Solar charging voltage question

With no load other than the propane detector, I am reading 14.1 volts at the brand new group 27 lead acid battery. Is that to high? On a normal day of camping with shore power and solar, and light loads the battery reads 13.7. When I bought the camper the old battery was very low on water and refused to hold a charge. I don't want to boil the water out of the new one or harm it with to much voltage.

I have a LMS2430 solar controller which I know nothing about. I have a blinking green light and a constant red light.

I read through this link and still know nothing. And I'm an electrician.

https://solarpanelskit.us/shop/energy-system/lms-series-intelligent-solar-charge-controller-1224-vdc-30-amps-with-lcd-display-2-usb-ports-and-load-controler-model-lms2430/

jrclen said:

With no load other than the propane detector, I am reading 14.1 volts at the brand new group 27 lead acid battery. Is that to high? On a normal day of camping with shore power and solar, and light loads the battery reads 13.7. When I bought the camper the old battery was very low on water and refused to hold a charge. I don't want to boil the water out of the new one or harm it with to much voltage.

I have a LMS2430 solar controller which I know nothing about. I have a blinking green light and a constant red light.

I read through this link and still know nothing. And I'm an electrician.

https://solarpanelskit.us/shop/energy-system/lms-series-intelligent-solar-charge-controller-1224-vdc-30-amps-with-lcd-display-2-usb-ports-and-load-controler-model-lms2430/

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I?m not sure about the lights but the 14.1 volt is not high.  And the 13.7 under load is not low. 

Maximum charging voltage is normally in the range of 14.4v - 14.8v on an RV solar system (most toward the lower number).

Depending on the level of monitoring information you wish to have, there are several setups that will give you the exact amount of amps you have used in a time period and also how many charging amps have been provided.  That gives a very accurate state of charge indication. 

You haven?t told us what size solar panel array you have.... 

Sounds about right. That's a three stage 30 amp PWM controller, and I found this about it on someone's blog. "When it reaches a full charge of 14.1 volts then it will be steady." So it seems like that's a programmed charging voltage for that controller.

Kev

It's very complicated to answer the float question accurately. To get true float you need to basically have the battery disconnected from every load. It is also ambient temperature dependent as well as battery temperature dependent.

14.1V is actually too high for a float charge for AGM at standard temps.  But you probably are never getting to float state anyway because you are using that battery constantly (like everyone does) - The bigger issue is repeated over discharging.

The only comment I would make is that there should be a battery type selection on any decent controller. Looking at the tech data on that controller the write up is horrible. I wouldn't throw it away but there is no way I would "buy" a controller if they can't even explain the basic functions in plain English - LOL...

Thanks Kevin. I will keep an eye on the water level. But it is nice to have the battery maintain a charge between using the camper. The problem with disconnecting it is my gas detector then goes off and I need to disconnect that too.

Ex-Calif - the battery is a lead acid, not agm. Is the voltage to high for one of those? I agree about the clear as mud instructions. That's why I'm here asking. LOL I did see something about adjusting the maximum charge. Just wondering if I should look closer at that and try to adjust it downward.

But if it sounds "about right" I'll just leave it alone and keep an eye on things.

14.1VDC is fine for charging, but is high for floating, without knowing the state of charge of your batteries, it is hard to know if 14.1VDC is ok with your system.  Do you have a solar disconnect, if so can you disconnect the solar, and check the battery voltage after the surface charge has bled off (disconnect all significant loads for an hour, then check voltage, you can leave LPG/CO2 detectors, etc. connected, just no lights, appliances, etc.).    This would give us a better idea of what is going on at the point in time of that snapshot.

I would look at the charging parameters for the battery because that is what matters. If your charge controller is adjustable as far as charging and float voltages, set them for what the battery manufacturer recommends.

The generally accepted range of voltages for charging a lead-acid battery is roughly 13.3-14.4, though some solar gurus give a wider range, maybe 13.1-14.8.  What is "right" depends on the details of battery type, temperature and the current state-of-charge.  Quality chargers manage amps as well as voltage, so a voltage that might be excessive under some circumstances may be fine if the charger is limiting current (amps) as well.

There are some good articles available that explain charging without going overboard on the tech stuff. Try one of these:
http://www.chargingchargers.com/tutorials/charging.html

https://www.batterystuff.com/blog/3-stages-of-smart-chargers.html


In my opinion, 14.1v is high for "float charge" to keep a battery at 100% but not for the earlier stages of charging that get it to 100% in the first place (bulk and absorption charging). Most battery experts agree that 13.3-13.6 is the target to holding a battery at full charge.

For the record, lead-acid refers to the battery internal chemistry; floodedcell, AGM and Gel are types of lead-acid battery design. Flooded cell batteries are the ones with a loose liquid electrolyte and can be either open or sealed. AGM places the electrolyte in a sponge made of woven glass may and Gel uses a thick gel electrolyte. All, however, are lead-acid batteries.

The controller manual says "All of control parameters could be set and modified" but I saw a few that couldn't.  I've come to expect that with the low end controllers.  The thing to do is match, line by line, as best you can the operating parameters of the solar controller and the charging requirements of the battery.  What I see is that this controller is probably better suited to "intermittent" use than "daily" use an RV might see but it will "work".  When you factor the vagaries of solar panel input and loads, the precision of the solar controller isn't the longest pole in the tent.  For sure, you've got a platform to play with and study cause and effect going forward, with which you can better understand what you'd want to change "next time" to suit your application.

Mark B.
Albuquerque, NM

Okay. Thanks everyone. I talked with a local battery shop owner and he told me the 14.1 was fine. I'll keep an eye on things and I still plan to disconnect the battery when the camper is not being used. I bought the battery from Walmart and have no idea what the specs for charging are. I could and might do a search to see if I can find them.

Gary, I'll look at those links.
Isaac, I don't have a solar disconnect that I know of.
I'll try to look up the battery manufacturer to ask them about it.

jrclen said:

Ex-Calif - the battery is a lead acid, not agm. Is the voltage to high for one of those? I agree about the clear as mud instructions. That's why I'm here asking. LOL I did see something about adjusting the maximum charge. Just wondering if I should look closer at that and try to adjust it downward.

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Monitor your fluid levels for a while. 14.1V float is a little high for flooded wet batteries. 13.3-13.5V is preferred - nothing bad will happen but it can gass off ore quickly so if you find you need to service it a lot see if there is a 13.5V float setting.

Thanks, I will look for a setting. I noticed when we are camping the voltage stays at 13.7. The 14.1 is when nothing is on other than the propane detector and it is not connected to shore power.

Most modern converter/chargers manage float voltage to 13.6v, so your 13.7 when on shoe power is pretty much normal.  It seems your solar charge controller is a bit higher, but its not much different than a car alternator.

It appears you have a common automotive-type 12v battery. Those aren't very fussy about charging voltages - they are designed to take high inrush and outrush currents and relatively high alternator voltages.  Assuming its not a sealed (maintenance free) battery, just keep an eye on the electrolyte level in the cells. If it goes a few months without needing to add distilled water, you probably have nothing to worry about. However, if you see a loss of liquid or a lot of wetness on nearby surfaces, I'd be looking to dial that voltage down.

My only suggestion at the moment is to upgrade to a better solar controller, after all this is a $20 30 amp solar controller, at that price for that many amps I suspect it has more than one shortcoming.

Victron makes a nice 30 amp MPPT solar controller that should drop right in https://www.amazon.com/Victron-Energy-BlueSolar-Charge-Controller/dp/B076N5PTBN  though the price is considerably higher , it could also be rewired for higher panel voltage and better off peak performance from your existing panel setup, this assumes you have around 400 watts of solar panels now which would be the limiting factor for a 30 amp solar controller, if less solar panels a smaller one would also work.

Here is the battery I bought.

https://www.walmart.com/ip/EverStart-Lead-Acid-Marine-RV-Battery-Group-27DC/164242687

I will keep an eye on the electrolyte level. So far it is still right on the mark. But it's only been a couple weeks. Thanks Gary.

Isaac, that controller is kind of pricey. So far it seems our camping will be at sites with shore power, so the solar at this point is just something that came with the camper. My concern is basically not trashing my new battery.

jrclen said:

I have a LMS2430 solar controller which I know nothing about. I have a blinking green light and a constant red light.

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The flashing green light means the controller is still in bulk mode so that voltage could be totally normal (even higher in absorb or equalize mode - green LED on solid).  The red light means the external load is enabled but that may not matter depending on how you have it hooked up.

What I see with a lot of controllers is that they default or are permanently set to overly conservative values, and tend to undercharge batteries that see a lot of use.  So while your concerns are valid I think they probably lie with the converter and not the solar controller.  The converter stands a much greater chance of overcharge and water dissolution since it can be on for days, weeks or months on end where solar is really only "on" a fraction of the day.  Watch voltages and water levels and over time you'll determine what the values for your system need to be.

Mark B.
Albuquerque, NM

That sure looks like an AGM battery not a flooded cell but either case you are fine, IMO.

I am suspecting you don't have 400W of solar panels - Maybe one 100W panel?  So the controller you have is "adequate" and I would definitely not buy an MPPT controller. I had 400W on my boat and used a PWM controller for years. Above 400W I would definitely do MPPT but that's a whole nuther conversation.

If you only have this one house battery and as I am guessing, one solar panel you are OK.

Keep in mind that what is more likely to kill your battery 10 to 1 is not overcharging by 1/2 a volt - it is deep dishcharging cycles. Even 50% discharges can cut battery life in half.  I personally like to target 30% discharges and you can make a deep cycle battery last 10 years or more.

1 - Size the battery bank for the consumption you expect. It is easy to burn though 30 amps in 12 hours... Your battery is 109 a/h
2 - Size the solar and other charging to fill that 30amps each day

A 100w panel makes 8 amps in full sun. Conservatively you plan for 70% efficiency so 6amps and then plan for 7 ours of sun = 40amps a day. If you have a couple days of rain you will likely be depleting your battery.

jrclen said:

Here is the battery I bought.

https://www.walmart.com/ip/EverStart-Lead-Acid-Marine-RV-Battery-Group-27DC/164242687

I will keep an eye on the electrolyte level. So far it is still right on the mark. But it's only been a couple weeks. Thanks Gary.

Isaac, that controller is kind of pricey. So far it seems our camping will be at sites with shore power, so the solar at this point is just something that came with the camper. My concern is basically not trashing my new battery.

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Thanks Mark and Ex-Calif. As we are always plugged in to shore power I consider the solar a good way to keep the battery charged between camping trips (no significant loads) which this summer will be every other week. When we dry camped (I think that's the term) with the old pop up, I monitored the battery voltage and charged it every day with the generator (with the converter).

The battery is flooded cell. And it's the only one. I will watch the battery and monitor the electrolyte as well as the voltage so as not to overly discharge it. 30% sounds like a good number to me.

Thanks for the info on the green and red light Mark, that's helpful to know. As it the tip about the converter.

Thanks to everyone for the information.

That sure looks like an AGM battery not a flooded cell

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Not an AGM.  An AGM is totally sealed and would not have the removable caps on top.  That is a basic Marine/RV flooded cell, which is a slightly modified car starting battery design.    In RV Use, it has a useful life of about 3 years if lovingly cared for and as little as 16-18 months if not.