# want to solarize 36 volt golf cart



## Sparticle (Nov 1, 2004)

I hope this question is not too stupid. Will 3 12 volt panels wired in series charge a 36 volt golf cart? Does it work that way? 

Is a charge controller necessary? 

The batteries are Energizer. 

Will 3 40 watt panels suffice?


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## TnAndy (Sep 15, 2005)

Will 3 12 volt panels wired in series charge a 36 volt golf cart? Basically, yes. It would help to know the way the charging system is already set up on the card.


Is a charge controller necessary? 
Yes.....BUT you may already have something like that built onboard with the cart charging system......again, a look at that would be helpful.

The batteries are Energizer. Doesn't matter. What IS more important is: how many, what voltage, and what amp/hr.


Will 3 40 watt panels suffice?Can't say. Like asking "will a gallon of gas get me to town and back." 

Depends on vehicle, how fast, how far town is, and so on. Basically, HOW MUCH power does the cart consume, and how often to you plan to consume it ? I can't tell you that from where I sit.....but my "guess" is 40watts of panel won't help you much....you won't be doing much more than keeping the batteries trickle charged enough to keep them topped off 100%.

Do this: Look on the charger you use NOW to charge the cart...what are the specs on it ? Volts/watts/etc. Now, how LONG do you have to plug in the charger to top the batteries, and how often ? You get THOSE numbers, and we can give you a far closer guess on what it will take in the way of panels for this project.
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## mightybooboo (Feb 10, 2004)

Everything Andy said and 120 watts ( 3 40 watt panels?) will charge at what,about 2.5 amps at 36 volts? So 4 hours good light will put back 10 amps into the 36v batt pack? I think thats about right.

So yes,will charge but take a while depending on what you pull out.If its total of 40 watts gonna take a long long time to recharge after a days running around.

Guess this wasnt too helpful.

Edit,lets assume you have 6 trojan t125 batts,your pack will have about 220 amps of power,if you use half that, and never should go below,that about 100 amps.

So 100 amps would take about 10 days to recharge(actually a little longer due to some losses which could be as much as 25% in battery losses,etc) if you ran them to 50% discharge.1 day if only 10 amps out but I have no idea how long of use 10 amps might be.

Someone correct me if Im wrong,my math on these things is awful so i could be.


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## wy_white_wolf (Oct 14, 2004)

MBB

Your calc's are in the right direction (given the assumptions) but your missing system effeciency and self dicharge on the batteries. 15 to 18 days would be close figuring them in. So much varies as we can't calculate how much loss will be with the panels not being at optimum orientation mounted on the cart. 

WWW


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## ace admirer (Oct 5, 2005)

yes if the golf cart sits for several months without use, otherwise........ NO.


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## mightybooboo (Feb 10, 2004)

wy_white_wolf said:


> MBB
> 
> Your calc's are in the right direction (given the assumptions) but your missing system effeciency and self dicharge on the batteries. 15 to 18 days would be close figuring them in. So much varies as we can't calculate how much loss will be with the panels not being at optimum orientation mounted on the cart.
> 
> WWW


Yeah,wondered if that 25% over was going to cover it,and panels too,thanks!


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## mightybooboo (Feb 10, 2004)

Sparticle said:


> Will 3 40 watt panels suffice?


Agreed,more panels elsewhere to plug into would be a nice touch if going straight solar.


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## Sparticle (Nov 1, 2004)

Thanks all. The charger puts out 36 volts at 21 amps. The Energizer G2 batteries are 6 volt and have reserve capacity of 105 min. I have 6 batteries on the cart. There is nothing built into the cart acting as a charge controller. 

Can't really say how much we'll use the cart. Solar BLVD has some nicely priced panels in the 40-60 watt range. Should I go with the 60 watters? I do have a Morningstar 30 amp controller that I can put on the cart. 

There is room for 3 60 watters on the cart. Will that work? Thanks again.


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## wy_white_wolf (Oct 14, 2004)

Sparticle said:


> Thanks all. The charger puts out 36 volts at 21 amps. The Energizer G2 batteries are 6 volt and have reserve capacity of 105 min. I have 6 batteries on the cart. There is nothing built into the cart acting as a charge controller.
> 
> Can't really say how much we'll use the cart. Solar BLVD has some nicely priced panels in the 40-60 watt range. Should I go with the 60 watters? I do have a Morningstar 30 amp controller that I can put on the cart.
> 
> There is room for 3 60 watters on the cart. Will that work? Thanks again.


36volts X 21 amps = 756 watts

180 watts of panels is still way small for this application. Need to look at least twice that size.

Is the Morningstar charge conroller setup for a 36V battery bank?


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## ace admirer (Oct 5, 2005)

please stop thinking you are going to be able to put enough panels on a golf cart to run it or charge it ...it would take several thousand square feet of panels to do that .....and how would one keep them oriented to the sun? and how about inclination? even a few degree outside of perpendicular would loose 20-40% reflective efficiency. the overhead canopy would prevent one from driving the cart anywhere but down an open area. 

buy a couple of thousand $ of good panels, a few hundred dollars of storage batteries and build your self a stationary recharge station for the golf cart and enjoy free solar energy.


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## PD-Riverman (May 24, 2007)

Correct me if I am wrong, but if you take 3 12 volt(open voltage would be higher I know) 60 watt panels and wire them in series, you will get 36 volts at 60 watts------not 36 volts at 180 watts.

He would need several times this amount to get a decent charge time. 

I am going to use 6 100 watt panels just to give the golf cart a little help/charge when I am at the back of the farm, but I will still top it off with the on grid charger.


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## mightybooboo (Feb 10, 2004)

If its only driven short distances every amp going into it is a plus,but you may still need supplemental.

180 watts on roof is going to help but its not going to be drive it hours daily with just that.

But dont let that stop you,its still a good thing.If you only drive it a bit to the pond every few days,or the end of driveway to get mail,you can solar power it with that (maybe?),but you wont get much.It surely isnt the only charge you want if that cart is to be a worker.

Get those panels up and see what they do,then send a pictorial to solar gary so others can see too.

Say you want to use your electric chain saw a bit...this little portable powerhouse will do it,not often,but it will.Shoot for 300-350 watts anyhow,look here,its been done.Bet he still plugs in though if he uses it much?

http://solarcarandtractor.com/Golf_Cart.html


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## TnAndy (Sep 15, 2005)

PD-Riverman said:


> Correct me if I am wrong, but if you take 3 12 volt(open voltage would be higher I know) 60 watt panels and wire them in series, you will get 36 volts at 60 watts------not 36 volts at 180 watts.


PD, your math IS off. Remember Ohm's law: VxA=W
or working it around a little different: W/V=A or W/A=V

A 12v, 60w panel put about 5 amps ( W/V=A ). 

When you wire panels in series, you up the voltage ( 3x12=36), but the amps remain the same 5.

Now the array is 36v @ 5amp = 180w.

That is still quite a ways from the 756w the grid charger puts out, and you're correct, it won't do a lot, but it would supplement the use some.


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## PD-Riverman (May 24, 2007)

Thanks Andy for straightening me out.




TnAndy said:


> PD, your math IS off. Remember Ohm's law: VxA=W
> or working it around a little different: W/V=A or W/A=V
> 
> A 12v, 60w panel put about 5 amps ( W/V=A ).
> ...


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## mightybooboo (Feb 10, 2004)

PD-Riverman said:


> Correct me if I am wrong, but if you take 3 12 volt(open voltage would be higher I know) 60 watt panels and wire them in series, you will get 36 volts at 60 watts------not 36 volts at 180 watts.
> 
> He would need several times this amount to get a decent charge time.
> 
> I am going to use 6 100 watt panels just to give the golf cart a little help/charge when I am at the back of the farm, but I will still top it off with the on grid charger.


Thats a lot of power youre talking there,thats going to be more than a little help.Discharging a 200 amp bank 50% is 100 amps.Thats your max discharge/range on a safe regimen.

You should be able to charge 40-50 amps a day in good sun?That should give you half of max range daily.Maybe 1/3 anyhow.

Are you planning max range/hours daily?

You get 600 watts up there you are going to be in real good shape,much better than just a little recharging.Thats a serious amt of juice,600 watts.

Hows it coming?


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## Sparticle (Nov 1, 2004)

Thanks folks for the replies. This cart will not be driven for more than 1 hour daily. No joy riding, just carrying our tired bodies from place to place on the farm. 

Please look at these specs and let me know if they will work. I think they will.

&#12288;Peak power(Pmax)	&#12288;60W
&#12288;Weight	&#12288;8 kg (17.6lbs)
&#12288;Dimensions	&#12288;630 Ã 540 Ã 30mm
&#12288;32.84 Ã 21.06 Ã 1.17 inch
&#12288;Maximum power voltage (Vmp)	&#12288;18.0 V
&#12288;Maximum power current (Imp)	&#12288;3.75 A
&#12288;Open circuit voltage (Voc)	&#12288;22.00 V
&#12288;Short circuit current (Isc)	&#12288;3.34 A
&#12288;Maximum system voltage	&#12288;DC 1000V
&#12288;Temp. Coeff. of Isc (TK Isc)	&#12288;0.058 %&#65295;&#8451;
&#12288;Temp. Coeff. of Voc (TK Voc)	&#12288;-0.367 %&#65295;&#8451;
&#12288;Temp. Coeff. of Pmax (TK Pmax)	&#12288;-0.485 %/ &#8451;
&#12288;Normal Operating Cell Temperature	&#12288;44.4Â±2 &#8451;

Thanks again for all the help.


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## PD-Riverman (May 24, 2007)

mightybooboo said:


> Hows it coming?


I am finishing up the solar trailer(18x120 watt panels) first, then I will get back to the solar golf cart charger.


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## mightybooboo (Feb 10, 2004)

Yes Sparticle,they will work,not sure you will get an hours worth of travel a day,I dont know what a cart uses in amps to go for one hour,but your panels,they will work.

Are they older panels,multicrystalline by any chance? I have some,nice panels.


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## mightybooboo (Feb 10, 2004)

PD-Riverman said:


> I am finishing up the solar trailer(18x120 watt panels) first, then I will get back to the solar golf cart charger.


Thats some trailer!!!!!!:clap:

Thats 2/3rds of my home system I have for deployment.


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## Sparticle (Nov 1, 2004)

The solarized golf cart is up and running. Its great! Fast and quiet. I put a meter on it to keep track of the battery levels. I'm not using a charge controller. The batteries are from 8/06 and 3/07. I took a chance and paid $10 for them. They're working great so far. I'm not expecting a lot from them but need to know something about how much to charge them by just using the meter. No charge control. I'm simply disconnecting the cables when I think its charged up enough. When is it charged up enough? It is a 36 volt system. 6 batteries. Please don't tell me to get a controller. Not driving all over the county, less than hour maybe per day. Today, I noticed it was at 42 volts. Thought that was a bit high.


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## wy_white_wolf (Oct 14, 2004)

42.6V max for sealed or AGM batteries.
43.2V for unsealed LA batteries.


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## idahodave (Jan 20, 2005)

Watch the water levels.....if they go down fast you're charging too much.

Better yet, get a hydrometer and check the specific gravity of the cells...charge until the cell with the lowest sg stops increasing sg. Then read the sg of this cell and use it as a reference for a full battery charge. 

Again, watch the water levels and you can't go too far wrong. An overcharged battery will bubble and outgas like crazy.


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## Sparticle (Nov 1, 2004)

Sounds good. The golf is doing great. The batteries are old and aren't really that good but they're doing okay. Thanks for all the advice.


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## Sparticle (Nov 1, 2004)

wy_white_wolf said:


> 42.6V max for sealed or AGM batteries.
> 43.2V for unsealed LA batteries.


Not sure how to use this. Should I stop charging when I each this level? The batteries are 6 years old and don't have lots of ability to hold charge long. Should I allow the batteries to go down much at all since they are so old?


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