Batteries and cold weather (brrrr)
- Thread starter Jed
- Start date
Yes, it can Jed, but it's the voltage drop you're most likely to notice. Batteries are chemical devices, and all chemical reactions depend upon heat for their efficiency. They're best at our mid year temperatures, and drop voltage as the temperature reduces. That said, it's the internal temperature of the cells that matters, not the outside air, so if you keep the battery indoors in a warm room and just have it in the bike for travel, there's not usually a problem. That's because the action of drawing current from the battery (which is a chemical reaction) generates heat which helps keep the cell internals warm.
Ideally then, bring the battery indoors at nights, and inside at work if you commute on cold days.
P.S. Nice to see someone using the word gotten in this context, perfect English, not just US practice as so many believe.
Ideally then, bring the battery indoors at nights, and inside at work if you commute on cold days.
P.S. Nice to see someone using the word gotten in this context, perfect English, not just US practice as so many believe.
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Hmmmm, my battery went dead half-way to work this morning, and I'm 99% sure I charged it all last night. I was pedalling a little less than usual, and I do stick it on full-power right from the start, but it's the first time I haven't made it to work. Hopefully this is a one-off experience, and not due to the cold weather or something like that. It's now charging under my desk at work, and afer 4.5 hours the charginh light is still orange, so it must've been empty.
The strange coincidence was that my MP3 player rechargeable battery went dead at almost the same time, and I had charged that one up yesterday too (at work this time, so it can't be blamed on a power-cut during the night). Maybe it's secret alien battery draining technology and they're using me as a tester!
The strange coincidence was that my MP3 player rechargeable battery went dead at almost the same time, and I had charged that one up yesterday too (at work this time, so it can't be blamed on a power-cut during the night). Maybe it's secret alien battery draining technology and they're using me as a tester!
Doesn't the outside temperature affect the battery at all, even if you are out riding in this cold weather for an hour or more? I am sure this week with the cold mornings and evenings that my battery performance does not seem as good as is was in the summer. I'm wondering whether to get something to wrap around the battery is an exercise in futility or not!
Yes it does Jed, perhaps my emphasis on voltage misled you, voltage drop still leads to reduced range and particularly performance drop. Remember, volts x amps = watts, and its watts our motors burn. In addition, as I've mentioned elsewhere, batteries are chemical devices and chemical reactions need heat for efficiency. As the temperature drops, the electrolyte becomes increasingly unwilling to give up it's charge, with zero degrees being really bad news.
If your run is fairly short the battery should keep enough heat internally to be ok, but after half an hour or so the cold like this morning's will get in and sap the performance. A cosy wrap around the battery will help to conserve the warmth in it, but unfortunately the frame arrangement will still probably mean plenty of points for the cold to get at it, so you might have limited success.
If your run is fairly short the battery should keep enough heat internally to be ok, but after half an hour or so the cold like this morning's will get in and sap the performance. A cosy wrap around the battery will help to conserve the warmth in it, but unfortunately the frame arrangement will still probably mean plenty of points for the cold to get at it, so you might have limited success.
Thought I'd add my experience from this frosty morning, as I took the Lafree out with the large trailer on my routine recycling and rubbish run. The nearly four year old battery had been indoors on trickle charge, but the bike is stored in the garage and was freezing. I spent 15 minutes picking up from three points, (I clear for 54 of my neighbour's properties since they have to go to work, poor things), then rode for just over 15 minutes (3 miles) to the council depot. Up there I was held up for quite a while by someone chatting, then 15 minutes cycling home, just over an hour in all. I had no problem with loss of battery performance, taking the easy option for the Lafree to do most of the work on the final stretch of 1 in 8 up to my home.
I'm wondering how useful it is to have this battery meter as mine seems to go all over the place and it can be confusing as sometimes you think you've got less power available than you really have.
If it could show green for the first 50%, yellow for the next 30% and then red for the final 20% then it would be more meaningful but just going straight to red when going up a hill isn't that helpful.
thanks
Jed
If it could show green for the first 50%, yellow for the next 30% and then red for the final 20% then it would be more meaningful but just going straight to red when going up a hill isn't that helpful.
thanks
Jed
I've answered in this vein elswhere, but as it crops up so often I'll repeat my answer here.
I wish manufacturers would do as the long established e-bike makers like Heinzman and Giant do, stick the meter where it can't be seen when riding so it doesn't worry people. You see, there is no way that a battery's content can truly be measured by a meter, the only measure we have for the content is watt/hours, so it can only be measured by using up the content over time. The meters we have just measure the small voltage drop as the battery content is used up, and that's roughly good enough a measure when the bike is standing still. Trouble is, when on the move and we open the throttle wide, the current drain into the motor also drops the voltage, so that's recorded on the meter as well, nothing to do with the battery content. The equivalent on a car is when we plug the starter with headlights on, the headlights dim due to the voltage drop the motor causes. Also, when the weather is cold, that drops the battery voltage as well.
The Li-ion batteries are nominally 37 volt, the NiMh are 36 volt. If I put the NiMh that I also have into the Torq fully charged, I can go onto the hill outside my home and get the red light on immediately, simply because it's started with a lower voltage point, nothing to do with what's in the battery. So my advice on that is, forget the meter when on the move, better still, put a strip of black PVC insulating tape over the LEDs, and just check the level when standing still. Find out your range, starting with an assumption of around 13 miles and gradually take a bit more until you find the cut out point near to home. Then reset the odometer at each charge and use distance to judge your remaining charge.
So all in all, you can see how pointless these meters really are on the handlebar, what you desire isn't possible since batteries are chemical devices, not electrical. To emphasize that point, older readers will remember the way charge was checked on lead acid batteries, drawing off electrolyte into a hydrometer to check it's specific gravity, i.e. chemical checking since electrical checking of charge contained isn't possible.
I wish manufacturers would do as the long established e-bike makers like Heinzman and Giant do, stick the meter where it can't be seen when riding so it doesn't worry people. You see, there is no way that a battery's content can truly be measured by a meter, the only measure we have for the content is watt/hours, so it can only be measured by using up the content over time. The meters we have just measure the small voltage drop as the battery content is used up, and that's roughly good enough a measure when the bike is standing still. Trouble is, when on the move and we open the throttle wide, the current drain into the motor also drops the voltage, so that's recorded on the meter as well, nothing to do with the battery content. The equivalent on a car is when we plug the starter with headlights on, the headlights dim due to the voltage drop the motor causes. Also, when the weather is cold, that drops the battery voltage as well.
The Li-ion batteries are nominally 37 volt, the NiMh are 36 volt. If I put the NiMh that I also have into the Torq fully charged, I can go onto the hill outside my home and get the red light on immediately, simply because it's started with a lower voltage point, nothing to do with what's in the battery. So my advice on that is, forget the meter when on the move, better still, put a strip of black PVC insulating tape over the LEDs, and just check the level when standing still. Find out your range, starting with an assumption of around 13 miles and gradually take a bit more until you find the cut out point near to home. Then reset the odometer at each charge and use distance to judge your remaining charge.
So all in all, you can see how pointless these meters really are on the handlebar, what you desire isn't possible since batteries are chemical devices, not electrical. To emphasize that point, older readers will remember the way charge was checked on lead acid batteries, drawing off electrolyte into a hydrometer to check it's specific gravity, i.e. chemical checking since electrical checking of charge contained isn't possible.
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I generally time my NiMh charge in order to have a warmer pack before starting!! Gets me the 8miles ish over hills to work fine. It will be interesting to see how my new charging point (outside) at work will affect return journey performance on the colder days. Last year I used foil backed foam to keep the chill out.
Andrew
Throttle Suede-e
2x 9Ah One old, one new.
Andrew
Throttle Suede-e
2x 9Ah One old, one new.
I charge my nimh batteries outside. So far i've noticed a rise in performance with this cold weather, this seems to fit with this faq http://data.energizer.com/PDFs/nickelmetalhydride_appman.pdf
Which says optimum temperature is 10 Celsius, with capicity reducing droping when either warmer or colder. Apparently its bad to charge them at freezing temperatures
Which says optimum temperature is 10 Celsius, with capicity reducing droping when either warmer or colder. Apparently its bad to charge them at freezing temperatures
You have me puzzled there Baboonking. Since that doesn't equate with published data on any battery, I checked the paper you've given the link to and it's graphs show peak voltage from 30 degrees C upwards, declining below that, exactly as I would expect. It also quotes capacity loss at lower temperatures, again as expected. Likewise it has 15 degrees C in a chart as the lower limit for charging.
The general rule on all batteries regardless of technology is that they are chemical devices, accordingly improving their reaction with temperature increase up to reasonable limits, generally about 40 to 60 degrees C. The downside of higher temperatures is a reduction in cell life expectancy.
The general rule on all batteries regardless of technology is that they are chemical devices, accordingly improving their reaction with temperature increase up to reasonable limits, generally about 40 to 60 degrees C. The downside of higher temperatures is a reduction in cell life expectancy.
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Hi all,
I've really noticed a drop in top speed performance since the weather has become colder this last month. With a little bit of headwind I could get 20mph on my bike when the weather was warmner. But since then I am lucky to get 17-18mph. I keep the battery charged and it stays indoors when not in use. Do nimh batteries perform any better?
thanks
Jed
I've really noticed a drop in top speed performance since the weather has become colder this last month. With a little bit of headwind I could get 20mph on my bike when the weather was warmner. But since then I am lucky to get 17-18mph. I keep the battery charged and it stays indoors when not in use. Do nimh batteries perform any better?
thanks
Jed
I'm not experiencing any speed drop on my bikes at present, but both the Li-ion (torq) and NiMh (Quando and Twist) are kept indoors. Most of my runs aren't too long and tend to be uphill leaving here with warm battery and therefore mostly down when I later return, so them getting cold wouldn't show up too much.
The cold does drop both voltage and capacity, but it's voltage that determines the speed, and a change can have a marked effect. In my Quando, the Li-ion battery with a nominal 1 volt more (37 volts) gave 18.5 mph in still air on my speed test stretch, a minutely downhill (0.6%) half mile. The NiMh with 36 volts did that run in the Quando immediately after in identical conditions at 17.4 mph. The difference isn't quite so marked on the Torq but that's probably due to the higher speed bringing air resistance into the equation, since it can reach over 24 mph on motor drive alone on that stretch. These were all Summer figures and the speedos have been calibrated over a 4.9 mile known distance, not just set to tyre diameter.
It could be that you're losing about 2 volts due to the cold gradually affecting the battery's efficiency.
The cold does drop both voltage and capacity, but it's voltage that determines the speed, and a change can have a marked effect. In my Quando, the Li-ion battery with a nominal 1 volt more (37 volts) gave 18.5 mph in still air on my speed test stretch, a minutely downhill (0.6%) half mile. The NiMh with 36 volts did that run in the Quando immediately after in identical conditions at 17.4 mph. The difference isn't quite so marked on the Torq but that's probably due to the higher speed bringing air resistance into the equation, since it can reach over 24 mph on motor drive alone on that stretch. These were all Summer figures and the speedos have been calibrated over a 4.9 mile known distance, not just set to tyre diameter.
It could be that you're losing about 2 volts due to the cold gradually affecting the battery's efficiency.
My first sub-zero electric bike experience
I have just been out for a run this evening to see how the batteries cope with the cold. It is about -1 C out there and very foggy. The result is that the cold weather gave my batteries a good kicking. I only managed just under 4 miles of constant use from my 6.8 Ah li-ion. In better weather I would get 7 miles absolute minimum if I rode the same way.
I brought the battery in the kitchen for an hour or two and gave it a top up charge before going out. It's about 15 C in the kitchen so the battery should have warmed up enough in that time. The battery pack (enclosed in a tough plastic cover) goes in a weather proof box on the rear rack and thus is double protected from the cold. The controller is in the same box and thus is giving off some heat (it was warm to the touch when the battery lost power).
Given all this I am quite surprised that they didn't last long. What can I do to get better cold weather performance from them? Did I charge them at too low a temperature and thus they weren't really fully charged? I have read somewhere that li-ions should be 21 C or so for charging. Is this the case?
I have just been out for a run this evening to see how the batteries cope with the cold. It is about -1 C out there and very foggy. The result is that the cold weather gave my batteries a good kicking. I only managed just under 4 miles of constant use from my 6.8 Ah li-ion. In better weather I would get 7 miles absolute minimum if I rode the same way.
I brought the battery in the kitchen for an hour or two and gave it a top up charge before going out. It's about 15 C in the kitchen so the battery should have warmed up enough in that time. The battery pack (enclosed in a tough plastic cover) goes in a weather proof box on the rear rack and thus is double protected from the cold. The controller is in the same box and thus is giving off some heat (it was warm to the touch when the battery lost power).
Given all this I am quite surprised that they didn't last long. What can I do to get better cold weather performance from them? Did I charge them at too low a temperature and thus they weren't really fully charged? I have read somewhere that li-ions should be 21 C or so for charging. Is this the case?
21 degrees C is an optimum charging figure for Li-ion, but not vital. I'm also getting troubles now the weather is really cold, despite my batteries and the bike being indoors, and the Li-ion capacity seems to be more affected than the NiMh that I also have.
This is probably due to the different chemistry, since they work in such totally different ways there's nothing at all in common other than storing a charge.
It is quite extreme at the moment though, and we don't get many periods of around zero degrees these days, so probably best to try and live with the shorter range for the few affected days. There's not much that can be done to offset the loss.
More global warming is what we need, lots more 747s and 6 litre 4 x 4s, that'll warm things up a bit.
This is probably due to the different chemistry, since they work in such totally different ways there's nothing at all in common other than storing a charge.
It is quite extreme at the moment though, and we don't get many periods of around zero degrees these days, so probably best to try and live with the shorter range for the few affected days. There's not much that can be done to offset the loss.
More global warming is what we need, lots more 747s and 6 litre 4 x 4s, that'll warm things up a bit.
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Good idea. Maybe I'll try the hand-warmer gel pack that my mum uses for playing golf in the cold. I could put one of those in the box and it should keep everything nice and warm. Not too warm though, I wouldn't want any explosions!
Hmm this is a concern to me. As a commuter, I need the battery to perform with stability and regularity. Maybe I can ask a relative to knit me a Battery Cosy
Me too. I went to town on the Quando (Li ion battery) and had to leave the bike outside for a couple of hours, when I made my way home it was much slower, I had to really push those pedals coming up home. Also I have noticed how the power goes quicker when you use the light, which i accidently manage to switch on on every trip!
Something else.. when I first got the Quando, my son had a go while i walked along side him and steered the handlebars.. he didnt like the noice when the motor kicked in, the handlebar switch was on zero, so took the key out... I wanted to ask apart from the switches on the handlebar is there another switch elsewhere? I say this as since then its not been the same, you dont hear the motor when in pedelec mode..
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