How to Increase Battery Capacity
After spending 10+ years studying RVs prior to buying one I’m amazed at what I still don’t know! Turns out the cure for that is this amazing forum. The latest issue I’m lost about is a LOT more ...
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Maybe this will help you some...
This is a spec sheet for TROJAN 24TMX which is very similar to the GP 24 Interstate we all seem to get with our trailer...
Google Image
AS you can read from this is this battery has a RESERVE CAPACITY listed in minutes of 140.
This means you can draw 25AMPS OF DC CUrrent for a total of 140 mines (2.33 hours) which will run your battery down to 10.7VDC or zero CHarge state. Of course you know you never want to run your down all the way down to zero charge and we have all foound out we can recover very nicely if we only take them down to 50% charge state. So divide your reserve number in half... You can draw 25AMPS DC current for only 70 minutes (1.16HOURS)... You have to add your your 12VDC Current demands to come up with number..
I have a good DC AMPS Current meter reading my current draw right at the main battery switch. I watch this meter to see how many DC AMPS I am draing and I also watch the DC VOLTMETER which start taper back as time goes on. When my 12VDC VOLTMETER gets to around 12.0VDC I know from experience this is going to be very close to he 50% charge state...
So the bottom line here in this case is if you start out with a battery charged to a minimum of 90% charge state you can draw 25AMPS from it running a bunch of your 12VDC appliances and devices for only 1.16 hours... If you want more ours of capacity then add a second 12VDC battery... This will now allow you to operate things that draw 25AMPS DC CURRENT for 2.3 hours now...
25MAPS by the way relate to things that add up to around 300WATT of rating.
A HDTV set will only draw around 50WATTs of DC energy so you can see this last a pretty long time if that is all you are running off the battery... If you add up a bunch of things you want to run and you get to around 300WATTs of energy needs that you can only run for a couple of hours at that rate...
My 12VDC Battery bank has the capacity of around 255AHs and I can run around 22-24AMPS draw from it between 6PM and 11PM in addition to having a parasitic drain of 1-2AMPS all the time for control modules etc.. and my 255AH battery bank will drop down to around the 50% charge by 8AM the next morning. This is what I planned for to happen. Now i can run my 2KW generator to operate my PD9260C converter/charger and get from the 50% charge state back up to the 90% charge in around three hours of generator run time. Now i am good to do this all over again for the next day/night run off my battery bank.
I can only do around 12 or so of these 50% to 90% charge cycles in a roll before I have to do a full 100% charge state which in my case takes around 12 hours of charging to make that happen...
So you can see my camping days are usually one week at a time so i can do my long charging times at home...
Been doing this since 2009 and it works out good for us. Camping off grid is almost second nature to us. My old 85AH 12VDC Interstate batteries stopped giving full performance last season so I am in the process now of replacing my 12VDC Battery Bank for this upcoming season..
Hope this spreads alittle light on how someone does this in the field... You just can't show out and do it - you have to plan oit all out otherwise it will get dark on about 9PM at night and you will be dead in the water...
Nothing magic here - You are just using the reserve capacity of your charged up batteries. The only perform so long without having to be recharged again and again and again... Car batteries won't do this very many time as compared to deep cycle batteries... If my car start battery ever gets low just one time I in most cases have to replace it pretty soon...
Roy Ken
This is a spec sheet for TROJAN 24TMX which is very similar to the GP 24 Interstate we all seem to get with our trailer...
Google Image
AS you can read from this is this battery has a RESERVE CAPACITY listed in minutes of 140.
This means you can draw 25AMPS OF DC CUrrent for a total of 140 mines (2.33 hours) which will run your battery down to 10.7VDC or zero CHarge state. Of course you know you never want to run your down all the way down to zero charge and we have all foound out we can recover very nicely if we only take them down to 50% charge state. So divide your reserve number in half... You can draw 25AMPS DC current for only 70 minutes (1.16HOURS)... You have to add your your 12VDC Current demands to come up with number..
I have a good DC AMPS Current meter reading my current draw right at the main battery switch. I watch this meter to see how many DC AMPS I am draing and I also watch the DC VOLTMETER which start taper back as time goes on. When my 12VDC VOLTMETER gets to around 12.0VDC I know from experience this is going to be very close to he 50% charge state...
So the bottom line here in this case is if you start out with a battery charged to a minimum of 90% charge state you can draw 25AMPS from it running a bunch of your 12VDC appliances and devices for only 1.16 hours... If you want more ours of capacity then add a second 12VDC battery... This will now allow you to operate things that draw 25AMPS DC CURRENT for 2.3 hours now...
25MAPS by the way relate to things that add up to around 300WATT of rating.
A HDTV set will only draw around 50WATTs of DC energy so you can see this last a pretty long time if that is all you are running off the battery... If you add up a bunch of things you want to run and you get to around 300WATTs of energy needs that you can only run for a couple of hours at that rate...
My 12VDC Battery bank has the capacity of around 255AHs and I can run around 22-24AMPS draw from it between 6PM and 11PM in addition to having a parasitic drain of 1-2AMPS all the time for control modules etc.. and my 255AH battery bank will drop down to around the 50% charge by 8AM the next morning. This is what I planned for to happen. Now i can run my 2KW generator to operate my PD9260C converter/charger and get from the 50% charge state back up to the 90% charge in around three hours of generator run time. Now i am good to do this all over again for the next day/night run off my battery bank.
I can only do around 12 or so of these 50% to 90% charge cycles in a roll before I have to do a full 100% charge state which in my case takes around 12 hours of charging to make that happen...
So you can see my camping days are usually one week at a time so i can do my long charging times at home...
Been doing this since 2009 and it works out good for us. Camping off grid is almost second nature to us. My old 85AH 12VDC Interstate batteries stopped giving full performance last season so I am in the process now of replacing my 12VDC Battery Bank for this upcoming season..
Hope this spreads alittle light on how someone does this in the field... You just can't show out and do it - you have to plan oit all out otherwise it will get dark on about 9PM at night and you will be dead in the water...
Nothing magic here - You are just using the reserve capacity of your charged up batteries. The only perform so long without having to be recharged again and again and again... Car batteries won't do this very many time as compared to deep cycle batteries... If my car start battery ever gets low just one time I in most cases have to replace it pretty soon...
Roy Ken
