AGM battery not charging up higher than 13.6V - Page 1
Forum section: electronics / beginners

author: ilitka1337
author_rank: Newbie
timestamp: November 09, 2024, 02:50:18 pm
content: Hi. Several years ago I bought abattery and an invertor for my PC so that I could work during power outages. I was happy, 6-8 hours of work with that battery helpmed me a lot but for the last 8 months I started noticing that capacity of my battery has dropped drastically down to 1 hour of work. I have an invertor that also charges up battery from mains and I thought the problem was it but I also tried to charge it via Bosch C3 charger in AGM mode but in vain - it shows that the battery is fully charged but 13.6 V is far away from full charge. Is my battery dead? It hasn't gone through thousand of cycles, all I was using it was just power my pc and a couple of monitors, that's it. Any advice what to do with the battery? How do I get it back to life? Thanks in advance.The battry -https://efitron.com/es/baterias-solares/baterias-agm/bateria-en-agm-de-12v120-ah-en-c10-upower-up120-12My invertor -https://www.amazon.de/-/en/PROsinus-800URZ3405-Emergency-Inverter-Charging-Function-White/dp/B076HXHB8S?th=1C3 bosch charger -https://www.amazon.com/Bosch-C3-Automatic-Battery-Maintainer/dp/B004TS1IB4UPD: Model is actually UPG-120-12, not UP-120-12, e.g. it's gel battery, not AGM.

author: u666sa
author_rank: Frequent Contributor
timestamp: November 09, 2024, 03:21:18 pm
content: Quote from: ilitka1337 on November 09, 2024, 02:50:18 pmIt doesn't say anything about cycles in the datasheet --https://www.upowerbatteries.com/pdfs/UP-DC120-12.pdfiPhone battery, we know should last about 600 full 100% charge cycles, on practice it is less, about 400 to 500 for genuine, about 200 to 300 for chinese clone. Your battery does not have to discharge full to 0 and then charge back to 100%, we talking about just charging up to 100%. That's why to extend battery life, it is charged to 95%. What are the chances that your UPS does same thing that iPhone does and charges your battery to only 95%?I believe your battery is dead. You could test it by connecting an automotive light bulb to it. Knowing how much light bulb takes and how long your battery lasts, you can draw a conclussion to its capacity.

author: ilitka1337
author_rank: Newbie
timestamp: November 09, 2024, 03:27:40 pm
content: But why has it died? I expected it to work normally for at least 4 years. Is it due full discharge/recharge cycles? Or it was supposed to work for several years and die?

author: floobydust
author_rank: Super Contributor
timestamp: November 09, 2024, 04:33:09 pm
content: 13.6V is too low, that is float (not charge) voltage.Confirm theBosch C3charger is in Mode4(AGM). Or the C3 might have a problem i.e. bad capacitors or it needs a reboot.Some smart chargers have bad software. Once a battery is charged, they switch over to float mode... forever. So any loads or drains on the battery do not get noticed and the smart charger fails to switch back into charge mode. The system is chronically not charged properly and the battery has a short life and easily goes dead. I don't know the Bosch C3 and how smart or reliable it really is.I would manually charge the battery with a DC power supply to see if it comes up.

author: BennoG
author_rank: Frequent Contributor
timestamp: November 09, 2024, 04:35:33 pm
content: that kind of battery's are 99% of the time topped off and my experience with UPS battery's is they last 3-4 years and need to be replace.

author: ilitka1337
author_rank: Newbie
timestamp: November 09, 2024, 06:46:03 pm
content: It might really be a threshold which C3 cannot overcome. Can combining that battery with another one (I have a car battery 50 Ah, but C3 should be used for batteries not more than 120 Ah) and trying to charge with C3 again help? Is there a device which is like C3 but I can regulate voltage and amperage? I'm a newbie in such kind of things

author: BeBuLamar
author_rank: Super Contributor
timestamp: November 09, 2024, 10:16:13 pm
content: Batteries often die before its rated life that something I come to expect. I don't expect your battery would last for a good number of cycles because you rarely actually use it but only charge it most of the time.

author: floobydust
author_rank: Super Contributor
timestamp: November 09, 2024, 10:19:52 pm
content: The charger is also too small, it's rated 3.8A for a 120Ah battery... that's days to recharge.

author: J-R
author_rank: Super Contributor
timestamp: November 10, 2024, 01:15:20 am
content: Lead acid AGM has nothing in common with lithium ion:- Lead acid should be kept at float voltage (100%), depth of discharge should always be shallow (10%-30%), and storing at lower charge states damages the battery permanently (you can partially recover by running a de-sulfation cycle).- Lithium ion should never be float charged, maximum life is obtained by cycling the battery at low charge states (between 20% & 50%-70%), and storing the battery fully charged (or high charge states) causes permanent damage (should be stored around 20%-30%, but avoid letting them drop lower during storage).The last page of the datasheet for that AGM battery DOES have a chart showing "Cycle Life in Relation to Depth of Discharge", which is essentially the same for all lead acid batteries where a deeper depth of discharge decreases the cycle life drastically.Also, the store page does have this (translated): "The 12V 100Ah UP100-12 battery from UPower is made of deep cycle AGM, which allows us about 550 life cycles, understanding life cycles as the full discharge and charge of this to 75%. For a much longer useful life, it is recommended that a discharge of more than 20% is not performed."There are big differences between AGM and flooded batteries. AGM should not be charged too quickly, since there is a catalyst inside that has to keep up with converting gases back to liquid. Charge too fast and it will vent that gas, and there is no way to replenish the liquid, unlike a flooded battery. Flooded batteries do need to have that extra sulfation cycle run every so often, which essentially is an overcharging cycle.What does all this mean ultimately?- For intermittent, short power outages, lead acid is still king because it's stable and cheap and you can keep them float charged at 100%. If you NEED the full capacity, you can get it, just with the catch that the battery life is impacted.- For off-grid use, lithium chemistries are popular because cycling between 20% and 70% could be very common with say solar, and this fits lithium's characteristics perfectly. If you have a week of little sun, this could destroy your lead acid battery bank, but lithium will be happy.So to answer why this battery is now degraded, I would say number of deep discharges and perhaps a battery that is not top quality. One of the internal cells is probably a goner.

author: SteveThackery
author_rank: Super Contributor
timestamp: November 10, 2024, 11:05:56 am
content: I think the problem is more likely to be the charger than the battery. Yes, OK, if the battery continues to draw too much current when fully charged then the charger might go into current limiting mode, thus causing its output voltage to drop. But for almost all circumstancesit is the charger which sets the battery voltage at the end of the charge cycle.13.6V is too low. 13.8V is a typical float voltage for 12V lead acid batteries. If the charger is only taking the battery up to 13.6V, it is faulty. As was said earlier, it could be bad by design, or something could have drifted out of spec. It could be a software fault, or hardware.But remember: the charger will push current into the battery until the battery voltage reaches a defined value. If that defined value is 13.6V, you need another charger.All of the above is nonsense - please ignore.

author: MrAl
author_rank: Super Contributor
timestamp: November 10, 2024, 01:33:41 pm
content: Quote from: ilitka1337 on November 09, 2024, 02:50:18 pmHi,It sounds like the battery may not be being charged enough. When you first start to charge the battery, it should start out at at least 14.2 volts at room temperature, preferrably 14.5 or higher, even 14.8v for a while anyway. If you do not see that, it is likely that it will never fully charge.I've had a lot of experience with this because I had the same problem with several of my cars in the past. The only way to correct it is to raise the voltage and charge it until it does not take too much more current. You can even extend the life of a battery a little bit this way.The current measurement is also important. If you raise the voltage to 14.0 volts (with an adjustable DC power supply) and it draws 10 amps, that is enough, but if not, go up little by little with the voltage untill you see at least 5 amps. After a while, the current will become much lower, then you can crank up the voltage again a little bit to try to get that 5 amps or more. Don't go over 15 volts whatever you do, that's probably not good. Maybe limit it to 14.8 volts max.While you are pumping the current into the battery, note the current and the time. If you charge at 5 amps for 1 hour that is 1 ampere hour, and if 5 amps for 2 hours that is 10 ampere hours (it's the current times the time, summed over all of the charge times and currents). For another example, say you charge at 5 amps for 2 hours and 2 amps for 3 hours, that is a total of 10+6 ampere hours, which is 16 ampere hours.The point here is that the battery should take a lot of ampere hours if it is rated as high as 100 ampere hours. If it only takes 10 ampere hours when it was pretty much discharged, no matter what you set the voltage to (limited at maybe 14.8v as above) then the battery is shot and may need a battery maintainer to get going again, although that may not help either. You may end up buying a new battery unfortunately.The history of the battery charge/discharge cycles current and voltage show how well the battery will keep performing in the future, but if something is not maintained correctly it could damage the battery and make it unusable.The above procedure will tell you if the battery is worth keeping or not. You really do need either a good DC power supply that is adjustable and can do at least 5 amps (less than $40 USD on Amazon these days) or a battery charger that can properly do the maintenance on a lead acid battery. Because chargers vary so much, I would go with the DC power supply because that will be a definite way to test the battery.Let us know what you do an how you make out.Of course when you charge batteries you have to be careful for a number of reasons, and lead acid batteries can explode unexpectedly I've seen it happen. Safety glasses a must, protective clothing not a bad idea either. Safety glasses a MUST. Safety glasses a MUST.

author: J-R
author_rank: Super Contributor
timestamp: November 10, 2024, 10:49:38 pm
content: No, 13.5V-13.6V is a standard AGM lead acid float voltage at room temperature.

author: Benta
author_rank: Super Contributor
timestamp: November 11, 2024, 12:46:14 am
content: AGM batteries are not suitable for deep discharge, unless they're specifically designed for it. And yours is not.Deep discharge is the certain way to kill a lead-acid battery, either wet or glass-mat.For this kind of application, choose the right battery.

author: floobydust
author_rank: Super Contributor
timestamp: November 11, 2024, 03:39:56 am
content: The inverter has a 10A dumb charger built-in, but you can't select battery chemistry.Who knows what charging voltages the battery has been getting for years. It also shuts down at 10V which seems pretty deep for discharge."100W load = 10A battery consumption." Then factor in 80% charge-acceptance so there are more losses there. Around 65% efficient.Brochurefor UP-DC series is "Deep Cycle AGM" but a black case, not the green OP...Difficult to know the truth -UP-DC120 datasheetshows charging to 14.7V discharge 20A to 1.75V... then it's charged 125%. From graphs below.

author: u666sa
author_rank: Frequent Contributor
timestamp: November 11, 2024, 07:51:23 am
content: Quote from: ilitka1337 on November 09, 2024, 06:46:03 pmCharge with lab power supply, that's what's called for. You charge with lab power supply, then you discharge it by connecting a somewhat powerful automotive light bulb, and you calculate how long it lights, that way you know battery's capacity more or less.Keep also in mind that temperature has a lot to do with things. It makes a difference if your battery operates at 22 degrees C vs outside 0 degrees C.

author: MrAl
author_rank: Super Contributor
timestamp: November 11, 2024, 08:22:06 am
content: Quote from: J-R on November 10, 2024, 10:49:38 pmYeah but that does not matter in the least.If the battery is not charging properly all the "float" charge in the world (hours and hours) will not charge it.I have a lot of experience with this because I had this very problem with some of my automobiles. That's when I came up with the "diode" solution, which tricks the alternator into thinking the battery voltage is lower than what it really is. Several people on the web also did this mod for their alternators too.It is mostly about current, if your battery has been discharged for say 10 hours at 1 amp, that's 10 ampere hours, and you need to put that (plus some) back into the battery in order to get it fully charged again. You can't do that at 13.6 volts in most cases because at that voltage you may get very little current flow. It would take a very long time to charge, but it's more likely it will not charge enough no matter how long you wait because there are inefficiencies that have to be taken care of first, which means more current.The ONLY way you can get this to happen is with a higher voltage, and that is why modern commercial battery chargers do that 4 or 5 step charge algorithm, and they have a 'name' for each stage. You can find info about that on the web.

author: Jeroen3
author_rank: Super Contributor
timestamp: November 11, 2024, 10:10:57 am
content: Quote from: ilitka1337 on November 09, 2024, 02:50:18 pmIf you look at the screenshotFloobydustshows, 1000 cycles is only achievable by not discharging too deep.If you take it all the way down, it is dead in a few hundred cycles.This is applicable to all sealed lead acids, even expensive ones, BEAUT has similar graphs.https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery#Sulfation_and_desulfation

author: J-R
author_rank: Super Contributor
timestamp: November 11, 2024, 10:17:52 am
content: First of all, there are some slight disagreements between manufacturers on precise float voltage. Because overcharging AGM is so vital to avoid, if the charger has an AGM setting but nothing else, it probably will stop at 13.5V - 13.6V. Some battery manufacturers do allow float up to 13.8V. I think some of this is due to the manufacturer trying to guess the temperature that the battery will be used at. So a charger that considers temperature is a better way to go.So ultimately you can use a constant voltage of ~13.6V to fully charge an AGM battery at room temperature. It is not necessary to use higher bulk or absorption charge voltage stages. At lower states of charge, the current flow will be high even at ~13.6V and needs to be limited. As the state of charge rises, the current flow will drop. So in a way the battery still receives "bulk" and "absorption" charge stages if you think about it in that way.Flooded lead acid batteries have some extra challenges when used in a battery backup/off-grid application and so additional stages (equalization) are important to deal with such things as sulfation and stratification. Most modern AGM batteries do not have issues with sulfation, and they would have never had issues with stratification because there is no free liquid.A multi-stage charge cycle is still an ideal option, however. You want your lead acid battery to be fully charged in a reasonable amount of time. So you'll increase the voltage later in the charge cycle to continue to charge the battery at a faster rate than just ~13.6V would alone. But both options result in a fully charged battery eventually.Attached is a graph of my battery bank after a recent outage. You can see once it transitions to the float stage that the voltage slowly rises and the current falls over the course of about 12 hours. This is a 15kWh battery bank. Eventually, the float current stabilizes at an even lower rate, around 300mA (48V system).

author: SteveThackery
author_rank: Super Contributor
timestamp: November 11, 2024, 04:17:07 pm
content: Quote from: J-R on November 11, 2024, 10:17:52 amNo, that's not right. You won't get an AGM anywhere near fully charged at 13.6V. It is important to know that lead acid batteries used in a float configuration are not fully charged. At best, around 80%, and often much less. Floating a lead acid at a high enough voltage to fully charge it will shorten its life.All of the above is nonsense - please ignore.

author: J-R
author_rank: Super Contributor
timestamp: November 11, 2024, 10:28:19 pm
content: Float charging is a valid method for AGM because it's still about 1V above the battery's resting voltage. Here is one manufacturer that outright states that a float charge method is valid:https://www.power-sonic.com/blog/how-to-charge-a-lead-acid-battery/This article also covers the concept of charging at more of a float voltage than a bulk voltage along with the plusses and minuses of each, and the equalization charge to combat sulfation:https://batteryuniversity.com/article/bu-403-charging-lead-acid

author: SteveThackery
author_rank: Super Contributor
timestamp: November 11, 2024, 11:54:44 pm
content: Quote from: J-R on November 11, 2024, 10:28:19 pmI didn't say it wasn't valid, I said it won't fully charge the battery, which is what you claimed. 13.6V float won't take the battery anywhere near to a full charge. The second chart in the link you gave shows 2.35V per cell in a constant voltage (ie float) regime, which is 14.16V. The text suggests 2.30V for float use, which is 13.8V.All of the above is nonsense - please ignore.

author: J-R
author_rank: Super Contributor
timestamp: November 12, 2024, 01:11:54 am
content: 80% state of charge would be a float voltage of 13.2V as shown in the graph. 13.6V will get it to 100%. I'm not sure where you are getting this 80% number from. Do you have some documentation?The chemical reaction in a lead acid battery is pretty straightforward:https://www.pveducation.org/pvcdrom/lead-acid-batteries/operation-of-lead-acid-batterieshttps://byjus.com/chemistry/lead-acid-battery/I do not see anything about this reaction requiring a higher voltage than the float voltage to complete to 100%. When the battery reaches the float voltage and little current is flowing, the chemical reaction is complete and the battery is fully charged.

author: SteveThackery
author_rank: Super Contributor
timestamp: November 12, 2024, 10:55:12 am
content: I've changed my mind - you are quite correct and I am wrong. I'm going to clean up my posts so they don't mislead anyone.

author: mtwieg
author_rank: Frequent Contributor
timestamp: November 12, 2024, 02:30:55 pm
content: Quote from: MrAl on November 11, 2024, 08:22:06 amI don't believe this is true, and it contradicts any reasonable model of a battery (unless somebody hid a diode inside for some reason). It may take a long time, but its charge will approach 100%. That's why for standby operation, float-only charging is often preferred.

author: SteveThackery
author_rank: Super Contributor
timestamp: November 12, 2024, 04:21:49 pm
content: There seems to be some vagueness in the referenced material. In the text it talks about floating at 2.3V/cell (13.8V).In the second chart, 2.35V/cell (14.1V).batterystore.co.uk confirm a float voltage of 2.26 V/cell (13.6V). However, it isn't clear whether this voltage is for maintaining the battery after it has been bulk charged at 14.4V.I must admit, I'm struggling with this. I am looking for an answer to this specific question:Will a discharged lead acid battery attain 100% charge if floated at 13.6V,withouthaving received any higher-voltage bulk charging?ChatGPT says "No", although we all know what that's worth. The charts we've been looking at seem a bit ambiguous, although that could be just me. I thought I knew this stuff, but obviously not.

author: MrAl
author_rank: Super Contributor
timestamp: November 12, 2024, 06:07:52 pm
content: Quote from: mtwieg on November 12, 2024, 02:30:55 pmHi,Well then look up 4 stage charging. Float charging is the last stage, but look up the rest too.Reasonable model of a battery? Where is that?

author: floobydust
author_rank: Super Contributor
timestamp: November 12, 2024, 06:50:22 pm
content: J-R I disagree with two points you're making.I'm not a fan of Battery University and find it full of gathered misinformation there, cut'n'paste errors etc.I'll go to battery manufacturers or research papers (but these can be behind a paywall).Although, I find tons of religious beliefs around lead-acid batteries and expect the thread to derail unfortunately."Most modern AGM batteries do not have issues with sulfation"The main (cycle life) wear mechanism for any lead-acid battery is... sulphation. Every time you discharge it, every time you stare at it, sulphate cystals are forming in the plate's pores until eventually they are covered in this insulating mineral and cell capacity plummets. There is a difference between hard and soft sulphate.The other wear mechanisms - plate/grid/interconnect corrosion, and water loss (AGM, SLA) from abuse- I am leaving out.It's been over 100 years of lead-acid batteries having the same old problems. Tons of research and attempts to stave off.The only advance I see is adding carbon to the plates to thwart sulphation and thus extend cycle life, towards the newer deep cycle AGMs.Desulphators I think are a pipe dream, I found them to not work aside from the accompanying benefit of constant charging.I say the absorption phase is required, that is where the (soft) sulphation is dealt with and mostly reversed."... Hardened sulfate also forms in a battery that is constantly being cycled in the middle of its capacity range (somewhere between 80% charged and 80% discharged), and is never recharged to 100%. Over time, a portion of the plate's active materials turns into hard sulfate. If the battery is continually cycled in this manner, it will lose more and more of its capacity until it no longer has enough capacity to perform the task for which it was intended. An equalizing charge, applied routinely every three to four weeks, should prevent the sulfate from hardening."sourceThat is likely for flooded batteries but I think also makes a good point that never seeing that 14.4V peak has a cost.

author: J-R
author_rank: Super Contributor
timestamp: November 13, 2024, 05:52:45 am
content: I agree that a big problem is that there are a lot of sellers/websites that just copy/paste. They aren't the actual manufacturer, but just slapping their name on someone else's battery. Or merging content without proper care.But I have seen the statement that modern AGM doesn't suffer from sulfation like flooded a few places. Here is one: "AGM batteries are less prone to sulfation"https://www.odysseybattery.com/news/next-generation-agm-batteries-featuring-tppl-technology-deliver-world-class-power-for-automotive-needs/I suppose you can say "gotcha" on my phraseology. Some battery manufacturers do still mention sulfation as an "issue" with AGM, but it seemed to becoming more rare. Overcharging AGM is a perhaps a greater concern than sulfation. Any time you vent a sealed battery (perhaps from equalization charging), it's probably far worse than a small sulfation buildup.When shopping for the batteries I have now, I definitely hit up a lot of battery manufacturers and chatted with them about battery life, maintenance, etc. Flooded, deep cycle lead acid was still touted as the premium option. If you had stratification, you could charge at a high rate, causing bubbles in the liquid to mix things up. If you had sulfation, you could run an equalization charge. But then you also had to monitor fluid levels religiously, or invest in an automatic watering system. Essentially, you could "fix" the battery if needed. People I spoke with about AGM really touted the maintenance-free aspects and they were confident that their AGM batteries didn't suffer from any of those issues. Or it was small enough of an issue to not be an issue.Quote from: floobydust on November 12, 2024, 06:50:22 pmIf the battery is discharged to 50%, then charged at the float voltage, the initial current will be quite high, which in my opinion could be considered enough to combat the "soft sulfation" as mentioned. Or are you saying that the voltage must be higher than the float voltage to deal with this? This might be the "religion" part of the discussion.

author: ilitka1337
author_rank: Newbie
timestamp: November 18, 2024, 09:10:48 pm
content: I am very sorry for misleading you all, my battery is not agm but GEL! upG-120-12. Does it change everything said before?Tried desulfation with FOXSUR for several days - voltage became 13.9 but I wouldn't say it helped a lot.I've found info about such battery but it differs slightly from the picture I attachedhttps://www.upowerbatteries.com/pdfs/UP-G120-12.pdf

author: J-R
author_rank: Super Contributor
timestamp: November 19, 2024, 06:39:36 am
content: Gel is slightly different from flooded and AGM based on my research, and I think even more sensitive to overcharging since permanent bubbles can form next to the plates. Side note: from my calls to manufacturers a few years ago, I got the impression "gel" batteries were falling out of favor compared to AGM and Li-ion. Trojan, a major manufacturer here in the US has discontinued all their gel batteries, for example.The "Charging Characteristics" graph on page two seems to indicate a preference for the float-charge method with a maximum voltage of 13.65V (+/- 0.1V) at 25C and a maximum current of 12A (0.1C). Of course with a multi-stage charger, you can go beyond that if restoring charge is critical, but in my opinion, the slower charge rate is better on any sealed battery just to avoid any chance of venting.How many cycles do you think you have on this battery, and to what depth of discharge??

author: ilitka1337
author_rank: Newbie
timestamp: November 21, 2024, 12:25:02 pm
content: I think 200 cycles of deep discharge, almost to 0.

author: floobydust
author_rank: Super Contributor
timestamp: November 21, 2024, 07:17:42 pm
content: I think your battery could be chronically undercharged or it's worn out or damaged.You will have to special chargeovernight or longer up to a limit of 14.4-14.9V and the battery must not be too cold i.e. outdoors. Measure the charging voltage to confirm you have the voltage come up and the battery was given good time to charge.UP-G120-12 lifetime graph gives 350-500 cycles to 100% depth of discharge (DOD).It is very hard on it, and even then you must NEVER discharge deep below 10.8-10.2V or you are just wrecking cells inside and will have even shorter life.The battery is rated 111Ah at the 10-hour rate down to 10.8VYou originally got 6-8 hours run-time which my math is about 16A average load for the battery.Looking at the inverter: Kemot PROsinus-800 URZ3405 rated 800VA/500W 80% efficiency and no mention of an undervoltage shutdown.Its charger rated "max. 10A" (chinese amps) so it's maybe 5-8A, and 14.5VThis is not enough (charge current) to recover overnight. Even to 60% you need over 10 hours to charge it.In simple terms, the battery takes twice as long to charge, as the time to run your loads.How were you making this work then?

author: ilitka1337
author_rank: Newbie
timestamp: November 21, 2024, 08:55:05 pm
content: Well it definitely had weeks without outages and it had time to charge fully, I guess. But I have never tested voltage when kemot stops charging the battery before. Now it charges up to 13.6 V. I'm thinking about buying a device where I can set specific voltage and amperage to recover the battery. Any decent variants? Budget is I don't know, 300$ max. And of course thinking about new batteries, maybe there are even better than I've bought. Would appreciate your suggestions

author: J-R
author_rank: Super Contributor
timestamp: November 22, 2024, 09:20:05 am
content: 200 cycles to 0% is definitely within the life expectancy range of that battery. Manufacturer ratings are going to be optimistic and under ideal conditions. Also, there are probably times where your specific battery was left at 0% for a while until the power returned.I don't know anyone familiar with this topic that would suggest a design that operates in this manner. Lead acid shouldn't be deep discharged, let alone to 0%.The top solution is to increase the size of the battery bank or otherwise monitor it better to avoid discharging so deep and so often.Another potential solution would be to switch to Li-ion. For maximum life, the latest research suggests cycling between around 20% to 70% SoC.

author: henryuan
author_rank: Newbie
timestamp: December 11, 2024, 02:45:12 am
content: The charging voltage for a typical 12V lead-acid battery is 13.8V or 14.6V.If your battery can only be charged to 13.6V, you need to consider what the charger's no-load voltage is set to. It may be to avoid overcharging by setting the charger's no-load voltage to 13.6V. If the maximum charging voltage is set to 13.6V, the actual 12V battery is almost fully charged when it is 13.6V.You can refer to the charging schedule of Henryuan 12V 10A lead-acid battery charger:https://www.henryuan.com/e_productshow/?221-Portable-CE-UL-SAA-PSE-Listed-Trickle-12V-10A-Lead-acid-Battery-Charger-221.html

author: Xena E
author_rank: Frequent Contributor
timestamp: December 13, 2024, 07:32:46 pm
content: Did not read the whole thread, too lazy.One thing to note if it hasn't been already, is that incomplete charging of any lead acid battery technology will ultimately shorten the life drastically, due to the incomplete reconversion of PbSo4. the remainder coating the electrode becoming crystaline, drastically reducing capacity and it can not then be converted from that state back to PbO2X