battery and wireing info please
Hi I am very new to this site and not sure how to post that I need some help. There has never been a battery on my camper since We got it and we have only ever been hooked up to shore power. We are fi...
Forum Discussion
Wendy Sue, congratulations on tackling a new project. As you are finding out there is lots of good help here.
Since you are going the expense of decent batteries I would suggest that you seriously consider a much larger panel than 45 Watts if your intent it to reduce you AC Electric bill. If you discharge those batteries even to 70 or 80 percent it will take a LONG time to recharge them with a 45 watt panel.
Say you take 55 Amp hours out of your batteries. To recharge to full you are going to have to stuff 55 Amp hours + a little more. That works out to 5.5 amps for 10 hours. I am guessing that the short circuit current (Isc) is in the neighbourhood of 2.5 Amps. Now you are looking at 22 hours of full sun.
BUT batteries don't charge in a linear fashion. For example it takes far longer to put the last 20% into the battery than it takes to get it up to that point. As the battery approaches full the charging current tappers off.
Also keep in mind that batteries should not be discharged below 50%, where they will read approximately 12.20 Volts at rest. In other words with 2 220 AH golf cart you will have 110 USEABLE Amp hours. My math says that at 2.5 amps it will take you 44 hours to recharge with a 45 watt panel. In reality it will take much longer.
The first thing that you need to do is calculate how much battery power do you go through in a 24 hour day. Add up the current draw of everything you use and how long they are on each day. This should give you a starting point.
Since you are going the expense of decent batteries I would suggest that you seriously consider a much larger panel than 45 Watts if your intent it to reduce you AC Electric bill. If you discharge those batteries even to 70 or 80 percent it will take a LONG time to recharge them with a 45 watt panel.
Say you take 55 Amp hours out of your batteries. To recharge to full you are going to have to stuff 55 Amp hours + a little more. That works out to 5.5 amps for 10 hours. I am guessing that the short circuit current (Isc) is in the neighbourhood of 2.5 Amps. Now you are looking at 22 hours of full sun.
BUT batteries don't charge in a linear fashion. For example it takes far longer to put the last 20% into the battery than it takes to get it up to that point. As the battery approaches full the charging current tappers off.
Also keep in mind that batteries should not be discharged below 50%, where they will read approximately 12.20 Volts at rest. In other words with 2 220 AH golf cart you will have 110 USEABLE Amp hours. My math says that at 2.5 amps it will take you 44 hours to recharge with a 45 watt panel. In reality it will take much longer.
The first thing that you need to do is calculate how much battery power do you go through in a 24 hour day. Add up the current draw of everything you use and how long they are on each day. This should give you a starting point.
