More Power! Tim’s bonus battery bonanza, Part II

~ A special, highly technical, data-driven guest series written by Tim ~

Tim the Tool Man’s “More power” grunt is repeated often around here.
(source: Giphy)

Did you know February 18th is National Battery Day? The history of this auspicious day must be electrifying, right? We’ll never know as my Internet search for this was a bust, but celebration of this day is a good backdrop to part II of our 2008 Heartland Bighorn electrical system upgrade (please read part I first). This second installment discusses equipment research, costs, and selections of the new components.

Costs and Suppliers

Gratefully, a budget wasn’t a limiter for this project; that said, I did not simply buy name-brand items or potentially overpriced packaged kits. Using a mix of online and local sources (to save time), I researched the best specifications for our requirements, and sought out the least expensive sources. My pre-tax and shipping & handling expenses were just over $2,900.

Many suppliers in the solar and renewable energy industries carry the necessary parts, most of which I found on the websites previously mentioned in Part I, or through my own searches. I was generally happy with all of them: Factory Motor Parts,,, and the lowest price providers I was able to find on


RV Batteries 

The RV dealer where we purchased our used Heartland Bighorn had installed the typical underwhelming RV/Marine 12V battery that barely provided enough juice get us through half a night of parking without hookups, especially if operating the furnace. True deep cycle batteries are the best for RV coach applications. Please search the Internet or ask in the comments below if you do not understand why.

Our requirements, discussed in Part I, showed we needed a battery bank capable of at least 400 amp-hours of energy (capacity), but I still had to decide on the type, voltage and manufacturer. Being a systems engineer, I identified important factors, and gathered data.

Weight (capacity per pound) was an initial focus. Lithium batteries (superb weight per amp-hr ratio) are an option, but I could not justify the cost. I also initially considered Absorbent Glass Mat (AGM) batteries, and would have gladly spent the extra money for them if warranted. The main benefits of AGMs include being able to use them in/near living spaces, operating them in extreme temperatures, and not having to do routine maintenance. The first two were not relevant in our application, and I personally prefer to put my hands on such a critical system component once a month. Combine this with the cost savings benefit of flooded lead batteries, and they became the obvious choice.

Two common approaches to provide 12V battery power in an RV are to use 12V batteries, or to combine two 6V batteries in series. However, a single 12V battery, or a single pair of 6V batteries, will leave you “dead in the water” if just one battery fails. Solutions with multiple 12V, or four or more 6V batteries provide important redundancy and capacity. Deep cycle 12V batteries exist, but their limited capacity means more are required. I opted for 6V golf cart batteries.

Trojan Battery Company’s T-105 6V batteries are a popular choice for RVers. I found Factory Motor Parts has FVP-labeled batteries they stated are made at the Trojan plant in California. The warranty isn’t quite as long, but at 75% of the cost, it was worth the gamble. The design and specifications match the T-105s.


Inverters apparently don’t rate their own day of celebration, but they’re important for RVers who want to boondock (dry camp) and be able to use their household-like appliances. An inverter changes 12V into 120V electricity — or as my wife says, “It performs magic!”

This purchase required the most research time after the battery decision.  The analysis in Part I of this series sized our inverter in the 2,000 to 3,000 watt range. I knew the 2,000W model would be sufficient if we managed the electrical load properly. To better protect my plethora of computers and electronics, I chose a pure sine wave inverter vice a modified sine variant. In most cases, using a combined inverter/charger (to keep those special batteries running) makes sense.

My research confirmed why many choose Magnum Energy products, but I selected a different brand for two reasons. First, most larger coaches take two 50A live wires (i.e., legs) from shore power, routing it to the inside circuit panel. This panel is designed to handle these currents, whereas not all inline inverters are. I only found one inverter I was confident could handle two full 50A legs. According to Jack Mayer, others existed previously, but most manufacturers now expect installation of a dedicated sub-panel for use by inverted loads. I felt the extra cost, work and weight outweighed the benefits. Please note my approach requires more personal discipline with load management.

The second reason was value. The option I chose doesn’t require the extra sub-panel and it meets or exceeds the specifications of comparable Magnum inverters at a fraction of the cost. The IC-2000-12 is a new product by GoPower (, a reputable company involved with inverters and solar technologies for many years. On Amazon, I was able to get the IC-2000-12 with the remote controller for several hundred dollars less than a comparable Magnum product.

Electrical Management System (EMS/Surge Protection)

Most long-time RVers I’ve spoken with can confirm that they’ve parked at locations with poor electrical shore power. Our older Bighorn came with a simple electrical setup that brought the shore power straight to the circuit panel. There was no convenient and simple way to ensure there was quality electricity feeding my sensitive computers and other appliances. The project already called for shore power service to be re-routed through the inverter, so the timing was right. This was one situation where I skipped independent research and trusted recommendations for the Progressive Industries EMS-HW50C, a box that is hardwired in the service line before the inverter.

System Monitoring & Control

The inverter and the EMS came with remote monitors/controllers, but I didn’t have anything to monitor my new battery bank, and I neeeeded that. Really. Seriously.

Do-it-yourself designers often look to Bogart Engineering’s Trimetric for their battery monitors. Thirty seconds on their website was all it took for me to realize that wouldn’t be sufficient. Remember when I said I was a geek? Get ready to get it on, because Bogart Engineering has the PentaMetric for us misfits — two more better than the Trimetric! The PentaMetric allows a computer to program and control the battery monitor, and capture bunches of data on the battery bank’s state, even every minute. Overkill? Perhaps for mere mortals.

Kidding aside, the former owner of Bogart Engineering stated that the PentaMetric is a superb tool to see the performance of your system over time, and to identify problems before they get worse and potentially cause damage. Right up my alley.

Other Stuff

Our beloved batteries and other equipment form the core of an upgraded RV electrical system. Cabling/wires, connectors, fuses, switches and shunts tie the components into a usable system. These need to be sized properly for safety and performance. An inverter’s installation manual may include cable size requirements, but they are likely to be the minimum. Connectors get sized based on the cable’s size and the size and type of the terminal.

In the final installment of this series, I’ll cover more about cable and connector sizing while showing the steps taken to complete our installation. And no project of this magnitude is going to be completed without learning some lessons. Stay tuned!

Disclaimer: Electricity and electrical systems can be dangerous to living things and electrical equipment if not handled properly. What I write will convey my own experiences. If you or anyone else should choose to use any of the information in this post, you do so at your own risk. If you’re not comfortable handling electrical circuits or equipment, find someone who is knowledgeable about such things to help you.

(Author’s note:  a version of this post appears at Heartland RVs. It is printed here with permission.)

More Power! Tim’s bonus battery bonanza, Part I

~ A special, highly technical, data-driven guest series written by Tim ~

Tim the Tool Man’s “more power” grunt is repeated often around here.
(source: Giphy)

Emily is the writer in our family. When she commented that our recent electrical system upgrades would make for a good blog post, I naturally wanted to help her. Being the ever dutiful husband, I launched into a discussion of the derivatives of Ohm’s Law, inverters, batteries and so forth.

I have been wrong about many things in my life.

Watching her eyes glaze over as I spoke let me know that I was wrong about helping to write this article. Clearly I’m on my own.

So here, in my own words, is the story of The Toad’s electrical system upgrade. Through a 3-part series, I’ll cover how I planned the system, decided upon and obtained the equipment, and carried out the installation, including lessons learned.

Disclaimer: Electricity and electrical systems can be dangerous to living things and electrical equipment if not handled properly. What I write will convey my own experiences. If you or anyone else should choose to use any of the information in this post, you do so at your own risk. If you’re not comfortable handling electrical circuits or equipment, find someone who is knowledgeable about such things to help you. 

My goal

Our adventure inspires opportunities for simplicity and self-sufficiency. RV resorts provide comforts, but can be expensive and are often booked solid, especially during the winter months or in popular areas. Having the option to park where comforts are defined differently is appealing to us.

Our RV lacked a robust source of 12V power, a useful electrical monitoring system, and the ability to convert the 12V battery power into 120V current necessary for the four computers we have onboard. Yes, four. I know, I’m a geek. We don’t have a residential refrigerator, or more than one TV, but my servers, external storage, backup system and networking gear consume more that 200 watts whenever they’re all turned on. If I only run the networking equipment, the consumption drops to about 60 watts. If you don’t understand what that means, stay with me and I’ll explain it.

In short, I wanted an electrical system that would allow us to boondock (camp without hookups) for several days while allowing us to run computers and other 120V electrical systems. Oh, and it needed to provide me with lots of data and control.

Where to begin? Planning!

As a naval officer of 25 years, I learned that plans often aren’t worth much, but planning is indispensable. I began by developing an understanding of our requirements. As part of this process, I turned to the Heartland Owners Forum for experience and knowledge. The best reference I found there was a website maintained by Jack Mayer, who has been full-timing for over 16 years, and has written extensively on RV electrical and solar upgrades.

Next, choose your path: Research how to size a new battery bank and inverter to meet your personal needs, or, accept parameters based on other system designs. The average RVers can likely run a reasonable number of electronics over a 24- 36-hour period without recharging if they have a battery bank capable of between 400-500 amp-hours.

Smaller banks are fine if your appliances run on propane and you don’t want to use a lot of electronics like TVs or computers for hours on end. Similarly, most inverters in the 1500- to 2000-watt range are sufficient for all but the most demanding cases. If that satisfies your curiosity, please skip ahead to the section “A drawing is worth a thousand words.” If not…

The devil is in the details

Developing your own personalized requirements is easier if you or someone in your family understands the fundamentals of electricity. If not, you can use resources available online, or I can answer questions below in the comments.

RV electrical equipment is designed to operate on either 12 or 120 volt electricity (but generally not both) using a certain amount of power in watts (W). Knowing the voltage is important for determining how much current (in amps) your battery bank should provide to keep the RV occupants happy. There is a relationship here that people a heck of a lot smarter than I am figured out years ago:

Power (W) = voltage (V) x amps (A)

This means that if we know either the power (W) or the amps (A) required (from the label on the equipment, or through online research), whether the equipment requires 12 or 120 volt electricity, and how long each day we want to be able to run the electronic device, we can determine how big of a battery bank we want. If we also pick which equipment we want to be able to operate simultaneously, we can then figure out how big of an inverter we should have.

In developing my plan, I could have used numbers provided in online sources, but I decided that doing my own calculations would help me better understand the cost of running any given piece of electrical equipment, and it made me consider how many hours a day we would have it turned on. Both pieces of information helped when choosing the new components. My basic list is shown in Table 1 below.

I admit now that I missed a couple of loads, like the vacuum cleaner and the stove’s exhaust fan. The more exhaustive (hahaha, get it?) you can make this list, the better will be your understanding of your system.

One catch: if the equipment in question is 120V, we need to convert the required amps to reflect the lower voltage of the battery bank (12V) when calculating our storage needs. An 1800W microwave needs a maximum of 15A (current = watts/voltage) of 120V electricity, but it will potentially draw more than 150A from the 12V battery bank while running through an inverter.

Table 1 accounts for this and adds a column reflecting how much time each day we think we’ll run each appliance. Multiplying the amps by the hours we need it gives us A-Hrs, and when we add the last column up, we have a decent estimate for the minimum size of the battery bank (350 A-Hrs). I recommend using the 20 Hr rating when comparing batteries. For us, this means we’ll likely need to charge the bank each day during typical use.

I also used the spreadsheet to help determine the size inverter I wanted to use. The column labeled Run Concurrently allowed me to see how much power I would use when trying to run different appliances together.

Table 2 reflects a situation where I would be running the full computer system and the microwave together. The number I focused on was the total power required, which would help me size the inverter. Rigorously thinking through load management is important to getting this right. If you think you’re going to run all your appliances at the same time, forget it. Likewise, please notice there is no air conditioner on my list, as it’s too big a load to run on batteries!

Table 2

A drawing is worth a thousand words

After determining our requirements, I drew my existing electrical system. Figure 1 shows how basic it was. The Heartland Owners Forum’s section called Heartland Users Guides has several documents covering typical 12V and shore power systems used in RVs.

Figure 1 – electrical system before upgrade (click to enlarge or download)

Figure 2 reflects my new system, but this was not the original plan I had (more on that in the third part of this series). My new system replaced the existing battery with a new battery bank, added a hard-wired electrical management/surge protection system, included an inverter to allow me to run 120V systems from the battery bank, and provided substantial monitoring and control.

My decision to install the new battery bank in my forward compartment was driven by the available space, proximity to the location I could put the inverter, and my desire not to use valuable basement space for this gear. In part 3 of this series, I’ll talk more about the specifics of choosing these places, and some limitations you need to consider.

Figure 2 – new electrical system (click to enlarge or download)

This brings us to end of part I. Perhaps you’re excitedly making notes, thinking about how you could modify your RV to give you even more freedom?

Or, you might be shaking your head in deep sympathy for my wife.

In either case, we hope you’ll stay tuned for Part II, in which I’ll describe how I selected and purchased the gear, along with a breakdown on how much we spent. Then, in Part III, I’ll tell you how I put it all together.

(Author’s note:  a version of this post appears at Heartland RVs. It is printed here with permission.)