# 48 v forklift battery

Solar Expert Posts: 102 ✭✭
Hi guys, can you give me some advice?

I just purchased a 48v forklift battery from the scrap yard, the funny part is that it came from the company I work for, our company has 2 facilities in the dallas area and they had no room for the old forklift so they sold it to scrap yard ,after i was told about it I ofered & \$300.00 for the 48v 765AH @ 6H rate, and I got it today, the battery self discharged down to 20v for the last 4 months that had been sitting without charging.

I know the battery is good and strong once get full charge, my plans are to split the cells to get two strings of 24v, my Samlex S2024A is capable to charge from 4-40 amps. using my generator, but I just don't know if my solar panels (1300w @ 24v) will be enough to keep the 2 forklift battery strings charged.
if this works I'm going to buy 2 more 100+w panels for my 4 200AH fairly new AGMs, righ now are taking the beat because my battery bank is 1/2 under sized.

How this works?, 765AH @ 48v = 1530 AH @ 24v ?, if is, how many more watts of PV do I need to keep it charged @ 24v?

and last question does my invercharger will be capable to equalize the forklift batteries strings?

thanks in advance for any repy.
«1

Re: 48 v forklift battery

In theory, the exact current from the charge controller should be:

PV watts in * controller efficiency * 1/battery charging voltage = batt amps

1300 watts * 0.92 * 1/30 volts = 39.9 amps maximum charging current

If you assume 10% charging current of the 20 Hour rate...

39.9 amps / 0.10 = 399 amp*hours @ 24 volt battery bank.

A forklift battery can take quite a bit of charging current--and probably would be better to have more solar panels because of potentially high self discharge. I would probably not try for a 5% charge rate (or an 800 AH battery bank).
How this works?, 765AH @ 48v = 1530 AH @ 24v ?

Yep--you are correct.

For 1530 AH @ 24v bank with a 10% rate of charge:

1,530 AH * 30 volts * 1/0.92 * 0.10 = 4,990 watts of solar panels...

You could try a 5% charge rate (~2,500 watts of solar panels) and fire up the generator (or use the grid) to equalize your batteries with a ~2,500 watts (2,500w/30v=83amp charger) once a month (or whatever the recommendation is).

Will give you a chance to tryout your battery bank without \$\$\$ for solar panels. You only need the high charging current to equalize your battery bank (mix electrolyte)--and obviously have enough solar to make up your daily use + bank self discharge (maybe 3% daily self discharge very worse case maximum?).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 313 ✭✭
Re: 48 v forklift battery

hey homes,

Not with standing the usual calculations that the guys here usually advise I would say that your 1300w going through a mppt to charge 1500ah will work and you may even be able to equalise using the panels.

This is the basis of my opinion. I currently have 24 2V traction cells (similar in construction and chemistry to your forklift) made by hawker. These cells were very well used in the submarine they use to operate in 24/7 for 3 years. The capacity of my parrallel banks of 24V is 1280ah and I have placed 10 of my KC130 to charge and equalise them going through a C60. the 10 panels easily achieve this day in day out unless i get a bad solar day. Therefore if you use an MPPT, which give you and increase in charging efficiency, I personally think you will get by. Again this is from my personal experience here in the caribbean. I also think that there is not a huge difference between my insolation and yours there in Florida. I believe you should give it a go. Oh let me mention that while i am charging them up during the day I am also discharging them running my entire house.

Let me give you some number that my meter give me.

I use approx. 5-6kw per day.

The 10 panels give me 180Ah - 250Ah depending on time of year

On bad days (totally overcast) I get 100Ah - 150Ah.

All of the above is at 24v and reading is taken off of the meter on the CC

Hope this info helps

Cheers...

Damani
Re: 48 v forklift battery

I'm new here and this might be somthing to think about. I'm a Test Engineer for a fork lift manufacturer and I us all types of batteries. We have issues with batteries that sit an self discharge, the lower the battery voltage goes the harder they are to get back. Our chargers hit them with at least 10% (start charge) of amp-hr capacity some a little more. And we have to charge and fully disharge them a couple of times to get the amp-hr capacity back if not the voltage/current never comes back to where it should be and we scrap them. It might be a good idea to charge the battery with their designed charger and disharge and recharge before you try to use it, this might get the battery back to it's capacity before you use it. It might make a big difference in the battery life....
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

Thanks guys for the reply, I called the plant manager on the facility were the forklift was used, he told me that he purchased the battery 2 yrs. ago, that's why is so nice and clean,and was on very light use (150x150 ft. warehouse with 2 forklifts) and charged every day, so @ \$300.00 dlls. I just couln't let it go..., yeap, I'm very sure I can get at least 10 yrs. out of it, the battery is so heavy that my 3/4 ton chevy almost look like low rider with the battery load on it. .

thanks again for your feed back.
• Solar Expert Posts: 313 ✭✭
Re: 48 v forklift battery

good luck brother,

I know how it feels to get batteries on the cheap or free. I am sure you will have fun with them. Let us know how it is going.

Cheers...
Damani
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

Sure, once a fully charge (after spliting the 2-24v strings) I'm eager to see how long I can run to deplete the battery 70%....thanks again.
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

Hi guys, well, today I split the battery in 2 strings of 24v, before I connected the Samlex S-2024 A inverter to charge the first string, I tested the voltage of both strings and gave me very close to10.11 volts ea. then I connected the invercharger to my 120vac. (from grid), my invercharger did not begun to charge, I thought that it may be happen just like on a cordless drill, if the battery too low, the charger woulndn't start charging cycle, so I took the Samlex back to my AGM battery bank and connected with the solar panels charge controllers, started the invercharger on charging mode (plugged to 120vac grid) ran 2 # 10 wires (Red and black) back to the forklift batteries one string, this worked kind a 1/2 way and I don't like at all because there is 33 ft. from the AGM batterty bank and inverter, I read 25.8v @ the AGM's and inverter connections with a charging current of 10.11 amps, because the distance there is a voltage drop to 24.11 at the forklift battery first string, I can not bring the forklift battery any closer because here it has been raining on and off for last 3 weeks, my porpuse is to bring the first string at least 24v then bring back out (closer) the invercharger to charge it., again my inver charger has a charging range of 4-40 amps.

any suggestions are greatly apreciated.
• Solar Expert Posts: 313 ✭✭
Re: 48 v forklift battery

hey homes,

what you can try to do is hook up a 24v panel or 12v panel (depending on type of panels you have) direct to the batteries. You will need to monitor the cells to make sure they dont over heat to much as you do this and to make sure they reach 2v plus voltage at rest. You will need to send the most amp you could so that you jump start the cells so to speak so you get them to read at least 2v. When the voltage is as low as you have reported a CC or charger will not turn on of sense them.

I have done this to a couple of agm cell from ups that were reading less than 5v and have revived them to the extent where they are performing as before. You will need to hydrate the cells after as well because it is like equalising them at a sometimes high voltage.

Cheers...
Damani
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

Well, after letting the first string reach 22.1 , I pulled out my invercharger and it did came on , so my trick worked, the inver charger is sending 33.1 amps to the first string, right after I used jumper cables for the second string, it went from 10.1 volts to 22v and drawing 1.6 amps and it has been sedliy climbing now reads 24.3volts and a charging current of 10+ amps, the first string reads 25.8 and drawing 33.7 amps, at the inverter connection lugs, so it might be taking 23+ amps...

Dapan, thanks for your tip, as soon I bring both strings at 24.8 at rest will check the specific gravity of cells, if any weak cell I will give the recomendation treatment you have suggested... thanks again.
Re: 48 v forklift battery

And remember that Testczar said to cycle the batteries a few times to get them back in shape before making the good/bad decision.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

Yes B.B., this forklift battery is 2 years old and coming from a good work history ( the company I work for) I'm very sure it will perform as good as \$ 6,500.00 new battery....thank you guys for all your help.:D
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

HI guys, finally last weekend I set my 48v C&D forklift battery on it's concrete pad (it wasn't ease to unload a 2850 lbs. by myself with no forklift but is done).

I connected the battery to my solar with an starting voltage of 22.6 v. and after 4 days of charging it came up to 24.3 volts. this is charging the first string ( I had to split the battery in 2- 24v. strings) I know that my panels (1300w) are not capable to charge the strings as fast I want, B.B. said I need 80 amps to properly fully charge my battey ( the 2 parallel strings), my output on solar panels was around 26 amps. at peak sun, today I started my generator, with my solar and invercharger(Samlex S-2024A) is sending a 36amps. and 27.2 volts at peak sun, I'm tring to equalize the first bank and then start to charge the second string ( now reading 7.6 , have put no charge since I split the battery because I want to bring 'em to a full charge one at the time), long story

my questions are:

are 27.2 volts @ 36 amps. are good enough to equalize? and for how long?

after I charge both battey strings do you guys recommend to wire'em in parallel to the inverter or use one string at the time?....

as previously posted, I need at least 3400w of pv. to charge the battery @ 5%....now too much battery for the 1300w of pv I have...

• Solar Expert Posts: 9,583 ✭✭✭✭✭
Re: 48 v forklift battery

1) I'd wire the batteries in parallel, and just be careful to watch my usage to not use more than the solar can replenish the next day.

2) get both batteries charged up first, no use hooking a bad battery to a good one. I suspect the battery with 7 volts is bad / dead / trash. Charge it, try to EQ it, and let it sit a couple days and throw a load on it. Use the generator on both of them, you don't want them to sulphate.
Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,

• Solar Expert Posts: 1,989 ✭✭✭
Re: 48 v forklift battery

Your charging voltages should be 28.8V for Bulk and 32V for Equalize ... at 27.2 your battery's are severely depleted
• Solar Expert Posts: 313 ✭✭
Re: 48 v forklift battery

Hey H,

As i have said before I will go by my experience. I have a total of 14 KC130 panels. 10 on one C60 and 4 on one c40. I also have to battery banks 1280Ah Hawker Lead acid cells and 900Ah GNB agms. I have equalised the 1280Ah bank already using only the 10 panels (1300w of PV). Therefore based on this you will be definitely able to equalise a single bank of 765Ah @ 24V not withstanding the 5%-13% rule the guys on this forum follow, but nothing beats actual experience IMHO.

Cheers...
Damani
• Solar Expert Posts: 705 ✭✭
Re: 48 v forklift battery

Dapdan I agree you can equalise your batteries with 1300 watt of PV. But the minimum 5% capacity rule is for real life living nobody puts in a large battery bank and adds solar just to float batteries and occasionally equalise. The batteries are a store for draining. and the 5% rule is a minimum for refilling.

When I first joined I proudly stated that I had 2100 ah of batteries and a massive 1600 w of PV To be informed I was a little low on PVs for my battery bank. Nonsense was my inner thoughts as long as I make more than I use Ill be fine.

But in the real world living off grid adding more creature comforts I was using most of what I was producing leave system in efficiency and poor sun days taking the route of genny run time to correct.

I upped my array to 2400 watts and genny runtime is nearly gone so I have a fairly balanced system now.

The clever guys here have grown up with some excellent rule of thumb equations and this is one of them IMHO
Re: 48 v forklift battery

Rules of thumbs are just recommendations that take into (usually) a whole bunch of different issues and experiences...

If you deviate from them--just understand what the possible issues may be (low charging current will not "stir" large/tall cells with "bubbles" and you may get acid stratification; but you can choose to work around this by running your genset, possibly with solar panels in sun, once or twice a month to properly equalize and mix the acid in the big batteries you have). If you have more loads than solar panels--then you will have to run the genset every few days anyway (which will provide mixing if charger is large enough). You want to keep the state of charge in your battery bank >75% anyway to reduce sulfation problems (that begin to occur if the battery is below ~75% for more than a few hours/day).

After you have run for awhile--and get your load numbers vs generator runtime (if not enough solar panels)--you can figure out how many solar panels you will need to add to offset your generator runtime (as your funds and needs dictate).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 10,300 ✭✭✭✭
Re: 48 v forklift battery

on the matter of an eq charge you must have enough voltage in the first place to even get it to bulk charge as sg pointed out. an eq charge is just an overcharge and can be slightly lower than the 5% rule and may even go as low as 3% in some cases. if the current is low then eq times just may need to be increased a bit. you'll know if it's right as the proof is in the results.
Re: 48 v forklift battery

Older forklift batteries may also have a self discharge rate as high as 2% per day (????--at least one place I read).

So, it is possible that a 3% charge rate minus a 2% self discharge rate leaves you with an effective 1% rate of charge (batteries are probably near end of life at this stage anyway).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

Thank you guys, as today started my genny, the voltage was 24.4 volts on the first string after sitting overnight, once I started the invercharger combined with solar panels the voltage whent up to 27.2, I removed the battey cups (on first string) and I saw some bubbling on every cell, is that good? I kept charging the string for 4 hrs. another question, as solar guppy recomends to charge the battery to 28.8 and equalize @ 31-32 volts do I really need the charge controllers on this battery bank? since my invercharge output is 27.2 volts and I need 28.8v to have a good chargewill affect the invercharger if I skeep the charge controllers and install a blocking diode as substitute of charge controllers to get the max voltage out of my solar panels? with the 1300w of pv it looks that I will not overcharge this battery with what I have...

P.S. I did not mentioned that my battery is exposed to sun on the south side of the house (back side), the sun always hitting it, late on the afternoon the metal case (forklif battery case) gets too hot, will this have a negative effect when charging the battery?
Re: 48 v forklift battery

Read a few Battery FAQ's like this one to get a feel for basic battery care.

The proper voltage to charge a battery at is dependent on cell temperature... The hotter the battery, the lower the voltage should be used.

You should ensure that the recommended charging voltage is attained and maintained for a period of time to ensure that the batteries are fully charged (confirm with Hydrometer and/or Battery Monitor).

The higher equalization voltage should be performed every few weeks or month (read the instructions for your battery--or similar if you cannot find one for yours).

The bubbling is good... Should look like a carbonated soda with bubbles coming up. Should not look like a rolling boil (too much current).

Normally, your charge controller will set the correct voltages based on mode (normal charging, equalization, floating) and battery temperature (or room temperature).

The optimal battery temperature is ~77F/25C... Very roughly, for every 10C (18F) temperature rise, the battery's life will be roughly 1/2 (and for every 10C drop below 25C, the battery life will double).

So running your battery at 45C... The expected life would be 1/2 * 1/2 or 1/4 the 25C life.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 9,583 ✭✭✭✭✭
Re: 48 v forklift battery

P.S. I did not mentioned that my battery is exposed to sun on the south side of the house (back side), the sun always hitting it, late on the afternoon the metal case (forklif battery case) gets too hot, will this have a negative effect when charging the battery?

Heat is bad for batteries, they will die much sooner. Shade them with something, a sheet of thermal plywood (with the foil on it). be sure there is air circulation for them too.
Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,

• Solar Expert Posts: 313 ✭✭
Re: 48 v forklift battery

hey mike,

I operate my system 24/7 running my home and when I equalise the batteries the house is still hooked up to them. So I am equalising while still maintaining my house loads and I have done this on several occasion successfully. The WLA i have came out of a submarine so there are similar in chemistry to the forklift batteries being "traction type cells". These cells operate tourist submarine that dove at least once a day 6 days a week for 3 years before they were decommissioned and then sold to me on the cheap. So the batteries are well used and are not in optimum condition. Yet I am able to equalise them (1240Ah @ 24V) with 1300w of PV. With those KC130 I am able to get between 200 - 250Ah @ 24V and consume 210Ah- 230Ah daily (by my kill-a-watt meter). So based on my experience since Sep 08' I am able to say that Homes will be able to equalise and consume at the same time with his 1300W of PV going into 765Ah @ 24V (one of his forklift batteries banks) not with standing the 5% - 13% rule of thumb.

Cheers...
Damani
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

Thanks for your advise to all of you, I read in another thread that forklift batterys will recover after several charges and discharges, I'll keep trying....thanks again.
• Solar Expert Posts: 705 ✭✭
Re: 48 v forklift battery

Dapdan enjoy your batteries, bucking the well troded path of advice may serve you well, ........but I prefer Obi one Konobi and Captain Kirk + Dr Who, from the UK,,, live long and prosper alas....................................................................................................................................... King Kanute did he stop the tide

My batteries are 12 years old fit and well thanks to Niels acidic and well taken advice to me many years AGO (nearly 3)

Niel that was a compliment of the best decree

Then Man who shuns best advice is

An Idiot sos

Nigel
• Solar Expert Posts: 10,300 ✭✭✭✭
Re: 48 v forklift battery

thank you nigel and i was glad i could help.:D
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

HI guys., even I can wire ac circuits, still learnig about solar, I can't understand why if my string of panels combined have an output to the battery of about 26 amps. (when sun shines at given time of the day) and as I start my generator to use my invercharger (S-2024 A) so I can add more charging amps, The combined reading of panels and invercharger is around 30 amps. so, I was expecting 26 amps from panels plus at least 30 from the invercharger = 56 amps. I can't understand where my amps are going , is like the solar panels had no ouput , any suggestions?.....

P.S. the battery is comming back, after I split the 48v battery in 2 banks of 24v., the combined voltage of the banks was 7 volts, after charging with the solar is about 24.5 to 24.8, it looks like I'll never make it to 25v because I'm using more that I can put back into the battery, (kids in summer break), unless I spend more \$\$ on PV as BB suggested. and still I belive that I shuld get more amps out of my set up( I mean panels and inver charger at same time).
Re: 48 v forklift battery

Probably need to look closely at the solar PV system first.
1. Disconnect the AC charger for the moment.
2. What is the Vmp of the array (should be over 30 volts)
3. What solar charge controller do you have?
4. What are the charge controller's settings (voltage, cell type, etc.)
5. What is the battery voltage when charging on solar?
6. What is the current from the charge controller?
7. What is the Array Voltage while charging?
8. Does the controller say what state it is in?
9. Has the charge controller/array's performance changed over time?
10. What is the voltage at the controller's output?
11. What is the voltage at the battery? (looking for excessive voltage drop)
-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 136 ✭✭✭✭✭
Re: 48 v forklift battery

Aloha, the forklift batteries should come back all the way to the 2.12V per cell (or so, I forget)

1: give one bank a complete charge up to 28.7 v and let your controller throttle back. If you afre reaching say 28.7 during the day that does not mean you are fully charged, you have to maintain the bulk charge for a certain length of time. After you hook up to your second bank and let the first bank sit for a couple of hours, test it and it should be around 25.3 or so. If not, go back to the first bank and resume charging.
If again, it does not keep up to 25.3, check each cell individually for weakness, (under 2.12) or just uneven with the others.
Up to this point do not cut any of the straps, cause you do not know how many cells are good and unless you plan to replace a cell, (kinda hard if you do not have the tools), you will need to jump over the bad cell and then you will have a "46V" max battery. (You really actually never need to cut the straps)
I use flattened 1/2" copper pipe as the jumper over the bad cells and use a lot of grease on the connections and 1" x 5/16" lag bolts. Be careful to not use a flame or drill with an exposed spark as Kaboom!!! can easily result.
I find with old forklift batteries, I get about 1/2 the theoretical rated output. ie 700amp/hr is actually 350 amp/hr, but you can use more than 1/2 of the 350 and the forklift batteries will bounce back. I have even drained mine down to 20.8 V on one occasion until my invert shut down.
Use distilled water or reverse osmosis, (not just purified) (less than 50 TDS

frank
• Solar Expert Posts: 102 ✭✭
Re: 48 v forklift battery

Thanks guys for your advice., I been charging and discharging the first bank for over 2 weeks, it came to a point that this string got floating when full sun , I have 3 pwm controllers and are wired, 4 panels , 4 panels and last one 2 panels, when the second controller went to float I felt that 520w of solar panels went to waste ( no output ) , I just wonder why the last 2 panel string did not went to float first , ..... will it be best to charge both battery banks at once (all panels connected) or charge one bank at the time with 8x130w solar panels (that probably never float) and hook last controller with 2 panels on second bank to put some charge on it? ... more panels are out of question for at least 4 yrs......just trying to use the \$300.00 dlls. that I paid for this battery in the best way possible and make it last.

any suggestions are welcome.

thanx.:cool:

P.S. by the way, Dapdan was right, my forklift battery is 765 AH @ 48v divided by 2 strings of 24v, first bank (765AH @ 24v) went to float I duno what how to deal (charge)the second one. thanx lobster on a beer can.