Tweet
I have 3 100 watt panels that I want to use to charge a golf cart that 48 volt. I believe I am going to have to use a 48 volt Boost Controller / Charger. I I would like to hear from anyone with experience along this line.
-
-
What is the voltage of your panels?
There are only a few boost charge controllers made, and they are typically advertised for use with golf carts. For the most part our members use only buck type CCs and put their panels in series to get enough voltage to charge their battery bank with buck. A good panel designed for use with grid tie systems will have an output voltage around 36 volts and will cost far less per watt than the same number of watts in so-called battery panels.SunnyBoy 3000 US, 18 BP Solar 175B panels. -
volt
12 volt nominal 17.9 max/peak. What is "buck type CCs" panels? Talk to me a bit about micro grid tie inverters. ThxsComment
-
Grid tie inverters in general only produce output when connected to the grid. And they are very good at detecting when you are trying to fake a grid connection.
A microinverter is a GTI which is designed to connect directly to one solar panel whose output is in the 20-50 volt range somewhere. You take all of the microinverters and combine them on the AC side.
A buck type CC would be a CC which has MPPT circuitry and accepts a wide range of DC inputs as long as the input voltage is somewhere higher than the battery voltage.
Your 3 "12V" panels in series would give you a Vmp of 54 volts. That would be just barely enough to use together with an MPPT type CC to charge a 48V battery.
And Vmp does not mean V max/peak, it means the voltage at which the panel will produce Maximum Power.
At lower load voltages or higher load voltages (up to Voc) the panel will still produce some power.
A grid tie panel is one which does not care about matching the voltage needed for a 12V battery and a PWM charger (about 36 cells in series) but instead uses the most efficient construction layout, which produces a voltage in the 32-40V range. (64-80 cells in series). There is a larger market for them, so the price is driven lower per watt.SunnyBoy 3000 US, 18 BP Solar 175B panels.Comment
-
48 volt recharging
So to be able to safely and have a system that will recharge the 48 volt battery bank I should add a few panels. Say one or two more.Comment
-
You could stay with what you have, but adding a couple of panels would not hurt, and depending entirely on the AH capacity of your 48V battery bank, you may actually need a lot more panel power to service them properly.
Rule of thumb for a 48V battery bank:
If the amp-hour capacity of the bank at the 20 hour discharge rate is C, then the panel wattage should be at least 4C. That holds true for flooded batteries. For AGM batteries even more panel power can be useful and may even be necessary for some brands if you are not going to be using an auxiliary charger from grid or generator.
I would guesstimate that your golf cart battery pack is made up of eight six-volt FLA batteries of about 200AH each.
So you should have a total of 800W of nominal panel power. Right now you have 300. You can do the math from there.
If your solar setup is just to reduce the amount of time that you need to use an AC input charger, then you can hold with just the 300W or go bigger at your pleasure.SunnyBoy 3000 US, 18 BP Solar 175B panels.Comment
-
golf cart batteries
I have 6 x 8 volt batteries 56 amp each. I'm basically preparing for any extended power interruption for whatever reason that might be. I have 48 volt inverter on the golf cart that I use around the property to power 12 volt tools. Being able to recharge the golf cart batteries without the electric grip being up and working is icing on the cake of survival. Thank you or your help, this a learning experience for me.Comment
-
battery amps
The 56 amps is not amp hours, only what I read off the label on the battery. The 5 days to charge the batteries with a 1000 watt system is some of the info I was looking for. Thank you.Comment
-
Maybe that 56 amp value is the "rate of discharge" value for say 120 minutes. From what I have research most 8 volt golf cart batteries have ratings from 150 to 200 Ah but 170 Ah is a nice round number.
So with a 48 volt 170 Ah system your total battery rating is about 8100 watt hours. So I think Sunking was being sarcastic when he stated a 1000 watt system would take 5 days to charge your battery. Even at a 50% DOD (~4000 watt hours) you can get that back in 4 to 5 hours or one day with a 1000 watts of panels and a good MPPT charge controller. Now with just 300 watts of panels it might take 3 to 4 days.
It all comes down to how much of the battery you use a day. Keep it to 20% discharge and on a real good sunny day (~6 hrs) those 300 watts should get you back to 100%. I would get more panels and make sure you have a good MPPT type charger to use those panels.Comment
-
Perhaps a bit, but my comment was based on 300 watts, my bad. On a cart the panels are not tilted and oriented into the sun, so you will never see anything close to full output.
Other problem is space. You have less than 2 square meters to work with. If you were to use the highest efficiency panel money can buy at 20%, you can only get maybe 200 watts of panel up on the roof. On a good day you may get 4 amps for 3 hours a day for a total of a whopping 12 to 15 amps hours @ 48 volts. Taking Peukert Charge Efficiency into account of 80% and a 50% DOD 170 Amp Hour battery and year you are looking at 6 to 7 days recharge with a 200 watt panel.
Realistically all the panel is a range extenders of a few miles per day if he runs it down to 80% DOD. Does not sound like he is running the batteries down enough to even justify range extension. If he did run the batteries down, who the heck wants to wait a week of sunny weather for a recharge? Plug the dang thing in and be done with it in a few hours.
I know there are custom golf cart roof with a 200 watt panel built in and charge controllers made to boost the voltage up to 60 volts to charge a 48 volt battery. Reality is it is a product looking for a SUCKER with money who want to look KOOL in front of the friends. In reality they do not do much. A golf cart battery to wheel efficiency is roughly 200 wh/mile. A 200 watt panel on a good day will generate 400 to 500 watt hours or about 2 miles range. That is fine if you only play 9-holes a day and can keep the cart in full sun all day from sun up to sun down. Me I look for shade trees when I play, and keep my cart inside out of the sun and weather to protect it when not in use.MSEE, PEComment
-
MPPT charge controller
Can you recommend a good MPPT charge controller for 48 volt?Comment
-
Golf Cart batteries
I've seen those and not part of the plan. The ultimate reason for doing this is back up renewable energy supply with what I got for batteries. A full off grid solar system is already more than a few $$$$$$. Saving on total cost by using what I already got. Seemed like a good idea at the time.Comment
-
I was thinking you would recharge you golf cart when you weren't using it so the panels could be set up in a fixed position. Sunking was thinking you wanted to mount the solar panels to the golf cart and try to recharge as you are driving the cart around.
The second method (charging while driving) really doesn't work well. But a fixed array of the right size will recharge the batteries when the cart is parked.Comment
-
cc
I found this cc on ebay at what seems a reasonable price compared to other. Do you think this is a decent cc for my application. I am getting a 4th panel to add to the set up that will be mounted on a pole in the yard.
Intronics MPPT75HV 75Amp 12/24/36/48V MPPT Solar Panel Battery Charge ControllerComment
Comment