I’m about to start yet another electrical upgrade to my RV’s 12V system. The main reason for this is that my office setup is using more power than I would have expected (mainly because the work I do keeps evolving) and I will need to start printing a lot while off shore power.
My current setup has:
-two 6V batteries offering me about 120 amp hours
-one 400W inverter
-one 150W solar panel
-one 15W solar panel
When I did the math to get my solar panel, I estimated that I use about 40A per day and that I’d ideally need 60A available to me. Those numbers still hold up; I have average 50A per day if I’m working and need to heat a little.
My unscientific experiment with the solar panel this spring told me that on a sunny day, my batteries are charged by noon regardless of how low they were in the evening. So that tells me that I have some wasted potential capacity and that I don’t need another solar panel right now. What I could use are more amp hours in the form of more batteries.
Because of weight and space considerations, I have decided to go from 2x6V batteries to 2x12V batteries. Assuming that my 12V batteries have a capacity of 180 amp hours and that I have access to 60% of that capacity (108 amp hours), I will have 216 amp hours available to me, for an increase of 96 amp hours.
I am also going to be adding a Xantrex LinkPRO Battery Monitor. There are monitors that are easier to install, but this one is available on Amazon and the entire cost was covered with two months’ worth of affiliate gift certificates. I should be getting it by August. Long time readers will know that I have been talking about a battery monitor for years and it’s finally going to happen! Thank you so much to everyone who buys products on Amazon through my links!
Next, I need a bigger capacity inverter to charge a laptop, run several external hard drives, and print. Oh, heck, and run the crock pot, too! I’ll check for sales and will be getting something in the 600W to 1000W range.
In terms of office equipment, my current Brother laser printer is woefully inadequate for my lifestyle. The power consumption of a laser printer is incompatible with life on an inverter unless you have a massive battery bank, a zillion watts in solar panels, and a generator as a backup. I am eying a multifunction HP inkjet printer with low power requirements and the cheapest operating cost in its class, but I won’t say anything more about the printer selection process until I buy one.
My mother and I are going to start doing some work on the rig this weekend and one of the projects will be to get 120V power on the passenger side of the rig in the front, right above the battery bank. What I am envisioning is a charging station there based on a power strip that I can plug into either my new 120V outlet or my new inverter. I will also be installing the battery monitor in that location. It will be much easier to get it there through the same hole used to run the inverter wiring than to run the monitor cabling to the location of the solar panel monitor.
What I like best about this plan is that it isn’t going to cost me a fortune. The most expensive component will be the batteries since I don’t have to put the monitor in the budget. I haven’t decided yet if I will be getting them here, in Canada, or in the US, but the latter is more likely. So I will probably hit the road with my monitor and new inverter installed, but won’t get to reap the benefits of my upgrades for a bit.
I SO envy you that you know what you’re talking about. My eyes roll with anything involving electrical issues. My level of incompetence kicks in with anything involving more than re-setting the GFI outlet. 🙂
Brenda, comprehension comes from doing! I didn’t know any of this when I first started RVing.
Consider 2 Trojan T-105 6V deep cycle batteries providing 224 AH. They are considered the best and will provide considerably more power.
David, is that 224 the total or usable amp hours? I suspect it’s the former, just like my current 6V bank. Total usable amp hours: 130 to 140, much less tan the total usable amp hours of two 12V batteries.
I’ve had this discussion numerous times on this blog. Yes, two 6V have more capacity than a single 12V, but you’d need four 6V to best two 12V. I only have space and carrying capacity for two batteries, so the two 12V make more sense for me.
Hi Rae,
Sorry but your math is off somewhere, I have the best group 24 battery I could get and it only has 100 amp hours capacity total. If you used no more than 50% capacity (recommended) that only leaves 50 amp hours usable per 12 volt battery.
Also, “true” 12 volt deep cycle batteries are much more expensive than the 6 volt golf cart type. The 12 volt RV / Marine deep cycle batteries sold at the auto parts stores are not really a true deep cycle they are a hybrid, due to being used as a starting battery, and you will not receive the performance or serviceable life you would expect from the 6 volt batteries.
Please see the RV Doctor here:
http://www.youtube.com/watch?v=tGNMenyNqwU
Also see battery capacity chart here:
http://www.marxrv.com/12volt/12volt.htm
Please let us know what you figure out.
Rae,
I don’t know what you might have available to you in Canada but the only 12v 180ah batteries that I can find on-line are a size 4D. I would think that if you had room for 2 of them you would have room for 4 Trojan 105 6v.
I also have my doubt about your 150W solar panel being up to the task of fully charging a 360ah battery bank. The usual rule of thumb is 1W per 1ah.
I look forward to hearing about what you end up doing and with what sucess.
Ed, I don’t know if you found my follow up post or not, but I did more research and decided to go with two Trojans, which I’ll pick up in the States.
As for your other point, you are absolutely correct if I were to operate from the basis of having 300 amps available to me. But I would still use only my usual amount of power (50 to 60 amps per day) and keep the rest in reserve for overcast days.