6V upgrade - bad batteries or huge phantom drain?

[Phantom]

Lat fall I had the battery box heightened on our 2007 Bambi 19'. Installed a pair of 6v golf cart batteries. Crown brand. I've charged with a 3 stage 'smart charger' and by shore power for a day or two. When I disconnect the charger or shore power, the batteries reads over 13v. I realize there is a 'surface charge'. Next day, with nothing on at all. (except the propane & CO2 sensors, the batteries are already down to 12.35 (approx. 75%)! What's up with that!?
Makes NO difference if I put the trailer into 'storage mode'. via the switch inside the door. (As I understand it, the sensors are still active). I've even tried pulling the fuse for the CD player... as it keeps a 'memory' (phantom drain) for the presets and clock (which I don't care about). Seems like the batteries should stay 'full' (12.6v) for at least a few days? No? Is it possible the Crown batteries are just not 'up to snuff'? They have always acted this way. Less than a year old, maybe still under warranty. Perhaps I should have gone with Trojans for extra money?

[guy99]

You could disconnect the ground lead and try the test again. This would reveal if there is a load you're not aware of.

[bryanl]

Crown? AGM? can't tell off hand. for wet cells in particular but also for AGM's but not as severe on the self discharge rate:

Check the electrolyte levels to make sure the plates are covered before charging or doing anything else if it is a wet cell and not sealed.

Have you had the batteries on a maintenance charge while not being used? Nowadays this means something that uses a desulfation technique plus an ability to keep a full, but not top, charge on the battery bank.

Take the batteries out of circuit with nothing attached. Measure the voltage every few hours for a day or two. They should get down to about 6.3 to 6.4 volts and steady out. At a 2% per week internal discharge rate, you shouldn't see much of a drop for a month or so.

Put a load on the battery (like a headlight) for an hour or two, let the battery rest for an hour or two, then check the voltage. It should still be better than 12.3v for the bank or 6.2v per each. This test should discriminate between a weak battery and one with a bad cell.

Battery brand or voltage (or even type of lead acid) is not an issue in this matter. Storage maintenance over winter, potential for battery failure, and measurement technique are what need to be properly considered.

[mello mike]

Bryan brought up an excellent point about maintenance--make sure there's sufficient water in each cell, but not too much. Just enough to cover the plates.

I recently installed a Xantrex Link 1000 battery monitor and inverter controller. Not only does it display voltage but also amps being used among other things. Even with everything off, my Sovereign is still drawing .5 amps to the CO2 and propane leak detectors. The Link 1000 really takes the guesswork out of battery use.

You may want to install a switch to the power lead to your radio. I did that and it really reduces the phantom power drains on my batteries.

Measure the amp draw across your batteries. If it's zero or very small that isn't your problem, the problem lies with your batteries. You're right in that they should be holding a charge longer than they have.

[Mexray]

go down to your local auto parts store and get an inexpensive battery hydrometer...

check the hydro reading in each of the six battery cells - they should be fairly even...

charge your batter bank as usual - check with the hydro to see that all cells are 'fully charged' and even...

unhook the ground battery cable from your battery bank to isolate them from any load from the AS...

do your voltage test as you mentioned, the next day...also check with the hydro to see if all cells are still even and fully charged - if voltage is around 12.7 or higher, and hydro shows cells are still 'up' - you know your batteries are in good shape, and the problem lies with some parasitic load in the AS....

If hydro shows one or more cells noticeably lower that the others, you probably have a weak cell and battery is defective...you may have to wait more than a day for the weak cell the decline enough for you to detect it with the hydro - a 500 amp type load tester would detect the weak cell immediately...

I personally think you have some kind of 'load' from your AS, or the batteries aren't actually being fully charged - the hydro will tell you...

6 volt golf cart DC type batteries use heavy waffle type separators between plates and rarely suffer cell failure (unless many years old with advanced sulfating of plates) - leaving me to again think your 'young' batteries are probably NOT the problem...

Ray

[Phantom]

Thanks fellow streamers... Batteries have been well-maintained over the winter's five-month travels. (see my blog). Water level is up just over the plates. Tried to tell with my multimeter yesterday. Not sure exactly how to use it in this mode. Disconnected the neg cable. Tested for milliamp draw. Seemed to get a reading of .66 milli-amps. I will now test with the hydrometer. Thinking of putting a switch in the radio hot wire. Also, switching emergency monitors to 9v un-wired models. Anyone done this?

[RickDavis]

Don't overlook the fact that if there is any acid residue, and there usually is that it will cause leakage across the top of the batteries. Try wiping it down with a little water and baking soda. If it bubbles there is acid present. I suspect this is a result of gassing when charging.
My 6 volt golf cart batteries from sam's club are starting on year 7 so they are pretty reliable.
I can't give you any input on the voltage to expect when they have been sitting since we charge with solar and I would have to disconnect it. It is possible you do not have a problem.

[pmclemore]

Are you sure that water that is "just over the plates" is high enough? I've always filled batteries to the place just under the cap that indicates the battery is full.

Pat

[bryanl]

re: "go down to your local auto parts store and get an inexpensive battery hydrometer..." -- not a good plan in these modern times. With modern DVM's you can learn enough about your battery as with measuring specific gravity and you don't need to pull out your battery and you don't need the hazmat procedures. Both need similar measurement considerations but hydrometers can contaminate cells and splatter acid around, risks the DVM doesn't have.

re: "Are you sure that water that is "just over the plates" is high enough?" -- The recommendation is that the optimum water level is above the plates up to where the plastic starts. Minimum levels just keep the plates covered.

A half amp (5 watts) is about right for residual loads but that is why modern Airstreams have disconnect switches. If you have a proper maintenance charger doing its thing, that load, and the normal self discharge, are handled (as is the sulfation problem and the plate corrosion problem).

[bhbdvm]

I don't have anything to add than the others but I have personally used the Trojan 6Volt 105's in tandem form my camper. I keep them on a constant "Smart Battery Tender" that keeps them leveled off. I have gone 7 days easily with moderate consumption using lights and furnance fan. Before making the transition to 6volt i used the attached link which was VERY helpful in many ways concerning batteries both 12v and 6 v for campers. Hope this helps. The 12volt Side of Life (Part 1)

[mello mike]

Here are a couple pics. The first shows the Link 1000 and the bottom shows my recent Radio install with the lighted power switch.

[bryanl]

re: "I keep them on a constant "Smart Battery Tender" that keeps them leveled off." -- one of the things to look for is a desulfation capability. The Battery Tender (tm) is a float only last I checked while the Battery MINDer (tm) uses a desulfation technique first noted in Homepower magazine about ten years ago. The desulfation business is an important issue for batteries that spend a lot of time under storage maintenance.

There are some other ideas surfacing here that I think need a bit of skepticism. They fall into two classes. One is the 'old school' class like the float only maintenance. The other is the precision out of line with accuracy school where the fact that there are many factors like temperature, age, cycle to cycle variance, and use profile that can influence battery capacity by up to 20% each tends to be set aside.

I know that raising questions and trying to answer defenses can get into a rather unpleasant conversation so I'll just toss these out and, if you have an open mind and are looking for useful information, you can do your own research like I did. See Basic battery guidelines.
. Examples: 6v batteries have no advantages over 12v except perhaps a bit larger size. An electron counter like the Link 10 is fun but there are other easier ways to keep an eye on your batteries. Hydrometry was mentioned.

Lead acid battery technology is 150 years old or so and rather mature. Modern batteries are a bit different (but not that much) from your grandfather's batteries. It is the techniques to charge and maintain them that have improved significantly.

[Mexray]

According to most of we 'battery sales guys', you need at least 1/4 inch of fluid covering the battery plates as a MINIMUM...

It's hard to see when you look down into the vent openings - so if the fluid looks 'low', refill each cell with distilled water up to the 'bottom' of the tube-like structure of the vent opening - DO NOT fill up into the 'tube' to the top of the vent opening, or during normal charging, fluid will weep (like blow-by) onto the top of the battery and begin to corrode stuff around the battery...!

Another hint - if you have to charge a battery that's heavily discharged (dead?) - check to see that fluid is covering the plates (if not add just enough distilled water to cover the plates)...charge the battery fully - THEN top off the fluid as described above...if you refill completely BEFORE charging, the fluid will expand as the battery becomes charged and will overflow the vent openings making a big mess!

Ray