Baffling Battery Drain
Dear RV Doctor:
The chassis battery drains on my mom’s 2014 Winnebago Vista. We were told the battery should be replaced because it no longer held a charge, but a new battery yielded the same result. If the battery is left disconnected for a few days, there is no problem. But when the same battery stays connected, it drains to nothing in a few days. The house batteries have no problem, just the chassis. Can you provide a general checklist to help me find what I’ve missed?
Tom Walsh
Naples, Florida
Most 12-volt operational problems are one of three types: battery drains like your mom’s coach is having; short circuits; and open circuits. My philosophy when troubleshooting 12-volt-DC systems is to consider the following:
- The system in general.
- The circuit in the affected system.
- The component in the affected circuit.
You’ve already identified the system in general — the chassis battery system. Next, determine which circuit in that system is affected. And then pinpoint the component in that circuit that may be the cause. Use the process of elimination. Work from large to small, general to specific.
Begin by making sure that all 12-volt components are in the off position. Then, set a reasonably accurate digital multimeter (DMM) to the 10-amp DC or auto-ranging scale. To check for a drain on the battery, make sure the shoreline cord is unplugged and remove the negative cable from the chassis battery. You now have an open DC circuit. Connect the DMM red test lead to the cable you just disconnected, and connect the black test lead to the negative battery terminal. This is a completed circuit with the meter inserted in series, in line with the negative cable. If anything is “energized,” you will see it register in amps or milliamps on the DMM.
Typically, the dash components, instrument cluster, lamps, defroster/heater fans, radio, etc., are wired to the chassis battery. It would be handy to have a chassis wiring diagram or schematic to determine which devices are wired to that battery. At the house fuse panel, remove each fuse, one at a time. If the measured current drops after removing a fuse, you’ll know that’s the fuse protecting the problematic circuit.
Be sure to check each load in every circuit in case more than one load is causing the battery drain. After you rectify that circuit, the measured drain on the meter should fall to within the acceptable standard of less than 100 milliamperes (mA), or one-tenth of one amp.
A few parasitic drains on both battery systems are normal, but if the current draw is greater than 100 mA, the system likely needs to be investigated more. Devices that contain a memory function may be drawing too much current, so it might be necessary to install a switch or relay to disengage such devices totally.
A few components may be tied to both the house and the chassis battery systems. A deeper look into the isolator or battery separator, emergency start switch, battery disconnect system, etc., might be in order. Also, negative (ground) connections somewhere along the way may be faulty. But if fuses are not blowing and breakers are not tripping, chances are some device simply has been left on. A commonly overlooked load is the propane leak detector. Some motorhome manufacturers wire that safety device to both battery systems.
It rarely happens, but sometimes a failed diode in the engine alternator can cause a drain on the battery system. If pulling all the fuses, one at a time, fails to identify the drain, a closer look at the alternator may be in order.
Toilet Tissue Talk
Dear RV Doctor:
I attended your excellent seminar on waste management at the FMCA Family Reunion in Pomona, California, and I kept the handout, which I occasionally refer others to. But I have not been able to find any information on a recommended type or brand of toilet paper to be used in our black water tanks. I have a Type A motorhome with a macerator toilet and a direct-draw toilet. In the water compartment I have an additional macerator that I use to evacuate the black- and gray-water tanks. Is there a particular brand of toilet paper that should be used in our systems to ensure proper dissolving? We have used various brands from accessory stores and now the rapidly dissolving type from Scott.
Alan Richardson, F386835
Brentwood, California
Even though I’m not a huge fan of macerators in general, I do recommend using one if it’s necessary to evacuate the holding tanks uphill. And if a coach comes equipped with one, that certainly isn’t a deal-breaker. I’m simply of the opinion that when a coach is properly equipped with today’s technology, there’s really no need for one unless extenuating circumstances prevail. The added maintenance requirements and the common problems associated with macerators have steered me clear, so far.
I am, however, a fan of macerator toilets. Normally I suggest simply using any type of single-ply toilet tissue as long as it’s biodegradable. But in the case of a macerator, it just might be wiser (and help reduce maintenance complications) to use the type recommended by the macerator manufacturer. If the system is cleaned regularly and the correct tissue is used, problems will be kept to a minimum.
As long as the Scott tissue is working, I’d stay with that until you see evidence of it causing a problem. However, if you prefer two-ply, success can be had with Valterra’s Softness toilet tissue. Adding Valterra’s Pure Power Blue tank additive also will help to break down tissue quickly. Don’t squeeze the Charmin, however! Thick, heavy tissue is not recommended for use in motorhomes!