Maximizing 6-Volt Battery Efficiency
Dear RV Doctor:
I would like to know the best way to hook up four 6-volt batteries that are in the bank of auxiliary batteries for my 2004 Excursion diesel-pusher motorhome. They are all brand-new batteries. Thank you!
J. Kochevar
Tacoma, Washington
It’s too bad you haven’t been able to attend my battery balance seminar at one of the FMCA Family Reunions. In that seminar I explain why balance is vital in an auxiliary battery bank configuration. Here’s a bit of what I discuss:
When adding more than two 6-volt batteries to a series/parallel battery bank, each pair should be considered its own 12-volt unit. Always think of 6-volt batteries in terms of pairs.
Just as 12-volt battery banks are often miswired, negating perfect balance, so are 6-volt banks. Looking at the example in Figure 1, can you spot the improper connection? Notice that the positive and negative cables originate from the same 12-volt unit (the top two 6-volt batteries). True, the four batteries are connected in a workable series/parallel configuration, but the top two 6-volt batteries will be doing the majority of the work and will age faster than the bottom two. Many coaches are wired in this unbalanced manner right from the factory.
Figure 3 shows a more balanced approach, accomplished simply by moving one negative cable from the top pair to the bottom pair. But it still is not configured in a way that promotes perfect balance and optimization. Though much better, it can be improved upon.
In order to achieve the best balance when configuring two or more pairs of 6-volt batteries, installing and utilizing dedicated connecting terminals is optimum, in my opinion. In this manner, adding additional pairs (as is often recommended or necessary) is accomplished by assuring that all cable lengths, the number of connectors, etc. remain equal on both the negative and positive sides of the battery bank. If this configuration is not feasible for some reason, opt for the one described above.
Individual, color-coded cable connectors (stud blocks) are available and can be flush-mounted or through-mounted to accommodate modifying the battery bank connections.
Appliances
Dear RV Doctor:
On my gas water heater, what causes a blowback, or a big puff upon ignition? This happens once out of 10 cycles. The igniter is arcing, and it cycles two or three times prior to the excessive gas ignition when it finally ignites. Is this a matter of cleaning? If so, what parts should be cleaned, and how?
Steve Fettig
Via E-Mail
This issue is not limited to just the water heater. You’ll often find the same ignition problems with the absorption refrigerator and the furnace as well. Before motorhomes awaken from their winterized slumber, the propane system should be checked, the gas pressure adjusted, and the three major appliances cleaned and serviced.
And it is indeed a matter of cleaning and checking the propane components of the water heater in order to eliminate those mini explosions you’ve witnessed as the main burner finally ignites. Cleaning and servicing the water heater includes soaking and cleaning the main burner orifice, removing the carbon buildup from the electrode assembly, verifying its spark gap, cleaning and protecting the electronic connections, checking battery voltage, and measuring the propane delivery pressure, as well as adjusting the primary air intake and a few other tasks. The typical RV handyman can adequately perform the first two, but special equipment is needed to set the gas pressure, test the regulator, and check the entire propane system for leaks. There are too many details to list all the procedures within the confines of this column, unfortunately.
The main cause of that “excessive gas ignition” as it relates to the water heater is misalignment of the burner tube. It’s that “J” tube-looking component that allows fresh air to be properly mixed with the incoming propane as it makes its way to the sparking igniter. It must be clean and free from debris and blockages. Spiders have been known to build nests inside that mixing tube. In addition, it must be laterally centered and in a straight line from the face of the orifice fitting. Further, the orifice opening must be centered in the middle of the open end of the mixing tube. Picture a clock face; the orifice opening must be positioned at the very center of the clock where the hour and minute hands attach.
If it’s been awhile since the water heater was cleaned and serviced, it’s probably a good idea to have a professional do it. That way, the technician can adjust the gas pressure and with 100 percent certainty determine whether your motorhome has any propane leaks, and then make any necessary repairs. And don’t forget those other two appliances. In a perfect RV world, all propane-burning appliances require annual attention.
Curious Cynicism
Dear RV Doctor:
I’m just curious why a 30-amp surge protector costs between $50 and $100 and the 50-amp versions cost upward of $250 to $345? I’m thinking that since the majority of motorhomes probably have 50-amp service, they just jack up the price.
Jerry Carver
Simply put, the 50-amp surge protector has at least twice as many components inside, since it monitors both legs of 120-volt AC in a 50-amp pedestal. The 30-amp version monitors only a single leg of 120-volt AC. Just more stuff packed in there is probably the main reason why 50-amp versions are more expensive.