theboondork's RV blog

Ideas are starting to coalesce in my age addled mind

9/3/2017

Since I'm going to have to replace my entire battery bank in the Arctic Fox this gives me the opportunity to rethink my battery system from the ground up. Like what kind of batteries do I need? How many batteries do I need? Did I have enough power before, or do I need more? How am I going to deal with watering the batteries? And what about the weight? My four Trojan T145s weight almost 300 pounds, that's more than my Yamaha WR450 weights.

These and probably many more questions need to be answered pretty quick because right now I can't use my microwave when I'm boondocked because after a few seconds of use the voltage drops to the point where the microwave wont work. And as soon as I get a cloudy day I'm probably going to run out of battery power pretty quick. I've been lucky up to this point with nothing but sunny days since my battery's went kaput but that won't last forever.

A quick look at things shows me that I have three choices in batteries, lead acid, which is what I have now, AGM which is absorbed glass mat, and lithium iron phosphate not to be confused with lithium ion. Each of these batteries has some upsides and several downsides that would apply to me. But after spending a few hours on the Internet studying these three types of batteries the picture starts to become a little clearer because it looks like one of these types of batteries has only ONE downside.... but it's a big one.

theboondork

8 Comments

Linda Sand

9/3/2017 05:47:49 pm

I chose AGMs because you can install them anywhere and never have to water them. LiPos weren't a thing yet, though.

theboondork

9/3/2017 07:07:44 pm

It sounds like you really know your batteries. It's hard to go wrong with AGM's and those are some of the things that a lot of people buy AGM's for.

Tom

Vall&Mo link

9/3/2017 08:34:32 pm

Hi Tom,

We agree with Linda, AGMs are established tech and won't give you much trouble. But they are more expensive than flooded cells, and as heavy as them.

We've been researching Li batteries; they have lots of advantages (much lighter than lead-acids, can be safely drained much deeper, recharge much faster, and last for many more charge cycles, to name a few), but the ones you buy from traditional suppliers (CALBs, Winstons, etc) are really expensive, and need BMSs and adequate chargers to work well.

One of the most intriguing developments we're following were some folks that have been using lithium batteries from EV cars (Chevy Volts) in their RVs; they cost a fraction of the "traditional" Li batteries (according to our calculations, even less expensive than good AGMs) and seem to be working very well for them.

Here's a couple of links:

http://rvnerds.com/2016/01/18/new-project-installation-of-a-new-lithium-ion-house-battery-bank/

http://montana3611rl.blogspot.com.br/2016/03/chevy-volt-lithium-battery-project.html

We're seriously considering following in their footsteps...

Cheers,
--
Vall & Mo.

9/4/2017 11:04:51 am

For some strange reason we often seem to be walking along the same path.

Darrell

9/4/2017 07:49:44 am

If it helps, here is the blog post I made when I was deciding on batteries
http://gozatravels.blogspot.com/2015/02/new-batteries-finally.html

good luck

9/4/2017 11:06:43 am

Thanks for the link to your blog post Darrell I read the whole thing. There was a lot of good information in there, and you laid it out in a simple and comprehensible way especially for something as incomprehensible as electrical stuff.

It was interesting for me to find out that you prefer not to boondock. I started out with your same basic philosophy of staying in RV parks and boondocking every once in a while, but when I started boondocking I didn't want to come back in again. I loved the solitude, the natural beauty, and sitting under my awning watching the sunset instead of looking at the side of my neighbors trailer. I was hooked.

Thanks for the information Darrell great to hear from you as always.

Tom

Barney Ward

9/4/2017 10:03:14 am

I was thinking about your usage. If your batts were at 12.5 volts in the morning, that means a little over 80% of your capacity was left. To me that means you had about twice the batt capacity (weight) you really need. Also flood batts bottom out at 12.02 volts but AGM bottoms out at 11.8 volts. Just more info for you.

9/4/2017 11:10:06 am

You're right about the capacity, but since I boondock 90% of the time, and I don't own a generator, that battery capacity has to carry me through both good times and bad. Bad times being several rainy days in a row and winter time when the sun is low on the horizon and I don't want to tilt my solar panels.

So the capacity I have now which is a usable 260 Amps appears to have been enough in the two years I've been full timing. But I haven't spent any time in the South which as you know is more cloudy and rainy than the West. So I'm not sure my 260 usable amps would be enough if I try to winter in the South.

Tom

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