Golf Cart Chargers

[ron]

What NEC article applies to golf cart chargers? Most importantly, whether I can apply some type of demand factor.

I have 100 carts, and it is unlikely all will be on full out for 3 hours making it a continuous load.

I realize 625 does not apply, but don't know a related article for golf carts.

 

[charlie b]

My boss and I had a discussion this morning on a similar topic. Our equipment was car stackers, and the building will have 90 of them. I said we could invoke 220.60 by making an engineering judgment of how many could be operating at the same time. I believe we would have an easier case to make than you would. A car stacker would have to be operated by an employee of the building, and the building is not going to hire 90 people to be on duty at the same time. So it is clear that far fewer than 90 can be included in the feeder and service calculation. Can you make a case for declaring that a percentage of the cart chargers will not be operating at the same time? If the project is in the design stage, can you get the power distribution equipment set up so as to limit the number of chargers being run at the same time?

Didn't we have a similar thread recently, perhaps on electric vehicle charging stations?

 

[zbang]

The thing with carts is that some laborer is probably going to bring in a bunch of them at the end of day and plug them all in. Yes, they won't start exactly simultaneously, but maybe 4-6 of them will be started in a few minutes, then 5 minutes later another group, etc. And depending on usage they may draw full load for the first hour or so (9a per charger?). So for a couple of hours, you could have lots of chargers running full-bore.

(Same applies if all the users bring them in at end-of-shift and plug them in.)

All that said, I don't know of an official demand factor, but I think it would be up to how the facility handles the carts- who parks & charges them, and do they all come/go at once? Is this industrial or a golf course?

 

[kwired]

Keep in mind at the end of the day it is possible there may be other loads that will be shed if the facility is being vacated. I know NEC doesn't really account for that either but it is a reality.

 

[ron]

Didn't we have a similar thread recently, perhaps on electric vehicle charging stations?

Yes it was about 625 and car chargers.

The result of that thread was that some car charger manufacturers are designing into their device and control circuit to dictate maximum combined load or some other method to cycle the operation time of the charger.

 

[ron]

All that said, I don't know of an official demand factor, but I think it would be up to how the facility handles the carts- who parks & charges them, and do they all come/go at once? Is this industrial or a golf course?

I will not have control over the long time operations of the golf course, so I cannot mandate when / how they plug in.

I was thinking that due to the natural charging cycle of a VRLA battery, that the charger cannot draw full current for more than 3 hours, irrespective of how and when people plug the carts in. Full current for more than 3 hours might dry out the VRLA battery and wouldn't be tolerated for long term usage of the battery itself and the charger designers.

 

[jap]

The thing with carts is that some laborer is probably going to bring in a bunch of them at the end of day and plug them all in. Yes, they won't start exactly simultaneously, but maybe 4-6 of them will be started in a few minutes, then 5 minutes later another group, etc. And depending on usage they may draw full load for the first hour or so (9a per charger?). So for a couple of hours, you could have lots of chargers running full-bore.

(Same applies if all the users bring them in at end-of-shift and plug them in.)

All that said, I don't know of an official demand factor, but I think it would be up to how the facility handles the carts- who parks & charges them, and do they all come/go at once? Is this industrial or a golf course?

I agree.
The only way to limit full load if need be would be some type of load shedding scheme.

If 25 campers pulled into an RV park at the same time in the middle of summer and plugged in, your demand factor calculations would not be near as accurate as your clamp meter would be when you were out there on the service call in 100 degree weather trying to figure out why with all your calculations the breakers are still tripping.

JAP>

 

[mgookin]

I think golf cart chargers are going to operate concurrently for greater than 3 hours. Rapid charging shortens battery life and those batteries cost good money. Imagine a busy day when the carts are used hard and they all come in during a 2-3 hour span, or faster if weather closes the course. A golf cart that is used hard can take 6-8 hours to charge with fresh batteries. Old batteries can take longer. I agree they're not typically going to be charging at full amperage of the charger, but what's to keep some kid from pumping up the juice? I think you need to design for maximum output of those chargers.
I've done plenty of golf courses from the bldg dept perspective and don't recall this subject ever coming up. The issue about a cart barn that gets the attention is ventilation of the cart barn from a life safety perspective. I can make a phone call if you want. I had an EE working for me doing plan review; he's done plenty of golf courses and he still works there. We have more golf courses than McDonald's here.

 

[ron]

The issue about a cart barn that gets the attention is ventilation of the cart barn from a life safety perspective. I can make a phone call if you want. I had an EE working for me doing plan review; he's done plenty of golf courses and he still works there. We have more golf courses than McDonald's here.

I've directed our Mech Engineer to the Fire Code Section 608 for ventilation requirements

 

[zbang]

FWIW, the last set of cart chargers I looked were 36v 30a (1kw) at full rate. They're run at that for a few hours then the current would taper down to an amp or so. These were not smart chargers and fed into flooded-cell batteries.

Anyway, the math is easy if you know the charger specs; could be 24v 5a or could be 48v 20a.

 

[ron]

I've directed our Mech Engineer to the Fire Code Section 608 for ventilation requirements

Actually IFC 608 will not apply to us since it is for batteries used for facility standby power, emergency power or uninterruptible power supplies. Golf carts are not that.

But the IMC has 502.3 which has nicely ambiguous language that says to provide ventilation in an "approved" manner. Approved by ..... I guess the AHJ.

 

[mgookin]

Actually IFC 608 will not apply to us since it is for batteries used for facility standby power, emergency power or uninterruptible power supplies. Golf carts are not that.

But the IMC has 502.3 which has nicely ambiguous language that says to provide ventilation in an "approved" manner. Approved by ..... I guess the AHJ.

Talk to the mechanical plans examiner and the fire marshal's plans examiner. The two of them have to agree on what you design.

 

[steve66]

I will not have control over the long time operations of the golf course, so I cannot mandate when / how they plug in.

No, but you can do load shedding as Jap suggested. You could have an electronic power meter on the service panel, and connect it to a contactor to disable half the golf carts when the demand gets too high.

The contactor will only shut off when they start charging more than half the golf carts at once, and it will turn back on as soon as the charging currents start to drop off. You could even use a couple of contactors if you think an even smaller service would work.

 

[kwired]

No, but you can do load shedding as Jap suggested. You could have an electronic power meter on the service panel, and connect it to a contactor to disable half the golf carts when the demand gets too high.

The contactor will only shut off when they start charging more than half the golf carts at once, and it will turn back on as soon as the charging currents start to drop off. You could even use a couple of contactors if you think an even smaller service would work.

Be careful with setup of that or when you shed load the current drops enough to allow it to start again - pushing current back into shedding levels and it will repeat this cycle.

 

[jap]

Be careful with setup of that or when you shed load the current drops enough to allow it to start again - pushing current back into shedding levels and it will repeat this cycle.

True.
More than one value would need to be assessed prior to bringing the load back in and some type of sequencing,if not,you would more or less end up with a cycling affect.

Much like putting a photocell in the beam path of a fixture..

JAP.

 

[Besoeker]

It isn't my area of expertise, I don't even play golf, but it strikes me that there is a relatively simple solutiion. Limit the number of charging stations to that which the supply can handle.

 

[kwired]

It isn't my area of expertise, I don't even play golf, but it strikes me that there is a relatively simple solutiion. Limit the number of charging stations to that which the supply can handle.

That is sort of what OP is asking though, how many can the supply handle? Since they are not a fixed load (charging rate drops off as the battery gains more charge) it is not necessarily a simple calculation. Then you can have the possibility of overloading the supply for limited periods and not cause any problems. If there were a power outage and they came on and drew 150 or even 200% of the supply rating but only for 10 minutes it may never be a problem that is noticeable to users. If the carts are brought in only a couple at a time and started charging you may never see same demand as if you started them all at once. Some may come back for charging near totally depleted while others maybe only need a little charge. Age of units, types of batteries along with how much has been discharged may have some impact on load demand from the supply. Some chargers could possibly charge at different rates then others as well.

 

[Besoeker]

That is sort of what OP is asking though, how many can the supply handle? Since they are not a fixed load (charging rate drops off as the battery gains more charge) it is not necessarily a simple calculation.

You could start by assuming that they will all in the same state of (dis)charge at the end of a days play. Sure, the load will reduce during the charging process but the supply has to be adequate for initial charging.

 

[kwired]

You could start by assuming that they will all in the same state of (dis)charge at the end of a days play. Sure, the load will reduce during the charging process but the supply has to be adequate for initial charging.

I'm no golfer, but some guys have to run around more to find lost balls or get to errant shots, there is also those that play only 9 holes while others play 18. Why do all the carts have to come in at same time for charging? Some places maybe they do, smaller country clubs like I have been to they may come and go at different hours and definitely not all of them at same time.

Sure one can always figure what maximum demand will be and make that the minimum supply, but chances are you can get away with less then that - the larger the facility the more likely you can probably apply a demand factor - we just haven't determined what that may be.

 

[mgookin]

All of the carts are brought in dead during a power outage. All carts are connected.
Some time later the power comes on. What happens?