Author Topic: What causes lead acid battery cells to short out?  (Read 2314 times)

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Offline Bratster

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Re: What causes lead acid battery cells to short out?
« Reply #25 on: June 27, 2019, 06:02:57 pm »
They're very expensive up front, but if you take into account the life of the lithium battery and compare that against the cost of the equivalent lead acid battery and the replacement cost of the lead acid to keep the same effective life and capacity they are cheaper in the long run.

Based on the information I could gather (and my own experience with Laptops, phones and alike) Lithium batteries do not have very long life, certainly not dramatically longer than good LA.

Also keep in mind that when comparing those 100ah lithium batteries you don't compare to a 100ah lead acid, you would compare to a 200ah. Since you don't want to take the lead acid below 50% discharge to extend the life.

Big deep-discharge LA batteries can be discharged to 80% DoD without problem. With Lithium batteries, you probably will want to cycle them between 20% and 80% DoD (60% usable) to make their life longer.
I will go double-check  my information  when I get home from work.

I'm talking about lithium ion phosphate (LiFePO4) batteries not standard lithium ion.

This is the company I was looking at:
https://battlebornbatteries.com/

(I'm not affiliated with them in any way shape or form, they are just the ones that I was looking at when I eventually put some solar panels on my truck.)




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Offline NorthGuy

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Re: What causes lead acid battery cells to short out?
« Reply #26 on: June 27, 2019, 09:52:08 pm »
This is the company I was looking at:
https://battlebornbatteries.com/

I found this comparison on their Web site:

https://battlebornbatteries.com/breaking-better-battery/

I cannot tell what are the LA batteries they're comparing, I can only tell you about mine. I bought them 7 years ago. They're about the same price (slightly over $1k/battery when I bought them). They have 673 AH capacity, but they're 6V, while "Battle Born" are 12V. Counting 200 AH per day, it's roughly 500,000 AH over 7 years. Re-scaling the cost to 12V, it's $2k/500,000 = $0.4 cents/AH. I cannot tell how long my batteries will last, but even if we only count up-to-date benefits, it's still roughly 25% of what they say the LA battery would cost and about equal to what they claim the "Battle Born" batteries can do. Of course, we don't really know how true their claims are - very likely to be exaggerated. Thus, I would conclude LA batteries win.
 

Offline Bratster

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Re: What causes lead acid battery cells to short out?
« Reply #27 on: June 28, 2019, 08:09:35 am »
This is the company I was looking at:
https://battlebornbatteries.com/

I found this comparison on their Web site:

https://battlebornbatteries.com/breaking-better-battery/

I cannot tell what are the LA batteries they're comparing, I can only tell you about mine. I bought them 7 years ago. They're about the same price (slightly over $1k/battery when I bought them). They have 673 AH capacity, but they're 6V, while "Battle Born" are 12V. Counting 200 AH per day, it's roughly 500,000 AH over 7 years. Re-scaling the cost to 12V, it's $2k/500,000 = $0.4 cents/AH. I cannot tell how long my batteries will last, but even if we only count up-to-date benefits, it's still roughly 25% of what they say the LA battery would cost and about equal to what they claim the "Battle Born" batteries can do. Of course, we don't really know how true their claims are - very likely to be exaggerated. Thus, I would conclude LA batteries win.

Looks like they don't stack up as best as I thought they did if you can take into account going with a gigantic battery bank.

Although if you're comparing their 100ah LiFePO4 to a 200 amp hour LA they may fair better, which is probably more in line with what their test was.

perhaps their intended application is only one or two of these, then they're better than LA maybe,  but if you actually have the space and weight capacity for some really high-end LA that route will be more cost-effective.


I'm curious what LA batteries you have? They sound like they must be pretty massive, size and weight wise.



Just thinking like for my truck solar power setup, I was going to do one or two of their 100 amp hour model.

So that would be either a 200-400 amp hour lead acid battery bank in my opinion for comparison.

I don't have the available space or weight capacity, so if I went lead acid it would be probably a couple 6 volt golf cart type batteries in series or two 12 volts in parallel.



I'm tired, been staying up too late too many days in a row. Please excuse grammar mistakes etc.
Also nothing I said was ever intended to come off as defensive / offensive whatever. I am more than happy to be talked out of spending a couple $1,000 on batteries that aren't as good as I first thought they were.

G'night

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Offline NorthGuy

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Re: What causes lead acid battery cells to short out?
« Reply #28 on: June 28, 2019, 03:11:31 pm »
I'm curious what LA batteries you have? They sound like they must be pretty massive, size and weight wise.

https://www.trojanbattery.com/products/deep-cycle-flooded/industrial-line-flooded/

About 300 lb per battery. The charging methods they recommend don't work and their support is absolutely unhelpful, but batteries themselves are well built and working OK so far.

Just thinking like for my truck solar power setup, I was going to do one or two of their 100 amp hour model.

For the truck you definitely need something lightweight - take into account all the extra gas you'd have to buy to haul the batteries around.
 

Offline floobydust

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Re: What causes lead acid battery cells to short out?
« Reply #29 on: June 28, 2019, 07:04:00 pm »
LiFePO4, they are 3X the price and 3X the life of SLA, so I didn't see any real advantage.
 

Offline NiHaoMike

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Re: What causes lead acid battery cells to short out?
« Reply #30 on: June 28, 2019, 09:48:27 pm »
LiFePO4, they are 3X the price and 3X the life of SLA, so I didn't see any real advantage.
Less weight and better endurance.
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Offline Red Squirrel

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Re: What causes lead acid battery cells to short out?
« Reply #31 on: July 01, 2019, 02:18:22 am »
Harder to find though.  Found a few on Amazon but I don't like to trust that.  And you don't know in a year from now if that seller or product will even still be around if you want to expand.

I really do hope they start becoming a more commodity item though.   I do like the bigger cells, easier to work with than trying to tack weld a bunch of 18650's together.  But even 18650's are hard to find in bulk.  The genuine ones are about 10 bucks a pop on Amazon.  The cheaper ones are probably fakes.

Most of the sites that sell them outside of Amazon are American so not really an option either.

Found a site that sells the big flooded acid batteries for solar here in Canada though, so chances are when I upgrade I might go with something like that.  Never took the weight into account though... no idea how I would move a 300+ lbs battery. :o  I guess I would need to design some kind of lift mechanism that can lower/lift it one stair at a time.   I wonder if a moving company could help with something like that, they might have special tools for that.
 

Offline Red Squirrel

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Re: What causes lead acid battery cells to short out?
« Reply #32 on: July 05, 2019, 01:47:42 am »
Well I just discovered something interesting.  So my server UPS charger is always charging at 13.5.  Perhaps that's too much.  Unfortunately I have no control. 

Today I just realized that I had one of these batteries in my shed powering my solar setup and it's been through all sorts of conditions from -50 to +30 along with being constantly discharged/charged.  We are in a heat wave right now and it's at least +35 inside the shed.  So it sees pretty harsh conditions.  Decided to go check the cells to top them up with water.  Believe it or not, after a bit over a year of operation they were completely full.  Being in a solar application, it does see 13.5 when sun is out, but it's not constant, since at night it discharges a little then it gets charged back up.  I wonder if having a constant cycling like this is actually better for the battery than being on float constantly with no discharge time.

I eventually want to learn more about power electronics and build my own rectifiers and do a telecom setup that way I'll have more control (and rectifiers are very hard to find), so it will be something to keep in mind.  I can maybe have a scheduled discharge just to cycle them a little.   Suppose an equalize is also good too.

I can sorta simulate that with my current setup by shutting the breaker off for an hour once in a while.  I have a feeling I would really need to be doing this every day to have an effect though.   Of course the fact that the solar charge controller is temperature compensated and this charger isin't might also play a role.   Though that just leads to a higher charge rate since the batteries are cold more often than they are hot, so not sure if it's that.   Today is kind of an exception with the heat wave.  I imagine these +30's are probably hard on the battery that's in the shed.  But given how full the cells are it seems to be doing good.
 

Offline NorthGuy

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Re: What causes lead acid battery cells to short out?
« Reply #33 on: July 05, 2019, 02:44:43 pm »
Being in a solar application, it does see 13.5 when sun is out, but it's not constant, since at night it discharges a little then it gets charged back up.  I wonder if having a constant cycling like this is actually better for the battery than being on float constantly with no discharge time.

IMHO, any discharge shortens the battery life. If you never discharge it, lt'll live the longest.

If you discharge it, then, while in discharged state, it'll sulphate (that is sulphate on the plates will harden). To combat this, you need to overcharge the battery from time to time. The overcharge causes corrosion end depletion of water in the electrolyte. Therefore you need to add water periodically. Corrosion decreases capacity and increases the danger of a short. Therefore, the battery will eventually die - either of sulphation or of corrosion.

You can measure specific gravity of the electrolyte. Low specific gravity in a fully charged battery will indicate sulphation.
 

Offline schmitt trigger

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Re: What causes lead acid battery cells to short out?
« Reply #34 on: July 05, 2019, 05:01:52 pm »
About 35 years ago, I serviced  large UPSs (50 to 100 KVA) for corporate main frames.

The battery bank would be either 300 or 500 volts nominal, made up of many individual 2 volts wet lead acid cells.

Each cell was about 60 cm tall, and had a transparent  vase, completely flooded in acid. There was about 10 cm separation between the bottom of vase and the bottom of the plates.  One could see lead sulfates, which had flaked off the plates, collecting at the bottom as the battery aged.
Once that the sulfates were getting close to the plates, the cell was flagged for replacement.

Of course, one would also observe the pitting and thinning on the plates.

And this is when it  interesting; if the thinning   started at the top,  eventually the plate structure  would not be able to support the heavy weight of the remaining plate, would fall off and short that cell. With the amount of available energy, the acid would boil and next morning one could not enter the room without a respirator. It was like a fork pitched up your nose.

I don’t want to make this post excessively long, but there were many maintenance procedures, as described above, to lengthen the bank’s life.
« Last Edit: July 05, 2019, 05:06:47 pm by schmitt trigger »
 
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Offline Red Squirrel

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Re: What causes lead acid battery cells to short out?
« Reply #35 on: July 05, 2019, 07:05:09 pm »
Being in a solar application, it does see 13.5 when sun is out, but it's not constant, since at night it discharges a little then it gets charged back up.  I wonder if having a constant cycling like this is actually better for the battery than being on float constantly with no discharge time.

IMHO, any discharge shortens the battery life. If you never discharge it, lt'll live the longest.

If you discharge it, then, while in discharged state, it'll sulphate (that is sulphate on the plates will harden). To combat this, you need to overcharge the battery from time to time. The overcharge causes corrosion end depletion of water in the electrolyte. Therefore you need to add water periodically. Corrosion decreases capacity and increases the danger of a short. Therefore, the battery will eventually die - either of sulphation or of corrosion.

You can measure specific gravity of the electrolyte. Low specific gravity in a fully charged battery will indicate sulphation.

That's what I kinda figured too, even our telecom ones are floated at 54v (same as a 12v at 13.5) but I just find it interesting the the battery that is in the more harsh usage scenario lost no electrolyte at all.  I guess that means nothing about the actual state of the plates though.    Ideally you don't want any material to shed, as no matter how deep the bottom is, it will eventually go bad.  The big telecom ones we have at work have really thick plates and some kind of foam material between each one so there's no material that can fall.   I imagine the more expensive batteries will be like this too hopefully.  Less chance of complete failures that way. 
 

Offline floobydust

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Re: What causes lead acid battery cells to short out?
« Reply #36 on: July 05, 2019, 07:13:26 pm »
Some research says that always-on float charging, the battery is being constantly overcharged and leads to more corrosion I think the positive plate, compared to sulphate on the other plate if not being charged.
The researchers tried switching to constant current just above the self-discharge rate. So maybe 50-100uA/Ah, enough to overcome self-discharge rate and then some. It seemed to have better life.

This might explain why some batteries last longer when they are not always being charged.
 

Offline tautech

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Re: What causes lead acid battery cells to short out?
« Reply #37 on: July 15, 2019, 08:33:01 am »
Seems a few of you here have worked with big 2V LA cells and since I've scored a set of 6 old ones maybe you can help with some advice.



Not that I have a real plan for these babies other than to attempt to get them back into some sort of usable capacity.
When I got them a couple of weeks back they were mostly ~1V OC and had been neglected/abandoned for some years.
They have a significant capacity of some 1000 AHrs/cell.


Initially I put some charge into each cell just to see that each would take some and as I could see each slowly taking more I figured they might be worth some effort although not much is involved with just clipping on a charger and checking them a couple of times/day.
However I've played with LA cells for decades and used desulphators to improve and lengthen battery life but first I'd like to improve the odds of a successful outcome.

Hunting out how others maintain and service these monstrous 2V cells I came across this Instructable  ::) (yes I know) that seemed very interesting in that Phosphoric acid can be used to renovate and/or prolong life of LA cells:
https://www.instructables.com/id/Lead-Acid-Battery-Care-and-How-to-Restore-Them/
Particularly Step 4 is worth a read.

Comments ?

Their current state (please excuse pun) after ~2 weeks charging.
One is damaged with a broken positive connection to the plates. (possible repair later)
The 5 other cells are seriesed up and taking a light charge (unrestricted A) that is growing some 20mA/day.

2 cells appear in reasonable condition in that they are ~2.1V while on charge which suggests they are taking what the series string can supply them. The remaining cells are 2.5, 2.7 and 3.3V in the series string charging @ ~13V. (CV)
The string is only drawing ~2A and up to 8A is available for charging duties when they might be able to withstand it.
All electrolyte levels were low but still above the plates and 2L water added to each to get them into the mid level range. Each cell is specified to hold 20L of electrolyte.  :o

Plans
Get each cell to where it's properly starting to take some charge and below a nominal 2.2V like the 2 better cells.
Buy some Phosphoric acid for cell treatment as described in the article above.
Electronic desulphation of some kind....tests to confirm my 12V homemade 70V 6A 1 KHz pulser will perform on just 5 cells.
Attempt to fix the 6th cell with the broken terminal link. The cell lid can be removed and the electrolyte tipped into a 20L bucket and the plates removed as a package for washing and then repair.
If successful, attempt to recover this cell too.

Lost cause ? Why ?
Possible ? Tips and guidance please.  :popcorn:
Thanks for reading.
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Online GeorgeOfTheJungle

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Re: What causes lead acid battery cells to short out?
« Reply #38 on: July 15, 2019, 08:51:08 am »
That's more than 13 kWh @C120. I'm green with envy. BP makes PV batteries? What do the tesla fanbois have to say?
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Offline tautech

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Re: What causes lead acid battery cells to short out?
« Reply #39 on: July 15, 2019, 09:07:53 am »
That's more than 13 kWh @C120. I'm green with envy. BP makes PV batteries? What do the tesla fanbois have to say?
Haha, nuthing like 13 kWh in their current state.
BP PV batteries are now Li and it’s hard to find these big 2V LA’s now.
The cells above are ‘96 vintage so already 20+ yrs old.
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Offline NorthGuy

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Re: What causes lead acid battery cells to short out?
« Reply #40 on: July 15, 2019, 12:17:43 pm »
The string is only drawing ~2A and up to 8A is available for charging duties when they might be able to withstand it.

8A is nothing. You'll need charge currents 100A or so. Normal bulk charging currents are between 0.10*capacity to 0.15*capacity.
 

Offline Red Squirrel

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Re: What causes lead acid battery cells to short out?
« Reply #41 on: July 16, 2019, 01:34:12 am »
At 1v open circuit I'd say these are probably completely pooched unfortunately. I suppose it won't hurt to try to get them to 2.25v to see how long they stay that way though but I don't think there is a good chance. 

That's a nice score though...  I would love to get my hands on big cells like that but they arn't cheap and is typically not something you can just buy around here.   There's lot of regulations about what companies can do with old batteries and usually they have to go to a recycler.  Otherwise I would try to get my hands on some of our work ones when they swap out battery banks.  For my own use they would have tons of life left in them even when they arn't good enough for telecom use.
« Last Edit: July 16, 2019, 01:36:20 am by Red Squirrel »
 
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Offline john61ct

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Re: What causes lead acid battery cells to short out?
« Reply #42 on: July 19, 2019, 04:23:14 pm »
The best deep-cycling battery value in NA by far is Duracell (actually Deka/East Penn) FLA golf cart batteries, 2x6V, around $200 per 200+AH @12V pair from BatteriesPlus or Sam's Club. Deka labeled same batts also sold at Lowes.

UPS standby mode is actually a specialist application, different from true deep cycling applications, but still for long-term value these can't be beat.

Ideally you use CC load testing for loss of Ah capacity, compared to a benchmark run after breaking the bank in.

Standard for EoL is 80% SoH, but consumer non-critical use cases, can push to 65-70% without much risk.

The other way to go is just buy cheap and proactively replace on a schedule say every two years.

Or go to "exotic" chemistries like LFP or LTO.

Obviously whatever you do, the charge profile must match the battery specs.
 


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