Re: how long will my battery last
Settle down and put your thinking cap on! You are throwing a bunch of numbers around and trying to make all of them come out the same. The only constant you have so far is that your light will draw 8 amps of current.
Lets start with the simple one first: You have one battery rated RC = 175 minutes @ 23 amps. (RC = reserve capacity).
Your light draws 8 amps. Think about the 23 amps. Isn't 8 amps roughtly 1/3 of 23? (8x3=24). So that battery would provide 3 times 175 minutes which is 525 minutes (or if you divide that by 60 minutes in an hour) that comes to 8.75 hours. Again, understand that you are only drawing 1/3 the power that the battery spec indicates. Therefore the RC (175 minutes) can be tripled. However, that is an absolute maximum and highly unlikely to run that long. 7 hours and perhaps a bit longer is possible depending on the age and condition of the battery. What the reserve capacity means is that battery can deliver 23 amps for 175 minutes before it is no capable of doing so.
On the other battery rated at 75 AHr, that means it can deliver 75 amps for one hour, put another way, 1 amp for 75 hours. Again, your light draws 8 amps. This is roughly 10% of the 75 amps so using that number the battery would last somewhere in the 7-8 hour range which is again maximum.
WATTS: This number is very different than AMPs and VOLTS but is just another measure of power consumption. W(watts)= E(volts) x I(amps). So 100W divided by 12.6V = 7.9 Amps. Funny how a light rated at 100 WATTs is the same as one that is rated at 8 AMPs eh?????
