In was eager to get the new DC-DC converter installed so I left work a bit early and got to work so I could still drive the car to breakfast with my girlfriend tomorrow morning.
Here's the mostly final installation. The wiring is a bit messy because I had to cut all the tie-wraps off from the original setup. I just wanted to try this out for awhile before taking the time to clean it up. The DC-DC converter fits rather nicely in the old space.
Here's a closer view of the top of the Iota DLS-45 converter. This is the slightly older model (I guess the shop was clearing them out). The newer version is the M series and is even smaller and has no heatsink fins on the sides. This version had mounting tabs that fit well with the bolt holes from the original kit. The right tab hole lines up with the bolt in the upper right corner of the battery box. The left tab hole was very near the upper left bolt that held the old DC-DC on, so I just drilled a hole and used the original screw. I didn't want to hassle with the bottom two tabs, so I lined the whole back of the converter with Velcro and it isn't budging!
Okay, the first test drive with the new converter was very successful. I turned on all the lights, including the fog lights and drove around for about 20 minutes. The 12V voltmeter in the center console never dropped below 12 and stayed at 13 volts most of the time, even with the headlights on. The new converter is dead silent. There is no squealing or buzzing like the old one. One additional advantage is that the input is really a rectified 115V AC input that I can plug into the wall in case I need to recharge the 12V battery with an external source instead of the main pack. So far, I'm very happy and will report back in a week or so if there are any problems.
The next big problem I'm working on is improving the brakes. With the added weight of the batteries, the vehicle is very difficult to stop, especially on downhills at stoplights. One common way of improving the braking on the 914 is to upgrade to BMW 320i front brake calipers. The later model 914s ('73 and later) need to have the 320i calipers machined for proper spacing.
I purchased the pre-machined calipers above from the classified section over at 914world.com. I highly recommend joining 914world.com or 914club.com to ask all non-EV questions about the 914. People have been very helpful and supportive in figuring out all those quirky bugs in a 35 year old car. One of the more difficult parts to find were the steel brake lines. These lines are from Schucks Auto Supply part number PAE312. They need a "European" bubble flair end to fit the calipers. Most auto parts stores carry these; however, the difficulty was in picking the correct ones since most places are not familiar with the 914 brake upgrade. I'll probably call Alan at A&P to get these installed in two weeks or so when I have a free Friday.