[M-BEAM]

Hi. We are a small group of engineers and EV enthusiasts, working out of our garage, that have converted a 2004 VW Golf into an electric vehicle. But our EV is a little different than others... We are using this as a proof of concept to illustrate the modular battery exchange concept. Instead of having one big battery that needs to be charged up, we have multiple smaller batteries that can be exchanged easily for fully charged ones. We are planning a trip across the country to prove out this concept and are hoping to set a world record for fastest crossing in an EV: 60 hours. We are trying to get the word out to people about our challenge, the idea, and to promote the feasibility and future of electric vehicles

 

[M-BEAM]

Forgot to add, if you want to know more about us, you can check out our website at modularexchange.com or like us on Facebook (M-BEAM) or follow on Twitter (MBEAMX).

 

[major]

Forgot to add, if you want to know more about us, you can check out our website at modularexchange.com

Hi M-,

I checked out the website. Interesting. I've long been a proponent of battery swap. I've done several systems for EV racers. Your battery module spec is 1.6 kWh which is close to the EnerDel module. Have you considered using it?

During a race, we did 7 second hot swap pit stop with these

Good luck,

major

 

[major]

....We are planning a trip across the country to prove out this concept and are hoping to set a world record for fastest crossing in an EV: 60 hours....

San Diego, CA to Charleston, SC is 2461 miles. At 100 miles per battery, you need 25 batteries strategically placed along the way. A conservative estimate is $10,000 per battery. That is a quarter million dollar battery budget, at minimum.

 

[M-BEAM]

Thanks for the support Major!

Your battery module spec is 1.6 kWh which is close to the EnerDel module. Have you considered using it?

Yeah we have looked into off the shelf batteries for this, but what we really are exercising is the battery management technology. Our batteries measure each cell individually and monitor and balance on the go actively. If we were to buy a OTS battery, that'd be a lot of wires we'd have to hook up. However, we are able to integrate the cells with our circuit boards, giving it a really clean package. I'll be putting some new photos up on our Twitter of the battery boxes if you want to take a peek (username = MBEAMX).

San Diego, CA to Charleston, SC is 2461 miles. At 100 miles per battery, you need 25 batteries strategically placed along the way. A conservative estimate is $10,000 per battery. That is a quarter million dollar battery budget, at minimum.

That's true. However, we thought of a bit of a different way to approach this. Instead of having to sink 250K into batteries, we will be following in a truck that will be recharging the batteries as we go. We will be have 18 battery modules in our car at one time, so another 22 will be charging (4 back ups) as we go (we will be able to recharge faster than we discharge). This will effectively simulate having battery pit stops along the way, while costing a fraction of that quarter million. We know that actual implementation of exchange stations one day is a big task, but we really just want to prove the feasibility of the modular technology and the exchange mechanism.

Thanks,

Steve
M-BEAM

 

[Frank]

Interesting project... so you are using 18 of these modules in parallel or did I misunderstand the specs? Are you using the transmission and is the motor force-cooled? When is the trip scheduled? This project should get a lot of attention.

 

[major]

if you want to take a peek (username = MBEAMX).

Sorry. Can't go there. Please post here.

You'd need to do the BMS for that module as well. It has the connector ribbon and thermistors on cells ready to go. It is also less than 50V which is the industry standard for safety.

we will be following in a truck that will be recharging the batteries as we go.

I thought about that but figured you wouldn't go that route due to the comments sure to follow about all the fuel burned by the chase truck and generator. Kinda like a HEV split between 2 vehicles. Still making stops at the gas stations. Best case for press sake would be to have all the batteries charged from renewables (wind, solar) beforehand.

 

[M-BEAM]

Interesting project... so you are using 18 of these modules in parallel or did I misunderstand the specs? Are you using the transmission and is the motor force-cooled? When is the trip scheduled? This project should get a lot of attention.

Thanks! Yes correct, we have 18 modules in parallel in the car. The Warp 9 motor is air cooled and is connected to the transmission. The controller we use is water cooled.

The trip is scheduled for mid-April, so we have some time to accomplish some testing!

 

[M-BEAM]

Please post here.

Here is a pic of our proto battery module: https://pbs.twimg.com/media/BZpIzjjCEAAhf8Q.jpg:large

I thought about that but figured you wouldn't go that route due to the comments sure to follow about all the fuel burned by the chase truck and generator. Kinda like a HEV split between 2 vehicles. Still making stops at the gas stations. Best case for press sake would be to have all the batteries charged from renewables (wind, solar) beforehand.

I agree, it would be best to say that the energy came from renewables. However, we don't have a huge budget for this kind of thing, so we will have to make do with this strategy for now. We anticipate those comments, but in reality this is not much different than the fossil fuels being burned at power plants that power electric car charging stations. I don't think it can really be compared to an HEV, but that I guess depends on the frame of reference. We are going to plan it out so that the gas stop is also a battery swap stop, so it doesn't eat into the time too much.

 

[dougingraham]

We anticipate those comments, but in reality this is not much different than the fossil fuels being burned at power plants that power electric car charging stations.

Before I make my comments and questions I want to applaud your effort.

There is a huge difference between burning gasoline or diesel to spin a generator and the output of a power plant. Power plants are about 4 times more efficient at the conversion to electricity. You are going to consume about 30 hp just to charge a battery at the same rate as you are using it. What is the plan to generate the electricity to recharge the battery?

A WarP 9 motor operating continuously for 60 hours at highway speeds may be pushing it even with additional forced air cooling. I suggest you install some temp sensors and keep a close eye on it.

Best wishes!

 

[Karter2]

Here is a pic of our proto battery module: https://pbs.twimg.com/media/BZpIzjjCEAAhf8Q.jpg:large
.

pouch cell packs ?
Who's cell are you using ?

 

[dougingraham]

Couple of more questions and comments.

How long does it take to swap a module? How long for all 18 of them?

The battery module spec sheet on the website has lots of questions. The photo looks like A123 pouches. Many of the pouch cells including the A123 cells can be charged at high rates, of 4C and some even claiming 10C. A 4C charge rate would give over 80% charge in 15 minutes. A 10C rate in 6 minutes. My own pack would allow a 3C rate if I had a large enough charger. Battery swaps when the battery can be charged this fast are unlikely to ever catch on.

I agree that for long distance travel a battery swap makes sense if you can't fully charge in under 20 minutes. But even if you can't charge that fast you have to somehow convince the Automakers to use a common pack design and I don't ever see that happening. Automakers have always had a terrible case of "Not invented here syndrome."

Looking forward to your drive.

 

[M-BEAM]

Before I make my comments and questions I want to applaud your effort.

Thanks Doug!

There is a huge difference between burning gasoline or diesel to spin a generator and the output of a power plant...What is the plan to generate the electricity to recharge the battery?

I agree, gas engines are not as efficient as power plants. However, we are trying to showcase the feasibility of the modular technology, anticipating that, in the future, energy in the battery will come from renewable sources. We are making do with the resources available to us. We plan on using generators to charge while on the road.

A WarP 9 motor operating continuously for 60 hours at highway speeds may be pushing it even with additional forced air cooling. I suggest you install some temp sensors and keep a close eye on it.

That was a concern of our initially (we thought about water jacketing it). But we looked at the draw of the motor, operating continuously at 70 mph (which is our estimated average speed for the trip), and it only takes about 15 hp to maintain that speed. The motor should operate just fine under those conditions.

How long does it take to swap a module? How long for all 18 of them?

The boxes are designed so that they just slide in and out of the battery rack. We haven't built the full rack up yet, but we anticipate it taking about 10 sec to switch a module with a new one. Having two people exchanging modules, it would be about 1.5 min to switch out all 18.

Battery swaps when the battery can be charged this fast are unlikely to ever catch on.

It is all about the the size of your charging station and the effect on the batteries. Let's say you have a Tesla Model S 85 kWh pack in a car and, assuming their max of 3.2 miles per kWh, you would still need supercharging stations (100kW) to charge up the full range in about 50 min. In order to get these times down to a more "palpable" charge time for the public, you would need much higher wattage charging stations. It is hard to imagine having charge stations that are higher that 1/2 a MW. Plus you have to take into account the effects of battery degradation due to the fast charging of batteries. I agree that it seems like the future of EVs is going down the path of fast charge, but I think that we are going down the wrong path with some severe limitations in the future, and that modular batteries would alleviate most of those problems. Heck, with modular, you could even fast charge if you wanted to or swap them out on long journeys!

Automakers have always had a terrible case of "Not invented here syndrome."

And yeah, our biggest obstacle in regards to the vehicle is the auto industry. They are slow to accept any slight change to their vehicle structure, so asking for common battery technology and changes to their vehicles is going to be hard. But it's got to start somewhere and now is the time.

Sorry for the essay! Thanks again for the support!

 

[M-BEAM]

pouch cell packs ?/QUOTE]

We decided to use pouch cell packs because we could have a better energy density to weight ratio, using custom enclosures. Each pouch cell is 10.67 Ah made of Lithium Iron Phostphate, and has a very low impedance. They were the best we could get on the market for the price.

 

[Karter2]

I can understand your reasons for the choice of Lico pouches ..capacity/ power/weight/price compromise etc...
..and you apear to have built some excellent packs,..
... but if you care to reveal the make of cell maybe one of the members on here would have some experience with them and could contribute useful advice.

 

[Karter2]

Question ??
WHY has this thread attracted 40-50 times more views than any other thread on this forum section ??????????????
Any of you "viewers" care to hint at what caused you to look at it ?

 

[rochesterricer]

Probably because it wasn't generated by the News Bot.

 

[Duncan]

Its related to the number of replies,
the more replies the more interesting it must be the more views

If you look back on the pages the pattern is quite clear

 

[M-BEAM]

Well we appreciate all the views! That's what we are trying to do, spread the word about EV technology and the potential for battery exchange!

 

[Karter2]

I am still really puzzled.
I went back thro' over 40 pages of posts ( got bored looking) ..and only one other post has 2000+ views. ( the Top Gear post)
Most never make even 100 views !
There must be some magic key word in the title to draw views in.