fork lift chargers and peak times?

[travish]

Hey,

I have 12 battery chargers for electric forklifts, need to make sure that they only charge during off peak times.

Does anyone have a better suggestion than a water heater timer and 12 automation direct relays?

Thanks
Travis

 

[petersonra]

Hey,

I have 12 battery chargers for electric forklifts, need to make sure that they only charge during off peak times.

Does anyone have a better suggestion than a water heater timer and 12 automation direct relays?

Thanks
Travis

sounds like a pretty good idea to me. Why do something elaborate and expensive when cheap and simple will work as well, or maybe even better.

 

[brian john]

sounds like a pretty good idea to me. Why do something elaborate and expensive when cheap and simple will work as well, or maybe even better.

Exactly why over engineer something simple.

 

[iwire]

I agree with the others.

The only simpler thing would be for them to train the employees. Yeah that will work. :lol:





It also seems the first time a necessary piece of equipment needs a charge they will be over-riding any timer you put in.

 

[brian john]

I agree with the others.

It also seems the first time a necessary piece of equipment needs a charge they will be over-riding any timer you put in.

And generally in a non-NEC compliant manner.

 

[travish]

thanks,
Travis

 

[Haji]

Simpler would be if the POCO offer off-peak tariff in which supply is made available during off-peak period only.

 

[broadgage]

My concern would be that the inrush current of 12 presumably large transformers energised at the same moment might be great enough to trip the feeder or even the service/main.

A better plan might be use a water heater timer or similar to control the chargers via time delay thermal relays. These introduce a short and semi random delay between energising the relay and the relay energising the load.
Thermal delay relays are often used for the control of large numbers of small air conditioners in order to avoid the starting currents coinciding.
A slightly more sophisticaed scheme would be to use 12 electronic time delay relays, all controlled by the same water heater timer.
Set each relay to a slightly different time delay, for example 5 seconds apart.

 

[kwired]

When you are looking for off peak time are you talking off peak for your facility, or a particular time of day where peak load is lower for the utility. What override capability is necessary? Like someone said there will be a time when something is dead and immediate charge may be desired.

How sophisticated is the charging units? Can they be set for different charging rates? Remember, a battery that is near full charge will take less charge current than one that is near fully discharged.

This can be real simple or real complex depending on what is wanted or needed.

Getting back to some of the simpler ideas,you could also use a timer and a contactor to control a distribution panel instead of a contactor for each branch circuit.

 

[travish]

Yes I am specifically speaking of off peak times for our plant, the utility sells us "kw's" cheaper at night. The chargers are all 480 3ph inverter style chargers, I don't think the inrush will be that great, I could put a $100 brick plc in the panel with the timer and contactors and stager the chargers on if needed.

 

[G._S._Ohm]

What is typical and max charge time? This may constrain how many chargers must be operated simultaneously.

 

[kwired]

Yes I am specifically speaking of off peak times for our plant, the utility sells us "kw's" cheaper at night. The chargers are all 480 3ph inverter style chargers, I don't think the inrush will be that great, I could put a $100 brick plc in the panel with the timer and contactors and stager the chargers on if needed.

What is typical and max charge time? This may constrain how many chargers must be operated simultaneously.

That is what would be nice about the PLC, the ability to change things by just changing programming instead of changing hardware, you could monitor current and have it limit how much can run at a time if needed. You could even monitor the load for the rest of the plant to know if you are below a certain peak before allowing operation or even build in a timed override if necessary to run during peak times if that is needed on occasions.

 

[frenchelectrican]

I am pretty sure you are aware that when you use the off peak mode for the industrial battery charger is that you have to make sure you get it charged up to 80% charged for good performace on the battery.

Most forklift battery which I know normally will take most of a shift ( about 8 hours ) to get it charged up good so that something you may want to think about it as well.

Merci,
Marc

 

[Shoe]

Photocell

If you have a bulding automation system, you could also set up a profile for energy savings during peak-hours and include disabling the chargers as part of this profile.

 

[G._S._Ohm]

What Depth of Discharge is recommended for these batteries?
You can play off charge time vs. A-h used during operation vs. DOD.

 

[kwired]

Photocell

If you have a bulding automation system, you could also set up a profile for energy savings during peak-hours and include disabling the chargers as part of this profile.

If peak demand time runs into the hours after sunset the photocell may not accomplish the task at hand. But is a simple way if peak does normally end before sunset.