agm's and the warm weather

[pgt400]

Its really amazing how much effect the weather has on sla performance. This weekend is in the unseasonalble mid 80's in NJ. I'd been riding in 55-70 degree weather till now and thought my batteries were dying as range and top speed were way down....now they are right back were they were last August! When I first rode this spring on a low 50's day I could only get about 9-10 AH from the 35 ah agms' and the ride felt very soft, top speed was about 45. On a low 70's day last week I got about 17 AH... Yesterday my speed was back to 53 and I got 23 ah's....just like last summer. I noticed also that my afternoon ride felt even stronger then the morning ride fresh off the 5 amp chargers.

 

[needWheels]

Yup, lead is like that though I have nothing else to compare to yet.
My bicycle 48v SLA won't go above 21mph when it's below 60 outside.
Now that it's 10 degrees warmer I am back to 25mph top end.

 

[pgt400]

From what I hear Lifepo4 is no different.

 

[needWheels]

Really? From what I have read lifepo4 is almost immune to temperature vs performance.

 

[dogman dan]

On my bike, I lost about 15% of my range in the winter. That was with a ping v1. It wasn't much of a problem when I rode straight from the house, where the bike was in a cold garage. But if I put the bike on the bus for part of the ride on a really cold morning, the bike would barely run once the wind chill riding on the bus cooled the thing way down. So I would get a few lvc's untill the battery warmed up a half mile later, and then it would be fine for the rest of the ride. All winter there seemd to be a bit more voltage sag at all times, untill it got back above 50F. Above 50F I would get a bit more top speed climbing hills. I may just need to insulate the battery box better next winter. I am more set up to shed heat, since that is what I need most 9 months of the year.

It's not as bad as lead though, for sure, and nothing a bit of insulation, or keeping the battery in the house won't cure.

 

[dnmun]

or you can do what GM is doing for the volt. immerse the cells in fluid and heat the fluid to warm up the batteries!!!

guess where the energy for the resistance heater comes from!

i kid you not.

 

[Ypedal]

http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=8452&start=75

Try 18f with SLA !!! :wink:

 

[needWheels]

I guess lifepo4's weakness in temperature is the BMS.

You can pretty much abuse SLA in 90+ degree heat, I am guessing my BMS will have to be well vented.

 

[swbluto]

I guess lifepo4's weakness in temperature is the BMS.

You can pretty much abuse SLA in 90+ degree heat, I am guessing my BMS will have to be well vented.

Dude, the BMS should handle just fine. In general, the colder electronics run, the better. However, if ice is forming on the BMS, then it could be a problem. :lol: