Help us build a better Ebike battery

[danielrlee]

Whatever you decide I would check out the latest developments on the proposals for new regulations on EU standardization for electric vehicle charging.

Check out this site:

http://extraenergy.org/main.php?language=en&category=extraenergy&subcateg=&id=88293

Funny really.... I read that article about 'standardisation' and only see intensions of proprieterisation and market control. That's just how they roll in Germany though.

 

[lnunell]

Most new bikes are coming with 500w batteries as the market progresses i would personally be delighted if my 500 w could be recharged in an hour never mind 15 mins. The biggest downside I have found on Ebikes is range even with 500w range is around 30 mile. If you developed a charger that could recharge quickly and was light enough to carry that would be fantastic.

Our system could likely do a full recharge on a 500Wh pack in 30 minutes. That may suit you?

 

[lnunell]

Hi Woosh the reference to reinventing the wheel was with regards to the OP looking to produce a full kit... why bother when there are plenty of suppliers out there already?

I ride my bike a lot commuting, shopping, leisure etc (500-700 miles a month), all three of our bikes are electric. Large batteries are good if a) you can afford them and take the risk after warranty period b) you want to lug the extra weight round and c) happy to replace if they get stolen (at a higher cost than a smaller battery.

Obviously I'm a consumer rather than a retailer, I know from our experience with the bikes and the electric car, that although the selling point is always the range, the reality is that you never do as many miles on a charge as you think.

I charge overnight as you describe, however I'd prefer to get back in and charge in say an hour as it gives more flexibility to pop out again later (e.g. early morning ride then to go shopping) or if I go a longer distance and stop at a cafe etc. My biggest dislike is of all the ebikes I've had they have all had different batteries, it's a pain in the backside to have different mounts, connectors etc.


John

Hi John,

That's the thing, our charging system is fundamentally different to the existing suppliers. We do not charge with DC and that's what makes us different technology wise; just because we have the same casing etc doesn't make us the same as market competitors.

Our patents actually originated from try to make a simpler and safer charging system which allowed us not to rely on temperature readings (which are a poor metric) and also found out that Lithium cells lower internal resistance the way we charge; we are also able to sample internal impedance (a very important and accurate metric) on the fly and up to 100 times a second, a serious improving to safety. Our charger acts much more like a portable lab than anything else.

So yes, we are very much different to what you see out there are the moment and why we think this is a viable market to enter.

 

[lnunell]

Funny really.... I read that article about 'standardisation' and only see intensions of proprieterisation and market control. That's just how they roll in Germany though.

To be honest I can understand why companies like Bosch and Shimano lock down their systems (at least the charger, BMS and cells) as we are going to do the same.

The simple reason is safety and liability. If someone creates a cheaper generic battery pack to use on our charger and the cheaper cells develop a fault, where do you think the legal liability will strike first? Us.

Locking down the system is a no brainier to be honest, a lot of companies that don't do this either originate in China where the manufacturer will very unlikely face liability or they are a ticking time bomb regarding safety.

Unfortunately that is life my friend.

 

[lnunell]

That's helpful, it moves him from a crank trying out ideas to a genuine entrepreneur.

Thanks

 

[Woosh]

I suspect manufacturers locking down their battery to stop customers overloading their components.
There are already plenty of Lithium ion charger chips, like the TI-bq-25871/25872 with 1MHz I2C sensing. In what way your system is better than those chips?

 

[lnunell]

Woosh,

All of our systems have been made from scratch, the reason is our charger charges batteries in a fundamentally different way, I cannot get into the very fine details but it doesn't charge through DC so we have to develop our own BMS to sense and monitor cell is a different way.

What it allows us to do is create a different topology with our charger, so it is more reliable and less complex to push costs lower and maintain a high level of safety through the online analysis on internal impedance.

Thanks,

 

[Simon C]

Our system could likely do a full recharge on a 500Wh pack in 30 minutes. That may suit you?

That would be awesome would it be available to charge a Bosch battery and if so when do you expect to bring the product to market ?

 

[lnunell]

We are transitioning to this project at the moment, there is always an issue working with other OEM products as most of them have safety features, we will be able to bring out a 500Wh pack of our own if demand is high enough.

This is why we wanted to set this topic up to discuss the technological requirements from the community so we can build on our development units. We are not advertising our company or selling products on here as it is against the forum rules.

 

[Woosh]

but it doesn't charge through DC

whichever way you monitor the charging process, the charge current goes one way, so it's the same way for all chargers.

That would be awesome would it be available to charge a Bosch battery and if so when do you expect to bring the product to market ?

You can't charge your Bosch battery faster. If the charging current exceeds 0.2C (eg 3A for a 500W battery), the BMS has to have sensing circuit to protect the cells. The reason inunell can fast charge his is because he uses LFP cells which can charge 10 times faster than Lithium-ion cells.

 

[lnunell]

whichever way you monitor the charging process, the charge current goes one way, so it's the same way for all chargers.



You can't charge your Bosch battery faster. If the charging current exceeds 0.2C (eg 3A for a 500W battery), the BMS has to have sensing circuit to protect the cells. The reason inunell can fast charge his is because he uses LFP cells which can charge 10 times faster than Lithium-ion cells.

This doesn't make sense, commercially avalible chargers charge via Direct Current (DC) using a fixed amperage and a ripple free voltage curve until the CC/CV phase has finished. Ours is fundamentally different to DC so it is not the same.

You are right about the Bosch BMS, we are also evaluating different cells and do not have a fixed cell type yet, yes we use power dense cells rather than energy dense, but our tech charges those cells up faster and safer than current charging tech. That's why we have the patents behind this process.

 

[Danidl]

This doesn't make sense, commercially avalible chargers charge via Direct Current (DC) using a fixed amperage and a ripple free voltage curve until the CC/CV phase has finished. Ours is fundamentally different to DC so it is not the same.

You are right about the Bosch BMS, we are also evaluating different cells and do not have a fixed cell type yet, yes we use power dense cells rather than energy dense, but our tech charges those cells up faster and safer than current charging tech. That's why we have the patents behind this process.

There are some knowledgeable people on this forum, in order to change the state of charge in a cell one must drive a greater voltage into the cell than the retarding potential difference due to the material. Whether this isas a steady DC , a pulsating DC , Pulse width modulated over voltage or whatever. If it is pulsed, then there is plenty of time to measure resistance during an off time, or even to measure over voltage decay as a function of time as the energy is absorbed . Modern electronics makes these type of monitoring low cost
Anyway I wish you well in your endeavours.

 

[lnunell]

There are some knowledgeable people on this forum, in order to change the state of charge in a cell one must drive a greater voltage into the cell than the retarding potential difference due to the material. Whether this isas a steady DC , a pulsating DC , Pulse width modulated over voltage or whatever. If it is pulsed, then there is plenty of time to measure resistance during an off time, or even to measure over voltage decay as a function of time as the energy is absorbed . Modern electronics makes these type of monitoring low cost
Anyway I wish you well in your endeavours.

I am not denying that at all, the reason I started this thread was to focus on what we could add to our system to make it work for the community, such as the 30minute 500Wh version, not to talk about the viability of our tech as we know it works.

One of the biggest discussions we have been having is the formfactor of the battery casing, most of the products being sold have been focused on the bottle frame style design and there are several options:

• Bottle frame style
• 'in tube' battery
• Panier battery pack
• hub battery

All of these have their pro's and cons, but the two that have been front running are the bottle style or the in tube, the in tube has a big advantage of harder to be stolen but the frame is a more universal design.

What are your experiences and issues with what is on the market at the moment?

 

[Woosh]

Thank you danidl for explaining. I meant exactly that.
Inunell, I wish you well in your endeavour too. I know how hard it is to get a project off the ground, you don't need doom merchants like me to make it more difficult. I concur with Daniel, there are a lot of technical people here on the site, they can help you go further and more cheaply. I think you need to go further than what has been achieved with the likes of the TI charger control chips to make a commercial product. I can envisage a fast pulse charger - piggybacked onto the balance leads.

 

[Deleted member 4366]

I don't think the market needs fast charging. Schwinn tried that with their lithium titanate batteries. They struggled to sell their bikes. In the end, they had to reduce the price of their bikes by 50%. Those batteries could be charged in 5 minutes and have a nearly infinite life. I have a couple if anybody wants to come and get them.

Instead, you should concentrate on specific energy. People want light-weight batteries with around 500 Wh.

 

[lnunell]

I don't think the market needs fast charging. Schwinn tried that with their lithium titanate batteries. They struggled to sell their bikes. In the end, they had to reduce the price of their bikes by 50%. Those batteries could be charged in 5 minutes and have a nearly infinite life. I have a couple if anybody wants to come and get them.

Instead, you should concentrate on specific energy. People want light-weight batteries with around 500 Wh.

Hi d8veh,

Yeah we have heard if the Toshiba SCiB cells, they are great for niche applications, their two main downfalls are the price (titanate is very expensive) and very low cell voltage meaning they are very heavy; I believe the pack was 24v @ 4Ah so very heavy.

You said you have a couple avalible, do you have the battery packs themselves or the whole bike? We are based in birmingham so not too far.

It would be interesting to see what chargers were used on these packs.

 

[Deleted member 4366]

It would be interesting to see what chargers were used on these packs.

i have just the batteries and chargers now. The chargers are massive. I think they're something like 8 amps, but the battery has two huge terminals for some sort of fast charger. The terminals look good for about 50 amps. They go directly to the cell-pack, by-passing the BMS. The BMS is very sophisticated. Unfortunately, it has a sleep mode and nobody knows how to wake them up, so anybody that bought one of these bikes and left in in the garage for a few months cannot use it anymore. You can find them on Ebay for next to nothing, swap the battery and controller for normal 36v ones, and you get a really nice electric bike for about £500.

 

[Danidl]

I am not denying that at all, the reason I started this thread was to focus on what we could add to our system to make it work for the community, such as the 30minute 500Wh version, not to talk about the viability of our tech as we know it works.

One of the biggest discussions we have been having is the formfactor of the battery casing, most of the products being sold have been focused on the bottle frame style design and there are several options:

• Bottle frame style
• 'in tube' battery
• Panier battery pack
• hub battery

All of these have their pro's and cons, but the two that have been front running are the bottle style or the in tube, the in tube has a big advantage of harder to be stolen but the frame is a more universal design.

What are your experiences and issues with what is on the market at the moment?

I run a Bosch system with a battery on the rear rack . It is a reasonable compromise. The battery can be removed or charged in situ .
My comments as a consumer .
1. Battery built into frame a designers delight but would be a nightmare for many users . The mains would need to be adjacent to the bike, and this may probably not suit if the bike is is stored in a shed. Also the bike will be heavier for transport say by bike rack.
2. Battery in the hub. This has a certain elegance from a designers viewpoint but would be even worse than option 1 . Not only does the bike need to be close to the charging point but it is at a lower level therefore more bending over by the user. Also any weight in the rotating part the wheel has an additional effect on effective bike weight. The weight is effectively doubled ... The actual weight of the battery. + The moment of inertia by a quirk of maths equals this weight .
3. Bottle types a good location but maybe limited in capacity?

 

[Danidl]

I don't think the market needs fast charging. Schwinn tried that with their lithium titanate batteries. They struggled to sell their bikes. In the end, they had to reduce the price of their bikes by 50%. Those batteries could be charged in 5 minutes and have a nearly infinite life. I have a couple if anybody wants to come and get them.

Instead, you should concentrate on specific energy. People want light-weight batteries with around 500 Wh.

I could see a value in having a charger of weight 0.5 kg capable of giving 80% charge to a 400 to 500 whr battery in under 30 minutes. It would enable the tourist break off for a coffee or lunch and then proceed for double the distance.

 

[tommie]

1. Battery built into frame a designers delight but would be a nightmare for many users . The mains would need to be adjacent to the bike, and this may probably not suit if the bike is is stored in a shed. Also the bike will be heavier for transport say by bike rack.

Two very important points,
i store the bike in a shed and a detachable battery means i can also transport and lift the bike on a car rack less the battery