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My approach isn't scientific, but my own common-sense attempt to
balance competing objectives, as William has identified. I
more-or-less address this in the current HP batteries article. To
me, insulating a battery box does little good in an otherwise cold
ambient environment. Batteries don't generate enough heat from the
charging process to overcome cold ambient (especially winter outdoor
in our cold climate) temperatures. I'd rather see the battery box
located in a tempered space. Indoors is good, but not necessary.
Indoors is unlikely to get and stay above about 75 degrees for long
enough (in our climate) to allow massive batteries to rise above
their stated ideal of 77F. But a separate tempered space - that is,
an insulated space that adheres to good basic passive solar
guidelines: glazing for warmth, overhangs for summer, mass (floor or
trombe wall) for storage - is nearly ideal. The batteries have their
own substantial thermal mass, so average seasonal ambient
temperatures of 50-75F are pretty close to ideal. With enough mass
in the larger space, the venting necessary to exhaust hydrogen
doesn't have much effect. I'll use a 12V Power Vent or two, each
controlled by an MX60/FM60/similar Vent Fan option on the auxiliary.
These combine a voltage-actuated switch function with hysteresis and
intermittent fan operation, so not much heat is lost. But hey, that's ideal, and means that I have some control of the entire building process. That's a rare and quite yummy occurrence. But it makes a great ideal to explain to the customer; then we do the best we can with what situation and budget will allow. Here we're more concerned about cold winter temperatures than summer overheating. I have historically taken the position that locating batteries indoors is a good thing, as long as the box is very carefully sealed and vented. I'm big on Zephyr Power Vents, especially because when correctly vertically mounted, they have a built-in backdraft damper, essential in an indoor space with a wood stove or similar. So far, in twenty years I haven't yet had an accident or close call that resulted from locating batteries indoors. Hope that this helps a bit, Allan Allan Sindelar On 12/11/2010 4:45 PM, William Miller wrote: Friends: |
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