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Post by biggkidd on May 5, 2022 19:49:03 GMT -6
I've been burning several gallons of gas a week getting around the homestead doing the chores etc.. About a year ago I decided I wanted to get another golf cart but boy howdy the prices were insane! I'm talking the price of an economy car here! I put feelers out and started watching Craig's list for one religiously. A couple weeks ago I saw a deal to buy 2 old beat to pieces non running electric carts for $600. Knowing it was a gamble I rolled the dice and bought them. The next day I had taken parts off one and gotten the other one running without spending another dime. Down side it still needs new batteries. Upside it's getting me around the place without buying gas. But I had to do something about the battery situation and quick. They are bad and getting worse. So thinking I had a few solar panels that hadn't been used yet I'd go solar. That started me on a quest for a boost charge controller. That's a charge controller that can charge a higher voltage battery bank than the voltage the panel supplies. Found several options and chose Renogy since I have had good luck with their products. It got here day before yesterday. So I spent the better part of the last two days getting a 300 watt 24 volt monocrystalline panel mounted in place of the roof and hooking up the charge controller. I finished right at dark tonight. Now I still need new batteries but this will help by me some time until I can afford them. Once I get new batteries I doubt I will need to plug in the charger anymore as I expect the solar will keep them up well enough. Plus unless I miss my guess it will greatly extend the life of any batteries I put in there since they will be charging everyday the sun shines. Figuring an average of 5 gallons of gas a week I am no longer burning to do the chores it won't take long to recoup what the cart and everything cost me. It's even able to pull the little trailer around and haul stuff. Now my only question is why did I wait so long to buy another one.
One of the best parts other than the fuel savings is NO NOISE! The older I get the less I like hearing engines run.
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Post by papaof2 on May 5, 2022 20:51:58 GMT -6
Most electric golf carts use either a 36 volt or 48 volt battery pack. Often 6 x 6 volt or 4 x 8 volt batteries to get 36 volts or 8 x 6 volt or 6 x 8 volt batteries for 48 volts. A few use 12 volt batteries (3 x 12 volt or 4 x 12 volt). To get full speed/power from the cart, you need the correct battery voltage. However, there are a limited number of solar charge controller that can handle 36 volts. 48 volt charge controllers are very common. To charge a "36 volt" battery, you'll need more than 40 volts and more than 53 volts for the "48 volt" battery. Those voltages mean you'll need more than one 250/300 watt panel to provide enough voltage to the charge controller (three 100 watt panels will work for 36 volts and maybe 48 volts - but that might need 4 panels - and the last ones I got from HQST were $83 each delivered).
The least expensive MPPT charge controllers that handle 36/48 volt batteries may be the PowMr and the MakeSkyBlue controllers (about $100). The MakeSkyBlue is probably my least favorite controller but the PowMr is fair. If you're using flooded lead-acid batteries, either is probably accurate enough when setting absorb/bulk and float voltages for the batteries. If you're using gel, AGM or lithium batteries, you'll need a better controller or an accurate voltmeter to set those voltages correctly - neither PowMr nor MakeSkyBlue has accurate enough metering in my experience. For more $$, the EPEver MPPT charge controllers have better metering and are convection cooled - no fan that can die and take out the controller - they also use much less power from the batteries when there is no sun. I currently have six of the EPEver controllers.
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Post by biggkidd on May 5, 2022 21:34:34 GMT -6
Papa this is the controller I bought for this project. www.ebay.com/itm/203775740406All I can say so far is that it came on and started charging at 50.9 with very little sunlight left right at dusk tonight. The batteries were at 49 something when I hooked up the last wire. If the sun shines tomorrow I should know a little more. I am running a single 300 watt panel as the roof now. This was a 36 volt system but OLD SCHOOL using resistor coils so I swapped the 48 volt bank out of the other cart as they were much better. That is not the same as saying they are good batteries as they most definitely are not!
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Post by papaof2 on May 5, 2022 22:10:00 GMT -6
A battery with 30% capacity is "better" than one with 10% capacity - but neither will get you home :-( That controller is one of the few that can do voltage boost to charge batteries that have a higher voltage than the solar panel. Most MPPT solar charge controllers are buck controllers, where the solar panel voltage must be above the battery voltage. Good choice for use with a single panel. From: www.interstatebatteries.com/support/golf-cart-battery-installation-and-maintenanceCharging at 10-13% of 20 hour AH rating - typically 200-220AH batteries, so 20-28 amps. Finish voltage of 48 volt flooded lead-acid battery is about 58-59 volts. Lots more info at interstatebatteries.com and batteryuniversity.com. Note that the typical charge rate is 20 amps or more. That assumes the batteries will be perhaps 50% discharged for any given use and they need to be charged back up quickly. If you do not use that much battery capacity daily, the slower rate of charge may work for you. You just check the battery voltage as you use the cart and see where it is. Mounting the panel on the roof of the cart isn't the optimum angle for generating power but it does provide some level of charge any time the cart is out in the sun. I have an idea for a solar-assisted trike: all bicycle wheels, cargo cart between back wheels, electric motor option to get home when you're tired, solar panels for roof, plexiglas "windshield" and side windows - roof plus windows provide rain protection. On level ground, the solar panels might be all that's needed to keep the trike in motion - not fast, just in motion. The two motors on a small wheelchair (Jazzy, etc.) draw maybe 3 amps total at low speeds. That's in the range of small solar power.
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Post by biggkidd on May 6, 2022 8:32:24 GMT -6
Late getting up this morning I was tired! Heck I'm still tired. Anyway I just stepped outside and checked the voltage 55.6V and it's cloudy no sun to speak of. I did go ahead and charge the batteries last night so they would start off today without being drained. Yesterday morning a little earlier than this after being charged the night before they were at 50.1 so it's working. I have an onboard volt & amp meter coming for it next week. For now using the old trusty multi meter.
As to panel angle and being mounted flat as the roof we talked about putting in a few selectively placed mounds for places it gets parked regularly to tip the panel towards the sun.
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Post by papaof2 on May 6, 2022 9:39:35 GMT -6
Go to this site: www.solarelectricityhandbook.com/solar-irradiance.aspx and plug in your location. It can give you how much power to expect by month based on the panel angle from flat to vertical and panel direction from southeast to southwest. Just some good-to-know info because you'll have some idea which months a flat panel gets enough sun and which months it needs to be tilted - and how much tilt. Skylight (no visible sun) can produce a little power. I base solar input on expected sunny hours and consider the few watts that happen during cloudy days as a bonus.
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Post by biggkidd on May 9, 2022 7:50:04 GMT -6
It's been pretty grey around here since installing the solar panel on the roof of the cart. Just ran out a few minutes before 9:30 am and checked the voltage. 57.1 volts now that there's finally some sunshine.
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Post by papaof2 on May 9, 2022 13:16:24 GMT -6
Even the cloudy days can produce a *little* power - more obvious if it's being used to charge idle batteries than if you're trying to run the fridge. The idle batteries just sit and accumulate the power and a few days later you get the pleasant surprise "It's almost charged!"
The solar-charged lighting in the shed out back is like that. 30 watt panel, 15AH AGM battery. LED strips that draw a little under 2 amps total. But when I turn the knob on the timer, I always have light! On the other hand, that shed doesn't see daily use, just a few minutes for in or out a couple of days a week, so even cloudy weeks keep the battery charged.
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Post by biggkidd on May 9, 2022 15:31:42 GMT -6
Had to come in to check what the flashing PV light meant on the controller on the cart. Found out it means the charge controller has finished charging the the batteries and they are in float stage! So that's working anyway. It's been bright & sunny all day and I've used the cart a few times and it still got to the float stage so I am a happy camper.
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Post by papaof2 on May 9, 2022 16:55:58 GMT -6
Nice to have stuff that works as you want it to ;-)
You're probably not racing across 16 holes with two guys and two sets of golf clubs loaded so you're putting a smaller than designed load on the cart - therefore you should find that even less-than-new batteries are useful for a portion of your day's travel. Remember that many of those carts are for rental service and would be covering that course several times a day. You might note how far (how long in minutes?) you drove and how fast to create a log of "This is how it works for me".
I know that the driver makes a big difference, as my average gas mileage in the wife's SUV (with instantaneous and average MPG displays) is consistently 1-2MPG better for the same trip in town. Possibly the "Driver Safety" classes I had every two years while at AT&T are still paying off?
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Post by biggkidd on May 9, 2022 20:00:47 GMT -6
Yes it is Papa. I don't know I go all over this property a lot and I plan to tow loads also. The volt & amp meter and lights came in tonight but that's a project for another day.
Lift is on still needs an alignment it's WAY out! Also found a few other pieces and parts it's going to need ASAP. I am worn slap out but it's done for the most part. It looks goofy with that big lift and small tires. Now instead of getting down in to it you get up in to it. lol The lift turned out to be a bit taller than I thought it would. But once it gets tires & wheels it'll be just about right to get nearly everywhere on the property. Which the tires will lift it another 2-2.5 inches giving it ground clearance at the axles.
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Post by papaof2 on May 9, 2022 22:06:44 GMT -6
Going from manicured greens to real world property, you need the lift and the bigger tires. I live in suburbia (an unincorporated area) and I've had a small pickup as my primary vehicle for 30+ years. 8+ inches of clearance isn't off-road but it allows for easy manuevering in shopping center (and home store) parking lots and on apparently blocked roads. I'd have no problem going over the 6 inch median and going back the way I came to get around a big intersection where the traffic lights were out - I even have a specific one in mind becuse it is such a complex intersection - but a half mile South of that intersection is a county road that eventually wanders right back home ;-)
Having even a small truck (Tacoma) is useful.
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Post by biggkidd on May 10, 2022 11:18:25 GMT -6
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Post by papaof2 on May 10, 2022 12:48:10 GMT -6
Looks like it's doing well. 266.5/300 = 88.8% of the rated watts. Not bad when it's flat. Looks like it should work well in the summer. You may need to be able to tilt the panel to take the best advantage of the shorter sunshine hours in winter.
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Post by biggkidd on May 10, 2022 14:42:40 GMT -6
It's got a layer of dust / pollen on top you wouldn't believe it could charge through. I can see washing the panel may need to be a daily undertaking. But for now I want to see how it does without washing. So far I am very pleased I drove it to the end of the road awhile ago plus around here a lot today.
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Post by biggkidd on May 10, 2022 18:51:28 GMT -6
Over the course of the day according to the meter I installed it made 1479 watts. I think that's pretty dang good.
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Post by biggkidd on May 10, 2022 21:37:36 GMT -6
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Post by biggkidd on May 12, 2022 21:07:13 GMT -6
Was planning to try and do wheels and tires next but considering everything I think batteries would be wiser at this point. Which has led me into looking at all kinds of battery options. I'm seriously considering dipping my toe in the LifePO4 type or something similar. I'm thinking a small bank for the golf cart might be a good way to learn if I might want to try and get some for our house power system next go around. The solar charge controller I bought for the cart will work with them just as well as lead acid. For what I use the cart for and the distance I drive it I can probably get away with a very small battery bank in LifePO4 around 50AH versus the 150-165 AH lead acid batteries. Which would save a lot of space and weight which is important in an EV of any type. The big thing for me though to be honest is the price. I can actually get these www.amazon.com/gp/product/B09TCXMB2Q/ref=ox_sc_act_title_2?smid=A1FCRZH3ASA306&th=1or possible these batteryhookup.com/products/super-beast-module-with-48-headway-38120-hp-3-2v-8ah-24v with a decent BMS for several hundred less than I can replace the 165 AH lead acid batteries. These would give me around 40 useable amp hours. Of which I would likely only use 30 or less of most of the time. Which is about as much as I would use out of lead acid batteries rated for 165 AH I try real hard to never take more than 30% out of a lead acid battery and I prefer only 20%. I think that's why they always last me so long. Plus I never blast them at the highest possible voltage. I would treat any Li type according to what's best for the batteries. To my understanding that's keeping them close in the high center range of their capacity. Say in the 40-90% or 30-80% state of charge range. My research tells me charging that last 10-20% at the top and using below 20-30% at the bottom greatly reduces lifespan. Compared to using from say 35% to 85% state of charge. Yes you can use them quite well outside of these parameters. According to what I've been seeing though says you can increase a 6,000 life cycle battery to an 18,000 cycle battery by keeping it in that center range. To me that's one heck of a game changer! Maybe I am understanding this incorrectly if so and anyone knows different please explain.
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Post by papaof2 on May 12, 2022 22:58:26 GMT -6
The US military brackets lithium ion batteries as "charge to 80%, discharge to 20%". However, one lab test that I read had 5000+ charge/discharge cycles with "charge to 75%, discharge to 25%" - or basically use the middle 50% of the batteries' capacity. From my experience with lithium ion laptop batteries, they last reasonably well if never discharged below 30% or so but they rapidly go downhill after a couple of discharges to 20% or so. I wrote a battery monitor for Windows (XP - Win10) that flashes an icon in the ribbon when it reaches the "Alert" charge % (mine is set at 40%) and starts beeping at the "Charge me" charge % (mine's at 38%). LiFePO4 can have 2000+ cycles of life but I'll guess that not pushing either end of the range will give longer life. I replaced the AGM battery in a small UPS with an LiFePO4 pack that has similar capacity but the UPS' "low battery shutdown" is at 10.7 volts where the BMS in the LiFePO4 pack has the typical LiFePO4 "12 volt battery" 10.0 volt shutdown voltage - the UPS will shutdown before the LiFePO4 pack reaches its minimum voltage so the UPS can run to shutdown without damaging the battery pack - running to shutdown with an AGM battery leads to very short battery life. The BMS for this pack charges the cells to 3.55 volts/cell (a little less than the typical 3.65 volts and much less than the 4.1 volts maximum voltage). From a paper on LiFePO4 in EV service: It is estimated that LFP batteries can support at least 2000–2500 cycles in electro-mobility applications, for example, daily use of a charge and discharge cycle for seven years, until the remaining capacity reduces to 80% of the initial battery capacity. This allows its use for another 1000–2000 cycles until the capacity reduces to 60% of the initial capacity. When this occurs, the aging process of the battery has advanced to point that the voltage drop does not allow further use of the battery. www.google.com/url?esrc=s&q=&rct=j&sa=U&url=https://scholar.google.com/scholar_url%3Furl%3Dhttps://www.mdpi.com/2071-1050/11/9/2527/pdf%26hl%3Den%26sa%3DX%26ei%3Dd999YuqHOOeEywSj_bbwCA%26scisig%3DAAGBfm3Z2fBx0IG-w8Pay04Ku54_52BBSg%26oi%3Dscholarr&ved=2ahUKEwjwmObY0tv3AhW6rmoFHcncBtQQgAN6BAgNEAI&usg=AOvVaw26j2oRu72vXgJzT95A58tC2000+ cycles to 80% of original capacity and then 1000+ cycles to 60% of original capacity. If you never take the LiFePO4 cells below 20%, those might be realistic numbers. However, you will need to allow for cold weather (can't charge the battery below 32F) and there are upper temperature limits. shop.gwl.eu/blog/LiFePO4/Operating-temperature-of-LFP-Cells.htmlThe batteryhookup.com pack looks good for a golf cart (they're 24 volts - Was the original cart battery voltage 36 or 48?) but do be very aware of how quickly these "go to zip" after they approach their minimum voltage - you might be able to limp back in slowly with very discharged lead-acid batteries, but when using an LiFePO4 battery with a BMS, the power is totally and permanently OFF when the minimum voltage is reached - at least until the battery is adequately recharged. Not something people typically associate with how golf carts or kids' riding toys work :-( Be sure that you know how much capacity is the battery pack before heading out on a long journey. These batteries are listed as 2000cycles 1C 80%DOD or 2000 cycles to 80% discharged at full rated current. If you're running less current or less total discharge, then you'll get more cycles. Remember the egg between your foot and the accelerator ;-)
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Post by biggkidd on May 13, 2022 18:44:44 GMT -6
Good info there Papa!
Got the other meter in today. Very glad I ordered it it is already teaching me quite a lot. First the chore run takes less than 5 amp hours. The motor draw averages between 15 and 30 amps for the most part. That's just driving it, it spikes higher on hills and of course taking off from stopped. Another thing it has taught me is that the easier you run the lower the draw on flat ground. There had been some question about that being as this is seriously old school.
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Post by papaof2 on May 13, 2022 21:46:15 GMT -6
Even ancient DC motors work the same: lower loads = lower power draw. If you don't need "slam me back in the seat" acceleration, don't use it. The slow and gentle of "egg under your foot" acceleration works to improve range on ancient golf carts just as it does on the newest gas- or diesel-powered road vehicle.
Being able to measure the power used to get from Point A to Point B lets you "budget" your power use and say "I'll do these three things close by, but the solar panel will be in the sun for that hour so the battery will be charged enough for the longer trip an hour from now." Each solar application is a learning process - just as I learned to check the AH meter to see how much power has been taken from or put back into the solar backup system's batteries to know how much "stuff" I can power and for how long.
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Post by biggkidd on May 13, 2022 23:21:32 GMT -6
I wasn't sure how the resistor wire worked. If it just burned off power to control speed or what. I still don't know the answer to that but I do know that the harder you mash the pedal the more amps you draw up until you're going about as fast as your cart can go then the amps fall off to about 15-16 and remain steady on a level surface with the pedal on the floor.
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Post by biggkidd on May 14, 2022 7:00:56 GMT -6
I never realized just how much smaller and lighter LifePO4 were compared to LA for equal amp hours of use according to manufacturers specs until starting in on this project. I'll be taking nearly 300 pounds off the cart by changing battery types. Plus it will open up about 2/3 of the battery compartment for storage. But the best part is with the slightly higher voltage and much flatter discharge curve gaining a lot of performance. Between the gain in power and the loss of 1/3 of the carts entire weight this should make a very large change to the overall performance!
Papa it was a 36 volt cart originally.
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Post by papaof2 on May 14, 2022 12:44:12 GMT -6
I wasn't sure how the resistor wire worked. If it just burned off power to control speed or what. I still don't know the answer to that but I do know that the harder you mash the pedal the more amps you draw up until you're going about as fast as your cart can go then the amps fall off to about 15-16 and remain steady on a level surface with the pedal on the floor. The resistive wire is a current limiter because a DC motor at rest is almost a dead short across the battery. The full resistance gives a gentle start and, as you take resistance out of the circuit the power available to the motor increases. The motor will speed up to its maximum speed (based on the load) and as it speeds up its EMF opposes the current from the DC source (battery) so the current drops until you have euilibrium among battery voltsge, motor speed and motor load. Increasing load slows the motor, redcuing the EMF and drawing more current. Removing 2/3 or more of the battery weight will make the cart more responsive on less power and increase its range for the same AH of battery capacity. Having only one person aboard and without XXX pounds of batteries, you should have good range with one 48AH 24 volt battery pack. Doubling the battery size should make that a most-of-the-day vehicle - unless you start moving a half dozen 100lb bags of feed or seed ;-)
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Post by biggkidd on May 14, 2022 15:20:48 GMT -6
Thank you Papa I love learning stuff, practical stuff anyway. lol
Yeah I shifted gears to 105AH EVE cells. I was afraid the 54 AH just wouldn't have the current carrying capacity to get moving on the hills and such. I have about 1/2 the cash in hand to order and plan to take a load or two of scrap early next week to hopefully make up the balance. The cells I am looking at are rated for 3500 cycles from 100% to 10% I think it was. Might have been to 0%. Doesn't matter much to me I plan to set the system up to charge to about 3.3 and down to about 3.2 per cell staying to that long life middle zone they recommend. Or in terms of the battery bank I'll keep the voltage between 52.8 and 51.2. Which should let those batteries out last me!
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