Large lead acid forklift battery self discharging

Hi all, I recently bought an electric forklift for use inside a farm shed. The truck itself is in good condition but the battery I think has been poorly maintained or just old. I think its about 15 years old.

Its a 48v battery bank of 2v lead acid cells with a capacity of around 24kw.

I have tried charging the battery and it does take about 50 amps at 50v or so but it will bubble quickly and continue bubbling once the charger has stopped charging. Even after a week of sitting uncharged I can still see and hear bubbles coming out of the water inside the battery? Im not sure if it can be saved? after googling the problem I can not find any information as to the reason for the bubbling after charge.

I am condsidering using some LiPo batteries instead of the lead acid. 1kwh of batteries should give me enough run time to get my jobs done but im not sure this is a good idea or not. I guess I would need to measure current draw from the original battery to get an idea if this is possible.

Many thanks
Gav

Hi Gav,

Be careful as often the battery weight is critical counterbalance and actually determines the lifting capacity. Of course with a small lithium battery you could just leave the dead lead in there, or replace with concrete.

A switch to lithium requires new charger and a BMS. That might end up costing near a battery repair or replacement. You should have a professional evaluate your battery and give you an estimate for repairs or replace. Those guys should make house calls as they regularly service factories and warehouses.

There was an old electric forklift at the University extension, 36 volt without battery. Before they bought the correct battery, they'd use it for like 2 minutes at a time from a 12V truck battery and jumper cables. Not the best way to go, but worked in a pinch. That was pre-electronic controls; just resistor and contactors. As long as contactors pulled in, it'd run.

major

I'm guessing your Battery Cell(s) has an internal short.
It happened to me, you could check for any hotspots while charging.
Not that it will be fixable though.


From the little I dabbled with Forklifts I know that most run at about 3-5Kw 36V/48V 100A.
I'm sure there are more powerful ones out there. But most don't need it because of the high gearing.
So building a 100A continuous Battery capable of maybe 250A peaks should be a piece of Cake :thumb:

My guess is internal short too, dammit.

Amazingly I think 7 of these would run the forklift for a few minutes at maximum current draw. which might actually work but charging them up and making some sort of high current bus bar to bring them altogether as one battery might be too much work.

https://hobbyking.com/en_us/zippy-5700mah-2s2p-50c-hardcase-pack.html

Bubble bubble Grinch in trouble. The bubbling one is probably shorted out at the bottom of the case. Maybe just one battery. Lead ? Lead can sometimies desulfuror. Whit a charger designed for that. Good point about the weight of the lead batteries counterbalancing your lift. Or find some Leaf modules and turn them into the voltage you need and amp your hours to power your demands. It could be so small you just put them on top of the Dead lead batteries and use your lead batteries as a counterbalance as they were meant to be. It also depends how much weight your forks can handle before they snap

Some opinion...

I debated recently with a friend re this forklift batts. He said that it is needed to be heavy to counter-balance with the front weight to lift so not to tip over. I said that it is true and absolutely perfect by the time when they designed this forklifts 80 years ago.

But for now, can we think out of the box ? Do we still have to carry that 1+ton dead battery weight all day long ? Not very green, right ?

Certainly, the the forklift will need counter balance weight in the opposite side of the load while the front wheel (or very close to that) is the fulcrum.

If the place is not too tight that vehicle turning radius must be limited i.e. narrow aisles of crammed warehouses & etc. Can we just shift the much lighter & smaller, higher energy battery further..like to the rear ? And remove that heavy batt out of the way and still have both sides of the lever at least balance, preferable heavier on the battery/driver side. Too much heavier is waste of energy. How much further is just simple leverage calculation. Distance x weight to both sides of the equation. Not very hard to figure. There actually can be done on other alternatives too like shifting fulcrum, etc. Imagine how much energy can be saved not to carry 1-ton battery in the back of the vehicle all day long.

If it can be done this way, much more energy will be saved with much better today-technology batteries. I have heard that it will require only 1 li-ion batt pack per 3 shift instead of 2-3 packs of lead-acid, plus other burden like slow charging, distilled water watch, battery room, etc. I bet the overall saving will not be a small carbon footprint figure. Now, what to do with the energy saved ? Credit it to the people implementing this ?

Just think out loud.

A 1kwh battery is ridiculously small and only a few hundred bucks. Just put it on the back and leave the lead acid pack in for balance. You'll probably want at least 2kWh for longevity and stress related reasons though.

ichiban said:

I debated recently with a friend re this forklift batts. He said that it is needed to be heavy to counter-balance with the front weight to lift so not to tip over. I said that it is true and absolutely perfect by the time when they designed this forklifts 80 years ago.

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And physics still works the same way, so you still need a counterweight equal to or greater than the max weight you need to lift.

Since many pallets are greater than a ton (and often poorly packed or balanced themselves), you need a counterweight that balances that with a guarantee that the whole thing wont' tip forward or sideways when used under normal conditions.

The battery in battery powered forklifts is already at the rear. In propane-powered forklifts, the counterweight (metal block, etc) is also already at the rear.

A lighter weight farther back would do the same job, but for a really light weight you'd have to have it so far back that the forklift could only be used outside in open spaces, making it useless for the majority of applications.

You can do the calculations if you like, or there's probably physics simulators out there that would let you work it out, or you could just do a scale-model test.

amberwolf said:

ichiban said:

I debated recently with a friend re this forklift batts. He said that it is needed to be heavy to counter-balance with the front weight to lift so not to tip over. I said that it is true and absolutely perfect by the time when they designed this forklifts 80 years ago.

Click to expand...

And physics still works the same way, so you still need a counterweight equal to or greater than the max weight you need to lift.

Since many pallets are greater than a ton (and often poorly packed or balanced themselves), you need a counterweight that balances that with a guarantee that the whole thing wont' tip forward or sideways when used under normal conditions.

The battery in battery powered forklifts is already at the rear. In propane-powered forklifts, the counterweight (metal block, etc) is also already at the rear.

A lighter weight farther back would do the same job, but for a really light weight you'd have to have it so far back that the forklift could only be used outside in open spaces, making it useless for the majority of applications.

You can do the calculations if you like, or there's probably physics simulators out there that would let you work it out, or you could just do a scale-model test.

Click to expand...

Yes, I understand your points completely amberwolf.

Just hate the heavy battery weight carried around all the time. Think we can do something about it and that will save a bunch of energy people are crying for. We achieved countless advanced technical challenges and why not this tiny problem of heavy battery in forklifts ? There must be a way out to this and that will change the forklift batteries forever. It simply starts from the "i-m-possible."

Maybe you missed AWs comment about the propane powered fork trucks needing an equivalent heavy counterweight in place of the batteries. ?
Note:- have you seen how construction tower cranes work with moving counterweights to suit the lift weight /radius ?? :wink:

Most forklifts are operated on flat concrete floors and the tires are made of solid rubber, so adding or subtracting a Ton isn't going to make a huge difference in operating time.


No one will stop you from removing the lead-acid batteries. You can do whatever the hell you want, don't forget that we warned you though.

Forklifts are necessarily heavy so they don't tip over lifting shit. If your mast tilts forward and / or your load is high, the problem can be amplified. If you remove the batteries you'll just have to install some other type of counterweight like concrete. I almost endo'd a 9000lb forklift at one point lifting less than 2000 lbs with a high mast coming on the brakes.

How much weight do you intend to lift with this forklift?

Just add support legs that extend forward then you need zero counter balance like the walk behind lifts...
Otherwise lift less or add some weight, concrete as suggested above would be most cost effective and coming close to the weight. Most battery's are 2k-3500lbs in those lifts (its stamped on the side of the steel case)
you can defiantly get away with less weight if your not using the forklift at its rated capacity.

Got a buddy with a FLIR or other than camera? Nice way to find out what's heating and where.

I have one of the Flirs that attaches to my smartphone. Great piece of kit. Will charge up the battery again and see where it gets hot. The current plan is to use 4 x 280w solar panels to charge the lead acid battery. I should be able to keep the voltage high and the forklift usable when needed. If that doesn't work or the battery is getting a overly hot I might need to think again.

I'm waiting on the price of 18650 coming down before trying a battery build Maybe in a few years.

Why is the quality of most of the Chinese 18650 so bad compared to the main producers like Samsung, sony, Tesla or lg chem. I mean the Chinese manufactures must be able to replicate their procedure? They dominate a lot of other fields like drones or smart phone with lower prices and comparable quality to the established brands.

gavztheouch said:

I have one of the Flirs that attaches to my smartphone. Great piece of ki
Why is the quality of most of the Chinese 18650 so bad compared to the main producers like Samsung, sony, Tesla or lg chem.

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In general:

Because it's good enough to make a boatload of money from, and since generally the purpose of most businesses is to make as much money as possible with as little effort or investment as possible, rather than to provide something people need or want (that's a side effect, as far as most money-makers are concerned), they're already doing everything they need to.

If that wasnt' the case, hobby RC LiPo would be very very good quality, and much safer than it generally tends to be. (so would it's chargers, etc).

Similarly true for most products by most companies--they're good enough to get people to buy them, but not so good that they don't have to be replaced relatively frequently for one reason or another (defects or features). If they were really good, they couldn't make nearly as much money, even if they charged a lot more, because there wouldn't be enough people buying new ones after the first.



There's exceptions, but this is a general rule of business. Make a bunch of cheap stuff that has to be replaced often, or provide services that are barely adequate (or even inadequate but are still sufficient for enough people to be profitable). Make a few really good things, or provide a few really good services, for those that won't pay for the cheap stuff but will spend more for the good stuff. Make a very very few spectacularly blingy or fancy or whatever-makes-them-seem-expensive things for the very rich to brag about with each other.

It's not universal...but it's very common, in every economy.

I just wonder what capacity of Li-Ion pack will be needed to replace the old lead-acid one. This is just plain question re battery capacity and just leave the counterbalancing weight out for a while. I know some are sensitive about that.

For example, a regular 400Ah, 48V, 24-cell lead-acid battery (2-V cells) are not utilized that full capacity at all time. Only during heavy lifting, heavy moving, frequent starts/stops will use high energy from battery.

If we were to design this new batt pack, what would be the appropriate batt capacity like 13S?P or 14S?P to replace the original one ? Also consider, as a good design practices,

1) most economical unit - light duty,
2) optimal cost/performance ratio,
3) highest performance set - heavy duty - work hard all day long.

And what type of cells will be chosen :

a) high energy
b) high drain

You would need 100 2Ah or 60 3+Ah Cells in parallel to get the same capacity as the Forklift Lead Acid.
But I doubt you really want to since the price of the Cells alone is in the 3000$ ballpark.

You also need to know how much the Forklift drains, my guess would be around 250A cont.
You could measure it with a Current clamp Multitool that can measure DC.

eee291 said:

You would need 100 2Ah or 60 3+Ah Cells in parallel to get the same capacity as the Forklift Lead Acid.
But I doubt you really want to since the price of the Cells alone is in the 3000$ ballpark.

You also need to know how much the Forklift drains, my guess would be around 250A cont.
You could measure it with a Current clamp Multitool that can measure DC.

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So it should be 13S60P (=780 cells) or 14S60P (=840 cells) of 3Ah+ cells. For a 250-Amp drain forklift at full load, per-P group-current-draw will be 250A/60P = 4.17A/P group >> not too bad for high drain cells (like LG HG2 2.9A/20A max, etc.) or even high capacity cells (like Panasonic 18650GA, LG MJ1 - 3.5A/10A max). Sounds interesting for a big pack like this. I bet cell layouts, nickel strips (or copper), welding, bus bar, cabling, ventilation, BMS and all those little details for e-bikes will play a serious game now.

BTW, 840 cells x 18650s weight only 42 kgs for just the cells (50 grams each). It is really amazing that this size+weight of li-ion batts can do the same work as the 1-ton league lead-acid counterpart. Let's find a project to try this out. Should be fun.

As regards the existing Battery. A shorted cell or two is probable. Shorts across the cell is not so likely since there is usually something like a fibreglass mat to keep the two parts of the cell apart. Plate material usually crumbles off of the plate due to miss use and gathers in the bottom of the cell over time. When the space in the bottom of the cell provided for this is filled up you tend to get a continuous low grade short in the bottom. A possible solution depends on the ability to sneak a soft small bore plastic pipe down through the filler/vent to the bottom and suck out the debris (works on big 800Ah cells with lots of room and clear plastic/glass sides). Otherwise carefully tip out the electrolyte and wash the cells out and refill with the correct acid concentration and then charge. A cheap but messy (battery acid is not nice to play with) thing to do before you throw it away(sorry have it recycled).

Bob

vk4bxi said:

As regards the existing Battery. A shorted cell or two is probable. Shorts across the cell is not so likely since there is usually something like a fibreglass mat to keep the two parts of the cell apart. Plate material usually crumbles off of the plate due to miss use and gathers in the bottom of the cell over time. When the space in the bottom of the cell provided for this is filled up you tend to get a continuous low grade short in the bottom. A possible solution depends on the ability to sneak a soft small bore plastic pipe down through the filler/vent to the bottom and suck out the debris (works on big 800Ah cells with lots of room and clear plastic/glass sides). Otherwise carefully tip out the electrolyte and wash the cells out and refill with the correct acid concentration and then charge.
....

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Now I can see why these things are so bothersome. It is just simply the existing thing and people just learned to live with it. If only we can replace that old crappy thing with new clean and high-efficiency new batteries, lead-acid would be very expensive and belong only to the museum & rare collectible items. :lol:

In the future, lithium might have to give ways to the newer waves too. Just simple mother nature fact.

vk4bxi said:

.... A cheap but messy (battery acid is not nice to play with) thing to do before you throw it away(sorry have it recycled).

Bob

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True. It is just things of the past and some area that have the absolute necessity for it. I can't think of much.