What kind of battery should I get for my plane? What about battery chargers? How can I learn more about selecting and maintaining batteries?
There is a very good write-up on aircraft batteries in the January 2004 issue of Aviation Consumer. They did a very thorough test of both Gill and Concorde batteries. To sum up, Concorde came out ahead on brand, and the sealed Absorbent Glass Mat (AGM) was the best battery type. These are not the same as the old gel cell batteries, and the sealed AGM is much superior to the wet cell type. This is especially true in cold weather. More info is pasted in below the following battery charger info. The same line of Concorde batteries has been expanded to include the XtraCranking line. The Concorde batteries have continued to outperform the Gill batteris in Aviation Consumer tests, and by a wide margin.
There is a new type of battery charger on the market, that can be found online for about $50. One source is Northern Tool Online. It is called the BatteryMINDer. It combines a fully automatic trickle charger with a pulse-charger, and is capable of both preventing sulphation and providing restoration. Note that all you need is the original $50 model, not the later larger and pricer versions.
If the battery has no shorted cells, and can be made to take even the slightest charge (for example, by hooking up a heavy charger in Boost mode and high voltage, 16V-17V), then the BatteryMinder can also be attached and set to “pulse”. You really have to watch things, because once it begins to desulfate, the charge rate from the heavy charger will climb. Once the battery is past the initial desulphation barrier, the BatteryMINDer can be used by itself. It can take months of regular use of the BatteryMINDer to completely reverse severe sulphation, but it will; and the battery can be in regular service during this time.
The charge rate from these small chargers is so low that they will not cause boiling or gassing. Their automatic control is so good that you can connect (short) the leads together and they just don’t turn on. They will not overcharge a battery. They will turn themselves on and off as needed, and will automatically stay in desulfate mode (a high-frequency ‘resonant tuned pulse’ that breaks down sulfation crystals) when not in charge mode. They can be used on many sizes of 12V batteries. The manufacturer is now offering more hyped-up models at higher prices, and perhaps they have more capabilities for specialized uses, but the $50 basic model works fine for both 6V and 12V batteries. They may no longer use the word “de-sulphation” in its description, and instead now call it a “conditioner”, so they can reserve the “de-sulphation” word for the more expensive model. But the basic model is still the same as it was, and it does provide de-sulfation.
I began using the BatteryMINDers about five years ago, and have not bought a 12V battery since then. I operate them on two lawn tractors, three farm tractors (two diesel, one gas), two boats, five automobiles, two airplanes, and a tugboat(!). Both lawn tractors are using batteries removed from the two airplanes, that were thought to be bad five years ago. Those two batteries (one Concorde, one Gill, both wet cell) are now nine years old. They still pass a new-battery load test. All the other batteries will also pass a new battery load test. When I last replaced my personal aircraft battery (to install a sealed AGM Concorde), it was six years old; still passes a new battery load test. Also keep in mind that if your battery is kept topped off with a BatteryMINDer, your alternator service life will easily reach 1,000 hours or more; and the regulator will also last a long time. They simply never get heavily loaded; just a few minutes of ‘top-off charging’ following an engine start.
In the absence of mechanical damage or internal shorts, if sulphation is controlled or reversed, there is no apparent life limit on good quality batteries. My long-term past experience has been that common automobile batteries will probably fail from internal shorts. However, the shorts are usually caused by material that has flaked off the plates. It is possible that preventing sulphation can reduce the material loss that causes the shorts; I will know eventually. Regular load testing is naturally needed to verify ongoing capability, and should be a part of any aircraft’s Annual Inspection. While it will be “nice” being able to have batteries last longer, the greatest benefit has been having batteries that always work when needed, no matter how long they have been sitting up. With the BatteryMINDer hooked up, a battery also will not freeze (unless you live in really cold country!). I used a lot of other “trickle chargers” in the past, but they all had faults. Most weren’t automatic enough; and either let sulphation occur, or they boiled out water over time. None were capable of reversing existing sulphation (which is a long, slow, process).
Special note: Any kind of higher-amperage charge requires that the battery be removed from the plane before charging. This is due to several reasons, ranging from hydrogen gassing, the risk of acid spatter, and the remote possibility of a battery fire or explosion. Having said this, if you have ready access to your battery connections, such as through a ground power outlet, I personally consider there to be no risk associated with leaving a BatteryMINDer attached. It turns itself on and off, and the charge rate is much too low to generate gassing. Particularly if the battery is the AGM type, it can’t generate any acid spatter. The charger sits outside the plane, so it can’t hurt anything. I have had these BatteryMINDers attached to many different sizes and types of batteries for many years now (since they first came to market), and have never encountered any adverse side effects from long-term connection during storage periods. In fact, they spend that time performing the slow but sure reversal of any existing sulphation.
You can learn a lot from these links:
BatteryMINDer source (one of many):
Aviation Consumer Battery Test Conclusions:
First, AGM Batteries look attractive if one is made for your particular aircraft—and most popular 12-volt and some 24-volt models are indeed covered. Handle ergonomics notwithstanding, Concorde is the best power choice, in our opinion, although you won’t necessarily find them at every FBO as you will the long established Gills.
That said, the Concordes in this test group weigh from .5 to 5.5 pounds more than the Gills depending on which model you select. But for the slight extra weight, you get three times the model choices in this popular size. Concorde batteries have a denser makeup and more active material to get the extra capacity.
AGM batteries perform better than the wet cells on most counts and are maintenance free—no water adding, no painting battery boxes, no corrosion to repair from acid mists. Further, AGM batteries can’t spill electrolyte and can be mounted at any angle.
The price difference between conventional flooded cell and AGM technology is minor and in aviation, surprisingly, this is one of the few product areas where we’ve found such price parity. Aviation AGMs are actually a bargain. The AGM battery commands a significant premium in the marine or auto markets, for example.
Another big plus for AGM batteries is that they self-discharge at about one-third the rate of wet cells. Your airplane can sit for three months and will still start… not that we would recommend that type of abuse. An AGM will also turn the engine over with more vigor and crank longer than a wet cell will. The Concorde Platinum Edition CB35A extra capacity model has one amp greater emergency capacity than the AGM extra capacity version.
For cold weather, the time when you will least want to fool with battery maintenance, the AGM is a must-have, in our opinion. The voltage level tends to hold up longer than a wet cell, which drops sharply as capacity drops due to higher internal resistance in the wet cell.