Hi Bruce, I put my blanket *under* the pack - with a thin sheet of something suitable between battery bottoms and the blanket to avoid damage to the blanket wires - and controlled it with a digital household thermostat that I brought the (de-soldered) sensor out of on a twisted pair of wires and poked into the middle of the pack. I had it wired so that whenever the EV was plugged into the mains the blanket was 'live' and heat controlled according to the stat setting. No reason you couldn't use the pack to power it when not mains-connected - especially if the pack were around the 120V mark and you used a US spec blanket.
MW On 8 Jan 2014, at 19:23, Bruce EVangel Parmenter wrote: > Using an electric blanket to warm a PbSO4 wet cell pack before an EAA > rally race was an trick the EAA old timers would use back in the 1990's. > The evening before the rally, the driver would put the blanket over the > top of the pack. It was a manual process for them to find a good spot to > locate the thermal-mechanical temperature control so it had somewhat > even heat. Their goal was to heat the pack up to 110F but no higher, > else risk aging/damaging the pack (this seemed high to me, but these ol' > timers said they knew what they were doing). While none of them won a > rally race, most were pleased with the better pack performance. > > But how does that PbSO4 pack trick apply to Li-ion? > With our recent really odd-global climatic changing weather, in the > short term, that electric blanket trick is a quick fix. But it will take > some effort on the driver's part to manually monitor the pack > temperature (something that was a given back in the 1990's and before, > but I state now, because we have become spoiled with today > smart-devices/equipment that do everything for us - plug-n-forget). > > So, Martin's idea to keep your Li-ion pack warm by using an electric > blanket could work. But, I would set it up hours before hand, and > monitor it before you go to sleep at night. If you have charging at work > with power available for the blanket as well, once you knew how your set > up worked you could bring it with you, and keep your pack warm while > your EV is at work. > > > On Martin's mat warmer ... > I had paid to put battery plate warmers under my packs (1 in the rear, > and 2 in front). At best I only used them a couple of months out of the > year because the weather is much more temperate in the SF, CA Bay area. > But I had proved that using the battery plate warmers available at the > time from a Canadian Auto Parts source (who knows winter in N. America > better than Canadians, eh?), worked. > > My set up was a costly smart temperature control, that adjustable and > had temperature sensors on all the packs. I had to strike a balance of > the front packs being a little cooler than I would want, to keep the > larger rear pack from being over heated. I had one of the front grill AC > inlets set up on a power switch so I could warm the batteries off a > separate 5-20 outlet. The warmers drew close to 16A, so I had to use an > outlet with a good break to keep the breaker from tripping in the middle > of the night. (I am not recommending the following items or their > vendor, I post as an example) > > http://www.canadiantire.ca/en/pdp/automotive/batteries-boosters-chargers/chargers/temro-50w-battery-warmer-0113118p.html#.Us2iwvuVOho > 50 Watt battery heater > > http://www.canadiantire.ca/en/pdp/automotive/batteries-boosters-chargers/chargers/temro-80w-battery-warmer-0113116p.html#.Us2ixvuVOho > 80 Watt battery heater > > http://www.ebay.com/bhp/battery-heater > -various- > > > If I was to do another conversion, I would not have warmed each battery, > only the outside ring of batteries that were more exposed to the outside > temperatures. Because the batteries were so close to each other, if the > outside ring of batteries was warm, the inner batteries in a pack would > be warmed too. You design will be determined by how cold it gets where > you are, and how your pack is arranged. > > > {brucedp.150m.com} > > > > - > On Wed, Jan 8, 2014, at 01:33 AM, Martin WINLOW wrote: >> You could just use an electric blanket or, for a more definable solution, >> some underfloor heat mat. *Much* cheaper! >> >> http://www.toolstation.com/shop/Twin+Conductor+Underfloor+Heating+Mat/p84378 > - _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
