“ I could always use a generator and the battery but the battery has a finite life and it is expensive. Not using it will allow it to last virtually forever as long as I care for it.”
I seem to have hit a ceiling of about 12 years with well-cared-for and lightly used SLA batteries. That’s pretty good, though. This is with continuous desulfating.
I’m sorry your only getting 12 years from your flooded Lead battery. With proper care, make that very careful care you should be able to get 10 years using them to 50% every day and 7 years not being so careful.
I will give a few pointers from what I have learned over the last several years.
Desulfateing is definitely the the most important part. You can’t care for them by just looking at the voltage and the plate condition. You have to depend on the Specific Gravity. A fully charged battery should be at around 1.280 and I prefer 1.300+. A lot of people are happy with 1.26. The specific gravity will tell you how much sulfate is on your plates. If you consistently run below 1.26 I would say it was time for a good equalization charge. I hate equalization but you have to do it even if you aren’t discharging the stupid things. I have a 48V system so I equalize at at least 61 volts and really stir them up.
When I first started I didn’t loosen the caps enough and blew up a couple battery cells, at first I assumed I got bad cells until a cap popped up against the battery box lid.
I’m using tow truck batteries that had been purchased and repossessed after a few months for nonpayment. A few of the cells were really pretty pitiful but a couple good equalizing charges brought them right up into spec. I don’t have any red caps in my 72 cells.
Something else that really helps battery life is temperature. My inverter has thermocouples on the battery to report temperature but since my battery is in the basement it never gets hot or cold, both extremes are hard on the battery. I don’t think I have ever seen it above about 24 or so degrees C. You might make it jump a few degrees during equalization but it will come right back down when you get done.
Since my system is a battery backup all my solar runs through the battery prior to the inverter so that the battery is always topped off. My 6 hour after charge voltage runs about 53.5 volts. Even during the hot summer running A/C during sunshine the voltage stays pretty high.
Something else I learned is that if you are grid tied you need do do inverter/Grid charging. You simply can’t depend on the battery controller to do the job from the PV’s, especially for an equalizing charge. I have two Outback 8048’s, they are a little loud but they are good. I have two PT 100’s, they are great but you need the inverter charging to get the most from your battery. They will produce double their rating for a short time if necessary.
Since we store stuff in the basement we keep a dehumidifier down there running all the time, that provides more than enough distilled water for the battery. The batteries are Enersys Desert Hogs. The hogs are nice because they have an extra tall case with extra space above the plates so that you can go two or three months without even checking the water level but water level is about an important factor in battery life as you can get. If you constantly run your water low your battery chemistry will be off, it will look good even though you have sulfates building up on the plates. Many people don’t know when to do an equalizing charge, well if you add a lot of water then it is a good time to equalize to mix up the chemistry.
I’m sorry your only getting 12 years from your flooded Lead battery. With proper care, make that very careful care you should be able to get 10 years using them to 50% every day and 7 years not being so careful.
I will give a few pointers from what I have learned over the last several years.
Desulfateing is definitely the the most important part. You can’t care for them by just looking at the voltage and the plate condition. You have to depend on the Specific Gravity. A fully charged battery should be at around 1.280 and I prefer 1.300+. A lot of people are happy with 1.26. The specific gravity will tell you how much sulfate is on your plates. If you consistently run below 1.26 I would say it was time for a good equalization charge. I hate equalization but you have to do it even if you aren’t discharging the stupid things. I have a 48V system so I equalize at at least 61 volts and really stir them up.
When I first started I didn’t loosen the caps enough and blew up a couple battery cells, at first I assumed I got bad cells until a cap popped up against the battery box lid.
I’m using tow truck batteries that had been purchased and repossessed after a few months for nonpayment. A few of the cells were really pretty pitiful but a couple good equalizing charges brought them right up into spec. I don’t have any red caps in my 72 cells.
Something else that really helps battery life is temperature. My inverter has thermocouples on the battery to report temperature but since my battery is in the basement it never gets hot or cold, both extremes are hard on the battery. I don’t think I have ever seen it above about 24 or so degrees C. You might make it jump a few degrees during equalization but it will come right back down when you get done.
Since my system is a battery backup all my solar runs through the battery prior to the inverter so that the battery is always topped off. My 6 hour after charge voltage runs about 53.5 volts. Even during the hot summer running A/C during sunshine the voltage stays pretty high.
Something else I learned is that if you are grid tied you need do do inverter/Grid charging. You simply can’t depend on the battery controller to do the job from the PV’s, especially for an equalizing charge. I have two Outback 8048’s, they are a little loud but they are good. I have two PT 100’s, they are great but you need the inverter charging to get the most from your battery. They will produce double their rating for a short time if necessary.
Since we store stuff in the basement we keep a dehumidifier down there running all the time, that provides more than enough distilled water for the battery. The batteries are Enersys Desert Hogs. The hogs are nice because they have an extra tall case with extra space above the plates so that you can go two or three months without even checking the water level but water level is about an important factor in battery life as you can get. If you constantly run your water low your battery chemistry will be off, it will look good even though you have sulfates building up on the plates. Many people don’t know when to do an equalizing charge, well if you add a lot of water then it is a good time to equalize to mix up the chemistry.