But how much current would it deliver then?i put a 18650 cell in a freezer for 24hrs and how much do you think it lost.
it went in at 4.2v and came out 24hrs later at 4.19v.
so not much lost there
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Are battery covers worth it?
- Thread starter Gaz
- Start date
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But they didn't just have sensible mudguards back then, they also rode at sensible speeds so their brakes were fine.I think we've improved a little with the brakes!
Dave.
Unlike today's Bradley Wiggins wannabees who race around needing hydraulic disc brakes.
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Mmmmm. Well you're in luck, plenty of new freezers on offer in the sales at the moment.
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The voltage did not drop at all of course, but if you attempt to draw current from it you will findi put a 18650 cell in a freezer for 24hrs and how much do you think it lost.
it went in at 4.2v and came out 24hrs later at 4.19v.
so not much lost there
1 the voltage will droop significanly indicating that the internal resistance has dramatically increased. .. use a 1 ohm load and you would hope to get 4 amps, f you get 2 I would be surprised.
2 the total time that the cell will produce current will drop
The best way to do that experiment is to charge two cells leave both for 24 hrs , one at room temperature the other in the freezer and compare.
The bottom left graph shows it all. The energy available from the cell is the integration of voltage x AmpHrs ... The area under the curve in each case.
i have a sky rc charger and did a discharge test on both cells and both had near the same capacity and done it at 1 amp.
there was no difference between the 2 1 at room temp and other out of the freezer.
to damage these cells with cold you will need -20 my freezer dont go that low it even says it in the chart above.
there was no difference between the 2 1 at room temp and other out of the freezer.
to damage these cells with cold you will need -20 my freezer dont go that low it even says it in the chart above.
How did you keep the battery at -18°C during your test? Panasonic seem to agree with us...
We aren't talking about damage but about the lower quantity of energy available at say -10°C. With wind chill factor and an aluminium bottle battery there is a significant loss - from last winters experience about 20% less range.
It's not about damaging them . As you can see the spec sheet did specify that they were operational below -20 , it is that the energy recoverable at low temperature s is less. What model of skyrc do you have and what rate of discharge can it handle. I note that some models can measure the output resistance of the cell on connection.
That would be informative!. A full discharge test as shown in the Panasonic graph is not feasible as the cold cell will warm up over the 2 hrs taken for the test.
i just took it out the freezer and tested it in room temp and it never stayed very cold for long tbh.
tho i have no idea if sustained cold temps will do any damage to them as it was just in the freezer overnight and i have no way to discharge them in the freezer lol.
tho i have no idea if sustained cold temps will do any damage to them as it was just in the freezer overnight and i have no way to discharge them in the freezer lol.
I believe you can see the cell warming at the beginning of the curve where the voltage increases from below 3 to just under 3.5 V
I've had same problem with my Steps battery, it is not temperature related but faulty battery pack. First battery went from 25% to 8%, warranty replacement does it at 15%. My theory is it is poorly balanced battery cells, one cell goes flat is 3v-1v, this 2v drop is enough to bring whole pack to 8% mark. I'm hoping they've built protection into pack otherwise using assist below 8% will reverse charge the flat cell.I went out today for my longest ride so far on my Coniston - 24 miles non stop.
I started off with the battery at 60% and by the time I got home it was at 5%. There was a noticeable and sudden drop between 18% and 8%. It was 6C outside and damp/misty.
I appreciate temperature will affect the battery, and see I can get a neoprene cover for it. Which I was thinking about...... until I just watched a vid on another thread which shows three german chaps cycling on snowy ground, with no battery covers
So, battery covers, worth it, or are they snake oil?
Gaz
I suggest you ask for replacement under warranty. When you test replacement make sure it is fully charged is charger light goes off. Pick location that will allow you to get back to car/home without assist when you hit 8% mark.
Let us know % where replacement battery goes to 8%.
Bosch say they individually test there cells before building battery pack, so cells are evenly match. With no % display it is hard to tell but range estimate seem right when ran my CX pack to 1km left.
Thanks Trevor, but I'm the second owner so the bike's no longer under a warranty. It didn't seem troubled when it got down to 8% though and still ticked away at what I'd consider a normal rate. It's been mentioned before by d8veh, but it could also be that last steep incline after a long ride that caused the sudden drop.
Gaz
Gaz
I live in Colorado and a good portion of my riding takes place in sub-freezing temperatures. Based on my entirely non-scientific observations, cold weather doesn't seem to impact battery life/usage.
I checked the outer case temperature after tonight's very muddy wet night ride of 11 miles, and ridden in tour mode. The ambient temperature was 2°C and the battery outer case temperature was 6°C
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