Lead acid...  it's dead isn't it? - Page 1
Forum section: electronics / general

author: paulca
author_rank: Super Contributor
timestamp: February 24, 2021, 10:23:34 am
content: Again, lead acid batteries. I hate them.100Ah Marine battery on the solar panel, just turning 2 years old. It's not being loaded at all over winter as their is barely enough sun to run the charge controller!Well, I was leaving it until it started to fully charge again. It has done that now, 3 days in a row. Even getting to run for over an hour in float 13.6V. Suggesting it's fully charged.However running just the charge controller (<100mA) over night the battery fell to 12.35V which doesn't sound good.Running the garage lights off the battery last night pulled the voltage down to 12.11V. That's only a 1.5A load. I expect a 2-3 Amp load will drop it below 12V.I need a new one, again, don't I?Is there a chance it will get better now the temperature is rising again? It's suffered 2-5*C for the past month.They aren't cheap to replace every 2 years, but Lithium options are still 5 times the price, maybe less taking the gamble on LiFePO4 100Ah cells from AliExpress - who are reportedly mixing second hand industrial cells into orders.

author: tszaboo
author_rank: Super Contributor
timestamp: February 24, 2021, 10:51:49 am
content: 13.6 is not fully charged, 14.4V would be for regular lead acid.Sudden drop of voltage is expected for these, after the charging is done.If you dont want to rip out all the electronics, just try to replace the battery with Enersys Cyclon batteries. They are the duck's guts when it comes to lead acid batteries. Not cheap, but it might be cheaper than buying a new battery every two year or replacing the entire electronics. Or blowing up your property with some junk grade batteries.

author: CJay
author_rank: Super Contributor
timestamp: February 24, 2021, 10:57:21 am
content: What's the alternative though, as you say Lithium ones are 5 times the price, LiFePo are more expensive and a gamble unless you pay top price from a reputable supplier, so calculate the lifespan of the alternatives, work out the cost per year of each and see where the numbers lead you.I've a feeling you may be surprised at how well lead acids fare in the comparison.Plus, a decent brand/quality lead acid should last longer than two years if it's specified, charged, discharged and installed/stored correctly.Personally I'd consider getting friendly with a UPS engineer, one of the guys who works on building size installs where batteries are made up of hundreds of 2V cells and have capacities measured in the hundreds of AH per cell, for instance we recently disposed of 24 of these during a telephone system renewal, I don't think they'd ever been used in anger:

author: CJay
author_rank: Super Contributor
timestamp: February 24, 2021, 11:00:12 am
content: Quote from: NANDBlog on February 24, 2021, 10:51:49 amCyclons are the balls, absolutely excellent, years ago I made myself a booster pack from a pile of junked Cyclon cells out of DEC/Compaq/HP SAN cache battery packs that were replaced on scheduled maintenance, it was a sad day when they moved to LiIon and my supply dried up.

author: Renate
author_rank: Super Contributor
timestamp: February 24, 2021, 12:05:21 pm
content: I've run on solar panels and batteries for years now.It's been a learning curve.Long term insufficient charging will kill your batteries.They need to see 14.4 V for a few hours, then 13.8 V for more hours.You have to look at how much current is going into them.You're running a light load so maybe LiFePO4 would be overkill (or over-budget).The one thing that LiFePO4 do well on solar is that they can absorb any electrons you want to offer them.A lead acid hits 14.4 V and it says, "I'm full" and starts slowing down.You have to coax if for hours, "Aw, wouldn't you like another 20 Ampere-hours for dessert?"This difference is significant if you only have a few hours at the end of a (solar) day to recharge a battery.A lead acid takes its time and won't get the job done, a LiFePO4 will greedily suck down the electrons.Current setup: 2 x 300 W solar, 2 x 6 V, 224 AH GC2 ("golf cart") AGM batteriesNext battery: 4 x 3.2 V, 280 AH prismatic LiFePO4 battery cells.

author: paulca
author_rank: Super Contributor
timestamp: February 24, 2021, 01:13:17 pm
content: Sorry, to be clear, I was considering fully charged to be when the charge controller switches from boost, 14.40V to 13.60V float.Heres is the chart for 2 days. The min value 12.11V occured when the 15W load was occuring. The left side shows what I considered the battery getting somewhere close to fully charged.The charge controller will handle LiFePO4 cells in 12V config. It doesn't handle LIon though, the closest alignment is 7 series which would need more panel volts... and you have to disable the float portion.I'll take a look now at those batteries people recommend.

author: paulca
author_rank: Super Contributor
timestamp: February 24, 2021, 01:15:29 pm
content: There are two figures which are very depressing on that graph.Average incoming power is 2.58W, average outgoing power is 0.12W, but the battery voltage is lower at the end of it.That's not efficient LOL

author: 2N3055
author_rank: Super Contributor
timestamp: February 24, 2021, 01:38:06 pm
content: Fully charged lead acid, non loaded, and without float charge being applied will have 12.6V in steady state, at cca. 23 °C°.So 12.5V is full battery, pretty much. And 11.5V is empty battery.. 9.5V is dead battery.Problem with lead acid is self discharge, and highly nonlinear/nonsymmetric charge/discharge curves.Also their life highly depends on depth of discharge. If you deep discharge them even once, their life will be significantly shortened..

author: paulca
author_rank: Super Contributor
timestamp: February 24, 2021, 02:24:36 pm
content: While I don't think the battery reached fully charged, it had dropped to around 1/50th C charge current at 14.40V when it switched to float mode. Which aside a prolonged period in float it's more or less fully charged.That night it was not loaded, except to run the controller and the ESP8266 sending the data, <100mA total. The voltage as start of solar the next day had dropped to 12.44V.Last summer, when fully charged it would hold 13V for a few hours and only end up down to 12.7V by the next morning.I think it's been damaged by the winter, it did get below freezing out there. The lowest I let it go was 11.9V, when I used a 4A charger on it for 24 hours to fully charge it again.Although... I asked for a deep cycle marine battery and took the Yusa 100Ah Marine battery I was given for what I asked for. It's odd I never really twigged before, but it does say "Marine START" on it. Suggesting it's not a deep cycle, but just a beefy marine diesel starter battery. Maybe 2 years of moderate cyclic activity and daily charge / discharge 50% all through summer for 2 years is more than it is designed for?

author: paulca
author_rank: Super Contributor
timestamp: February 24, 2021, 02:31:01 pm
content: Enersys Cyclon batteriesOuch! 12V 25Ah is £400+

author: Renate
author_rank: Super Contributor
timestamp: February 24, 2021, 02:40:12 pm
content: Lead acid is still a bit voodoo to me.Can you get a battery acid hydrometer reading off it?Is it sealed? How are the levels?When the capacity goes down the voltages can stay about the same.You start noticing when the charge time (and discharge time) starts turning really short.Then there's equalization, giving a charge at 14.6 to 14.8 V to drag the weakest cell up.Some solar chargers do it once a month.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 24, 2021, 04:22:53 pm
content: Lead acid really hates standing around while discharged or even partially discharged. If the solar system isn't generating enough to keep the batteries topped up during winter, you will get much better life out of the batteries if you hook up a float charger during that time, just to keep them in good condition.I do that with cars. I just noticed that the battery in my wife's car (daily driver) is getting a little weaker than it used to be, but still passes the load tests. It will likely need to be changed this year. That battery is 8 years old now...

author: paulca
author_rank: Super Contributor
timestamp: February 24, 2021, 04:36:35 pm
content: Quote from: SilverSolder on February 24, 2021, 04:22:53 pmThat's impressive innings for a car starter battery. My last one lasted 3.5 years and lockdown - stood for weeks and short trips to the shop - killed it. That is one advantage of having a 100Ah marine lead acid sitting in the garage. I can just disconnect it from the solar panel and jump start the car with it.

author: Nauris
author_rank: Regular Contributor
timestamp: February 24, 2021, 04:58:35 pm
content: I think a Start-Stop AGM type battery would serve well for your solar system. It is designed to withstand cycling at partial state of charge and readily accepts charge when available. They are maybe twice the price of regular starter battery but much better.For car batteries I have found that BMW-branded batteries sometimes found among scrap batteries do well in regular car or tractor even when they are past ten years old.

author: CJay
author_rank: Super Contributor
timestamp: February 24, 2021, 05:11:43 pm
content: Quote from: paulca on February 24, 2021, 02:31:01 pmYeah, they're scary expensive but they really are the business.Worth chasing down government surplus auctions though, they turn up on those quite regularly as do 'dry charge' batteries which may be useful, they're more cranking and starting and aren't sealed. You also need a supply of sulphuric acid.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 24, 2021, 06:06:05 pm
content: Quote from: paulca on February 24, 2021, 04:36:35 pmA float charger is your friend.I like the cheapy Harbor Freight ones, they are often on sale for around $6!They work like a champ and I havent broken one yet (oldest one >10 years). I measured mine (I have 3) and they are bang on spec.

author: paulca
author_rank: Super Contributor
timestamp: February 24, 2021, 06:09:12 pm
content: Quote from: Renate on February 24, 2021, 02:40:12 pmGood point. I think it's sealed. It has a plastic top where you can see circles for the cells, which I think is just the cap. I haven't found a way to open it yet though. It doesn't have anything affording opening. So I expect it is sealed.I think I just bought a marine starter battery. Too much YouTube has led me to know that boats have two batteries. The starter battery and the house battery. If you leave the lights on you drain the later. You can still start the engine. I got the starter battery when I wanted the house battery for solar.

author: Ian.M
author_rank: Super Contributor
timestamp: February 24, 2021, 07:09:12 pm
content: When it comes to flooded cell Lead Acid batteries, read 'maintenance free' in the advertising as 'unmaintainable'. In cyclic use they NEED an equalizing charge at somewhat regular intervals, which involves overcharging till the cells are gassing sufficiently to stir the electrolyte, sampling the S.G. periodically until it stops rising significantly in all cells, then topping up with distilled water to the correct level. Obviously you cant measure the individual cell S.G.s of a sealed battery, so the best you can do is a timed equalizing charge, but the reserve electrolyte capacity is minimal and you cant top up the cells, so the total cumulative time you can equalize for before the electrolyte level is down to the plates is very limited so the service life is likely to be significantly shorter than a comparable battery with removable caps. Also with no caps to remove to allow the hydrogen to freely escape, the equalizing charge fills the battery's cell headspaces and vent passages with a highly explosive hydrogen/oxygen mixture, so you are one spark (e.g. from a cracked link) away from a nasty explosion.A good quality flooded Lead Acid battery with removable cell caps, properly charged, regularly maintained and not deep discharged for significant periods should be good for a service life of five to seven years, assuming its of the correct type for the application, with sufficient capacity to have an adequate reserve so the reduced capacity towards the end of its life isn't problematic.

author: Renate
author_rank: Super Contributor
timestamp: February 24, 2021, 07:36:46 pm
content: I think that the solution is Leyden jars.They are very efficient.Ok, volumetrically they aren't so great.Also converting several hundred kilovolts to 12 V is not currently efficient.

author: duckduck
author_rank: Frequent Contributor
timestamp: February 24, 2021, 09:46:28 pm
content: Quote from: paulca on February 24, 2021, 04:36:35 pmI kept my deep-cycle battery for my electric trolling motor even after I sold the boat. I have the battery in a trolling motor battery case that has a couple of cigarette-lighter plug connections. When there is a power outage (frequent out here in the sticks where live) I just pull the USB charger out of the car and plug it into the battery and we've got USB charging outlets for a couple of phones. I'm sure this 20+ kg SLA battery could power our phones for a week. Yes, I'm looking into getting a natural-gas powered generator and the whole electrical switching stuff so we can open the refrigerator without worrying during a power outage. Usually the utility gets things back up in a few hours, so I usually just grill dinner and we bust out the flashlights. Anyway, my point is that I agree that it is nice to have a big SLA around the house. Comes in handy for sure.

author: tszaboo
author_rank: Super Contributor
timestamp: February 24, 2021, 09:50:33 pm
content: Quote from: paulca on February 24, 2021, 02:31:01 pmThat is more than what I remember. Maybe I had bulk pricing.I am genuinely sorry.

author: bdunham7
author_rank: Super Contributor
timestamp: February 24, 2021, 11:35:24 pm
content: Quote from: paulca on February 24, 2021, 01:13:17 pmYour battery needs a good boil. It's probably sulfated and has an internal impedance that is now way too high--you're just getting a 'surface charge' on it. If you have the means, connect it to a charger or power supply that can supply 10 amps and force it to take 10 amps up to a limit of about 16 volts. If it won't take a full 10 amps, just leave it at 16 volts. You should see the current ramp up to 10 amps (if it wasn't there already) then you'll see the voltage start to go down. Or, you'll see just one cell start to boil, in which case you battery is likely done. If that works, give it 10 amps for 16-20 hours starting from the time that it actually takes the 10 amps. If this works, you won't be able to raise the battery voltage back up beyond 15 volts with a 10 amp charge. You probably want to do this outside and not near flammable objects, sources of ignition or things that would be excessively bothered by acid fumes.

author: tautech
author_rank: Super Contributor
timestamp: February 24, 2021, 11:55:11 pm
content: Quote from: bdunham7 on February 24, 2021, 11:35:24 pmThis ^Decent solar controllers have an Equalise function that you would normally set to automatically run once per month.RTFM to see if your controller has such a function and engage it.

author: paulca
author_rank: Super Contributor
timestamp: February 25, 2021, 10:56:26 am
content: Quote from: tautech on February 24, 2021, 11:55:11 pmIt does have an equalising mode and I believe it's set to default. I have seen it charging the battery to just over 15V but only rarely.If I try this 16V 10Amp thing on a sealed battery, surely it's just going to force it to vent... assuming it has a suitable vent.

author: Ian.M
author_rank: Super Contributor
timestamp: February 25, 2021, 11:20:01 am
content: As a fellow pessimist, "What could possibly go wrong?"If the vent is restricted, (it *shouldn't* be but do you care to bet?) there's a risk of gas pressure buildup causing the casing to warp, which has a tiny risk of one of the links breaking loose, sparking and *BANG*!Equalize it outside with the battery in an open weave cloth sack (not mesh or plastic film coated) to contain any explosion but still let gas freely escape, in a catch-tray for any acid escape on a surface you either don't care about or that is acid resistant. Wear appropriate PPE, have a large pack of Bicarbonate of Soda handy for neutralizing any acid spills, and have clean water (e.g. several 2L bottles of still water) immediately available for personal washdown!

author: Renate
author_rank: Super Contributor
timestamp: February 25, 2021, 11:41:32 am
content: Quote from: tautech on February 24, 2021, 11:55:11 pmThat what I illustrated above.Mine does it on the 28th of each month (so that February can get it).

author: bdunham7
author_rank: Super Contributor
timestamp: February 25, 2021, 03:05:43 pm
content: Quote from: paulca on February 25, 2021, 10:56:26 amIf you actually get it up to 16 volts with 10 amps the battery is probably not in good shape. 10 amps shouldn't make it vent forcefully, it might fume a tiny bit. If you have an equalizing mode that can supply 10 amps and it has been running even occasionally, then you probably just have the wrong type of battery for this.

author: paulca
author_rank: Super Contributor
timestamp: February 25, 2021, 03:19:42 pm
content: Quote from: bdunham7 on February 25, 2021, 03:05:43 pmThe charge controller wont get anywhere near 10Amps, as it's only a 50W panelI think 3.2Amps is the max at 14.40V

author: paulca
author_rank: Super Contributor
timestamp: February 25, 2021, 04:49:02 pm
content: I hooked it up to my beefy PSU and at 16V it only took 4A which started to fall towards 3A immediately. You think prolonged 16V will start the current rising again?The battery has a condition sight glass and it's supposed to be green when fully charged and red if it needs replacing (is this a chemical SG measurement or something?), it shows "Black"... Recharge.

author: Ian.M
author_rank: Super Contributor
timestamp: February 25, 2021, 05:06:48 pm
content: The indicator 'eye' is a fixed threshold hydrometer containing a colored ball of known density trapped in some sort of cage immersed in the electrolyte of a single cell. If the S.G. is high enough the ball will float against the window and display its color clearly. Three color indicators have some arrangement where the background color also changes due to a float moving or by reflection from the electrolyte surface if the electrolyte level is too low. It only monitors one cell and only gives a crude go/no-go indication of the S.G. so is essentially useless except as an indicator that batteries in store stock need recharging!

author: bdunham7
author_rank: Super Contributor
timestamp: February 25, 2021, 05:14:55 pm
content: Quote from: paulca on February 25, 2021, 04:49:02 pmThis is a 100AH car-sized battery, right? Yes, if the battery isn't complete toast, the current will rise to 10 amps and then the voltage should start falling. If it doesn't do that it's gonski.Edit: And do be careful! If you have one cell venting or one section of the battery getting very hot compared to others,tossrecycle it.

author: paulca
author_rank: Super Contributor
timestamp: February 25, 2021, 05:38:45 pm
content: Quote from: bdunham7 on February 25, 2021, 05:14:55 pmYea 100Ah marine battery. It's risen now to 4.2A but it's fluctates around 3.5-4.2A. No heat that I can feel and no hot spots. I can hear is fizzing gently though.

author: tautech
author_rank: Super Contributor
timestamp: February 25, 2021, 06:34:00 pm
content: Quote from: paulca on February 25, 2021, 10:56:26 amOf course they are vented but depending on the battery technology the vents may retain some small positive pressure in each cell to assist with retaining electrolyte.An equalising charge is also known as a gassing charge amd when we used dumb LA battery chargers leaving them ON too long led to a gassing charge then we topped up the electrolyte something that's much more difficult with a low maintenance or SLA.IME in periods of low battery activity keeping them fully charged is very important to maintain an acceptable service life and vehicles we have that might get little use over certain times of the year get a smart charger on them monthly at least overnight or until the Charged light comes on.

author: bdunham7
author_rank: Super Contributor
timestamp: February 25, 2021, 06:51:12 pm
content: Quote from: paulca on February 25, 2021, 05:38:45 pmKeep cooking!

author: paulca
author_rank: Super Contributor
timestamp: February 25, 2021, 08:33:47 pm
content: Quote from: bdunham7 on February 25, 2021, 06:51:12 pm4.3AI'll let it run a while longer, but I'm not leaving it overnight at 16V, not unattended. So I'll cut it when I am off to bed. I might drop it back down to 13.6V and leave it overnight then hook it back up to the panel. Maybe it helped.

author: bdunham7
author_rank: Super Contributor
timestamp: February 25, 2021, 08:40:16 pm
content: Quote from: paulca on February 25, 2021, 08:33:47 pmDon't reduce it, just stop until you can resume supervised cooking. Definitely don't leave it unattended! It doesn't look good, if C/10 or less gives you 16 volts. But there's no point in not continuing the experiment tommorrow--nothing to lose at this point.

author: paulca
author_rank: Super Contributor
timestamp: February 28, 2021, 07:35:12 pm
content: Well, so I turned it back on the next day and it took 6.5A for a few minutes, I left it for a few hours and it dropped to 3.2A.I gave up and hooked it back up to the panel.Seems to have had some effect. It averaged 13.0V the first 24 hours and running the garage lights it only drops to 12.44V now.

author: tautech
author_rank: Super Contributor
timestamp: February 28, 2021, 07:57:46 pm
content: Quote from: paulca on February 28, 2021, 07:35:12 pmGood.What this shows is LA likes some exercise so bump the battery back up to ~14.4V and drag it down a time or two more and you should get some more useful life from it.

author: paulca
author_rank: Super Contributor
timestamp: April 09, 2021, 06:01:14 pm
content: Battery is doing ok, but as it's Spring and the panel is generating more than enough power...Is it wise to bring the battery down low, maybe 10.8V at 1 amp and THEN give it the slap in the face charge at 10amps at 15V?

author: tautech
author_rank: Super Contributor
timestamp: April 09, 2021, 07:46:27 pm
content: Cycling LA's is often beneficial like the occasional gassing charge just don't overdo it.

author: paulca
author_rank: Super Contributor
timestamp: January 21, 2022, 04:41:14 pm
content: So nearly a year later, battery has been fine, but is showing "surface charge" issues again.So this time, I drained it safely, first with the 3Amp garage lights, then with then 200mA USB outlet/voltmeter on the caravan electrical panel I use for distribution. The low voltage cut out each time cutting it out at 11V. It did not recover during the day, because when it rose above 12V the load got switched back on.Confirming I had drained it enough, I let it settle for the evening and the voltage read 11.3V, turned the lights on and the low voltage cut in immedaitely.Then... a "slap in the face" charge. 10 Amps@16V until the CC limiter started dropping voltage down to 15V, when I reset the CV voltage to 15V and left it overnight.That should fizz it up a bit.14 hours later it was happily sitting at 14.40V taking about 0.8A, <0.01C.Put it back into service and we'll see if I can get another year out of it.

author: paulca
author_rank: Super Contributor
timestamp: January 21, 2022, 04:48:00 pm
content: Battery torture evidence: