Lithium Battery charging.

[Vim Fuego]

Have solar panels and it makes sense to charge my ebike whilst the sun is out.

This might mean topping up from any capacity, very low or almost full.

Does it damage a Lithium battery (Bosch) doing such a thing?

Looking for facts please, as there are many old wives tales around battery charging and longevity.

Thanks.

 

[rich c]

First, you will be saving about 10-15 cents by partially charging with solar. You'll have to ask Bosch for hard facts about charging the battery. Facts are few and far between on the internet in general.

 

[Jeremy McCreary]

Many credible sources agree that you should keep your battery charge in the 20-80% or 30-80% range. My bike mechanic says that a day or two above or below is OK, but you should stick to that range for long-term storage.

That's what I'm doing.

 

[Skywagon]

Have solar panels and it makes sense to charge my ebike whilst the sun is out.

This might mean topping up from any capacity, very low or almost full.

Does it damage a Lithium battery (Bosch) doing such a thing?

Looking for facts please, as there are many old wives tales around battery charging and longevity.

Thanks.

All lithium based battery’s are finicky by their chemical nature.
They should never be discharged below a certain level, about 3.4 volts per cell, and never over charged, 4.2 V per cell.
The idea of using a smaller solar cell to act as a charger can definitely work. But one has to know the current, amps, it can put out in the brightest of sun light is very low which is ok, but will take very long time to charge a typical e-bike battery.
The rider controls the “never discharge” below a key voltage level. And the upper charging level is auto controlled by a BMS (battery management system) built into the battery.
Suggestion: adjust your e-bike display to show Battery Voltage. The normal Power graph display is not very accurate for showing the key low discharge voltage point when you should stop riding the bike.

 

[m@Robertson]

Li-ion packs have no memory effect which is what I think you are driving at. But they also have a limited lifespan (charge/discharge cycle count), they tolerate heat poorly (generated by fast charging) and they degrade significantly if left to sit at 100% charge.

There is a great deal of highly detailed information on li-ion (and specifically Li-NMC which is almost certainly the flavor your cells use in your pack). @Skywagon is giving you a good thumbnail sketch; hitting the high points. Beyond that, here's some reading below.

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

Are you killing your lithium batteries?

Lithium-ion batteries are expensive, and large battery packs such as those in everything from electric cars to electric motorcycles and...

electrek.co

This is a little deep for the layman. Maybe skip to the Conclusion once you understand where this advice is coming from in the introduction.

How to make a lithium battery last, or…kill it, if you like.

We have written in the past about tips that will help your expensive lithium battery pack last as long as possible. This article will cover some additional information about what happens inside the…

www.electricbike.com

Prepare yourself to hear all manner of anecdotal "I do 'X' and my battery is just fine so I don't need no stinking knowledge" opinions.

 

[GizmoEV]

If you are charging the battery so that the BMS is monitoring everything, you should be fine as long as you stay within the current and voltage limits. Battery cycle counts are based on full cycles, not partial cycles, so say you discharge your battery to 50% on part of a ride, charge a while to say 80%, you have only completed 30% of a cycle, not a full cycle. Partial cycles of Li-ion batteries is not an issue like it might be with other chemistries. Periodically you want to run a full cycle or at least a majority cycle like from below 20% to 100% for the BMS to balance the pack and possibly calibrate the capacity, though I'm not sure how many e-bike battery packs do that.

Caring for your batteries will make them last longer, for sure. Unless time is an issue, I always slow charge my phone batteries, RV batteries, boat batteries, tool batteries, and the batteries in my EVs. The batteries in my first EV, which I upgraded to LiFePO4 and put on the road in January 2010 are still going strong for the current owner.

When using voltage, make sure you find out the voltage range of the specific Li-ion chemistry you have so you follow the correct parameters. The 3.4V-4.2V that @Skywagon mentions, for example, would not be good for the LiFePO4 batteries I put in my car in 2010 or for my RV, boat, or tool batteries. Their max voltage is 3.38V though depending on the end of charge profile are typically higher than that by a little.

 

[scrambler]

The key is how do you use your e-bike?
Do you use it on a daily basis AND need full capacity for that?
If so, by all mean top the battery off with solar.

But if not, it is better for the battery not to sit fully charged so:

• If the bike will stay unused for a while, better off leave the battery at 70% 80% charge max
• If you dont need the full 100% capacity for your ride, Dont fully charge the battery either.

 

[tomjasz]

it’s so easy with batteries that do not have a comm wire. just pos and neg.

 

[tomjasz]

See MPPT.

Here’s my bits. lots of accurate info here too. https://ebikes.ca/adjustable-400w-boost-mppt.html

my components for my ev.

Solar Bike Package

Bundle of Solar Panels, MPPT Charge Controller, and Solar CA3 Device for Solar Bike Builds. See Solar Info Page for More Details

ebikes.ca

 

[PedalUma]

If each charge from the grid costs $0.15 and the bike's battery is good for 1,000 cycles. For the life of the battery you will have spent $150. It is not as 'cool,' but it is less expensive and more reliable. Factoid: Did you know that PV development was driven by pot growing hippies in Northern California? At first they just wanted to listen to some Dead while watching their gardens miles from the grid. Here is a long format trailer about it.

 

[Vim Fuego]

To be clear, I'm charging using the manufacturers charger but from a solar source., Rather than the grid.

To charge my battery from the grid costs certainly isn't "cents" where I live charging when the sun is out is free.

 

[Vim Fuego]

I also found some info from Bosch that says top ups after every ride, however small isn't a problem.

 

[tomjasz]

where I live charging when the sun is out is free.

wow! free sun!? where is this?

 

[m@Robertson]

I also found some info from Bosch that says top ups after every ride, however small isn't a problem.

I would take advice from brand-neutral sources. Not those that are in the business of selling you replacements. Especially since battery chemistry is what it is regardless of whose label is on the pack exterior. If you have Li-NMC 18650 or 21700 cells inside (which is pretty much every ebike on the planet save for a relative few DIY builds) then your cells are going to behave the same in a Bosch plastic case as they are any other. So topping up is fine if it means 80% for tomorrow's ride, or 60% if being stored... but never 100% if its going to sit. Blah blah and etcetera. The battery-chemistry-dependent answers remain constant regardless of brand name.

I missed a resource. This one is pretty good and housed right here on this site.

E-Bike Battery Guide

This thread is dedicated for helping new E-bike owners to understand and maintain their batteries in the best possible way. There is a lot of confusion for any new E-bike owner as to how one should treat their batteries: Shop owners may say one thing, online resources may another thing, someone...

electricbikereview.com

 

[Mulezen]

Two questions:
I recently was forced off my ebike by injury…so it sat for 6 weeks with 95% charge. When something unexpected happens how do you discharge the battery to a safer level?
I’m soon to hit the road for a trip…how helpful/paranoid are the innkeepers now about allowing the bike inside?

 

[PedalUma]

It is only free after the capital investment is paid off on the solar setup.
The best way to slowly an safely discharge a battery is to run a USB fan off of the battery's USB port.
Because of the pollution and energy required to produce an electric car, it does not have any environmental benefits until the eighth year of driving it. Then it needs new batteries. So, that brings us to year 10. By then you want a new car, so start from the top.

 

[Jeremy McCreary]

The best way to slowly an safely discharge a battery is to run a USB fan off of the battery's USB port.

Useful tip! The charging habits of a certain household member leave room for improvement. Recently found their battery at 98% on the eve of a 2-week trip. Our ebikes had to stay behind in the garage. Wasn't the end of the world to leave it that way, but now I don't have to.

 

[Mulezen]

Thanks for the idea on discharge PedalUma.
I have read recently somewhere, and persuasively, that the payback numbers on an EV is much lower. For example: a commercial user of e-vans said that the savings on fuel and maintenance is so stark that after five years of savings its like getting a free truck, not to mention perks like no longer hauling a generator for his plumbing.

 

[PedalUma]

@Mulezen, This is very common. Environmental payoff is different than Economic payoff. I was talking about the environmental payoff time. Electric is much easier to maintain.
A USB fan has enough load to slowly and safely take down a battery. It still can take much of a day.

 

[m@Robertson]

When something unexpected happens how do you discharge the battery to a safer level?

I use one of these

Load Resistor 6.8

6.8 Ohm 400 Watt Load for Battery Discharge Testing.

ebikes.ca

You connect it to your battery and it creates a constant 400w draw. In practice, you set it on a brick on your garage floor so it doesn't burn what it is sitting on... The electricity it draws goes to heat and this thing can hit 450+ degrees. It will take a battery down from say 58v to something more manageable like 55v in less than an hour. For me, something like a USB fan up against a 30, 32 or 35ah battery is going to take quite awhile to make a meaningful dent.

I use it on occasion if for example I charge to 100% and then it turns out the ride I was going to take doesn't happen.