On Wednesday, May 18, 2016 at 5:49:09 PM UTC-7, SF wrote:
Glad to hear the positive responses. As far as the questions regarding the K2's vs. less expensive batteries. I can't answer those questions except that small businessmen like soaring suppliers, operating in a small market, with small margins don't generally sell problem merchandise for very long. The alternate battery choices were not available to me when I was purchasing and evaluating.

The Lithium Iron Phosphate chemistry, gives you a lithium battery that will not supply it's own oxidizer in the case of a thermal event (fire), like the lithium ion batteries that are featured in laptop, hover board, and cell phone fire videos. Batteries that supply their own oxidizer are next to impossible to extinguish once they get going, so the battery chemistry choice is important.

That being said, these things contain a lot of energy. dump that out all at once, or treat them poorly, and bad things happen. So an internal battery management board (BMS) to prevent under and over charging is a really good idea. Most BMS boards also equalize the cells to improve charging and battery capacity. Some batteries can be purchased with and without them, so pay attention to what you are getting. The board should be internal so you can't look at a battery and see if it has a BMS board or not.

Buy a charger appropriate for your battery. Don't save money by attempting to re-purpose your old SLA battery charger.

The lithium Iron Phosphate batteries seem expensive unless you consider the life cycle cost. They are usually given a 2,000+ charge/discharge cycle lifetime. My limited experience with SLA batteries indicates that 200 cycles is about all they are good for.

Install an appropriately sized fuse (125% of the normal load is usually ok) as close to your battery terminals as possible. Then do a good job of protecting everything from the terminals to the fuse. My personal preference is to puddle hot melt glue over the terminals encasing them in a thick non conductive difficult to dislodge coating, and installing an automotive type blade fuse on the battery. Good insulated wire ( aircraft rated insulation, also a fire thing), and liberal use of heat shrink tubing can protect the rest. It's not pretty after I finish with it, but its not going to short out either.

I switched to Anderson PowerPole connectors after hearing the HAM radio guys rave about them. After you buy the crimper and watch a online video on how to use it, they are pretty slick connectors. I put hot melt glue in the open end of them to stress relieve the internal crimp connector when someone pulls on the wire instead of the connector.

12V isn't a lot to begin with, Use a wire at least one size larger than you think you need. The only penalty for larger wire is it's increased weight and size which is not usually much of a factor for the typical glider installation. Unless you don't put a fuse near you battery, in that case, your plan is to use the wire as a fuse, so use a small wire size in that instance.

If you don't know what you are doing around this kind of stuff, then get someone else that does to help. These things contain a lot of energy and they can dump it out in a hurry, so be careful. One of my electronic techs shorted out a lithium battery, and we had to evacuate a 200,000 Sq Ft manufacturing facility. No fire, but an impressive amount of foul smelling smoke. The firemen were impressed.

SF

I took the easy (but more expensive) way out by buying the Walter Dittel battery box and mounting plate when I upgraded my battery mount. When I got the glider it had a box that only came halfway up the sides of the battery, the connectors were simple spade lugs which had to be slid on to the batter terminals and there was a simple strap over the top to hold it in. There was also no fuse or breaker at the battery itself. The Dittel box can only hold a PS1270 size battery but if that's the size you're going to use it's pretty damn good overall. The DIN connector (The Germans love those things don't they?) is kind of Mickey Mouse but aside from that I can't think of anything that would improve it. Someone years ago in my club came up with the idea of gluing a plastic project box over top of the terminals of the club batteries which both protects the terminals and provides a mounting point for the connector socket and fuse or breaker. They also used 3 pin XLR connectors - unconventional but I have to say that they seem to work perfectly. Power Poles are fantastic connectors too.