I get more range in the afternoon than the morning

For those of us who don't know(me) what kind of batteries are you using?

Hey Dave. I have experienced the same with my Honda. It is 42-46 degrees in the morning here, and 65-70 in the afternoon. I loose 5 miles of range when it is cold. In the afternoon, my range comes right back. I also noticed that the pack voltage recovers better after a short ride. If I ride to the store, when I arrive the pack might be at 82%, I come out after a few minutes, and the pack has recovered to 95%. (not plugged in). I think if you exersize the battery and let it sit, it warms up and some more of the stored capacity is available. My batteries are 75AH AMG SLA's

The chemical reaction is faster when it's warm out. I know this applies to all lead acid type batteries and I also think I read that shortens their life. I do not know if this applies to nimh li-ion li-po etc. as I think they don't have a liquid that changes viscosity with temperature. In lead types this phenomenon has similarities with "surface charge".

Hi David,

I too experience this on my emax, there are a couple of reasons for this:
1) as has been previously said, warm batteries just off charge have far more capacity than cold batteries charged, and put on float since the night before.
2) warmer air has a lower density, so the wind resistance decreases. on your setup you encounter it as reduced cruising power required. on my setup, i encounter it as an increase in top speed aswell.

Matt

When I was working as a A&P Aircraft mechanic I helped prep some turbo prop
Aircraft for Alaska. We put electric heaters under the instrument panel, one
in each Engine nacelle and a electric heating pad under each of the two 28V
Ni-Cad batteries. Batteries loose charge when cold.

How are you recharging the batteries at home? All at once in the evening?
How about splitting the charge using a timer and do a partial charge at night
with a finish up charge just before your commute. That would warm up the
batteries just before you need them.

Maybe it's because the air pressure in the tires is lower in the morning than in the afternoon.
In the afternoon when it heats up, the air in the tires expands thus lowering the rolling resistance of the tire.
Or maybe it's just because you have more climbs on the way to work than on the way back ...

I noticed this a well with my bike. 72v 35 ah AGMS. We had our first couple of cooler days this week. This morning was about 50 degrees, the bikes power felt soft and I was only able to hit 46 mph down my road when I normally hit 50. Also, my LVC kicked in under acceleration at 12 miles, where as it normally does 18-20 miles. I could still do 45 mph but had to ease my starts. I've noticed that it feels the strongest when I leave work, warmer temp and right off charger.

How much should the cold affect LiFePO batteries?

My EVD was giving me what appears to be a low-voltage warning this morning when I tried to go full throttle: the voltmeter dropped a little lower than I've seen it before, and the status light was flashing. This is my first morning commute when the temp has been near the 50 mark, so it's at least 5 degrees cooler than I've ridden before.

I'm perfectly willing to ride my gas scooter to work with temps into the mid-20s: I've got nicely insulated motorcycle clothing. Living in GA, that means I can ride all winter. But are my batteries going to be able to handle that?

If LiFePO doesn't lose much capacity as it gets colder, then I may have a bad battery, which is going to be even more annoying to find and replace.

The colder morning temperatures will affect your batteries performance. Some say 40 to 60% reduced performance depending on how cold it is. In electric RC we tried to keep our 123 and LiPo packs in the 75 to 90 degree F operating range for best results. Some kept their packs in insulated coolers filled with warm sand, or stored them in a warm car with the heater running. Others would warm the packs in an oven or warming tray to 100 degrees F.

Here are a few solutions that may help:

Run the charger just before you leave for work to heat up the batteries.

Keep the scoot inside the warm house. (no worry of dripping oil on the floor)

Buy some plug in AC battery heater pads or mats, put the heaters in the bottom of your battery tray reinstall the batteries, run the heater pads thru a timer so the pack will be nice and toasty when you leave for work. They even sell these heater wraps for automotive batteries.

Insulate the battery pack or battery compartment so the pack will retain the heat longer.

Gordon

Thanks Gordon.

I just finished my afternoon commute, and I was still seeing the low voltage warning when at full throttle. Temps are now around 66F, and I've ridden in those temps before without an issue. I'm leaning towards the bad cell diagnosis now, but I may see how it runs after an early-morning recharge via timer. (Getting the body apart to do a voltage check on each cell is quite a bit of work.)

The bike sits in a carport, so it will get cold overnight, but I might be able to figure out a way to warm it up, if that's what it needs. I'd hate to have to use extra electricity producing heat to pre-warm the battery pack, that would seem counter-productive to my overall goals here.

At least some electricity to warm the batts will not cause local pollution like an ICE engine would. Depends on your local source of power of course, but even coal electicity is said to pollute less than electricity.

For those who may not know it, even Lifepo4 gets more sluggish in the cold. Not so much lower voltage, but shorter range for sure. One old EV trick is timing your charging, so when you ride in the cold morning, your batteries are warm from the charge. This works with lead acid, but I don't think my lifepo4 gets noticably warm charging. If you use a hot pad to warm your batts, they use very small ammounts of power. All you need is a timer to turn it on about 2 hours before you ride, so you leave the house toasty, and some insulation so you don't blow the heat away in the first block.