing without any equalizing circuit.  I am going to be watching these cells closely tomorrow during the charging cycle.

I decided the best way to do this would be to charge each cap up to 1/6th my battery voltage.  So I started the LONG process of charging each capacitor.  It over 30 minutes to charge each capacitor (12v @ ~10 AMPS!!!) and I had to monitor them the entire time to ensure they didn't go over my 2.18 target... ARRGH... Took forever.  I used a 10 amp light bulb in series with my 12 volt battery to control the amperage of the charge.

When I assembled the pack I accidently touched my wrench across 3 caps wired in series.  All I can say after seeing that is WOW.  It took a pencil size chunk out of the wrench.  I would like to know how many amps that was.

Then I had to re-equalize the pack.  The voltages on those three cells were down .3 volts from where they should have been.  Imagine all that damage and it didn't even discharge the caps.  I could have done that over and over and they still would have had a charge.

After I connected them to my battery (pre-charged to near perfect voltage match) I turned on my radio equipment.  I did some high power transmissions to test the voltage sag difference.  The improvement is nothing short of amazing.  This is the perfect application for this setup.  Typical transmissions are 50% duty cycle. (1 minute transmit 1 minute receive)

The first thing I noticed is that the voltage sags much less and much slower.  I cannot wait to assemble the other pack and connect them in parallel with these.  Previously I would see a voltage drop of about 1 volt.  Now that is down to about .3 volts and slowly sags but never past 1/2 volt during a 2 minute transmission.

The second odd thing I noticed is that after the voltage sags it doesn't bounce instantly back up like normal.  Its obvious when a battery has these caps on it.  The voltage returns to open circuit voltage very slowly.  It shows they are doing their thing.

At the beginning of the night I started with 12.6 volts on the batteries.  Its currently at 12.53 volts.  That is a huge improvement over what it was however I don't have any nice graphs to back it up yet.

Travis

Hi Tom,

Thanks for the response.

I went ahead and ordered these to do some testing.  They look like the answer to a lot of problems in the off-grid world.

Yes it is true that inverters have capacitors in them.  My goal though was to shield the batteries from seeing high current bursts.  The caps in the inverter are there to assist it without any real regard for the battery.  The battery is still expected to come up with these massive currents.  These caps are going to be physically larger than the inverter itself and much higher quality/capacity than anything inside it.

When the fridge goes to start there is a huge high current burst that the deep cycle batteries are forced to produce.  I can tell by the voltage drop that the batteries don't really like this to happen.  In my studies of how lead acid batteries work this is one of the main things that causes short battery life. 

I know that the batteries/inverter are capable of producing this current however it comes at a huge cost in terms of charge longevity.  It is a unsustainable chemical reaction that causes a runaway between voltage/amps.  The more amps the inverter draws the more the batteries sag which causes even more amps to be needed.  This is especially true when the batteries are close to 50% charged.

http://cgi.ebay.com/Maxwell-2600-Farad-2-5V-Ultracapacitor-EV-used-Qty-12-/300561259628

Those are the capacitors I went ahead and ordered. 

The article that I referenced in the first post is my reasoning for doing this.  These capacitors came out of a hybrid bus.  They are used to provide the burst current needed for the bus to accelerate from a dead stop.

There are videos on youtube of people starting large diesel engines and car engines from these caps.

There are even videos of go carts totally powered by these caps.  I didn't even know they had caps this large until I ran across them by chance.

I am going to be doing a lot of research and I'm going to post all my finding in a scientific way.  I ordered a 500amp shunt and I'm going to be using data logging software to graph the difference in amp draw seen by the battery.

If I can "smooth" the current draw seen by the battery by 25% (or more) I should be able to achieve a lot longer run time on my battery.

Sorry for the long winded reply.  I have been really enjoying my solar system and learning about all this.

Travis

I ran across an article in my travels (see link below) detailing the use of ultra capacitors in forklifts to extend the battery life.  This got me thinking about how this could be applied to solar systems.

I am considering setting up my system so that the battery bank feeds the ultra capacitor then the loads are connected to the ultra capacitor.  My idea is that when heavy loads are applied the start-up current would come from the ultra capacitor then the batteries would be constantly charging the ultra capacitor.  This would spare the batteries the high current bursts needed by things like motors starting and similar "burst" loads.

I figure that if it works in a forklift it should work for our applications also.

I have found pricing on ultra capacitors and they don't look that outrageous. I am considering 2600 Farad 2.5V ultracaps.  I would be running these in a series parallel 6 per string to give me 15 volts @ 5200 Farad.  According to my math this is 271 watts.

That 271 watts could be delivered in a fraction of a second (or longer) as needed and the batteries would charge them at a modest amperage.  From my brief experience with my solar system it seems that the higher the load the less you can get out of the batteries.  Also the higher the load the more the voltage sags which makes it require even more amps to keep up (cascade effect).  My hope is that this would stop all voltage sag and a nice steady low amperage load would be "seen" by the batteries.

Has anyone considered/tried this?  I figure anything to extend the usefulness of existing batteries would be worth it.

Quote from the article:

"In a typical forklift application, the equipment can draw up to 700 A from the battery under heavy load conditions. But when the battery is operating with a parallel EDLC pack, this battery current can be reduced anywhere from 30 to 45 percent depending on the effective series resistance (ESR) of the EDLC pack and its interconnecting bus. The lower the ESR of the EDLC bank and its connecting bus, the greater the reduction of current drawn from the battery pack."

Please also see the nice graph they have provided detailing the benefits of this system in a forklift application.


http://www.how2power.com/newsletters/0910/articles/a2/index.html

I am willing to be the guinea pig if I get some positive responses.  I have already found a source for reasonable priced ultra caps.

I decided that I wanted to equalize my battery today.  After doing some research about what voltage to do it at I decided to try connecting my 110 watt solar panel directly to the battery without the charge controller to see if that would work.

I carefully monitored the battery voltage and battery temperature.  I stopped the process once the batteries hit 15.5 volts.

After I did this I checked the batteries using a specific gravity tester.  This technique seemed to have worked.

Previously using my radio in its high power setting would cause the voltage to sag nearly a half a volt.  After this charge I'm seeing a sag of 0.1 volts.  I use my system mostly for radio equipment, lighting, and my computer.

I just wanted to throw this method of equalizing out there for others that have charge controllers that are not capable of doing this.

Any comments, suggestions, etc welcome.  Please remember I'm new at this.  

*All load testing (before and after) was performed at 12.32 volts to ensure that I wasn't measuring a surface charge or being otherwise deceived.

I had never heard of earth tubes so that was a good addition to this thread.  I will have to do more research to find out if this is a viable solution in Florida.  I am looking for ways to avoid air conditioning at all costs.

I feel like an idiot for not checking on multiple meters before posting this topic.

The cheap harbor freight meter I was using had a low battery in it.  This was causing it to give incorrect readings.  When I checked that meter against a known good meter I discovered the error.

I knew something was wrong when I started to see voltages in the 18 volt range on the battery during charging.

I am going to replace that multimeter with a standard panel type analog meter.

After doing a lot of thinking on this subject I've decided that all of you were right all along.  I went ahead and added some more battery capacity to my system and that seems to have solved everything.

It is harder to achieve a full charge but I guess that is the point.  If its too easy to fully charge then all of that power is just wasted.

The plastic shroud that the fan is mounted in would require very little modification to put it into a duct.  This fan is so powerful that if I turn it on it makes it hard to open the door if all the windows are closed.  You can feel all the air rushing out of the house.

I plan to install it using a standard cold air return type duct for an A/C unit (filter on ceiling type) and have the air vent into the attic.  The air should be able to escape through the roof venting.  That will solve two problems it will draw cool into the house and it will cool off the attic.  A double whammy for the watts

Thats my crazy plan anyway.

Total cost thus far.  15 dollars (Junk Yard Fan)

I was hot the other day (Florida) and decided I needed a new fan.  Suddenly the solution came to me a car radiator fan.

I went to the junk yard and picked one up.  When I got home I hooked it up and to my surprise its the most powerful fan I have ever seen.  Its powerful enough to blow your hair straight back and everything lite on shelves starts blowing off.

I currently have it mounted in a window however I think this fan is more than powerful enough to be a whole house fan.  I talked to a mechanic friend and he thinks they produce about 1100-1400 cfm.

The fan I got draws 8.4 amps for anyone that is wondering.  I hooked it directly to my 110 watt panel for testing and in direct sun it will drive it to nearly full speed.

I just wanted to throw this cheap/awesome idea out for others.

I have been watching my voltages closely and I think my charge controller may be overcharging my battery.  I am seeing a voltage of 13.4-13.6 volts at the end of charging after the battery has been at rest for 4 hours.  Is the controller overcharging?

I am sure you guys are right.  I have another question for another thread.  Thanks for the replies.

Tom,

Thanks for the quick replies.  There is little doubt in my mind that my battery is undersized for the amount of power that I'm creating daily.

Ok lets say hypothetically that I add the second battery and now both batteries are approaching full charge.  Is the controller going to pull back to the same degree as it is now?

Currently what I'm seeing is that as the battery is approaching ~80% charged the controller goes into a constant voltage mode.  When it goes into this mode the current pulls WAY back.  I know that this is to protect the battery during the acceptance part of the charge. 

I suspect (don't know) that no matter the size or number of batteries that its going to pull back to the same degree when it reaches this voltage.  Is that correct?

My goal is to be able to put in this acceptance charge and still be able to use the excess power.

I'll give an example.  Lets say the controller is in the acceptance part of the charge and I start to use a small load such as one of my amateur radios (~30 watt load).  I see that the power comes directly from the sun and that the controller compensates for the additional load by allowing extra current.  I can tell this because the voltage doesn't sag much below the 14.4 charging voltage.  I want to be able to harness this extra power that it has available. 

I'm not always going to be around to use this excess power directly during the day as I am typically at work.

My crazy idea is to upgrade to a new set of batteries (370AH golf cart batteries) and to use the battery I have now as a diversion load of sorts.  When those golf cart batteries start to approach full I'll have the current battery sitting @ ~50% charged just waiting for that extra power.

I was going to create a circuit that once it saw the voltage going to 14.2 or above it would engage a secondary charger (my own design) and that secondary charger would be current limited so it doesn't disturb the primary charge controller.

If the sun falls behind a cloud the secondary controller would see the drop in voltage and would start pulling back on current so the primary controller would get the voltage it needs for the acceptance charge.  It would keep pulling back on the current all the way to turning off the secondary controller if need be.

When the sun comes back out from behind the cloud the secondary controller would be able to pull more current without causing the collapse of voltage.  It will continuously monitor the voltage to make sure its 14.2 volts or higher.

I am thinking this would allow me to use 100% of my solar panels abilities.


If simply increasing the capacity of the battery bank would achieve the same thing I'm not opposed to that.  My concern is that if I get a larger bank of batteries I will be really tempted to use even more power.  If I start using more power then the likelihood of getting a full charge during the day drops way off and the batteries never get fully charged and possibly cause damage to them.


Thanks again for the quick replies and humoring my many questions.

If I just add a second battery wouldn't it start pulling back from the solar panels at the same voltage?

I want to be able to put the final acceptance charge to the battery for its health but I want that excess solar to go somewhere when the controller is doing its PWM thing.  The solar panel is sitting there with all this power available and nowhere for it to go.

I would imagine that if I simply added the second battery the charge would take twice as long in the bulk charge mode but then when it hit the PWM part of the charging cycle it would pull back just as it does now.

I am still new to all this so I hope that I am explaining this correctly.

Hi all,

I just got my first solar system all setup.  I bought a used 110 watt Mitsubishi solar panel and a morning star sun saver 10 charge controller.  I have these connected to a NAPA Marine/RV Group 27 battery.  They couldn't tell me the AH rating however I suspect it is approximately 100AH.

My question is about charging this battery.  When the battery is approaching full the charge controller starts pulling back by design however this is allowing my precious solar power to go to waste.  How do I fully charge this battery yet waste little power?

I have come up with an idea however I am not sure if it will work.  My idea is to setup a second battery hooked to a second charge controller and to enable that controller whenever the primary battery is at 14.1 volts or above.  That seems to be the point where the charge controller really starts pulling back.

EDIT:  The second charge controller would be on a switch/relay and would be in parallel with the primary charge controller.  Both controllers would be getting the solar power at the same time.

Is that something that could work?  How do all you solar pros out there keep from wasting this power?

If I increased the size of my battery would that prevent this pull back on the charging?

Just a FYI for anyone that reads this.  Off my 110 watt panel I am able to power my laptop all night, run LED lighting, amateur radios, fans, and charge all my portable equipment.  I have been doing this for a few weeks now and in the morning I have still only used 40-50% of the battery.  (All loads are DC to avoid the use of wasteful inverter).  I actually have to try hard to use all this power.