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  • 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
    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

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    • #3
      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

      Comment


      • #4
        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

        Comment


        • #5
          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

          Comment


          • #6
            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.

            Comment


            • #7
              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 Files

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              • #8
                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.
                Powerfab top of pole PV mount (2) | 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

                Comment


                • #9
                  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

                  Comment


                  • #10
                    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.
                    Powerfab top of pole PV mount (2) | 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

                    Comment


                    • #11
                      Truck usage

                      Hi SunKing, I wouldn't be using it much during the winter months. I generally use it to attend my bee hives, riving from field to filed with the equipment and collecting frames for honey extraction. This would be daily, but only driving for 1 or 2 hours. This would only really take about 15-20% out of the batteries. Occassionally I would collect a few loads of logs, which might take a little more out of the batteries, but never been below 30% overall. During the winter, there is very little usage, if any. I was rather hoping there was such a thing as a "trickle charge" type of set up which could keep the batteries maintained. I guess I can be flexible and arrange my usage to suit the charging regime. What are your thoughts ?

                      Comment


                      • #12
                        Originally posted by Lord Welby View Post
                        I generally use it to attend my bee hives, riving from field to filed with the equipment and collecting frames for honey extraction. This would be daily, but only driving for 1 or 2 hours. This would only really take about 15-20% out of the batteries.
                        No disrespect Sir but those numbers do not compute.

                        I do not know how much power your cart uses or the terrain, but I speak with experience with regards to 48 volt carts that 1 to 2 hours run-time takes a lot more than 15 to 20% of the capacity of a 48 volt 160 AH battery.

                        A golf cart running on a flat level paved surface uses about 200 wh/mile at an average speed of 12 Mph. Translated to Euro units 125 wh/Km at 19 Kph. So with running 1 hour will use 2400 watt hours out of a 7600 wh battery or 30%. Run two hours and double the numbers.

                        Based on your comments solar is not an option for you for daily recharge. You need a gas or diesel buggy.

                        FWIW here where I live with a 48 volt Golf cart using AGM 48 volt 200 AH batteries takes about 40 to 50% of the battery capacity to play 18 holes on unlevel mixed paved and grass pathways. Actual run-time is 30 minutes at most to go about 5 miles or 8 Km.
                        MSEE, PE

                        Comment


                        • #13
                          Timing errors

                          Hi SunKing, I think I may have misled you. When I say that I use for 2 hours, I really mean that my job takes that long. Drive time to get to hives is only about 10 minutes or so either way, with a little movement going along the rows of hives, probably another 10 minutes driving. Therefore total drive time would be more like 30 minutes max. It usual knocks off about 2 bars on the battery usage indicator. I would say that the winter drive to the woods to get logs is about 20 minutes total, once or twice per week (probably 6 per month). I appreciate your attention, but if this application is not suitable then I will respect your advice. Cheers Jim

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                          • #14
                            more on timing

                            forgot to mention. I thought the significance of mentioning 2 hours use time, was to give some idea of the unused time available during daylight hours for charging.

                            Comment


                            • #15
                              Do you have a good digital volt meter?

                              After you have done a days work, let the cart sit for an hour or two to let the batteries rest. Measure the voltage and get back to us. The rested voltage will give us a fairly good idea how deeply you discharge them.

                              100% = 50.8 volts
                              90% = 50.0
                              80% = 49.84
                              70% = 49.44
                              MSEE, PE

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