Owning your own Electric Company
Being the owner of your own power source is an amazing feeling, knowing that you will never again have to pay for electricity, and that everything you can power with electricity runs for free. You’re taking control of a major part of your own destiny.
I have a propane gas range at my house, but instead of using it to heat water for coffee or tea I use a very quick electric kettle. Propane costs money and electricity is free. I tell myself that over and over.
Owning your own power company still needs your attention and you can make it as easy or as hard as you wish, depending on the initial designs of your system.
Yes with a lot of study and due diligence you could scrape together a design on your own, but given the number of times I have had very intelligent and cleaver people tell me “Boy I wish I talked with you first” I have to ask “why do it?”
This certainly doesn’t mean that you shouldn’t learn all you can about you new venture. It just means buy your system from someone with lots of experience who can design and train you on your system.
I talk to people every day who have spent weeks crawling the web trying to get the cheapest of everything only to find that the stuff they bought cheap does not work together at all. There was no one at El-cheapo solar.com to ask. An alarming number of these little start-up companies are just middle men who were making pizza last week with no experience and no hope of support.You will certainly need support, good support. You don’t want to have to replace that very heavy, expensive battery bank in three years because the guy at El-cheapo solar didn’t mention to you that you have to program everything based on what you really have and not some off the wall “rule of thumb” or worse yet the “Default” settings in the inverter and charge controller.
Keeping You and Your Batteries Alive Go to Top
Batteries are the biggest problem for most folks who have renewable energy systems. Those problems typically stem from just three causes:
All of the above constitute abuse.
Let's talk about the first two problems.
All lead acid batteries are made up of two volt (2V) cells. Thus a six volt battery has three smaller 2V cells; twelve volts have six 2V cells, and so forth. Many folks are unaware that batteries also come in large amp-hour two volt configurations as well.
A common battery choice is paralleling small batteries together to make a large one. Paralleling looks good on paper, but because the way batteries are made they all have different internal resistance. So if we take eight six volt batteries and connect them in series for a 48 volt bank, in the series configuration electricity has to pass through every cell, resistance is not a problem.
If we were to take eight more batteries and parallel them to the first string of eight, we will have two strings with different internal resistance. One will have less resistance than the other. So when we start to charge these strings electricity will naturally take the least path of resistance and more will flow toward this string causing the voltage to come up sooner, while the second string will lag behind somewhat.
The problem starts to arise because the energy source (solar charge controller, inverter/charger or any other type of battery charger) it can only “see” the highest voltage in the system. When the first string comes up in voltage it cuts the charge rate back, and the second string doesn’t get fully charged. Now this doesn’t make much difference at first because everything is still pretty equal, but over time, the string that’s being charged fully will develop significantly less resistance, while the other, by never being fully charged, will develop more resistance because of sulfation starting to harden. The problem just exacerbates from here.
Generally speaking… "Every time you add a parallel string of batteries, you cut the life in half."
Note: Lead sulfate crystals form as a natural part of the discharge process on the surface of the plate pores of the active material. If the sulfation is left in this condition (by not charging properly) the sulfation starts to harden. Hard sulfation = large lead sulfate crystals. Sulfation becomes a problem when large crystals form and become difficult to decompose by normal charging. Eventually the crystals “grow” completely around the plates preventing any contact between the electrolyte and the plate. When this happens the battery capacity drops dramatically. Typically at this point the battery “”Charges” quite fast and also loses its charge fast as well.
Hard Sulfation is caused by:
Deep-cycle flooded lead acid batteries ideally require being fully charged after each discharge to stay in good health. A low State of Charge (SOC) is acceptable only for a very limited duration.
Flooded lead acid batteries also require a regular equalization charge (overcharge) to fight against stratification and to “equalize” any uneven battery cells, which will always happen over time.
The Third Problem.
We can use all sorts of devices to attempt to charge batteries; the problem is the manufacturer of the device had no idea what you were going to charge. They only knew the voltage of the bank or battery. They could not have known how big (Amp Hours) the system was and that’s the problem.
Charging with a good three step charger starts with the Bulk Charge; in this mode there’s constant current (amps) and variable voltage (the voltage will slowly rise). When the voltage has risen to a pre-programed point the Bulk passes off to the Absorption Mode. At this point the battery is around 80% charged.
In the Absorb Mode we have constant voltage and variable current, the amps typically start off at about 50% and slowly taper down to around 20% if the charger is held in the Absorb Mode long enough the battery will be theoretically fully charged.
The Absorb Mode is the most important charge mode, because it’s the one that actually charges the battery fully. Batteries need to be fully charged at least once every ten days, for longest life and overall health, which will avoid abusive premature failure.
There is nothing “Built-in” to any charger that senses when the battery is fully charged. Lots of folks mistakenly assume that when the charger goes into Float Mode the battery is full… WRONG! The charger only goes into float mode when the Absorb Timer times out. This timer has (or has not) been set by someone. The factory default is purposely set short, because they have no idea of the size of battery bank you intend to hook to the charger.
Either you or your installer needs to program this setting (as well as all the rest) based on the engineering computation for your particular system i.e. the amount of solar panels, the size of your generator, the type of charge controller and the size of the Inverter/Charger that you’re using. If you’re doing this yourself and need help call us 6126-1253. If you go with the factory defaults, you batteries will fail, sure as God made little apples.
The Float Charge is relatively useless for charging. Never bother to run your generator during Float as it wastes fuel. Float Charge only fights against self-discharge of the battery; the floating charge voltage setting is never enough to fight against non-uniform specific gravities (voltage) between the different cells of the battery bank.
Equalization Charge is a nice sounding term for “overcharging” When you equalize you bring the electrolyte to a very corrosive state; in this state what corrodes are the plates. Too much overcharging just wastes the battery, but done judiciously it’s a good thing. When the battery plates corrode they are also cleaned of any impurities that are sticking to the plates, which is good.
The second benefit of Equalization is you “mix” the electrolyte up to avoiding stratification (S.G. low at the top of the jar and high at the bottom of the jar). When stratified, denser acid sinks to the bottom of the battery making a very nasty corrosive environment for the plates at the bottom to live in which will in turn corrode them away and your capacity with it.
The third benefit is the equalize part of equalization where you bring all the cells to equal voltage (and Specific Gravity) If your Equalization Charge didn’t bring all the cells to equal… Do it again!
You can’t read what has happened too soon after equalization as the batteries must sit “at rest” for a minimum of four and preferably twenty-four hours to do a good voltage reading or Hydrometer reading. Elsewise you readings will be inflated and inaccurate.
Equalization is almost all voltage and little amperage so the battery must be at full charge before programing an Equalize event elsewise it will never properly Equalize.
NOTE: If you use an accumulating amp hour meter to monitor your batteries like the TriMetric Meter or the Xantrex/Trace TM-500, and you should be, Equalization will bring the meter back to accuracy every time you equalize.
In the normal course of using a battery you ”cycle” it (you take it from full charge and discharge it, then you charge it back up) every time you cycle your battery a small amount of material flakes off the positive plate and falls to the bottom of the case never to see again. Over the whole life of the battery the plates turn into filigree and then fall apart at this point it’s no longer a battery. This sadly will never happen to most batteries sold however because 87% of all batteries “die” from abuse.
One last scenario
Equalization of your battery Go to Top
Equalization is required to mix the battery acid, and to bring every battery plate to an equal charge. Equalization should only be performed when required or once every six months. Over equalization or too often simply wastes the battery life. Equalization is required when the cell specific gravities vary from highest to lowest by +/- 0.015 (1.245 - 1.260 at full charge).
The exact equalization settings are dependent on the system voltage and battery type. However, equalization is to bring the batteries up to the specified equalization voltage and hold that charge for 1-2 hours at a low current, without excessive heat. If the battery temperature rises to or exceeds 125ºF the battery should be immediately taken off of charge and allowed to cool before the equalization is continued.
There are two ways to determine that you have successfully achieved equalization, Remember the Equalize part of equalization is to get all the cells equal in voltage and Specific Gravity. You don’t need to do both, but you must do one right.
The first is by voltage readings of the individual cells, which is not possible with most 6 and 12 volt batteries. However you can get a close estimate of the overall bank by reading individual battery voltages, all must be within .05 volts of each other.The second method, which will read all the individual cells, is when two consistent specific gravity readings are taken a half hour apart the battery is equalized. Obviously at this point all cells read equal SG and voltage.Don’t fill the batteries first because you’re going to heat up the electrolyte and it will expand and make a mess. We recommend you add water to the battery cells half way through the equalization. This is to assure the water is completely mixed into the electrolyte.