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 - -- http://www.fastmail.fm - A no graphics, no pop-ups email service _______________________________________________ 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)
