Opinions on Second hand batteries (See Attached link to Ad)

[scloughcarroll]

Hey!

So very aware of all the negatives on using a second-hand battery, and have been researching proper care and battery maintenance etc.

BUT today saw this ad in my local area, have not called the guy yet as I wanted to get spme questions together to try to get a good idea if he has been good t othe batteries and if they are a suitable option.


With this price I could have a 900 AH 12 V bank for $450 not bad!

Link to ad
https://sunshine.craigslist.org/for/...930021701.html

Right off the batt I saw the stickers, if thats voltage readings the bank is screwed ( that's my first question)

Second I saw there are two types of batteries, maybe in separate banks? I hope so, if not maybe a red flag.

I will be asking about

Length of time batteries have been owned - In use - Sitting unattended etc

Details on current setup and appliance load

Reason for selling

Voltage readings and info (If records have been kept)

Any other question you guys can think of? Opinion on if you would take the risk etc? Seems almost too good to be true, but at $450 for my entire bank I'm feeling willing to take the risk.

Thanks everyone!

[TheHubbardBus]

Hell of a deal if they're in good condition, and were maintained properly.

l'm curious about those tape stickers too... and would be equally concerned if those were the voltage readings.

It sounds from your $450 you don't need the whole bank. I'd stick to just one brand if everything else proves good.

Not sure if it's a shadow or what, but in that first pic, is the case distorted?

[scloughcarroll]

My thoughts exactly! Going to give him a call and gather some more info.

Very good eye on the first pic, does look as if the case is bulging out on the one side... not a good sign

Wishing I could visually inspect the batteries but they are a ferry ride and drive away so we will see what the guy says...

Any other builders on the Coast of BC I only need 6 of them so if anyone needs some hopefully they find this post, will update when I know more.

[scloughcarroll]

Well.....

Just spoke to him and a nice guy, but not much knowledge of batteries.

Purchased 2 years ago, from a guy who said they were used as a backup bank for computer servers, no idea when they were originally purchased.

Used in an off-grid cabin to power some lights and was supposed to be used on a fridge, charged from a "Solar Panel" possibly just one... was tough to stay on track with the convo

Those stickers are in fact the voltages of the batteries before he hooked them up to his solar panel, so the bank is not in good health

and finally 2 types, but the same AH, possibly purchased at the same time but unknown.

I think I'm out, that's a lot of red flags for battieries in a full time livein. Looks like its a "you get what you pay for" kind of thing!

[peteg59]

Used batteries are a total crapshoot. They're either good or bad, with no in between. Even if good at the time of sale, one never knows how long the good will last!
Having said that I'd never waste my time and money buying used batteries, unless I knew and trusted the seller...

[john61ct]

Run away!

Maybe if going for $100.

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle 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.

So 400Ah top-notch true deep cycling brand new with a warranty.

Do you know you really **need** bigger capacity?

[Iceni John]

Used batteries are worth no more than then the core charge you get when buying new ones, i.e. about $12 to $15 each tops. It's safe to assume that any used batteries are having their mid-life crises and will all race each other to their early graves.

Costco has their Interstate GC2s for about $90 each, perfectly good for our needs, and cheap enough that if you do something dumb and shorten their lives it's not a financial disaster.

John

[john61ct]

JCI makes the Costco GCs, far inferior to EPM/Deka in longevity used for deep cycling.

[Iceni John]

Originally Posted by john61ct

JCI makes the Costco GCs, far inferior to EPM/Deka in longevity used for deep cycling.

How deep? I don't plan on drawing either of my house banks down below 30% (70% SoC), and they're for my solar system which guarantees they're always fully charged.

One of my original 8D start batteries was an East Penn / Deka, and it died long before the other 8D that was a cheapo generic Chinese one! "Made in USA" means very little these days, and it's no guarantee of anything any more, at least for batteries. I assume that any battery, regardless of brand or price, is something that can potentially die at any time for any or no reason. This is one of the reasons that my house batteries are in two separate banks, so if/when one battery suddenly dies and mortally wounds the other three in its bank, I need only replace the one affected bank of four batteries, not all eight, at one time. (And if all my batteries live long and fruitful lives, I can then replace each bank a few years from the other, meaning that I should never have all my batteries needing to be replaced at the same time.)

John

[john61ct]

"Deep cycling" just means "used for more than cranking a starter", which draws under .01% DoD. Also as opposed to UPS/standby, a third design goal / use case.

Lead usable capacity is usually ballparked at 50%, so drawing down 30% is over halfway.

If you are never going below say 10% DoD the bank will last much longer, but you're carrying lots of extra "dead lead" around. Still deep cycling though, stupid to buy batteries not properly designed for that usage, or poor quality.

12V batteries in automotive sizes are 99.99% **not** good for deep cycling.

There are only a handful of quality makers in the NA market.

You should only have one House bank - see Peukert - buy quality and learn to care for it properly.

https://marinehowto.com/what-is-a-deep-cycle-battery/

[Iceni John]

Originally Posted by john61ct

You should only have one House bank - see Peukert - buy quality and learn to care for it properly.

https://marinehowto.com/what-is-a-deep-cycle-battery/

Who says? Each bank feeds through a 250A Schottky diode to prevent one bank back-feeding into the other, then the two diodes' outputs are combined at the DC load center's busbar. This way I have complete redundancy: if one array of panels, or one combiner box, or one charge controller, or one bank of batteries, ever failed, I would still have 50% (or more) of my house power, very useful if I were boondocking off-grid. I am well aware of Mr.Peukert - if I need to power heavy loads, I can temporarily connect the two banks together to minimize Peukert inefficiencies, but that will rarely (if ever) need to be done.

I do buy quality. Sharp PV panels (eight of them, all individually tiltable) are not low quality, Morningstar TS-MPPT-60 charge controllers (two of them) are not low quality, a Flow-Rite Millenium SPF battery watering system (not yet installed) is not low quality, a Magnum MS2000 inverter/charger and RC50 remote are not low quality, umpteen feet of 4/0 cable and tinned lugs are not low quality. (That's almost $6000-worth of house electrical stuff, more than some folk spend on their entire skoolie and conversion!) The only part of the entire house electrical system that I consider less-than-durable and in need of regular routine replacement are the batteries themselves. And those batteries are still religiously checked every month with a proper hydrometer, and topped up if needed. One thing I am not is lackadaisical or careless, and my choice of equipment (and the bus itself) reflects that.

John

[john61ct]

Talking about nothing here but batteries.

Splitting your House bank means greater V sag, deeper DoD cycling, less total capacity and shorter life.

Did you research the Peukert effect yet?

[TheHubbardBus]

John61ct (or anyone else who has input)...

If you had to guess, what would you think the most likely cause(s) for the large discrepancy in voltages? Imbalanced cabling, poor charging practices, something else?

[john61ct]

Doesn't matter the cause.

If they were free, within 10-20 miles of me, I might pick them up just for the fun of putting them through a set of proper load test cycles.

If they (some of them) turned out to be worth using, thought they'd last more than a year, then I'd give him say 50¢ a pound.

But only for the good ones.

[Iceni John]

Originally Posted by john61ct

Talking about nothing here but batteries.

Splitting your House bank means greater V sag, deeper DoD cycling, less total capacity and shorter life.

Did you research the Peukert effect yet?

Please read my post again, carefully.

John

[john61ct]

So, no.

You rig, your choice, but not optimal for living full-time off grid.

[TheHubbardBus]

Originally Posted by john61ct

So, no.

You rig, your choice, but not optimal for living full-time off grid.

Apparently the redundancy Iceni's separate battery banks provide is important to him. So how would he achieve the same goal utilizing one battery bank?

[john61ct]

With proper care and monitoring there will be no surprises.

Two strings in parallel give redundancy. Only separated in emergency.

[joeblack5]

With Iceni's several battery banks linked together with diodes and the assumption that each is discharged in relation to its capacity the capacity from a Peukert standpoint would have nothing to do with it.


Besides I like redundacy, having four charge controllers,, besides from that My house battery and starter are the same contrary to what most advocate



Peukert gets only interesting when you have large loads on a relative small battery . It seems that for a living / full time situation you would have made a design error if you find peukert limiting you on your path.



Better to move on to lithium.

[jbeech]

Don't do it. Just don't.