SLA battery questions - Page 1
Forum section: electronics / beginners

author: cigmas
author_rank: Regular Contributor
timestamp: April 18, 2023, 12:15:37 am
content: Regarding typical 12V 9Ah (or 7Ah) SLA batteries used in UPS units:1. Can they be used upside down?Some sources say they can be used in any orientation due to being "sealed", while others (eg. a SLA retailer) said they can be used in any orientation except upside down. Incidentally, the CyberPower CP1500PFCLCD takes two SLA batteries, with one oriented right side up and the other upside down. The batteries have failed the unit's self-test after 5 years. A check with a battery tester (Ancel BA301) reports the right side up battery as good with 19mOhm internal resistance (typical spec for SLA), and the upside down battery as bad with 75mOhm internal resistance. Coincidence, or possible cause of failure? And/or bad UPS design? (APC's equivalent units have both batteries oriented sideways.)2. If one out of a pair of batteries fails, is it ok to replace only the bad battery as long as the internal resistances of the pair are ok/matched, or must they be replaced in pairs?3. Many sources say SLA batteries deteriorate with age, but how? Another UPS has a 2-3 year old replacement 12V 9Ah SLA that now lasts only about 20% as long as the original 7Ah battery for the same load, but the battery tester reports it as a good battery with low (~22mOhm) internal resistance.4. Thoughts on adding distilled water to SLAs to revive them? If so, which batteries would be good candidates? (high internal resistance failed battery, and/or low internal resistance but low capacity battery) Lots of people/videos report this can work, others say it provides marginal and unreliable improvement. I wonder about how much water to add without diluting the acid too much, if that even matters. Also, how to know what the source of the weakness is, and whether water will address it.5. What is proper maintenance for SLA batteries? All of the batteries are kept fully charged in UPS units, so not stored discharged. All of the batteries, including the failed one, show full voltage ~13.3V.

author: BradC
author_rank: Super Contributor
timestamp: April 18, 2023, 03:24:19 am
content: 1 - No. There is liquid in there, even if it's not very much. When an SLA is over-charged and generates too much gas for the catalyst to re-combine it farts. If the valve is at the bottom it'll fart any liquid that happens to have settled in the valve.2 - It works. Not ideal if there is a great age disparity, but we've all done it.3 - Sulphation from undercharge or anode corrosion from overcharge. They all die.4 - No. Waste of time.5 - Read the manufacturers data sheet, particularly the float voltage window, temperature compensation and ambient temperature specs. I have 2 similar UPS, both with 4x55ah 10 year rated SLAs and the float voltages adjusted the same. One lives outside in an uncontrolled environment and one lives inside. The average (12 month) temperature difference is the inside one is 7 degrees warmer. The inside batteries last about half as long.I've found ESR measurements to be ineffective. The only accurate measurements I've found are trying to match a data sheet parameter (for example the C/10 rate) and actually measuring it with a CC load.Lead acid batteries have a limited life. "." (full stop). Some are designed and built to last longer. They're generally more expensive and you get what you pay for.

author: radiolistener
author_rank: Super Contributor
timestamp: April 18, 2023, 06:33:23 am
content: 4. I tried to add distilled water on two batteries - there is almost no effect for both, this doesn't works.5. For a longer lifetime it's better to not store the battery under standby charge in UPS, it's better to remove it and periodically charge it (once per 3-6 month). When the battery is always under charge voltage it leads to a shortened lifetime.

author: cigmas
author_rank: Regular Contributor
timestamp: April 18, 2023, 09:42:47 pm
content: 1. If no, then the CyberPower CP1500PFCLCD has a design flaw, and surely a UPS manufacturer knows better.. How nice of them.3. Would sulphation and anode corrosion necessarily mean higher internal resistance? Can a battery be deteriorated while still having low IR? This article says IR/CCA and capacity are somewhat independent, but I'm not understanding why/how:https://batteryuniversity.com/article/bu-905a-testing-starter-batteries-in-vehiclesI would guess loss of water could become a limiting reagent in the chemical equation, thus reducing capacity without affecting IR, but this is a pure guess.4. Ok, I don't feel like wasting time with it. Maybe it is possible to repair if it is just missing water and not damaged in other ways, but so far I'm unaware of how to discern this.5. I don't think I have control over float voltage. Hopefully the UPS implements it properly. Temperature, yes. One UPS is in a basement so it should always be < 25C, but another sometimes sees hotter temperatures in summertime. I thought being discharged takes away from the battery's life, but perhaps not being cycled enough also damages it? Does any manufacturer recommend partial or full discharges periodically? I haven't seen this. Is external charging different/better than the UPS trickle charge? The only external charger I have is a car battery charger with a trickle mode of max 0.25A and I forget what voltage.I've attached the datasheet for the CSB 12V/9Ah HRL1234W which I'm considering for my next replacements, due to its 8 year standby life. The float voltage is specified at 2.275 V/cell and shows 8 year life at 25C or less. P.S. any clue what the "PA" is for units of current?HRL1234WF2FR.pdf(661.98 kB - downloaded 537 times.)

author: SmallCog
author_rank: Frequent Contributor
timestamp: April 19, 2023, 11:21:20 pm
content: 5 years is a fair lifeWe renew them every 3 years in critical applications

author: MrAl
author_rank: Super Contributor
timestamp: April 20, 2023, 10:50:38 am
content: Quote from: cigmas on April 18, 2023, 12:15:37 amHi,In your application how often do the batteries actually have to supply current (and thus power) to a load, rather than just be maintained at the proper float voltage? This would be interesting to hear about i have dealt with these batteries too in the past and a little now too.What i can tell you is that the batteries do go bad after some years, and i dont think there is any way around that. I think manufacturers collect the cores so they can use the raw materials over again, such as the lead. They probably melt them down and use that metal for new batteries.I had an older Fios wall box that used a 12v 7AHr battery (much like the 9AHr type) and it would run down after about 2 or 3 years.There seems to be no good way to revive these batteries once they become bad. Adding water probably would not do anything because i've read that sulfur is not water soluble, but does work in wet batteries to replace lost water due to evaporation. I've read about all kinds of stories where users tried different methods to revive, such as extreme overcharging. Others tried to "clean" out the inside of the battery by dumping all the fluid, then replacing the fluid with a solution, then dumping that, then putting the original fluid back in. That did work, but the tests done afterwards were at low current which says nothing about the true state of health. The ones that had to produce high current that a LA battery would typically have to do never worked. They tried various solutions and nothing worked.The light current applications did work because as the internal resistance goes up they can still provide some current, but not at the original voltage because the voltage sags. For example, i have a 12v 7AHr battery that i can still use to run LEDs even though it is probably 15 or more years old. That's because there are only two LEDs in series and the current is less than 10ma. They are dimmer now than they used to be though, because the battery is so old now. When it was just 10 years old though the LEDs were still bright and i used it as an emergency storm light and it would run for 24 hours a day 7 days a week, although the longest stretch i ever had to use it for was about 4 or 5 days.Lead acid batteries have a limited lifespan, and a limited charge cycle life that's why i asked about the way the batteries were being used. The cycle life is very short relative to other battery chemistries, the only advantage i think is that they can supply a large current without having a problem.The newer type batteries are the LiFePO4 type as they have a much larger cycle life, upwards of 500 times. They have to be oversized though for something that has to supply a high current. They are very lightweight though when you pick up a 12v 7AHr battery it feels like a feather compared to a lead acid battery. Unfortunately, you can not replace UPS batteries that use LA type with the LiFePO4 type as the charge regime is much different and so is the loading specifications. It would not only not work, it could be dangerous. I dont know if you can mod it to work with those type but i would bet you cant use the same size battery you would probably have to go 2 times higher in capacity to get that kind of current without a problem. It would be a serious mod too you'd have to test very carefully so i cant recommend this kind of mod.As i was saying, in lighter current applications you can overcharge slightly and get more life out of the battery, but that means a different kind of charger or charge manually, and i dont think you can get the capacity you need for a UPS that way either. UPS systems are very demanding so the wise buy systems that are much higher rated than they actually need, as much as 400 percent higher. That means if you need 10 minutes then buy a system that will give you 40 minutes. If you need 10 minutes and you buy a system that can handle 10 minutes you could end up getting 1 minute because that will tax the batteries a little too much.In the end what most people do is just bite the bullet and buy new batteries when needed. It's a bitch but any other way just doesnt seem to work. We can be happy that at least we have these batteries, imagine life without them. As time goes on we may see better batteries that can take the place of these noble devices as there is a lot of battery research going on mostly due to the continuously growing EV market. It takes a long time to get to market though so we just have to wait patiently.Just to note, i have never heard of an application where the sealed LA battery was mounted upside down.I have seen one application where the sealed LA battery completely dried out. I actually took it apart to find out what happened and it was completely dry inside.

author: SmallCog
author_rank: Frequent Contributor
timestamp: April 20, 2023, 10:44:47 pm
content: Agree with the above, often seen on their side in things like UPS's but never seen them intentionally upside downI Just bought 50 of these yesterday for a maintenance run next monthThey often have some life left, people here will reuse them for various things, its just that we've found that they don't regularly fail before 3 years so we do them at 3 years.I've never managed to "rejuvenate" one though. Once they're dead/damaged that's that.

author: cigmas
author_rank: Regular Contributor
timestamp: April 21, 2023, 01:11:14 am
content: I know 3-5 years is the typical lifespan on average, but that's average. Makes sense to go with a replacement schedule when dealing with large installations, but for an individual situation, I'd rather diagnose and see what I can do to maximize service life if possible.Quote from: MrAl on April 20, 2023, 10:50:38 amI'd guess the UPS got tripped roughly half a dozen times in the past 5 years, with maybe half of those being deep discharges. Basically, quite rarely. Nowhere near the 200 cycles on datasheets.Also, the load is low on both UPS units, at ~10%.As a side note, I discovered that the CyberPower battery test software on linux has a flaw where it does not report a result if the load is too low, less than ~20%. It was such a hassle dealing with CP outsourced tech support, suggesting reinstallation, saying the unit is too "old", etc until one agent finally asked about the load and suggested retrying the test with >20% load.I briefly considered LiFPO4 "retrofit" replacements but soon abandoned that idea. Even though they are advertised as upgrades for UPS battery replacements, when I contacted a vendor with questions, they admitted that the charging system in a UPS isn't right for the LiFPO4 batteries so the full capacity will not be used and will cause degradation, and they will not be able to deliver anywhere near as high a current as SLA, but said they're not aware of any safety hazards.. Long life SLA seems better until we get UPS units made for LiFPO4.Quote from: MrAl on April 20, 2023, 10:50:38 amQuote from: SmallCog on April 20, 2023, 10:44:47 pmFrom CyberPower's user manual:

author: thm_w
author_rank: Super Contributor
timestamp: April 21, 2023, 01:29:09 am
content: Quote from: cigmas on April 18, 2023, 09:42:47 pmFrom this website it looks like both batteries are mounting with the terminals pointing up, no?https://www.linuxlookup.com/review/cyberpower_cp1500pfclcd_pfc_sinewave_ups_review

author: Rick Law
author_rank: Super Contributor
timestamp: April 21, 2023, 02:13:20 am
content: I attached a photo,I believe after you review the photo you would want to keep your SLA upright.To orient you on this partial view of a battery top-side viewed from top, here is some info: I have disassembled about 1/2 dozen SLA's, some from UPS, some from car jumper-booster. While I am sure there are different designs, the ones I disassembled all have these in common:- A top cover, typically glued down. Upon removal, you can access individual cells.- With top cover removed, you can see rubber caps for each of the 6 cells. See attached photo, you see the top cover removed laying on top (rotated) covering 3 cells but with 3 cells visible. One rubber cap was removed and sitting on the side so you can get a idea of the depth of the cap.- The rubber cap can be removed to add battery acid or to add water. They are rubber (instead of a glued on plastic plug) to allow gas to escape if/when gas pressure is too high -- I've had these caps popped while I experimented with recovering a dead SLA with top-cover off. Acid can and do split out depending on how strong the pressure was when it popped.- While the small fill holes are not design for measurement, but if you have a small SG (Specific Gravity) measurement device, you can get the exact charge level of the cell based on the SG of the acid in the cell. That is how car owners/drivers used to measure charge level in car batteries before "sealed" ones take over. SG measurer may still be available in auto store, the small SLA's hole is too small for those old car battery SG meter. But I suppose you may be able to fit a thinner tube extender so it can be used for the small SLA's.Now take a look at the attached photo again and imagine it sideways or upside down -- I think you would agree is really a good idea to always put SLA upright.

author: floobydust
author_rank: Super Contributor
timestamp: April 21, 2023, 02:44:47 am
content: Upside down SLA I'm not sure if there would be condensation at the bottom and get pushed out the vent? The gel electrolyte is pretty thick but they do put extra water in there.I have seen problems in metal enclosures, the terminals would short out when the battery put in or taken out.OP's UPS appears to have issues:"We checked Amazon's user reviews of the CyberPower CP1500AVRLCD and counted 47 reviews where users complained of smoke and popping noises coming out of their units."https://www.tomshardware.com/news/cyberpower-ups-smoke-reports-continuehttps://www.reddit.com/r/homelab/comments/voy9kl/cyberpower_cp1500pfclcd_fire_hazard/

author: MrAl
author_rank: Super Contributor
timestamp: April 21, 2023, 09:29:35 am
content: Quote from: cigmas on April 21, 2023, 01:11:14 amHi,Oh ok a deep discharge will ruin the battery pretty fast from what i have read and experienced.About the newer batteries...Yes i know you cannot replace LA with LiFePO4 that's why i said this:"Unfortunately, you can not replace UPS batteries that use LA type with the LiFePO4 type as the charge regime is much different and so is the loading specifications. It would not only not work, it could be dangerous. I dont know if you can mod it to work with those type but i would bet you cant use the same size battery you would probably have to go 2 times higher in capacity to get that kind of current without a problem. It would be a serious mod too you'd have to test very carefully so i cant recommend this kind of mod."Also, the typical charging voltage is higher for LiFePO4 type so it may not even charge enough.What i meant was i have never seen an application that used an upside down LA battery myself in the PAST.It's strange that they would do that they must have found some wiring advantage, maybe.I think all these products are still evolving. I cant wait until some company starts to use the new batteries instead of SLA. They would have to be oversized though to handle the current demand.Both these battery types are interesting though. A few general specs:LiFePO4: Long cycle life, deep discharge, light weight, less current drain, higher charge voltage.SLA: Short cycle life, no deep discharge, heavy weight, high current drain OK.Neither of these batteries will work right in an app that takes the other battery type.The main advantage of the SLA is the high current drain without too much of a problem. There is a limit there too but it's generally higher than LiFePO4.

author: cigmas
author_rank: Regular Contributor
timestamp: April 22, 2023, 03:19:02 pm
content: Quote from: thm_w on April 21, 2023, 01:29:09 amThat is a newer revision with a USB-C port in front. I have a revision 2, and there are at least 3 revisions. Interesting that the newer version seems to have changed the battery orientation. One is right side up as before (the removed battery) but the second one is on its side vertically (you can see the wires to its terminals).Quote from: Rick Law on April 21, 2023, 02:13:20 amIf you take a look at the photo I posted, you can see it is impossible to keep both batteries upright. They are set up opposed to each other.Besides, manufacturers have this to say:"With its sealed container, the battery is not limited to direction, or position in place. It can be put in horizontally or vertically while not affecting performance or safety. "https://csb-battery.ca/collections/hrl-seriesQuote from: floobydust on April 21, 2023, 02:44:47 amInteresting, but unclear if that's due to a defect of the unit or just bad batteries. Pictures suggest issues with batteries. Could be the unit lacks detection of bad batteries and charges them till they go boom, but that is another matter.Quote from: MrAl on April 21, 2023, 09:29:35 amFor car batteries, yes. But UPS batteries seem made for deep discharge. This data sheet for the replacement batteries I'm looking to get says:"It can be used for more than 260 cycles at 100% discharge in cycle service, up to 8 years in standby service."https://cdn.shopify.com/s/files/1/0191/5482/files/HRL1234WF2FR.pdf?303==========Anyway, this is all getting rather off topic. So far the answers seem to be:1. No, upside down use is not recommended for SLAs (suggesting the CyberPower UPS has a design flaw).2. Recommended to change both batteries at the same time to ensure matched IR and capacity and age. Maybe it's not as bad in a series configuration compared to if it were parallel, but still.3. Still unclear what happens to the chemistry of the SLA due to age, especially if the IR still measures low. But it seems clear that capacity can degrade even if IR is still ok. To be continued..4. Trying to revive SLAs seems mostly like a waste of time for reliable use. Seems it could be ok to try to get a bit more use for low draw applications but it obviously won't undo any chemical or physical degradation due to age or condition.5. Other than controlling conditions like temperature, it's still unclear if any maintenance is helpful. The advertising from the manufacturers says "maintenance free". Maybe discharging the battery (how much?) and letting it recharge could help instead of trickle charging all the time, but unclear how the tradeoff works between standby and cycle use.As for measuring the state of the battery health, high IR is clearly bad, but low IR seems not sufficient to declare a battery good. Ultimately, capacity testing or using a constant current load and comparing results to the data sheet might give some idea, but isn't very practical. Not the most satisfying answer, but that seems to be the state of affairs at the moment.

author: Rick Law
author_rank: Super Contributor
timestamp: April 22, 2023, 04:45:05 pm
content: Quote from: cigmas on April 22, 2023, 03:19:02 pmThis reminds me of a common joke: When the wife came home unexpectedly early and found the husband in bed with the woman next door, the husband in his own defense says: "Don't believe you lying eyes. I was not sleeping with that woman!"The top cover is glued on, thus sealed. A side way battery or upside down SLA will have liquid acid at the opening merely held in by the rubber cap. As you charge, hydrogen will be generated in the process thus the interior pressure will increase pushing the the liquid against rubber cap when it is not directly up-right. The cap is merely held in by the glued top cover preventing the liquid from leaking out. All is well... But in time, glues can dry out. Heck, even plastic will dry out. Even without pressure, gravity will encourage the liquid to sip out. Gravity doesn't get tired and give up. It will just keep trying to get the liquid to give up it's gravitational potential energy.One can of course just count on the rubber and glue seal... I'd be happier if it is GEL instead of common SLA.