Solar Virgin gets lucky with panels and battery but can any help with set up tips

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Keith
Keith Registered Users Posts: 1
in Solar Beginners Corner #1
hi Folks,

First thanks for taking the time to read this, ill try n keep it short. I have got my hands on a forklift battery running at 95% effiecency (24v 165amp -5hrs) Dont get the 5hrs bit btw. Plus ive got 10 x 120w mono panels. Want to run led lights and 2 60ltr engels fridges (all 12v dc) and smaller items like laptop etc. Air/C with go through mains power i think.... all in our reefer container cabin. also id like to help the battery live as long as possible so would like to conect to the mains to kick in at idk 70%..... Also i read i should discharge/fully recharge the battery to keep in in good condition is this a daily,monthly yearly thing?... ;o/

What would be idea controllers and invertors plus any other advice would be great, Thanks Guys!

Keith.

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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Solar Virgin gets lucky with panels and battery but can any help with set up tips

    Welcome to the forum Keith.

    Well the first problem is that 5 hour rating. Normally for sizing and comparing batteries in RE we use the 20 hour rating. It's about how many Amp hours can be delivered over a fixed period of time at a given discharge rate. Unfortunately it is not linear, so the 20 hour rate is not simply 4X the 5 hour rate. It will, however, be higher. Much higher.

    That means for RE use the capacity is likely 600-ish Amp hours, and the ten 120 Watt panels you have will not be capable of fully recharging this battery.

    Next problem: your lights and refrigerators are all 12 VDC when your battery is 24 VDC. Without using a DC to DC converter it doesn't work.

    Frankly the best thing you could do at this point is unload that forklift battery and pick up something more suitable to your needs. To that end a few more details as to the application would help. For instance you mention "mains" which implies grid power is available which begs the whole question of why you would be spending money on solar since the grid is inevitably cheaper almost everywhere.

    The battery discharge/recharge thing is for two purposes: in the beginning it helps form the plates and gets it up to full capacity, then as time goes buy you need to make sure it still has capacity. A battery that just sits, charged or not, dies anyway; not using it is a waste of money.

    What you could do with that 1200 Watt array: about 77 Amps peak current using an MPPT controller on a 12 Volt system (this is Outback FM80 MidNite Classic territory). That would be a large battery bank indeed: 770 Amp hours +/- such as two parallel strings of L16's. The stored power would be up to about 4.5 kW hours, which is a fair amount for an off-grid application.

    So I guess we're back to "what exactly are you wanting to do?"
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  • Ks Solar
    Ks Solar Solar Expert Posts: 47 ✭✭
    #3
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    Re: Solar Virgin gets lucky with panels and battery but can any help with set up tips

    If you already have this stuff and you can't get your money back it looks like you could set up a 24 v system . Depending on the rating of the panels. A 24v charge controller and 24v inverter and run everything on 120v Except those fridges.. hmm It is kinda mixed up start.:)
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
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    Re: Solar Virgin gets lucky with panels and battery but can any help with set up tips

    If the fork lift battery is known to be good, you might be able to switch it to 2 parallel strings of 12 volts. I would recommend having someone who works on lift batteries do this, but you could do it your self. Here's a video of guys replacing a cell in a lift battery. Note this is being done outside or in a very large warehouse, by people have done this before. but at least you can see the interconnects of the battery cells.

    Once separating the 12 cells into 2 - 6 cell strings. You could have flag terminals put on or have cables attached. Likely this is something they could do on site, if you could convince them to come out.

    The 165 amps at 5 hour rate is likely around 280 amps at a 20 hour rate (what we tend to use in solar applications) 2 strings in parallel would be 560-600ah at 12 volts which would work nicely with your array. Particularly if your using a cheap PWM charge controller.

    I personally have never intentionally drawn down my lift battery, it does get cycled down to near 30% SOC from time to time. I think this is more for the seasoning of the battery early in it's life. That said these type of batteries require equalizing at least monthly. Forklift batteries are pretty robust and can take deeper cycling, I wouldn't worry about taking it down to 50% on a regular basis if it can be recharged the next day, and it's been equalized monthly.

    I have no idea of what your loads are, the freezers are not known to me. So I'm not saying this will power your needs, but that it might be a functional system.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Ks Solar
    Ks Solar Solar Expert Posts: 47 ✭✭
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    Re: Solar Virgin gets lucky with panels and battery but can any help with set up tips

    I think Photowhit has a good idea. I would imagine they are doing that when the battery has been resting-not producing much hydrogen. Still made me wince when they lit a torch .. Good link btw Photowhit.. Why the pwm controller recommendation? Cost?
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
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    Re: Solar Virgin gets lucky with panels and battery but can any help with set up tips
    Ks Solar wrote: »
    Why the pwm controller recommendation? Cost?

    Just sounded like he was trying to get by cheaply, I made the assumption that the 120 watt panels were 12 volt nominal panels, likely correct, don't recall seeing any other than thin in this wattage that weren't. You can find C60 or TS60's in the $150 - $175 while a MPPT Charge controller would be $500+. Either way you would exceed the limits of the Charge controller, but just by a little bit, likely fine. I've been quite happy with a PWM charge controller, though I like the Midnite Classic's design and the Whiz Bang Jr is a game changer!

    He does ask for 'ideal' inverters and charge controllers, but for a first system, a C60 or TS60 and an inexpensive Xantrex pure sine inverter in 1000-1800/2000 watt range would be my suggestion. We need more info on loads as I think 'Coot expressed, to give any better recommendations.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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