THE SPECIAL HIGH-TECH BATTERY IN OUR AIRCRAFT:
The batteries in our aircraft are made by Enersys here in the U.S. These batteries are sold under the "PowerSafe" brand-name and with model designation "Powersafe SBS8", or under the "Odyssey" brand name as model "PC310." Same battery. These are 12v 8 amp hr batteries, AGM (Absorbed Glass Mat) type, and they weigh about 5.9 lbs. They are very high-tech batteries that are small and lightweight -- yet they can deliver a very strong amperage for engine starting.
WHY DO YOU NEED TO "MAINTAIN" YOUR BATTERY?
It is essential to maintain a good charge in your battery, to protect the battery health and life. All rechargeable batteries have a fairly high "static discharge" rate. This is why if you leave your truck or car sitting someplace for a month or two without running, the battery can be down or dead (and even require replacement). This is the same situation with our our light aircraft -- and our Enersys high-tech batteries are especially expensive! (usually about $160.00)
So, to prevent your battery from going down or dead and perhaps require replacement when you aren't going to be flying your plane for awhile you should use a "battery charger/maintainer".
WHAT SORT OF CHARGER/MAINTAINER SHOULD BE USED?
Many people use the typical small battery chargers that can be found at low cost everywhere from Wal-Mart to Sears. For the short-term or in a pinch, these can be better than nothing, but they are normally designed for regular lead-acid batteries, and these chargers may put out a slightly different "charging" voltage and a slightly different "trickle" voltage than is best for our special AGM batteries.
The Enersys company has specific recommendations for the battery charger/maintainers that are appropriate for their AGM batteries. Overall, probably the best for our purposes is a battery charger with a 2-amp max output and made for AGM batteries, the Battery Minder Model 2012-AGM is about $90.00 (2018 prices) as shown on an Amazon web page at... Battery Minder Model 2012-AGM
For a more sophisticated charger/maintainer that has higher output and also can be used on typical lead-acid and other batteries, there is available the Model 12248 charger (which costs about $150.00 in 2018 prices)...
Battery Minder model #12248 charger/maintainer/desulphater
These battery charger/maintainers are specially designed to work properly with AGM batteries and it will properly and fully charge-up your battery, it will maintain it at a full charge, and it even has a special design that will "desulphate" your battery -- which can restore it to full capacity (or repair damage to battery cells that have not been properly maintained).
The Battery Mindel model #12248 is available from suppliers including Amazon.com, Northern Tool, and many others.
These $90.00 or $150.00 "battery chargers" may seem ridiculously expensive when there are so many small battery charger/maintainers that can be bought for $20.00 or a little more. However, using these other chargers for extended periods could risk eventual damage to your battery, or at least reduced battery capacity and performance due to imperfect charging and maintenance -- and these low-cost battery chargers will NOT "desulphate" your expensive Enersys battery. Considering that new batteries cost perhaps $195.00, and considering that we need our small batteries to be kept in prime condition for reliable starting, spending $90.00 for the "optimum" battery charger/maintainer/desulphater may be worth it. This is more true for people living in the northern part of the U.S. (or Canada) where they may have to go months without flying, and "maintaining" a good charge in their battery is very important for battery life and capacity. For people who will be flying at least once a month or so, this is not much of a concern -- and for them, just a small cheap trickle charger might be good enough for occasional use.
In our planes, the battery is located under the right seat. This isn't readily accessible (without removing 11 Phillis-head screws and lifting the fiberglass seat base up a bit). It is more convenient to charge and maintain your battery by connecting the battery charger/maintainer through the cigarette lighter socket on the right side of the instrument panel. Many battery charger/maintainers offer a "cigarette lighter plug" as an option, and this is also something available from from the Battery Minder company. It is their...
Battery Minder model# VPP-12 cigarette lighter plug
The VPP-12 cigarette lighter plug is available from Northern Tool and should be available from most other suppliers that offer the Battery Minder model #12248 charger.
At our shop, we mostly use some very low-cost Black & Decker 12v trickle chargers (1-amp) that cost about $15.00 and include a cigarette lighter socket adapter. To just top-off a battery that might be a little low, these are just fine. As of July 2018, we see these available on Walmart.com at... B&D charger at Walmart.com
But remember -- we must not try to charge our high-tech small batteries at more than 2-amps. Trying to charge at higher amps can damage the battery (or the battery simply won't take the charge).
IF EVER NEEDED -- WHERE TO BUY A NEW BATTERY:
We don't stock the Enersys batteries because they are very infrequently needed by our aircraft owners (and so if we stocked them they would probably sit on the shelf a long time) and these batteries are readily available from a good number of suppliers in the U.S.
To find the best availability and pricing, just do a Google search for "Enersys Odyssey PC310" and/or "Enersys Powersafe SBS8" and see what you can find. If you need any help, please contact us.
July 2018 note: At this time, it seems that this company may have the best pricing on the Powersafe SBS8 batteries... www.osibatteries.com with a price of about $195.00 (plus usually about $16.00 UPS shipping cost).
FOR ADDITIONAL INFORMATION:
for more information about Enersys batteries... www.enersys.com
a great tutorial about batteries in general and with really good specific information about AGM batteries, please see the web page at... www.batterystuff.com/tutorial_battery.html
