What To Do With Free Lead-Acid Batteries?


Active member
Mar 2, 2019
I am not sure if this is the right section:

A uncle (scrapyard owner)of mine can have for almost free all the lead acid batteries he want(and i also...of course!)
He won't sell to other of course, law sorry
The batteries are most forklift batts, deep cycle, 1.2v cells, traction-semi tractionect......name it...lead acid...
BUT:Second handed, scrap ect...
What would you do? if you would have the space for it.
I know how to handle them and how to check them(my unclenot)
I am not talking about 10 kwh, but 2-3-400kwh if possible with good batts in 6 months

Options suggestions ect are welcome, and what would you do????

thanks in advanceFree


Staff member
Jan 7, 2017
Fork Lift batts and similar are great. Most of the time it's just a single cell or 2 that are causing the issues with the whole pack. Replace the cell and you're back to operation.

I'm trying to get a fork list battery from a local store. They have two of them that have been sitting in the store for over a year. So, gotta get hazmat license first before I go back to them.

Using these batteries, you wouldn't be putting the stress that a fork lift puts on them. they use LOTs of amps to run.

If it were me, I'd get them for sure. The more you have, the easier it is to have nice good solid ones.


Well-known member
Nov 16, 2018
If you can get them for free, great. But, lead acid has:
* only about 85% charge/discharge efficiency, vs near 100% for lithium. That's not counting the losses in the charger/inverter
* loses about 10% charge per month to self-discharge
* degrades when left (partially-)discharged for long (couple of days?) due to sulfation. Basically, _requires_ a full charge at least every couple of days.

So if you want to use it to supplement your lithium ion powerwall, how to implement in a compatible, useful, and efficient manner? I don't know, so my SLAs (semi-deep cycle) are just sitting pretty, seeing action only when there is a blackout.

Jim Jr.

Jun 3, 2018
I would leave there in your uncles yard.

Unless you have a way to properly cycle lead acid batteries , you will not be happy with the results.

Fork Lift Batteries require a minimum charge amps to prevent acid stratification , how many depends on size of battery.

Partial charging leads to the next problem

Lead sulfate is difficult to to redissolve if it has been there too long. The sulfate crystal gets tighter together with age and

gets to impossible redissolve because the charger shuts off at amperage drop off , Thinking that it has a full charge.

As for cleaning or taking the battery apart . It is next impossible to get the cells out of the case because they have

swelled outward for a very tight fit . I have tried to pull out a cell and yanked the top clean off , with acid and lead going

everywhere. Unless you know the magic word , its not coming apart cleanly.

Those batteries in your uncle's yard are there for a reason, bad cells. Now if they came for a company that gets new ones every

four or five years because the warranty is up , You might get lucky.

Unless you have lots of free watts laying around , I would stick with the 18650's



Active member
Mar 2, 2019
They will stay where they are now, thanks for the clear answers.
I was in doubt to do it or to leave it.
I learnt one very important thing over here: first ask than buy....best advice!

with best regards


New member
Feb 16, 2021
My lead acid forklift batteries were 2 years old when I bought them. Li was too costly back in 2014. They were sold because of 20% degradation and were phased out of the wharehouse forklifts. They lived for another 7 years in my PV storage. Sold them last year. 90kWh total.
Lead ist cheap and easy. But only if its not too old. Charge it to 100% more than once a week to equalize the cells. Forklift batteries need a higher voltage, at least 2.55V per cell for equalisation.
The charge/discharge losses and the equalisation losses are high. The older the battery gets the higher the losses are. Usable capacity is 40% of its actual capacity (with degradation). Using a lead battery 50% will kill it sooner than later.
Check the acid density often.
An air pump for acid circulation is important, but that cannot be retrofitted on older cells, they usually are too swollen to insert the air tubes and guarantee equal air delivery. So high equalisation charges and more losses.

If you need a pack for a forklift with little use, thats great. Pick the good cells and arrange a new battery pack with them.
If the cells are too old and lossy, do not bother to use them. You will waste too much of the PV and a couple of jeans too (acid).

Got used EV batteries now (Li from a Nissan Leaf) and thats a difference like night and day. Never lead again. Lead was the only available option earlier, but not today.