SLA "Battery Warmers"?

[TylerDurden]

And this idea applies to other batteries too... seems that even the lithium batteries need preheating in order to get maximum performance...

It's still chemistry, duh?

Think about a supercapacitor: "No heat - less filling."

 

[safe]

And this idea applies to other batteries too... seems that even the lithium batteries need preheating in order to get maximum performance...

It's still chemistry, duh?

Think about a supercapacitor: "No heat - less filling."

I'd love it when the Supercapacitor gets developed enough to compete. Right now the Supercapacitors are running 10 times heavier than the battery, so they aren't usable yet.

How many people are preheating their batteries now?

My guess is next to no one and for SLA this can amount to a difference that is as high as 30% in performance... so it's a big area of improvement that other than Nissan Motor Company seems to be overlooked.

 

[magudaman]

Safe I think it is time to get away from lead, look at all these disadvantages and look at the advantages of the competing chemistries. As much time and money is spent on trying to get lead to perform for its 300 cycles of life could be spent on getting a nice a123 pack up and running.

 

[safe]

Safe I think it is time to get away from lead...

I've got other machines being built in my bike creation pipeline that will use other chemistries. However, my current machine has already gotten to 3000 miles which translates to 300 cycles and I expect to get another year or two out of them. (they show no signs of premature deterioration) It's DEPTH of discharge that kills the battery as well as time at low charge. I do my 10 mile ride which drains me to about 50% and then I stop and recharge. After two to three hours I get another ride. It's possible to go for three 30 minute rides per day. And don't forget that having oversized batteries means you don't fall below your controllers current limit so soon. It's the small size selection of SLA batteries that gets people into trouble.

But this issue of preheating is NOT just about SLA.

In fact, the people at Nissan Motor Company got the patent for a hybrid that uses Lithium as there chemistry. So preheating is something that might apply just about everywhere.

 

[safe]

Cold Starting

I noticed today that at first my batteries were cold. At first there was very little power with the bike. But over time it "seemed" like the batteries might be warming from the inside as the current flows through them. Eventually, in the middle of the ride, I actually got the most power. Then towards the end the actual energy was getting used up and the drained battery started to fall off.

Can other people comment on there similiar experiences...

At first the battery is like cold syrup, but as the syrup warms it begins to work better until the battery runs out of it's syrup. The metaphor might not be great, but you get the idea. It SEEMS like the battery has to first heat up itself before it can release it's energy. If you preheat the motor then you can get ALL the energy out of it. If the battery is already warm then the battery doesn't need to do work to warm it. Warming the motor takes energy... this is why you don't get as much out of the battery because it has to go through this preliminary step of heating to get the energy out.

Make sense?

So preheating should be a mandatory process if performance matters...

 

[TylerDurden]

People in very cold climates preheat batteries before cranking their engines. For the past fifty years or so.

They also eat syrup.

They make it a point to not confuse the two chemistries.

 

[safe]

People in very cold climates preheat batteries before cranking their engines. For the past fifty years or so.

The only question that remains is:

Heat the battery by external heating source.

Heat the battery by internal resistance.

The advantage of the internal is that you need nothing but a circuit, but the disadvantage is that there is a patent that Nissan Motor Company owns. (so it could never be made into a product legally)

 

[D-Man]

I've already noticed a loss in torque just this morning. Driving on the new smaller tires early in the morning. It wouldn't accelerate to well and I thought maybe a brake was dragging. Brakes ok so I blame it on the cooler weather affecting the sla's. It happened last year. Temps in the low 50's. I only have 2100 miles on the sla's. It couldn't be that.

 

[safe]

I've already noticed a loss in torque just this morning. Driving on the new smaller tires early in the morning. It wouldn't accelerate to well and I thought maybe a brake was dragging. Brakes ok so I blame it on the cooler weather affecting the sla's. It happened last year. Temps in the low 50's. I only have 2100 miles on the sla's. It couldn't be that.

The charts don't really even tell the full story I think because they tend to portray a constant low load (like 0.25C) and how temperature effects that. The higher the "C" factor the more having thick syrup for a battery is a problem. I do find that after a while the battery heats itself as it fights it's own sludge.

Manual battery warmers could do the job, but building a special circuit to do it would be ideal. The big problem is that a big corporation like Nissan Motor Company owns the patent so if you tried to build this as a product you will get pounded by some big time lawyers and they will break you.

So we are left with home grown solutions...

 

[safe]

This sort of thing might be a good buy.

http://www.sitincomfort.com/kisielhepadt.html

Winter is coming anyway, so I could use it to warm myself (the warming pad, though the girl would be nice too :wink: ) and I could also wrap the batteries and preheat them before I ride. By the time my usual half hour is up the batteries will have cooled off, but by then it doesn't matter.

This is a very low tech solution, but it might be the easiest.

My garage is already getting down to the 50 degree range and in a few weeks it will be in the 40's... my bike runs at about 15+% less power than the summer levels.

$33.95

 

[fechter]

That's pretty close. You do need to worry about vibration causing a failure in the heating wires. It would be safer to remove the heater when riding. They do make an industrial rubber mat type heater that is rugged enough to stay on the bike.

The girl would work better. Just stay home to keep warm.

 

[TylerDurden]

Just park your bike inside. The pad would need to be on the batts constantly to keep 'em warm, otherwise, it would take many hours to warm your batteries.

 

[Eric G]

Safe maybe you could heat the area in the garage where the bike is.One of those ceramic space heaters beside or under the bike leaving enough room inbetween so nothing burns/melts.

I use one of these heaters in a small room and it works really well and it doesn't add much to the electric bill at all.

Eric

 

[safe]

Just park your bike inside. The pad would need to be on the batts constantly to keep 'em warm, otherwise, it would take many hours to warm your batteries.

My bike is kind of heavy to be lifting through the door all the time and there are steps and a screen door to make it even more awkward. My garage is very large (2x2 shaped 4 car garage) and so heating all of it is impossible. Using a fan might help a little, but most would be wasted. The direct pad approach would get the heat right where you need it. I would guess that a heating pad working for an hour while the charger is used to do a float charge (thus topping it off) would do it.

By the time it's icy outside I really don't want to ride anyway...

Next time I go to Walmart I'll look at what they have. Ideally I need one that is like the one shown and is 24" long because that's the length of my batteries on the bike. All I'd have to do is wrap the pad underneath and maybe place some sort of velcro strap to keep it on. Just before the ride I undo the velcro and then ride.

It would be sort of like this:

 

[Eric G]

Placement of the pad underneath the batts would be perfect as heat rises.

I'm lucky as I'm able to haul up my batts up the stairs to my living area and charge them there ~72F. Not perfect but it'll do

Eric

 

[safe]

I'm lucky as I'm able to haul up my batts up the stairs to my living area and charge them there ~72F. Not perfect but it'll do

In the summer my batteries stay in the garage where it seldom drops below 90 degrees. The power I get out of the batteries is excellent. Today, before I rode, the garage temperature was about 55 degrees and it warmed up later in the day to about 70 degrees. If I could preheat the batteries to 85 - 90 degrees (which is what I'd expect a heating pad to do) then my ride would be very near what a summer ride would be like. (without all the sweating! :lol: )

The only way to know is to buy a heating pad. I'd like to actually hold it in my hand and look it over rather than buy over the internet, but if I can't see anything that I'm happy with at Walmart then I'll do the online thing. The main thing is to have it be long enough (24") to cover all three of the batteries. Most of the pads out there are about a foot by a foot in size, so I'd need two of them to get the job done.

You can see how wrapping the pad underneath (as you said) would warm pretty well, the only thing that is even slightly in the way are the footpegs and they're close to the back.

 

[TylerDurden]

temp rise of 25F, 90lbs of batteries, 3.4btu/watt...

...how many heating pads were you planning on purchasing?


:lol:

 

[safe]

temp rise of 25F, 90lbs of batteries, 3.4btu/watt...

...how many heating pads were you planning on purchasing?

Just one if it's long enough.

It might also be a good idea to wrap a blanket around the warming pad and bike to keep what heat you get from escaping.

It doesn't need to be perfect, but if it can raise the temperature by even 10 degrees that translates to 2-3 mph more speed in every gear or alternatively the ability to climb a steeper hill.

I'm finding that the battery ends up warming anyway because when it tries to push through the "sludge" it warms the battery as it goes, so the electrical internal warming action is very real. But using your own battery as a heater is wasting the energy. (increasing the Peukert's Effect) The warmer the battery is the less internal resistance, so pre-warming is a great idea.

The BEST idea would be that one that Nissan Motor Corp patented that warms the battery from the inside using AC electricity...

 

[TylerDurden]

For some reason ho-medics dont sell heating pads anymore:

 

[Eric G]

Test the pad first Safe.I once had a heating pad and burned my leg with it.
I only have partial feeling in my legs (due to being born with Spina Bifida,a spinal cord disease).My ankle was swollen due to a fall a sprain most likely and I wrapped a heating pad around it and put it on high.Sometime later when I removed the heating pad it was all beet red seems I had 1st degree burns. (the degree that's opposite of the worst).It eventually healed up in a week or so.Turns out you were to wrap the body part first with a towel then apply the pad,I only happened to read the instructions after the fact

Eric

 

[safe]

I bought a warming pad that is 12" x 24" (which is just the right size) for $20 at Walmart. I tried it and it does help, but I'm going to need to find some sort of wrapping to help what heat gets created contained near the batteries.

It's not very powerful...

It's the maximum heat allowed by the laws that apply to warming pads, so this is the limit of this technological approach.

 

[TylerDurden]

 

[safe]

It's Works!

Using a warming pad, a plastic tarp and an electric heater with fan I'm able to heat my big batteries up enough so that they work pretty close to my summertime levels. It's a huge difference and it makes the bike worth riding again. Since I usually keep my house at about 65 degrees indoors during the winter to cut down on heating costs the act of placing the bike indoors isn't enough to achieve the summertime like performance, so I'll keep the bike in the garage.

I'd advise using just a heating fan... those small little ones that you heat a room with... and just a tarp. Just be sure that the heater is underneath the tarp and not touching anything directly. The heating pad is good and it's probably the safest thing to be using, but to really get the batteries hot you need that extra 125+ degree heat that the heater produces. What has worked for me is to run the heating pad during the morning to raise the base heat level up to about 70 degrees and then half an hour before riding I add the heater into the mix to raise it a little more. (I'm thinking I'm lucky if I'm getting to even 80 degrees)

After about 15 minutes riding all the heat is gone and the batteries revert to their poor cold weather performance... so unless you can figure out a way to keep the batteries warm this solution is pretty limited.

I'd guess in 40 degree weather the batteries would cool off in about five to ten minutes on the road after a whole morning of heating them up.

But for now when it's 32 degrees in the morning and 60 degrees for a high of the day so you do get an extra ride in that you otherwise would not get compared to the normal cold weather performance.

 

[Eric G]

Interesting,using both approaches space heater and warming/heating pad Safe.The emergency blanket that Tyler proposed would probably work better than the tarp,they're cheap too.

Getting cold out there had the motor going wide open and only attained 29kmh as opposed to 33kmh in summer. It's going to get a lot colder here when winter actually arrives.Bummer!

Eric

 

[fechter]

If you could insulate the batteries and had the heating pad inside the insulation, the batteries would stay warm much longer.