# 48v Small System



## RazrRebel (Apr 16, 2013)

Ok I have 4 T1275 batteries from my golf cart. They are rated at 12v , 150 amp hours each. I also have the 48v, 13 Amp charger. If i have the four in series for 48v, then I would only have 150 amp hours of capacity right? Right now I have a 32" flat screen tv. A DVD player, and four led lamps. Just wondering if I have enough batteries to run what I have now. If so I'll be charging from a small generator. This is all I have, as I had a house fire, and the golf cart body took major damage. If I do have enough batteries, what would be a good 48v invertor for now and later down the road "bigger system" and will I need a charge controller?


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## ET1 SS (Oct 22, 2005)

RazrRebel said:


> ... will I need a charge controller?


Yes.

A charge controller has different modes; bulk charge, float charge, equalize charge, etc. These are needed for long-term battery health. They are each set at different voltages, depending on the battery manufacturer specs.

I run a 48vdc system.


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## wy_white_wolf (Oct 14, 2004)

You won't need a charge controller unless you add solar to the system. I assume the charger you have if for a golf cart and should have it's own charge controller built in.

As far as having enough power until you total up the usage (watt-hours) we can't answer that.

I would suggest about a 500-600w pure sine wave inverter. Anything larger will waste energy and may not work if you happen to only be running 1 or 2 of the LEDs bulbs (minimum load requirements).

WWW


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## MichaelK! (Oct 22, 2010)

Yes, you have only 150 Amphours of capacity, but that's at 48Volts. So, you have 150AH X 48V = 7200 Watthours of electricity. Assuming you don't want to ever deplete your batteries lower than 50%, and routinely deplete them less than 20%, you can get 3.6kwh and 1.4kwh of power respectively out of them. You yourself will have to add up your loads, but lets say the TV uses 100 watts per hour, the DVD player 50 watts, and the LEDs combined 50. At 200 watts continuous consumption, you can drain your batteries for more than 6 hours before hitting the 20% mark, and 18 hours of continuous use before hitting 50%.

This inverter could work for you.
https://ressupply.com/inverters/samlex-s600r-148-pure-sine-wave-inverter

If you want to go premium with the thought of future expansion, I'd go with this hold-house inverter. Note that it's designed to be hard-wired into your main electrical panel.
https://ressupply.com/inverters/schneider-electric-conext-sw4048-120240-invertercharger

About 750 watts of solar panels could easily replace the 20% usage above on a typical winter's day.

You want to charge at about 1/10 of your amphour capacity, so to get 15amps at ~59.3V (Trojan spec) you'll need
15amphour X 59.3V X .8derating ~ 710 watts of panels. Get three 250watt grid-ties, wire them in series, and funnel that into a MPPT controller. Your batteries will stay happy with that configuration.

If your real-world numbers turn out to be different, just replace my examples with yours and do the math.
As you enlarge the capacity of your system, you can add more panels, then add bigger batteries, such as Trojan's L16s, which would bring your storage capacity to 18kwh. You'll need 2700 watts of panels though to keep a battery bank that size fully charged, but you get almost triple your daily capacity.


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## MichaelK! (Oct 22, 2010)

_You want to charge at about 1/10 of your amphour capacity, so to get 15amps at ~59.3V (Trojan spec) you'll need
15amphour X 59.3V X .8derating ~ 710 watts of panels. Get three 250watt grid-ties, wire them in series, and funnel that into a MPPT controller. Your batteries will stay happy with that configuration._

Uoops, I see a typo here! I should have divided to get the derating. The correct math is
15amphour X 59.3V / .8derating ~ 1112 watts of panels. So that's 4 grid-tie panels. Sorry!!!


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## Murby (May 24, 2016)

RazrRebel said:


> Ok I have 4 T1275 batteries from my golf cart. They are rated at 12v , 150 amp hours each. I also have the 48v, 13 Amp charger. If i have the four in series for 48v, then I would only have 150 amp hours of capacity right? Right now I have a 32" flat screen tv. A DVD player, and four led lamps. Just wondering if I have enough batteries to run what I have now. If so I'll be charging from a small generator. This is all I have, as I had a house fire, and the golf cart body took major damage. If I do have enough batteries, what would be a good 48v invertor for now and later down the road "bigger system" and will I need a charge controller?


You should change your system over to 12v or 24v. The reason we go with the higher 48 volt systems is so that we can use smaller wire to deliver the higher power levels to the inverter. Larger inverters have minimum operating power levels and larger operating losses as lower power outputs. 

A cheap 400 watt inverter running a 25 watt bulb, will use far less energy than a 3000 watt inverter doing the same thing. 

To run a 32 inch flat screen, dvd player, and a few common led lamps, you could probably get away with a 600 watt inverter system running at 12 volts and using common 6ga wire.. or go with a 24v system with even more common 10ga wire.

Also, 12 volt chargers are common and cheap and can be found anywhere.

If you want to expand your system, we'll need to know by how much you want to expand. If you wanted to double its size and go 1200 or 1500 watts, then operating at 12 volts gets to be problematic and you'd be better off with 24v or even 48v. But for something small like 600 watts, its kind of silly to go 48 volts for that.

Inverters come in a couple flavors, quality units and cheap Chinese junk. That's a decision you'll have to make on your own.
inverters also come in two configurations, Modified Sign Wave and True Sign Wave. True Sign Wave is always always better than a modified sign wave unit but they are also 3 times more expensive.. (although they have been getting cheaper).

Inverters also come in a few application categories.. Light duty, medium duty, and heavy duty. 

Light duty inverters can be found at your local Walmart or hardware store and are usually designed to plug into cigarette lighters or have jumper cables to connect to a battery terminal. These are designed to charge power tool and laptop batteries, run small appliances, or have lights connected to them.

Medium duty inverters are mostly stationary models with a way to mount them and generally do not come with any cabling or fuses. Medium duty inverters are designed to be mounted in a boat or RV, or even your home so that you can run a microwave or a sump pump or regular power tools and things of that nature. You will need to purchase fuses, cabling, etc.

Heavy duty inverters are designed to run entire homes as if the home had grid power. These inverters are (always?) true sign wave in design and usually start off at around 2500 watts in size. 

I have several inverters in various categories. I use a 400 watt modified sign inverter (Brand = I don't know) in my truck when camping to charge flashlight batteries, laptop, phone, etc.. I also have two medium duty pure sign inverters (Brand = Go Power!) at 600 watts and 2000 watts and one heavy duty super-inverter (Brand = Outback Radian 8048) at 8000 watts 120/240 split phase to run an entire home if the grid ever failed permanently.

I strongly suggest a pure sign inverter, and whatever your power requirements, get an inverter with twice the rating. So if you need 400 watts of power, I'd get an 800 to 1000 watt inverter. If you need 1200 watts of power, I'd get a 2000 watt inverter.

If you're under 1000 watts, I'd suggest just sticking to 12 volts. From 1000 to around 2500 watts, I'd suggest either 24 or 48 volts.. but over 2500 watts, you pretty much want to stick to 48 volts.. That's my suggestion, not everyone would agree.

I am an electrical engineer by education so I don't come at this stuff blind.


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## Studhauler (Jul 30, 2011)

MURBY has good advice.


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## JeepHammer (May 12, 2015)

As an example, not saying you sould reproduce...

I have a 48 volt golf cart, 4 seats & cargo area.
The 'Sun Roof' accepted 3 solar panels, most will only take 1 or 2.
The three panels (older models) will charge the batteries, but since I was working weekends it had 4 or 5 days to charge itself, and it would in that time.
I did work the daylights out of it on weekends, so it was often close to dead by Sunday nights...
I didn't get a charger when I got the golf cart, so no charging with a generator or grid power I've never had out here in the woods...

I installed a 1,500 Watt (3,000 'Surge') inverter, with battery disconnect switch, to power corded 110VAC tools around the farm (MUCH cheaper than battery powered tools and always 'Charged').
I got an extension cord reel from a discount store and installed it.

With a series/parallel switch, it provides power at 12 VDC for the small inverter, and an on board 12 VDC air compressor,
And when the series/parallel switch is in the 'Normal' position it provides 48 VDC to the cart drive.

With an 'Anderson' connector & welding cable, I plug the battery bank into the home inverter when I'm not using the cart.
No sense in letting that much power just sit idle when I'm not going somewhere or doing something...

I don't worry too much about what it looks like, just how much work it does.
The inverter is a left over from when I first started, and this will probably be the last set of lead/acid batteries I buy, so who knows what the future holds with LiFeP04 batteries on the market & getting cheaper...

If I were going to use it part time, I would get an inverter with remote On/Off switch.
Simply turn the inverter off when not using it.

------------

While the guys recommend you switch to 12 or 24 volt system, the cart will be useless for transportation, simply a battery rack, and your charger won't function if you rewire for less than the charger is rated for.

With a small 12 volt inverter, and a stout set of battery terminal clamps, you can tap two batteries at a time for an inexpensive 12 VDC inverter to fit your needs.
When the batteries you connect to get low, simply move your clamps to the next 2 battery set in the string and draw off them.
When all 8 batteries (4 each two battery sets) are depleted as much as you want to discharge them, remove your inverter for charging.

6 Volt batteries wired in series for 48 VDC don't care where you tap two batteries for 12 VDC,
And you can charge a 48 VDC string with a 12 VDC charger simply by connecting two batteries at a time to the charger, charge them like 4ea 12 VDC batteries.

You just don't want to drive the cart while the inverter is hooked up.
A good set of clamps will provide enough contact to power up a small inverter, people do it every day to 12 VDC batteries for 'Emergency Power'.
This will save you the loss of transportation if rewired for 12 or 24 VDC,
And it will save you the cost of series/parallel switch & confusing wiring of that switch.

Just an inverter, cables & clamps.
I would choose an inverter with remote shutoff, and I would tape that wire to your extension cord so it ran to where you are powering your TV & stuff.
Cord reels are cheap if you decide to drive the cart, and with the two taped together, it's easy plug/unplug and go.


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## Steve_S (Feb 25, 2015)

I use a 24V battery bank to power a Samlex EVO 4000 Watt /24V Inverter/Charger that feeds my home and with 18W in power-save mode it uses next to nothing and can provide a surge rate of 9000W. 120V only, no need for 240VAC.

Pure Sine versus Mod Sine... Generally, mod sine will run most things but not suitable for motors or fine electronics (makes them buzz (phase issue) and motors get hot, harming them. There are lot's of Qualified Discussions on this subject.

Pure Sine "Low Frequency" is the way to go. *Many are now producing "High Frequency" Pure Sine Inverters (cheaper) *which can also create some problems (although it takes time). Many of the cheaper Inverter Generator are High Frequency (avoid them)

Good Inverter/Chargers are NOT cheap and should be viewed as a 10 year investment (I say 10 because things change fast) so you should consider that when contemplating purchases and trying to maintain a budget over a few years.



> *High Frequency Inverters (HF)* The large majority of inverters available in the retail market are high frequency. They are typically less expensive, have smaller footprints, and have a lower tolerance for industrial loads. HF inverters have over twice the number of components and use multiple, smaller transformers. Their application is appropriate for a wide variety of uses like tool battery chargers, small appliances, A/V and computers, but have a decreased capacity for long term exposure to highsurge loads like pumps, motors, and some high-torque tools.
> 
> *Low Frequency Inverters (LF)* UL-listed, low frequency inverters and inverter/chargers are the pinnacle of electrical durability. The massive iron core transformer is aptly capable of absorbing surge loads because of the “Flywheel Effect” inherent in the physical amount of a transformer’s iron. LF inverters have larger and more robust Field Effect Transistors (FET’s) that can operate cooler, in part due to the slower frequency of switching required to produce AC power. These inverters are feature rich to include the optional ability to hardwire additional external GFCI outlets, input of multiple DC voltages, provide regulated dual output voltages (120/240VAC), and integrate chemistry appropriate battery chargers and transfer relays for shore power.
> 
> ...


Interesting how no one mentioned Fuses or Breakers - You know this funny thing about safety and not getting fried, somehow that stands up to be noticed. It's not Voltage that kills you, it's Amperage !


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## JeepHammer (May 12, 2015)

Steve_S said:


> Interesting how no one mentioned Fuses or Breakers - You know this funny thing about safety and not getting fried, somehow that stands up to be noticed. It's not Voltage that kills you, it's Amperage !


Was this a thread on circuit protection or can you run a small inverter on golf cart batteries?
If we talk circuit protection, shouldn't we talk with gauge sizing?
And before we can talk either, wouldn't the OP have to say what inverter he settled on?

I did learn a couple lessons on circuit protection,
While the DC side is pretty straight forward, the inverter output AC side is another story.

My breaker box (Square D visible trip breakers) were the typical grid type choice, OVER AMPERAGE protection and a good quality choice for grid power.
When I pinched an extension cord between sharp metal edges and shorted out the conductors I learned an expensive lesson...

Inverters FRY IMMEDIATELY, long before the OVER AMPERAGE breaker trips.
OVER CURRENT breakers are a requirement for most inverters...

I've experienced this twice, once myself, and once helping another off grid family get up & running when a screw got run through an outlet feed line.
In both cases the inverter fried BEFORE the standard over amperage breaker tripped.
Neither breaker was over rated, mine was actually conservative, smaller than usually feeds the average wall outlet string.

One was a Sunny Boy and the other was an Outback.
When I contacted the manufacturer's service rep, he spelled it out for me, and yes, it was mentioned exactly once in the Outback instructions...

SO, I changed breakers, which was a kick in the wallet, but it DOES solve the issue.
Don't be me, it's expensive to learn everything the hard way...


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## Steve_S (Feb 25, 2015)

@JeepHammer BTDT (work related) and ouched their wallet too. Lessons learned & applied, once is enough. 
BTW: This thread was somewhat necro'd till march this year so not likely it's entirely relevant but might help someone else..


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## JeepHammer (May 12, 2015)

I got lucky, Outback fixed mine for free, but the Sunnyboy owner wasn't nearly as lucky.
The over current breakers aren't cheap, but a crap load cheaper than a new inverter big enough for an entire home!
Mine ran about $30 each (averaged), so about double for what I was running, and they are Square D direct replacements.
Good thing it wasn't a big breaker box or it would have been Ramen noodles for a month...

Until 2013 there wasn't a solar section in the National Electrical Code and over current breakers wouldn't have passed code...
NEC is how the locals strangled grid inter-tie solar around here, nothing in the NEC about it, it wouldn't pass code no matter who made it or installed it.
Now in the city and annexed areas, you have to carry a million dollars in liability insurance 'Just In Case' your NEC/UL approved system fails and electrocutes line workers...
They went after wind too.

I'm lucky, I'm completely off grid and 17 miles from the idiots...
That didn't keep them from protesting my solar panels & little wind generator.
These idiots actually believe solar panels 'Damage' the sun! How stupid can people get?
Or, more to the point, how low will big energy sink to discredit RE?


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