why not use a forklift battery?

dBeau
dBeau Registered Users Posts: 24 ✭
in Off Grid Solar & Battery Systems #1
I am still in the planning phase of my (mostly) whole house battery backup system. I've hit the point where I now realize that it will cost about twice what I've initially estimated. Regardless, I am still pressing forward. So far, I have a 6kw generac ecogen and transfer switch though will most often be charging from th grid. I'm pretty convinced that an XW6048 (or two) will be the way to go. The GS8048 is quite interesting but also seems to be a bit too new to consider. I've yet to see a discussion comparing the two.

Batteries are still an open question. My plan to add PV to the system at some point, along with my 25-30kwh per day usage, tells me I need a lot more battery than I had originally hoped... perhaps 700-800ah. I had consider small-ish GC batteries at first. But, once you add in delivery charges, cables, etc. they dont really seem all that cheap and take up a lot of floor space. AGM's dont have the floor space problem, but are just too expensive. L16's have some appeal. They should last longer than GC's need fewer strings, less floor space etc. But when looking at the total cost there, going for a single unit 48v fork lift battery just dropped in it's final (easily accessible) location with just two cables to supply seems like a real deal. It also seems reasonable to expect this beast to last longer than the L16's too. So, total cost of ownership likely goes to the 24-85-13.

A remaining design detail here would apply to any FLA solution: ventilation. Is an outside vented battery enclosure always necessary? I plan to place the battery in the back corner of a basement garage ( 20x24x8 ). Is there a room size to battery size ratio I should consider, or should I just plan to build an enclosure and vent it to the outside?

So please, talk me out of the forklift battery. Or, tell me what else about it I should consider when ordering. Cables? Auto-watering? monitoring? Brand?
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Comments

  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #2
    Re: why not use a forklift battery?

    Hi dBeau,

    Regarding teh Folklift battery, they do seem to be the cost-effective solution right now.

    THink that any FLA battery needs to be in a tight enclosure that is vented (inlet and outlet) outside.

    These batts appear to mostly be a single inseparable unit, and are heavy. So as you know, the target location needs to have good access by forklift, tractor or similar lifting/carrying device.

    Generally, basements are good locations for batteries, if the basement has good ground contact, access, and the noted ventilation.

    A common topic for GT hybrid systems, at this site, is the minimum battery capacity required by Hybrid inverters. THink that you alluded to this.

    The main advantage of the competing large capacity batteries on the market is that they usually come in smaller weight units, that can be much more easily handled by human-power. Also, Traction batts appear to have higher self-discharge, and ideally were originally designed to be recharged completly within one day.

    A number of folks here use traction batts, and they will be the folks to give you the most accurate advice.

    Good Luck with the new system, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #3
    Re: why not use a forklift battery?

    AND, just Googled the 24-85-13 string, thinking that perhaps that was a battery. It is! BUT, if you wind up using two XW 6048s, it is possible that it does not have enough capacity.

    IIRC, the common wisdom for GT Hybrid XWs, that for eack KW of Inverter power to be delivered, 100 AH of battery capacity is REQD. This may be a faulty recollection. OR, perhaps you will not be delivering as much as 12 KW to the grid.

    It is possible that Traction batts have higher peak current capability (lower ESR) vs more traditional FLAs.

    This was posted in the Off-Grid section, but thinking of a whole house backup system, it would make sense to GT it ... am guessing.

    Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: why not use a forklift battery?

    Vic,

    That is what Solar Guppy's recommendations have been:
    • 6kW XW inverter would require a minimum of 600 AH @ 48 volt battery bank
    And, that number appears to be related to a 12 kW surge (6XW rated surge current) and a C/2.5 maximum supported surge current:
    • 12,000 watts * 1/48 volts * 2.5 max surge current rating = 625 AH @ 48 volts
    Obviously, different maximum surge currents and battery bank voltages will result in different rule of thumb numbers (i.e., 6kW XW requires 600 AH @ 48 volt battery bank).


    Also, it appears that this is important for Hybrid systems that use solar panels to charge their DC battery bank and even with AGM batteries that have high surge current capacities.


    I would use the same above rule for AGM on a Hybrid inverter... It appears (from reading around the forum) that some (many, all?) AGM batteries when they go 100% full don't start generating a bunch of O2/H2 gas (like a flooded cell would) and (sort of) provide their own short term dump loads--AGM's (at least Concorde Brand) appear to just stop accepting current... And the MPPT charge controllers, during normal sweep operations (at least with some MPPT controllers) are slow enough that they will take the Battery Bank >72 Volts for a period of time--which faults the XW hybrid inverter.


    So, I would not, for example, put a 200 AH 48 volt AGM pack on a 6kW solar array with a XW hybrid inverter (or in any installation with a MPPT controller) as it appears that it can over voltage the battery bank and connected loads (may not damage battery bank, but can damage loads).


    Again, the above is my personal observations from reading here--I may very well be wrong in may assumptions. Also, different brands/models of MPPT controllers may manage over voltage battery buses more elegantly than the Xantrex MPPT charge controller appeared to a year or so ago.



    -Bill ":confused:" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • dBeau
    dBeau Registered Users Posts: 24 ✭
    #5
    Re: why not use a forklift battery?
    Vic wrote: »
    AND, just Googled the 24-85-13 string, thinking that perhaps that was a battery. It is! BUT, if you wind up using two XW 6048s, it is possible that it does not have enough capacity.

    IIRC, the common wisdom for GT Hybrid XWs, that for eack KW of Inverter power to be delivered, 100 AH of battery capacity is REQD. This may be a faulty recollection. OR, perhaps you will not be delivering as much as 12 KW to the grid.

    I was under the impression that rule of thumb was based on the sell capacity. My only reason for possibly needing two XW6048's would be to draw more from the batteries, not to sell to the grid. If I'm lucky, I'll be able to get a 6kw array on my roof but no bigger. My typical peak usage is well under 6kw but I have seen it go higher. Initially, my plan is to only put most of the house on the inverter subpanel. Oven, dryer, pool pump, etc will stay in the main panel. I did get crazy one day and turn on every light in the house... I watched the peaks go over 7kw. While that doesnt normally happen, I might want to be prepared for it. You are probably right that the battery wouldnt do well with both inverters maxed out, but I doubt I could do that without trying really hard. Honestly, I hope to get away with just the one inverter... led lighting might make the difference.
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  • dBeau
    dBeau Registered Users Posts: 24 ✭
    #6
    Re: why not use a forklift battery?
    Vic wrote: »
    This was posted in the Off-Grid section, but thinking of a whole house backup system, it would make sense to GT it ... am guessing.

    Yeah, since it was a battery question I figured off-grid would be the place to post. But in reality it will only be off-grid when the grid is off ;) That said, it might be fun to run the numbers against my TOU rates to avoid the grid during peak rates and recharge during off-peak. If I recall correctly it's about a 25% difference between the two, so weighing that against the added wear and tear on the batteries might even be cost effective (considering the already sunk cost for the batteries) as well as fun.
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  • dBeau
    dBeau Registered Users Posts: 24 ✭
    #7
    Re: why not use a forklift battery?
    Vic wrote: »
    Hi dBeau,

    Regarding teh Folklift battery, they do seem to be the cost-effective solution right now.

    THink that any FLA battery needs to be in a tight enclosure that is vented (inlet and outlet) outside.

    The inlet from the outside, I'd assume is for energy (heat) efficiency. In my case it's an unheated space. So Im thinking a single 1-1/2" or 2" pvc will do the trick with the help of a small fan. But if anyone can point me to any reference to a more rigorous design methodology I'd appreciate it.
    Vic wrote: »
    These batts appear to mostly be a single inseparable unit, and are heavy. So as you know, the target location needs to have good access by forklift, tractor or similar lifting/carrying device.

    I started with thinking that keeping the batteries in the heated part of the basement would be a good idea. But, the thought of lugging them in 100lbs at a time didnt feel right. The location I am now thinking of, while unheated is easily accessible from the outside with a pallet jack or anything else that can fit through the 7ft door.
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  • SCharles
    SCharles Solar Expert Posts: 123 ✭✭
    #8
    Re: why not use a forklift battery?

    I wouldn't want to talk you out of them. I just last week sold my 22-yr-old forklift batteries [I bought them new back then] which were still working. I equalized them maybe five times in two decades. They are great. I have no clue why more people don't use them.

    They are, as said, very heavy. Each of my six cells was around 300 lb. The case they sat in was another couple hundred. I moved them, one cell at a time, into and out of my house by either rolling them on a board on top of some short pieces of steel pipe or with a hand truck, depending. They are also unstable, or mine were, as they are very tall and narrow and therefore "top heavy." In other words, great care must be taken not to let them get away from you while moving because if they fall over it is a bear to get them raised back up.

    But I found that they last a long, long time and just keep on working.
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  • abrockca
    abrockca Solar Expert Posts: 72 ✭✭✭✭
    #9
    Re: why not use a forklift battery?

    Not a comment on the forklift battery, but more a comment on your plan to be able to replace your full house's load with the backup system.

    My thought is - that you don't. Backup systems are for use when the grid is down; at that point, you should be economizing what you use anyway. So rather than planning for peak load, maybe you should plan what would you have on during a power loss emergency - phones, laptop, internet, a few lights, heater if it's winter. Stove if it's electric. Frig, of course.

    Basically, if you lose power, you go into low-power mode, and don't plan to use your normal 25 to 30 KwH a day. This could reduce the cost of your system if you can do that.

    Just a thought!

    Anne
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #10
    Re: why not use a forklift battery?

    I just bought a crown 24 volt fork lift battery at the distributor that weighs a little over 1000 lbs. I didn,t want the anderson connectors so they showed me different terminals they had. Took my inverter cables with me so they could see what the terminals looked like. They had some terminals that they welded on for me that were made so you can connect 2 sets of inverter cables to. Thier cells are all welded together. I am going to keep my battery outside in an insulated box. I decided it was less cost than 8 l16 batterys and all the cables. I like the idea I only have 12 cells to take care of and onlt 2 battery connections I have to worry about outside. :Dsolarvic:cry:
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  • dBeau
    dBeau Registered Users Posts: 24 ✭
    #11
    Re: why not use a forklift battery?
    solarvic wrote: »
    I decided it was less cost than 8 l16 batterys and all the cables. I like the idea I only have 12 cells to take care of and onlt 2 battery connections I have to worry about outside. :Dsolarvic:cry:

    That's about where I'm coming from. Once you start talking about 2, 3, or 4 strings of 6v batteries, the cables really start to add up. Maintenance and foot print are also a big concern. Also with a smaller number of cells to deal with the auto watering systems might start to make sense. Though I'd like hear some comments in that direction.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #12
    Re: why not use a forklift battery?

    dBeau, what you describe is basically what I did. Nearly every 120 volt circuit in my house is wired through a subpanel, powered by one of my UPSs. My genset panel powers the UPS panel, with my water heater and well pump plus a few other 120 volt circuits on that panel too. However, as abrockca said, when the utility is down AND the genset is off (overnight and during the day), conservation comes into play with loads of around 200-300 watts or less. The only reason most of my 120 volt circuits are on the UPS are because it is an online (always on) model and I get lots of brownouts and brief outages - now I never know about them unless I happen to glance at my oven displays during an "event", which aren't on any backup.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #13
    Re: why not use a forklift battery?

    If yours is a backup system, they'll be in float service most of their life so will need very little watering. I bought my forklift set about a year ago and they've been in mostly float service all that time with a handful of 20% discharges. Watered them once when I got them, and added a few ml to each just the other day. So an auto-watering system would have been a waste.

    But if you're starting from a new bank, I would ask about electrolyte-circulation systems. This is one accessory I'm sorry I didn't order with my bank. It's not that expensive and improves charge acceptance, prevents stratification and helps cool the bank down. We have discussed it before here (including promotional material from a number of different manufacturers who sell these systems):
    http://forum.solar-electric.com/showthread.php?t=9733
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  • JonF
    JonF Registered Users Posts: 18 ✭
    #14
    Re: why not use a forklift battery?

    I had a watering system installed on our 48 V 1040 AH forklift battery (Hawker Powerline) and I recently switched it for water-miser caps. The reason I did was that I noticed that 2 of the floats were not functioning properly and left me with a partially exposed plate when I was checking battery specific gravity. I simply don't think its worth the risk to use an auto watering system when you are talking about serious money if a cell goes dry for a prolonged period of time.

    Secondly, when you are checking gravity with an auto-watering system, it makes a mess, the caps are all interconnected and it takes much longer, so you lose some time savings there.

    Third thing here is that for you to invest in a battery backup system of this magnitude, I hope that you have a very good reason. Very high quality batteries can be expected to last about 10 years under good treatment. For a 10K battery this is 1 K a year in depreciation costs, not to mention the cost of continuous trickle charging to keep it topped off (even 2 A @ 48 V is going to be 2.4KW/day). For that money you can buy a whole lot of gas for a backup generator. Put it in a sound proofed enclosure and set up an auto transfer switch and you have a much cheaper backup system for much less cost.
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  • dBeau
    dBeau Registered Users Posts: 24 ✭
    #15
    Re: why not use a forklift battery?

    Would anyone who has gone through the process of installing a forklift battery care to offer suggestions on cables, connectors, or terminals for connecting to an XW6048 or two. It looks to me like less than 10ft between the battery and the inverter's PDU. Assuming 2 inverters, that's a worst case (surge) of just under 500amps @ 48v! Is there anything I should mention when ordering the battery?
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  • jagec
    jagec Solar Expert Posts: 157 ✭✭
    #16
    Re: why not use a forklift battery?
    JonF wrote: »
    Third thing here is that for you to invest in a battery backup system of this magnitude, I hope that you have a very good reason. Very high quality batteries can be expected to last about 10 years under good treatment. For a 10K battery this is 1 K a year in depreciation costs, not to mention the cost of continuous trickle charging to keep it topped off (even 2 A @ 48 V is going to be 2.4KW/day). For that money you can buy a whole lot of gas for a backup generator. Put it in a sound proofed enclosure and set up an auto transfer switch and you have a much cheaper backup system for much less cost.

    I was under the impression that forklift batteries regularly exceed 10 years if they are taken care of.

    But yeah, it's still a lot of money to plunk down on something if he isn't going to be using it regularly.
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  • abrockca
    abrockca Solar Expert Posts: 72 ✭✭✭✭
    #17
    Re: why not use a forklift battery?
    jagec wrote: »
    I was under the impression that forklift batteries regularly exceed 10 years if they are taken care of.

    But yeah, it's still a lot of money to plunk down on something if he isn't going to be using it regularly.

    of course if he DOES have the money to burn ... can I suggest a solar system in my neck of the woods he could invest in? I wouldn't mind more panels, more batteries, a second inverter....

    Anne
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #18
    Re: why not use a forklift battery?
    But yeah, it's still a lot of money to plunk down on something if he isn't going to be using it regularly
    Might consider a reconditioned forklift battery with 90% performance guarantee. These usually can be had for around 1/2 price. My 940 a/h 20 hr rate cost me $1200 delivered.
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  • System2
    System2 Posts: 6,290 admin
    #19
    Re: why not use a forklift battery?

    MikeO,

    Could you let me know where you bought your battery? I am in southern Missouri and havent found a supplier of used industrial batteries...needing 48 volts worth for a 5000 watt array.

    Thanks, Glen
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #20
    Re: why not use a forklift battery?

    You can try Giant Battery
    http://www.giantbatteryco.com/MO.html

    There are others, if they don't have what you want, ask them for others to call.
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  • System2
    System2 Posts: 6,290 admin
    #21
    Re: why not use a forklift battery?

    Our company offers a EZ Link industrial battery for solar applications... We have a national network of locations too.
    I agree with the watering caps vs the watering system. It is much easier to check the specific gravities with flip top caps. We have many options for batteries available.
    http://www.remispowersystems.com/catalog.php?category_id=110 for some reference material.

    Melissa Remis
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #22
    Re: why not use a forklift battery?

    Dear Melissa,

    We generally do not allow advertising on the forum (moderators and posters are volunteers, forum funded/maintained by Northern Arizona Wind and Sun)--But for folks that are willing to offer help and advise on the forum--we do bend the rule a bit.

    So, if you have other suggestions and observations from your experience with off grid power systems and your battery/watering systems, we would very much welcome your participation here.

    Sincerely,
    -Bill B. moderator
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #23
    Re: why not use a forklift battery?

    Melissa,

    Most of the information on how to charge a forklift battery is directed at users of forklifts, so deep daily discharges and 8 hour rechargers. How would you recommend we charge a forklift battery in a typical solar install? i.e. generally shallow daily discharges and in winter only a few hours of recharge time available? Charge controllers for solar use a bulk, absorb, float and occasionally EQ charge profile - what settings would you recommend for absorb and EQ in a solar install?
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  • aglicknmex
    aglicknmex Solar Expert Posts: 40 ✭✭✭
    #24
    Re: why not use a forklift battery?

    Attachment not found.
    Here is a photo with the big forklift battery located just a few feet from the array. Upper metal frame now has roof and sides and encloses the inverter and charge controller. 240 volt line to the house. Located in sw New Mexico, Lots of sun. First 2 days of charging yielded 9.3 kw per day (midnite classic data)into the battery. Weight of the battery is about 2200 lbs. I was able to move it into place with a medium sized bobcat. Feel free to email me if you want any details. Forgot to mention, 9-235 watt panels in place now, 9 more soon. Midnite classic controller, 4448PAE magnum inverter,
    big al from NM
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #25
    Re: why not use a forklift battery?

    i don't think i'd have made the walls that close to the battery.
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  • aglicknmex
    aglicknmex Solar Expert Posts: 40 ✭✭✭
    #26
    Re: why not use a forklift battery?

    There is a little more space than it looks. Whole top picks up and is removed if I need to lift out the battery. I was wanting some thermal mass around the battery for both winter and summer tempering.
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  • topper
    topper Solar Expert Posts: 113 ✭✭
    #27
    Re: why not use a forklift battery?

    I've been mulling this over for a few years now.I still haven't broken ground, but soon I hope.
    I am basically in the same boat/similar circumstances as you are. If you plan on 6KW on your roof, you will not require dual 6048's. After PV losses, Charge controller losses, Battery losses, Inverter losses, you should never max out your single 6KW inverter.
    As far as forklift batteries go, my nieghbor has a VERY old 24V C&D bank. It still has 80% life in it. Requires a lot of water, but only cost him $75 at a scrap yard with no guarentees.
    Personal opion(with lots of input from this forum) A single 6048, forlift bank to match your 6KW PV (600-750Ahr). You should be good to go for years and years.
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  • SCharles
    SCharles Solar Expert Posts: 123 ✭✭
    #28
    Re: why not use a forklift battery?
    stephendv wrote: »
    Melissa,

    Most of the information on how to charge a forklift battery is directed at users of forklifts, so deep daily discharges and 8 hour rechargers. How would you recommend we charge a forklift battery in a typical solar install? i.e. generally shallow daily discharges and in winter only a few hours of recharge time available? Charge controllers for solar use a bulk, absorb, float and occasionally EQ charge profile - what settings would you recommend for absorb and EQ in a solar install?

    Yes, that is the normal use profile of forklift batteries...one shift uses them for 8 hours, or til they are discharged so much the forklift won't move fast any more, then they put them on a big charger during the following shift. The place I bought mine from told me that, using them like that, they usually saw about an 8-year life for a set if they were charged up promptly and properly.

    I just recently sold my 20+ yr. old set of them, which since new had been running our house. [PV charging] You don't use them any differently from any other battery, except that they can be used harder if you want [discharged to a lower level]. I sized mine so that, hopefully, I would never discharge them more than 20%. This did not always work: those occasional winter storms, for example, with several days of dense clouds and dark skies. But the norm was about 20%.

    I used only my solar array for charging. The usual charge controllers [Outback, whatever.] The set-points for absorb, float are provided by the manufacturer and, again, are "normal." I took mine up to 14.4 v. daily, if I was able to. I don't recall how long I set float, I could look it up if you need it. I still have the owners manual from when I bought them.

    By the way, when I sold them, they were still working. Nearly 22 years. Except for the weight [my cells were 275 lb. each, something like that], I still have no clue why people don't use them more for solar. They cost a lot, but when you consider their life span, they are a good deal compared with other batteries you change out every dozen years or fewer.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #29
    Re: why not use a forklift battery?

    I'm only 2 years off grid so hopefully I won't be buying my next batteries for quite awhile... But we all know that many beginners have to buy new batteries sooner than originally planned so I have read this thread with great interest. One thing that concerns me is this from the Giant Battery FAQ:
    Each time you charge a battery, regardless of how long, it constitutes one cycle. Consistently charging a battery twice per day, during lunch breaks for example, is known as Opportunity Charging, and reduces the useful life of a battery by 50%.
    <snip>
    Routinely charging the battery before it is 80% discharged is another common form of over charging. For example, if you only use the battery a few hours a day, it’s best to use it until it is truly in need of charging before actually plugging it in. Remember, each charge constitutes one cycle, so try not to charge unnecessarily.

    If I were to take the manufacturer's recommendations seriously, I would run from these batteries in a PV system. But that's only if I were to take the manufacturer's recommendations seriously.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #30
    Re: why not use a forklift battery?

    From their FAQ http://gbbattery.com/FAQ.html they go on to say:

    "The additional heat generated by opportunity charging a battery usually reduces the run time equal or greater in proportion to the amount of charge it actually received, making the practice completely ineffective and costly.
    Routinely charging the battery before it is 80% discharged is another common form of over charging.    "

    Reading between the lines here, the problem appears to be heat generation and over-charging, and not opportunity charging in itself. Again, the forklift world uses different chargers with different charging profiles and I suspect that those chargers aren't suitable for partial charging, so they'd throw the full Amps at the battery no matter it's state of charge - which would result in overcharging.

    Another manufacturer (who sells different chargers other than "Standard" forklift chargers) says:
    "...and opportunity charging and insufficient watering can reduce cycles by as much as 50%. But if you invest in the right charger up front, you can all but eliminate these problems. "

    From: http://www.cardinalcarryor.com/news/the-wrong-charger/

    RE chargers are much gentler than the forklift variety - i.e. longer absorb times at a lower voltage so overheating a battery usually isn't a problem during a normal charge cycle. And many chargers can vary their absorb times so as not to over-absorb if the battery is only lightly cycled, thereby reducing the wear on the positive plate through over-charging.

    EDIT: And another bit about opportunity charging being recommended!: http://www.crownbattery.com/?page=support_chargingprocedures

    "New charger technology has been developed to allow batteries to be charged faster and at substantially higher charge rates, called Opportunity Rapid Charging or Fast Charging. Opportunity charging is charging the battery at every opportune time possible. The battery should be charged at breaks, lunches, and at the end of each shift and any other times when the battery can be charged for at least 10 minutes. Rapid charging is defined as charging the battery from 20% to 80% state of charge in two hours or less. By opportunity charging the battery the state of charge is maintained between 30% and 80% during the normal work shift. Once a day, the battery is allowed to recharge to 100% of its rated capacity. On weekends, the battery will be automatically equalize charged while it is still connected to the charger. Opportunity Rapid Charging can only be safely accomplished with a specially designed charger with sophisticated control capable of monitoring battery conditions."
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  • aglicknmex
    aglicknmex Solar Expert Posts: 40 ✭✭✭
    #31
    Re: why not use a forklift battery?

    Good Morning,
    Im the guy with pic of big battery a few posts back. Been running the system about 3 weeks now and am very happy indeed with the forklift battery (750ah 48v). I have not discharged it below approx 50% even after couple partly cloudy days. Most days I appear to run it down to about 80 %, but as you prob know, when a battery is in use and loaded, it is not easy to make a very accurate indication of its state. I have switched over to grid a couple nites, letting the bat. rest till am and then i checked both hyd. and voltage. Thats where I got the 80% figure.

    I read all the lit. as you guys have done and then made my decision based on two things: the stories of folks using industrial batteries successfully, for years and years. And contrary wise, the stories of folks paying big bucks for agm's etc and being v unhappy to need new ones in 4-5 yrs.!!!!!!

    I was able to by a guaranteed, reconditioned ( all cells installed in the case at least 84% of new capacity) for $2200. This is half of a new forklift battery. You must be very careful who you buy from. It must be frpm a battery dealer who can buy this type of battery from the very few industrial factories who produce a true reconditioned battery These batteries are assembled from cells selected from other batteries that are received for recycling or repair. Mine has Dekka cells. All my cells were very close when i checked upon arrival.
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