Only getting a fraction of battery capacity

[Mike90250]

Stratification and Sulfation do not show up in voltage readings.

Stratification is an abnormally low SG reading, because all the heavy acid settled to the bottom of the cell. Drive around and mix the battery juice up.

Sulfation shows up as reduced capacity (I should be getting 80A but I only get 20A) and a weak SG reading ( because the sulfur is locked up in the crystals on the plates instead of in the acid) It also shows as a "low battery charges right up", since it's really only a 20A battery now instead of 80A

[angelakelly]

Okay, I'm going to mark this as solved.

As Bala suggested, the system hasn't been getting fully charged. I believe I -am- putting about as much in as I take out (100Wh out vs 135Wh in), but the issue is that when the CCs switch to float (they're on a timer, I verified), I'm generally only about 80% charged. So over the last few months, there have been clouds, etc that kept me from replacing all my used power, and I probably started with less than a full charged to begin with.I believe the effect has been cumulitive, a little loss here, a little there, adding up over the past few months, so I'm not hovering between 65 percent charge to 80 percent charge. A 15% usage is much more what I expected to see from a single night. The math adds up now.

Going forward, I'm going to work to start getting more charge in, even if I can only do it once a week or so. I may also switch to a mppt controller or even add another panel, but at least I know what's going on now, and I know what I need to do to fix it- the question will be as Bala posed, how much is it worth it to me? Throw good money after bad, or make the best compromises with what I have and plan better next time? Either way, it's working for me.

Thank you to everyone who replied. I got a lot of good advice, and you were all so patient with me as I grappled with concepts that don't tend to show up when you're looking at pure, ideal numbers.

Angela

[Bala]

This is my opinion based on my experience. I had flooded batteries for 13 years and now have sealed batteries which are frowned upon for off grid on this forum. But my life is as much about convenience rather that $ per kwh to power my house.

You may be able to get a better hydrometer but this one is telling you all cells are the same and you have a reading for discharge after a night. I would be getting them up to a known state of full charge so you have a hydrometer reading for that. Then you can work with Voltage and charge current as your indicators.

As I cant take SG from my batteries I use a combination of things to gauge my battery SOC and what to do for the next day/night. Voltage, charge current, what the weather was and is going to be, if we are going to be home or not. I know that when charging if I have a good sun and my charge current is down to single digits i am good, that will change as the batteries age.

IMO you have a good grasp of what your system is doing. What you do now really comes down to longer term cost. The ideal for long battery life is to minimize discharge and return to 100% ASAP. You can do nothing and budget for new batteries often or you could spend a lot of money on charging systems to extend battery life. Only you know your budget and lifestyle so only you can decide on where to go from here.

I would be looking to connect the car alternator to the house bank for charge while driving. If that can be done with a VSR then it will not be a big expense.

[angelakelly]

Two more questions- and sorry to be continually taking up your time.

Regarding stratification, I was reading that the mixing of the electrolyte isn't as much of an issue if your system is in an rv/camper and you are driving around, as normal driving will do the mixing for you. Is that accurate, to your knowledge? If so, that might be a load off my mind as I do a good bit of driving, usually going into town every day or two for supplies, etc- or even just exploring mountain roads.

Second, I've been reading this particular post over and over again: https://www.solarpaneltalk.com/forum...your-batteries. If I am understanding it, it's really just applying as much current as possible and hoping to find a voltage you can set at that will have your batteries charged at the end of the day. Do I have this right? If so, does it damage the battery not to have the absorb stage where the current tapers down toward the end?

[angelakelly]

So, the second thing I wanted to test was how well the resting battery V corresponded to the SG. I figured that would give me a clue about how bad the stratification issue is. The voltage behaved like normal. Last night when I went to bed it was at 12.3, and jumped up to 12.4 when I turned off the computer. This morning it was at 12.4 resting. I took a SG and came out with about 1.210, which corresponds to about 65% charge vs 70% as indicated by the voltage. Considering the precision and accuracy of my hydrometer, I'd say that was pretty close.

In this case, the hydrometer is the issue. It's got a series of ticks, each one 25 points from the next. Even if my technique is perfect. I'm estimating the last couple of digits, and such estimations become less reliable beyond the halfway point between the set values. I wish there was a better way to read this? Perhaps with a refractometer? Of course, then, you're dealing with taking a few drops of electrolyte out of the cell each time you do the reading. It's messy and you're depleting fluid. For beer and wine, refractometers are great.

Do you think it's safe to say that I can (within reason) rely on the voltage once it's rested, but when it comes to the charging, I really need the SG? It seems that with my small loads, I'm not impacting the readings very much. The influence of the solar panels, however, is pretty dramatic.

[Bala]

For the jumper lead option you need to be above idle.

If your van does not have a high idle function then you will need to sit there or put something on the pedal to keep the rpm at 1000 to 1500.

If it is a late model with a smart charge system the negative needs to go to chassis not battery post.

Some vehicles electronics are not happy about jumper leading. You can get leads with surge protection. But best to check for your vehicle.

Monitor the voltage, the batteries should not get hot as the car system will not charge to high.

If they get hot stop as you have a battery problem.

[angelakelly]

No generator or jumper cables, but I could (and probably should) get some jumper cables anyway. With the cables, I could let the car idle and use that to charge the batteries up? How would that work? Would I keep it going til the battery started getting hot, etc? I ask though, because according to the SG, even with the clouds I was up at 75percent. We're just really trying to hit it up to get the electrolyte mixed?

[Mike90250]

Do you have a generator to charge them with, or can you start your vehicle and use jumper cables to charge them ?

Generally, you can charge flooded lead acid batteries at very high rates until they are at about 80% full, then you have to throttle back or you will overheat them

[Bala]

And if I use that technique where I set all the charging phases for my CCs to max and keep the current going full boar for the day, I might or might not be able to get enough charge to circulate the electrolyte. Sounds like doing as much of the equalizing as I can with what I have might be better than doing nothing until I can afford other means. I've a quick question. I know charging current is C/10, and while I don't know the true 20h capacity for these batteries (They state 101Ah @1A), I figure I'd need 8.5A-10A going in. Is that per battery? Since these are in parallel, it seems like I'd need to treat the two batteries as a single 202Ah battery for charging purposes. Am I right on that? If so, perhaps I can do the equalizing one battery at a time. In good sun, I'm pushing 10-12A with the panels I have.

Thanks to you both for your help.

IMO you are onto it,

I would separate them and give them all that 10 to 12A for as long as they need it. They will get to hot if there is a problem, but I doubt that will happen. Just use your hand on the side to feel temp.

Basically at the moment they are dying on you, the sooner you do something to get them fully charged the better.

[angelakelly]

And if I use that technique where I set all the charging phases for my CCs to max and keep the current going full boar for the day, I might or might not be able to get enough charge to circulate the electrolyte. Sounds like doing as much of the equalizing as I can with what I have might be better than doing nothing until I can afford other means. I've a quick question. I know charging current is C/10, and while I don't know the true 20h capacity for these batteries (They state 101Ah @1A), I figure I'd need 8.5A-10A going in. Is that per battery? Since these are in parallel, it seems like I'd need to treat the two batteries as a single 202Ah battery for charging purposes. Am I right on that? If so, perhaps I can do the equalizing one battery at a time. In good sun, I'm pushing 10-12A with the panels I have.

Thanks to you both for your help.

[Mike90250]

You need to insure the batteries have not stratified - meaning layers of dense acid sink to bottom, and plain water floats to top. Regular charging bubbles gas through the cell and stirs it up, as would a trip around the block followed by a good day of charge. If you have not been getting enough charge, or driving, the likelyhood of stratified is strong. That does nothing to improve the life of the battery, the bottom of the plates corrode faster because of the strong acid.

[Bala]

You should have your car alternator connected to the house batteries so you charge while driving. You can get a lot of charge in a short time.

Depending the the make/model it makes a difference to how the system can be set up. If it is a late model it may have some sort of smart charge type alternator.

It may just need a Voltage sensing relay VSR or it may need a DCDC charger.

I have a late model Ford and it has smart charge so I have a Redarc DCDC charger with solar input.

Big difference in $ depending on what it needed.

[angelakelly]

I don't, no. However that might be a good way around things. I can look up (or test) my alternator specs, np I also have the option of spending a night at a campground once a month that has a hookup. Would just need a decent battery charger.

[Bala]

The different level of fluid in the cells may just be that they were not the same to start with.

Generally the need to equalize is determined by cell sg being out of balance but as they have been getting undercharged they really need an equalize charge but that will require more panel power than you have.

https://batteryuniversity.com/learn/...alizing_charge

Do you have these batteries connected to the Van alternator? for charge while driving and what type of Van is it? The alternator charge systems can vary a lot from make and model.

[angelakelly]

Okay, so following up on this, I got a temp corrected hydrometer. It's one of the bulb kinds with a plastic needle that rises to the correct reading. My two batteries are between my seats, so while the forward battery was easy to read, the more inner one required an angle I couldn't quite get, so those readings weren't as reliable.

I wanted to test what Bala suggested- that when the charger goes into float, that doesn't mean a full charge. They were right.

The SG readings across the board were 1.225, which corresponds to a 75% charge. This doesn't surprise me, as I've been charging 5-6 hours with almost 100% cloud cover, though the last hour or two that thinned out and I"ve had some periods of direct sun. This wasn't meant as a rigorous test however. It was meant to practice a little at taking readings. I'll be doing a much more focused testing come Wed when the skies are supposed to be clear. Since Bala mentioned that I could test while charging, I'd like to try to confirm the SG at the various voltages, what it's state of charge is when the system goes into float, and then what it takes to get close to 100% charge. I expect that what I'll find is that those voltages are surface charges, and that the rise in SG doesn't correspond to them in the way I've been thinking of it- and will probably end up better understanding the one sticky that talks about "smoke" charging... basically going full bore as much as one can and using the SG to determine when charging is complete. I don't know, I'm still getting my feet wet on this.

One question. While the charges of each cell seemed to be the same, On one of the batteries, the outer two cells seemed a little lower than the middle four, and those middle four seemed to have climbed up the chamber a little. Is that normal?