Richard Evans's posts

Posted by Richard Evans on Aug 12, 2011 05:28 am

#1 -  Renewable Energy > Technical Discussion: Other > Re: Using Ultra Capacitors To Extend Battery Life
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.... [/quote/]

I found some more info about those Capacitors and some formulas and graphs to go with them.  The next thing I would look for would be a schematic of the forklift application.

Your practical application tells you what your system will do. About a minute of transmit time means you start to seriously use the capacitor bank and after two minutes the battery is probably delivering some current.  I still think a half volt head start would set your capacitors up for more usage before the battery started to contribute any thing.

Posted by Richard Evans on Aug 11, 2011 08:59 pm

#2 -  Renewable Energy > For Sale > Re: 80 gallon solar hot water tank &other stuff for sale.
Off topic I don't live close enough or know anyone that does
to purchase your tank. My dad and I built a solar heating system back in the late 70's.  The way we did the hot water was to run a fifty foot copper coil inside one of the tanks. That was the pre-heater for the regular hot water tank. The tank had 170 gallons of water in it and the solar panels heated that water up to 206 degrees.  Needless to say you could run the shower for 4 hours  before the regular hot water heater kicked in. There were 4 tanks and it took about 1 day to charge them all from stone cold and they would last about 3 to four days for home heating and hot water use. The tanks were in the basement and when the pump shut off all the water drained to the tanks by gravity feed so no anti-freeze was needed.  This was a non-pressurized system.  Not bad at all for home made. My dad just thought 5 cents a KwH was too much to pay for electricity.  The house was all electric.

Posted by Richard Evans on Aug 11, 2011 08:31 pm

#3 -  Renewable Energy > Technical Discussion: Other > Re: Using Ultra Capacitors To Extend Battery Life
I went ahead and followed your links and the links embedded in the pages and from what I can see my initial impressions are correct. Two controllers set at  different voltages, and charge rates would take advantage of the system in the best way possible.  One for the capacitor bank and one for battery bank are needed if you are going to get the most out of the system.  If you use three or four diodes in series between the batteries and the capacitors in the system to set the capacitor bank a little higher than the battery bank then they can be used a as charging supply for the batteries. I would use a large power relay to shunt around every thing when the high demand load kicks in and then drop the diodes and the controllers back in after the high demand ends. A short run from a generator or a brief connection to the grid with a high rate charging system for just the capacitor bank at night could be used to kick the capacitor bank back up to 2 volts higher than the battery bank. It will rise that high because the shunting relay is disconnected and the diode block is back in the circuit. Then the battery charging controller would send the capacitor charge to the batteries at a much tamer rate than hundreds of amps which the capacitors could provide but is not so good for batteries.  All this stuff only seems worth it if you have a demand higher than you can normally get from your available battery supply.  I have just been using car batteries and playing around with this stuff but I got my education B.C. (Before calculators)  Back then they taught us to do the math and show the work.  You got a much better feel for a problem that way. Fork lifts have to use deep cycle batteries because it is a guarantee that they will be abused.  The caps are helping
avoid that abuse and providing an additional punch for the lift. Typically an electric fork lift will be rated at a 5000lb lift limit.  The graph on the page about the ultra caps shows the battery current but doesn't show the capacitor current.  I would guess that they made up the remainder between 720 amps and what the batteries provided.

After the lift you will notice a slow smooth decline in the battery current.  It looks like to me that when the demand is off the caps have a small resister between them and the battery so the batteries can charge the caps back up gradually.  I saw a car battery blow the hood open on a car once. Nobody was anywhere near it but a charger that had switched to a 35 milli-amp trickle had just been removed from it. It made a mess. I wonder how big a bang those forklift batteries would make.


Posted by Richard Evans on Aug 11, 2011 08:04 am

#4 -  Renewable Energy > Technical Discussion: Other > Re: Using Ultra Capacitors To Extend Battery Life
To check and see if the battery life will be extended you need a control for this "experiment".  The amount of energy storage you have in the capacitors alone can substitute for all the work the battery would do for small average loads.  At some point though if you have no charging supply hooked into the system the battery will be giving a large surge to charge the capacitor bank equal pretty closely to what the load draws because you do not have hardly any resistance between the battery and the capacitors.  If the idea is to extend the battery life, the only way to do that is to not use it and don't use it as hard.  So it seems to me that a small resistance between the capacitors and the battery would be a good idea and then have your load hooked up to the capacitors only.  Another way to do this would be to give the capacitors a head start. You can do this by hooking a Diode pair between the battery and the capacitor bank.  The resistor could then be used as a current limiter on the diode that returns the charge from the battery to the capacitor bank.  The diodes in a microwave are pretty rugged.  They handle about 1kw on a daily basis.  Be very careful not to hook the panels directly to the capacitor bank. Solar panels always make more voltage than the battery.  That is why you nave a controller.  I would be tempted to put this booby trap in the ground outside with a plastic lid over it be cause above ground nuclear testing has been banned for a long time.     

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