At four years I have suffered battery failure. It was a combination of things, but I have to tell everybody that battery manufacturers have gotten too carried away with raising charge voltage recommendations. Time for a reality check, and again… If all of these manufacturers use the same lead and acid, in the same boxes dyed different colors, why do they all have different opinions about how to charge them? It is because none of them live on the batteries they make. The off grid life is foreign to them. It is not the same as being able to plug a big charger into the grid overnight. Don’t forget that the biggest name doesn’t even make their own deep cycle batteries, so how in the world would they know? I am reminded of a friend who built a bus and suffered failure at less than 4 years using that brand and he said to me “I seem to remember some guy warned me about this.” When he went to one of their dealers, they did a quick voltage check and told him his batteries that had two dead cells were fine. They didn’t even have a hydrometer! “Outrageously reliable!” Back then he bought Trojans to replace them.
Notice these are the standard deep cycle batteries, not the “green” ones and no water saver caps that didn’t work as advertised. I like these new caps. Does anybody really believe there is some magic difference inside an RE battery? Give me a break. Yes, that is a whole house vacuum system next to the box… Not a small load. I found it on eBay really cheap.
What batteries do we now have? Crown, of course. I am not changing my mind about these folks. This is the best manufacturer I have ever dealt with. They listen and they respond like no other big outfit I have ever seen and remember, I used to be an independent sales rep, so I know what the norm is. Their western regional sales manager has gone so far as to have visited both us and Ralph Hiesey, the Trimetric inventor. That is dedication. BTW, what batteries do you suppose Ralph is using now? He also used to have Trojans. Crown warranted my batteries that were out of warranty and then I added. Then they paid for shipping the old ones back so they could dissect them and then even sent me a copy of the report, including pictures. The conclusion is why I am writing this today. We now have (16) CR390’s because that was what was in stock at the time. This is the right thing, even though many will not understand and I knew going in that the (8) batteries I bought initially might not be enough, but I could not afford more. I will be posting a page about Rules of Thumb in Sizing Solar Systems to explain. The only way to make solar power work on short winter charging days plus cloudy conditions is through shallow discharges and gentle charging. Anybody who still talks about 50% discharges is not talking about off grid living using solar charging.
Here is what happened. First was the MidNite Classic fiasco that I documented in my rant about the MidNite Classic. I don’t know what else to call it. I still don’t think much of MidNite and am convinced they are clueless. (I will use 12V settings here to make this easier, but my system is a 24V one.) Here goes… Using a 14.8V absorption setting was not enough with the Classic to prevent my cells starting to diverge in specific gravity only 18 months in. Part of this was probably that their programmed monthly equalization was not happening. It simply did not work. Their automatic adjustment of absorption time also did nothing and the damn thing did several times just lock up and refuse to work until reset. However, doing a manual EQ did not fix the SG problem. I got mad and installed two Tristar’s in place of the Classic and voila… Only a week later, using the same settings, the SG in all cells was exactly the same and it did NOT take equalizing. Ask yourself how this could be. The charging amps in absorption from exactly the same array, using exactly the same settings and in full sun went up too much to believe and I am afraid to tell you just how much. The simple truth is that Morningstar’s voltage control pushes more amps into a nearly full battery and in some conditions it is not just a little more. I still have that Classic and I can prove my statements. These are not opinions, they are facts.
After seeing what was happening, I started experimenting, first by trying Morningstar’s factory provided charging algorithm for L-16’s, 15.4V for 3 hours. That was disastrous, leading to a lot of heat and way too much gassing. Morningstar gave me the form letter type of response to my questions about how they came up with that setting and after asking four different people there about this, I still have never received an answer. I gave up. I have put off saying this for a long time and do not do so lightly. They are still installing this setting in their latest controllers. I find this indefensible. People do use it, and with disastrous results. Another thing that needs to be said is that Morningstar STILL does not have meter based charge control… No battery monitor. Their extra bulk setting that is needed for recovery from deeper discharges simply cannot work reliably since it uses voltage as it’s trigger. Think about it… If my batteries are at 60% in the morning when I make coffee, the voltage will vary depending on how high the sun is. I found that it impossible to make it work right. It needs to be triggered by State of Charge, not voltage and the Morningstar meter does not show that. Several times I have complained about this. Morningstar builds great equipment, but they are unresponsive to input from the field. I have given up. Go ahead and ask them how many of their employees live off grid… I did and I found the answer to be very revealing. Building equipment is not the same as using it. On the other hand, my Tristar’s never get warm even with no cooling fans and they have NEVER shut down due to anything. I have observed 2263W, 84 amps of 29V charging from these things when my 2000W of panels were very cold, so they work extremely well. They just sit there and silently make electricity better than any other charge controller can. So when somebody tells you that the Tristar is an old design, know that only the box is old. They continually work on improvements. You just need to program them correctly and unless they figure out shunt based metering, you will need to be careful in making sure that programming is working.
Next I tried Crown’s then recommended 15V setting and started playing with the time in absorption, ending up at only one hour. It seemed to work well, but the batteries ran too warm in summer and they used a lot of water. Crown has since removed that recommendation from their web site. If you ask now, they say 14.5V with monthly EQ, but even this may be changing.
At the end of the day, I killed my batteries with too much voltage, too much heat and too much abuse. They still warranted them. What else can I say?
As of now I would never go higher than a 14.6V absorption setting on flooded lead acid, even though I successfully did get over 8 years from T105’s I charged at the 14.8V Trojan was recommending. The secret there is that those batteries never saw over 100F temperatures and spent most of their time at far less, plus they were treated gently with most daily discharges at less than 15%. Also, having only 4 batteries means that all have two sides exposed to cooling air. Putting 8 big batteries in a box turns out to be a big problem. We also moved our house on wheels if we got too hot. It is a bit hard to move a house, so I am now doing things a lot differently.
I have spent the past two months doing daily SG checks and experimenting with the new Crown 14.5V recommended setting and keeping a daily log. As expected, it is a bit difficult for this to work on short winter days, but I have been tweaking things and working with Crown. New recommendations are in the works and when you see them, know that they have gotten quite a bit of input from me. Basically, you need at least 2 hours of 14.5V absorption to recover from discharges down to 75% SOC and another hour or more if you go to 50%. (I am now using three hours, but I do have a lot of batteries for the solar power on my roof.) Pay attention here… The quality of the charge controller can make a huge difference in the charging late in absorption (more time may be needed) and if you use anything but Morningstar, you better be extra careful in paying attention to the next thing I say. Daily spot checks with a hydrometer are critical to verifying this is working for a few weeks after system start up and rechecking when going into winter is a must. If you decide to use AGM’s (and cannot use a hydrometer) you will need to do some verification that you are overcharging enough to keep them healthy. The Trimetric TM2030 has a new readout that will help, rPC (returned % of charge). At first I thought this was going to scare people, but I now find that looking at this on recovery days does indeed give you a good handle on whether or not you truly are recharged even if the SOC says you are. If you see large overcharge numbers either you have the voltage set way too high or the batteries are failing. Even a Trimetric will never be 100% accurate and by just trusting any meter, you risk early battery death from under charging. Custom programming of temperature compensation has proven to be the answer to the need for more voltage during winter, plus lower voltage in summer to reduce heat. I use double the generally recommended .003 V per cell per degree Celsius. This gives me 30V in cold conditions with no gassing to speak of and nearly no water use. It is like using 29.2V (14.6) in winter and 28.8V (14.4) in summer. As of December 2018 I can now say that these settings have worked perfectly. The batteries are a year old and working exactly the same as they did when installed. All 48 cells show exactly the same specific gravity, 1.275 when dropping to float.
Summary of my charge controller settings: (These are 24V settings. Just divide by 2 for 12V or double for 48V systems.) Pay attention to what I said above about verifying with a hydrometer and that all charge controllers are not equal. I hate to have to repeat myself, but people who refuse to read will blame me if they use these settings blindly and then have problems.
Absorption: 29V for 3 hours daily. This will work for daily discharges of 20% maximum (down to 80% SOC). On days that I am recovering from deep discharges I have found that manually recycling the controllers to do a second absorption cycle can be needed. The voltage triggered extra absorption setting does not carry over to a second day after a deep discharge, so it does not work.
Float: 27V This is NOT critical. It can be higher for those who run loads like irrigation pumps after their batteries are full, ensuring that the batteries stay fully charged.
Temperature regulation: .006V per cell per degree Celsius above and below 25C. This has given me up to 30V during winter and it has worked perfectly. If you cannot custom set this, you can manually increase absorption voltage .1V in winter and reduce it .1V when the batteries are warmer than 25C in summer. I have talked with people who do this. My goal was to set and walk away. If you do enough research you will find that the general consensus says .003V per cell, while Morningstar uses .005 and others have their own ideas, while nobody could tell me how they arrived at their numbers. It seems to me that what I ended up with is working perfectly now that I am approaching a year on my new batteries and have only needed to add water every 4 or 5 months.
Equalization: 30V for two hours, only done on a sunny day after the batteries are charged. I equalize only after adding water in order to prevent stratification. It appears this will only be done quarterly. As long as daily discharges are less than 15%, the specific gravity will stay high enough to prevent sulfation, except after a couple of cloudy days. If this were a very common occurrence, I would equalize monthly during winter. I would never equalize when the batteries are over 25C (78F).
One other thing I must add. In the AGM world I hear Full River is recommending some insane voltage and Life Line is now at 14.6V. Are you kidding me? They have over reacted to all of the undercharging problems and it is going to end in disaster there, too. Follow their recommendations at your own risk. I would never set an AGM system at over 14.4V. Crown’s still relatively new Crown 1 line is extremely successful. They are very competitive with batteries made in the USA. Give this some thought if you have the money or are space challenged for watering and hydrometer checks.
Please stop asking me about Lithium. It is not ready. If you are made of money, go ahead, but I already have a report from somebody who is not very happy and I do not expect this to change very soon. The people pushing them are interested in the higher profit margin, nothing else. They also lie about recycling and ignore just how dirty it is to mine, refine and ship all the way around the world to manufacture them. The inconvenient truth is that the lead acid battery is the success story of the century when talking about recycling. I also just laugh about both Tesla and the salt water fiasco. People were telling me about how the salt water ones were going to take over and they went bankrupt… Big surprise! The Tesla Power wall is not suitable for daily discharges and they say that right in their literature. Just read the fine print.
Now the latest thing I see is an electric powered semi truck… There are no charging stations, the grid is already over loaded and wait until the government figures out there is no road tax on electricity. Boy is this a stupid idea! And do I have to address the solar powered motor home somebody is thinking can use solar electricity for propulsion? Is the roof of that thing going to be the size of a Wally World?