What data is needed to calculate the power of an AC adapter for forklifts?

[fanzak]

Hi Everyone,
It is great to be here. I have a problem concerning the estimation of power of AC Adapters that are used for the charging Forklifts batteries. What data would I need to calculate the Power of such charger / inverter ?

Thanks,
Marcin.

 

[berkeman]

Hi Everyone,
It is great to be here. I have a problem concerning the estimation of power of AC Adapters that are used for the charging Forklifts batteries. What data would I need to calculate the Power of such charger / inverter ?

Thanks,
Marcin.

Welcome to the PF. The datasheet for the battery should have some recommended charging rate(s) on it. A typical rate might be 1/10 of C (the capacity of the battery in amp*hours). Do you have access to the battery's datasheet?

 

[fanzak]

Thanks Berkeman for a quick respond. I have the following data.

C = 700Ah
Voltage = 48V
Average battery life = 7 or 8hrs

 

[berkeman]

Thanks Berkeman for a quick respond. I have the following data.

C = 700Ah
Voltage = 48V
Average battery life = 7 or 8hrs

Whooya, that's a big battery. But I guess it makes sense for 8 hours of battery life for a forklift.

0.1C would be 70 amps for 10 hours to recharge, but that's high enough that you should definitely check the battery datasheet or check with the manufacturer. What brand is the battery, and what is the part number?

 

[fanzak]

I don't have this data now. What if I could get a output voltage of the charger / inverter and electric current that flows through it?

Then I suppose, it would give me a max power of the charger, right?

 

[berkeman]

I don't have this data now. What if I could get a output voltage of the charger / inverter and electric current that flows through it?

Then I suppose, it would give me a max power of the charger, right?

You really need to know more about the battery, to pick the right charger for the job.

I googled Forklift Battery 700Ahr Charging, and got lots of useful hits.

http://www.google.com/search?source...US301US302&q=forklift+battery+700Ahr+charging

Here's a hit for safety considerations when charging forklift batteries:

http://www.westmont.edu/_faculty_staff/pages/physical_plant/forms/HazardPrevention/forklifts.pdf

What country are you in? In the US, OSHA has regulations pertaining to forklift safety, including battery charging:

http://blog.forklifttraining.ws/2009/01/forklift-battery-charging-eye-wash.html

And this is one of the battery/charger vendor hits:

http://giantbatteryco.com/

You really need to talk to the battery vendor about how to charge those batteries.

 

[fanzak]

berman, thanks for your help!

The only thing i need to calculate is the charging cost for 8hr period.

 

[berkeman]

berman, thanks for your help!

The only thing i need to calculate is the charging cost for 8hr period.

A ballpark recharge cost could be calculated from the energy that you put back in a discharged battery. Multiply 700Ahr * 48V to get an idea of the energy stored in the battery. Then look at your electric bill to see what the cost per kWhr is.

 

[fanzak]

What if I have other devices plugged in?

I thought that best approach would be to get calculate output power and then multiply it by charging time and Price for kWh.

 

[berkeman]

What if I have other devices plugged in?

I thought that best approach would be to get calculate output power and then multiply it by charging time and Price for kWh.

Multiple devices? Output power?

 

[mheslep]

Regarding the electric bill, add ~10% wasted as heat by the charge above the rated full charge capacity of the battery. So typically: 700ah*48v = ~33.6 kWhrs in the battery, requires that plus and additional ~3 kWh from the grid, for a total ~$3.7 per charge at average US retail electric rates.

Also if these are lead acid batteries (traditionally they are for Forks), the fully charged battery will waste ~30% as heat instead of delivering motor power.