Hot Batts! [Edited]

Few people seem to realize that Lead Acid batteries of whatever construction have only half the capacity near freezing than they would have on a hot day. The various curves published by manufacturers would have you believe you only lose 20-30% of your capacity (and therefore range) as the temperature drops. Most of that is based on slow discharge information (C/20) rates. At high discharge rates (over 100Amps) things are somewhat different.
So, when it's cold out you either accept the much reduced range, Kill your batteries dead, or keep them warm. Fortunately the manufacturers know this and only sell cars with unheated, uninsulated battery boxes in southern Texas and some warmer sections of Hawaii.

This is the pair of battery heater pads and thermostat I picked up off Amazon. The pads are silicone material with embedded heating elements and are made by Kats. They are big enough for three batteries each. The Thermostat is by Lux and is designed to switch 1500W heaters so the pair of 80W pads should be no problem. It has an external temperature probe, but the wire is only 2in. long so I spliced it out to more like three feet (not shown in the photo)
I also got some foam insulating board and some of that silvered 'bubble-wrap' insulation. A short chat with Sean about the best way to get the battery lid off (a non-trivial task as the seats are attached to it) and I should be good to go for heating up next weekend.

[Edit] Installation process below...Two weeks later (So I'm slow...)
First ya just remove the seats and attached battery cover.

Easy as pie. Very complicated, exacting pie.
This is what it looks like with seats and battery cover removed.


The thick black wires are the high current cabling that goes to the controller and motor. The mid sized colored wires are the battery equalizer system and the thin wires go to the PakTrakr battery monitoring system.


Batteries removed and two layers of foam put down on the first half of the bottom. We had room for two layers on the bottom and the front and back (kinda wedged in due to the taper angle) but only one layer on the sides and middle. Hope it's enough.


The foam was notched out a bit to accommodate the cord attachments, although the weight of the battery would have probably pressed it into the foam without a problem.


Both heater pads are down and you can see the foam sections installed around the perimeter. Although you can't see them here there are also sections installed in the center.


This piece of foam covers the temperature probe to try and keep it at the same temperature as the battery itself. The wires run back up to the thermometer.

Now all we need is a nice cold night to try it out!
Just our luck. get the heaters in and what happens? Warm balmy spring.
Wait, this is Oregon. It'll change...