Increase SLA performance in winter!

I had a good idea today! Perhaps if you chucked two of those chemical hand warmers (with the little metal discs, that set off a chemical reaction causing heat from shock) while you performed a top up charge for a while before you go out for a ride( half an hour?) then when you go outside with the pack chuck another two in the battery bag to keep things nice and warm in there. Those things stay warm for about 45minutes, they're cheap and they're rechargeable and they get pretty hot. I think if you insulated the batteries seperately in the battery bag and then put the warmers between each battery it would increase performance nicely!

Even just keeping the batts inside, and then putting an insulated bag on em to ride should help. Pet stores have little heat pads that plug in for reptile cages that would be perfect to toast the batteries with if you can't bring em inside.

Best way to get warm is to pedal. Once it gets below 48F, I don't take the bike out very far or go fast as its just too cold.

I've seen a few guys that used battery heaters. I forget where they got them, but it looks like a flat sheet of rubber with wires coming out. Heat the batteries for a few hours before heading out. With a little insulation, those lead batteries will hold the heat long enough for a good ride. Some heat may be helpful during charging if the temperature is low. Don't exceed around 100F.

fechter said:

I've seen a few guys that used battery heaters. I forget where they got them, but it looks like a flat sheet of rubber with wires coming out. .

Click to expand...

Sounds like a waterbed heater pad

http://www.waterbeds-airbeds.com/digital-heater-pic.htm

I think i still have one in my lil staorage shed from my old waterbed i might have to have a hunt for it

Pretty much exactly like a waterbed heater, but smaller. Hot air balloons do a similar thing, to warm propane tanks to operating temp. For that we use regular heat pads from the pharmacy under the tank insulation jackets. The snake heaters come in sizes that are similar to battery packs for ebikes, so those came to mind first. A waterbed pad might burn out without the waterbed. I seem to remember some warnings about that on ones I had years ago. Maybe they get real hot? The snake heaters stay about 100 f i think.

I use my kit maybe once or twice a week in cold months (now living in eastern Pa.) Having previously biked thru Wisconsin winters,
and knowing how to dress for those temps, coming back home has been easy With a Crystalyte Sparrow from Electricrider,
I simply put my batteries in a Coleman six-pack cooler (good to around 20 degrees F.) or a leather gymbag with some one or
two-inch upholstery foam (just stuff lying around) between batts and outer skin (good to near zero) and find performance pretty
much on par with warmer days.
Pre-purchase, this had been a worry for me, having read some stuff from e-bikers in Carolina about scary drops in efficiency at 30
degrees. Just bundle the batts like you bundle y'self, and no probs...

I did the battery heating by blowing heat from a heater against the cells from underneath. The result was that the cells did in fact heat up and start to work like they would in summer... but the unevenness of the heating seemed to have caused one of the cells to die a little earlier than I might have liked.

The best way is to bring the bike indoors overnight and that gives plenty of time for the battery to get warm gradually. My guess is that rapid heating probably hurts the cells because the uneven warm and cold areas of the battery probably function at different rates causing uneven wear. I'm just guessing though.

It does produce more power... heating that is...

It's a good idea to use a battery heater designed for such uses. I've used the ones from KTA services with great results. The key to even heating is using a thin aluminum plate the size of the footprint of the batteries between them and the heater. With good even contact with the botom of the entire battery pack you get very even heating results. A thermostat is a must and a HVAC snap disc thermostat (with the right temp range) is small (coin size), reliable and inexpensive. I found some that turn on at 80 F and off at 104 F. Great for the winter!. Depending on battery size it can take 8 to 12 hours to warm them up. The good part about that is, that it takes more than half that long for them to cool down.

Aerowhatt

You guys reminded me of an assumption I shouldn't have made. I ALWAYS keep my batts indoors.
The other thing I meant to include - the batts work fine as I described above for ten-mile round trips,
with maybe twenty minutes, a half-hour in between five-mile legs. Didn't mean to over-promise here.