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Thread: 48V Battery Array charging

  1. #1
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    Default 48V Battery Array charging

    Hi, I am new to solar panel stuff so please excuse my stupidity !
    I have a 48V Toro Workman utility vehicle (like golf buggy). I would dearly love to keep it, problem is, I have to take it home to charge it as there is no mains electricity up on my land. I have a cattle shelter and shed where I can park it securely but no means of charging it. I wondered if it would be possible to have a solar panel set up that would be up to the job of maintaining charge of the vehicle. It must be added, that I do not use it every day (usually) and in any case, would never usually take it down to below 30% charge. I do not have money to burn, so cost would be an issue, but I natuirally expect any solution (if at all possible) will not come free. Please help. Cheers Jim

  2. #2
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    Well it can be done, but cheap is not likely in the picture. Before I give you any examples what size are the batteries in Amp Hours and your location.

    Typical 48 volt golf cart batteries AH capacity range a bit from 180 to 300 AH. Using a medium of say 225 AH at 30% discharge is 3300 watt hours. That is a lot of power for a solar system. Using a 2 day model to recharge depending on your location could be anywhere from a 1000 to 2500 watt solar system, easily $2000 to $6000 just in panel cost alone.
    MSEE, PE

  3. #3
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    Default Reply

    Hi Sunking - thanks for the speedy response. I am actually in the UK. The battery array is not the originally supplied one - sadly, Gypsies stole the original batteries. I couldn't afford to replace them , so I used some 80AH 12v (4 in series + 4 in series then paralleled) which if my account of the rules is correct, should be 160 AH 48v. I had these batteries, which came from a wind turbine project I bought. Unfortunately, my local planning department would not let me erect the wind turbine, so the batteries were going spare. I decided to try them on the Toro and have to say it works fine for me, so I don't feel I need to upgrade back up. hence, it is a smaller capacity system. Is this still feasible ? Cheers Jim

  4. #4
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    Quote Originally Posted by Lord Welby View Post
    Is this still feasible?
    I cannot answer that question only you can. What I can tell you is what will take. Then you have to decide if you can afford it. I have my doubts because initially the batteries are the least expensive component.

    OK I still do not have all the details, most importantly how often the cart will be used, and exactly how deep you are discharging the batteries. You said 30% discharge, so I have to go with that for now. Based on 160 AH @ 48 volts discharged 30% is 2300 watt hours. That means the panels will need to generate 4600 Watt Hours to replace 2300 watt hours.

    For now I can tell you the minimum panel wattage with using a PWM controller is 900 watts. That will generate the minimum C/12 charge current. But with your location and low radiance levels it can take up to 3 days to fully recharge from 70% SOC depending on the time of year. The maximum panel wattage you can run on your batteries with a PWM controller is 1350 watts to obtain a C/8 charge rate.

    At these panel wattage you can justify the expense of using a much more efficient MPPT controller which also allows you to use less expensive grid tied panels. To achieve the same charge levels as above the minimum is 640 watts, and a maximum of 1000 watts.

    In US dollars you are looking at a range of about $1700 on the low end using 640 watts of panel with a MPPT controller, and $3000 using 1350 watt panel with PWM controller.
    MSEE, PE

  5. #5
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    Default Feasable or Not

    Hi SunKing, Thank you once again. I think the solution(s) you have offered would not be cost effective for me. I don't use it that much, certainly not daily. I also have a gas powered Cushman Hawk and even though gas over here is around $8 / gallon, I do not see me getting to break even within the lifetime of the truck. So once again, thank you for your help. I shall continue to attend the forum as I do plan at some stage to put some solar power up at home and may once again need some guidance from you guys (I feel it is better to get information from forums such as this as there is no one trying to sell something). Cheers Jim

  6. #6
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    Quote Originally Posted by Lord Welby View Post
    ....so I used some 80AH 12v (4 in series + 4 in series then paralleled) which if my account of the rules is correct, should be 160 AH 48v....
    Wouldn't 4 strings of 4 batteries be 320AH at 48V?

    Double SK's last figures for the array.

  7. #7
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    Default Check on AH rating

    Hi Wy_White_Wolf , I used 8 x 80AH 12v Batteries wired Thus: 4 in series then another 4 in series and parallel wired the two banks. I thought this equalled 160 AH (ie 2 x 80AH) ? If this assumption is wrong, then I have a more powerful set up than I thought - no wonder it hasn't had any detrimental effect on the performance. Would someone please confirm. Cheers Jim
    Attached Images Attached Images

  8. #8
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    Gypsies stole the original batteries
    Wait till you place an expensive solar PV array out for them ! Then they will have both batteries and PV.

    Sorry you will have to factor theft into the business too.
    Since the dawn of time it has been mankind's dream to blot out the sun.
    Montgomery Burns

    "Always listen to experts. They'll tell you what can't be done and why. Then do it."

    spreadsheet based voltage drop calculator:
    http://www.solar-guppy.com/download/...calculator.zip
    http://www.solarpaneltalk.com/showth...oss-calculator

    http://www.mike-burgess.org/PVinfo_2.html

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,
    battery lugs http://tinyurl.com/LMR-BigLug
    Setting up batteries http://tinyurl.com/LMR-NiFe

    gear :
    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 || || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

  9. #9
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    Quote Originally Posted by Lord Welby View Post
    Hi Wy_White_Wolf , I used 8 x 80AH 12v Batteries wired Thus: 4 in series then another 4 in series and parallel wired the two banks. I thought this equalled 160 AH (ie 2 x 80AH) ? If this assumption is wrong, then I have a more powerful set up than I thought - no wonder it hasn't had any detrimental effect on the performance. Would someone please confirm. Cheers Jim
    Jim it is a 48 volt 160 AH battery setup. That is a very typical golf cart setup.

    Before you totally give up how many days of the week do you use the cart and what time of year? If you only use it every 3 or 4 days in summer months we can down size a bit. If you use it every 2 or 3 days year round I stick to my original recommendation.
    MSEE, PE

  10. #10
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    another thought is a small-mid generator to power a mains charger for the cart, give it a quick bulk if needed, and let the solar top it off.

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