# back seat/trunk battery



## sj281708 (Apr 29, 2014)

Does anyone know if I can wire a secondary battery to my existing battery for an EV or directly to a motor and flip a switch to draw power from it when my EV battery is out of juice?

So if I am in a remote area with no charger, and my car is a full EV, can I use a battery sitting in the backseat or trunk of my car to power the motor WHILE driving? How do you think these people did it? http://www.popsci.com/cars/article/...space-and-700-extra-miles-range-electric-cars


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## brainzel (Jun 15, 2009)

Two different voltage levels would be problematic.
F.ex. your "drive" battery is 144V normal voltage and 121.5V when low, and your "reserve" battery is 90V, than you could not bring them together easily.

If they have the same voltage (and ah!) level, why not running the two all the time?

If they have the same level of voltage, but different amp hour ratings, then you have to count ah to bring the second battery at the right time in.
But you would have to charge them separately after your ride, because of different end phases.

Fourth possibility would be a charger who charges your first battery with the support from the second one. Kind of DC/DC converter.

However, it's not easy and would effort, cause trouble or losses.


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## crackerjackz (Jun 26, 2009)

Just cut off the first traction pack and then turn on the second ... Thats what i was thinking of doing with a trailer system to go further sometimes ... All you need are two traction pack contactors and a security to make sure only one is on at all times ... Use a normally closed aux contact on each contactor and pass the opposites contactor coil by it ...


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## sj281708 (Apr 29, 2014)

brainzel said:


> Two different voltage levels would be problematic.
> F.ex. your "drive" battery is 144V normal voltage and 121.5V when low, and your "reserve" battery is 90V, than you could not bring them together easily.
> 
> If they have the same voltage (and ah!) level, why not running the two all the time?
> ...




So for two same voltage and amp-hour systems, I run them all the time, meaning that it extends my range? And when both gets depleted, i either charge the car or recharge the external battery? How would I wire such a thing?

For different ah, and counting when the bring the external pack, do I do so using a relay or some manual switch? By charging them separately, I'm assuming you mean 230V AC wall to car, and then using a battery charger to charge the external? So for example, if I am stuck, I can tell my brother to come meet me on the road and bring along a fresh battery so i can recharge the EV battery and come home/run the motor with fresh one to drive further?

I mostly like the DC to DC converter idea, but again, how do I best wire it, and can it charge while I am driving the car?

Thanks so much for your input, I really appreciate it!


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## sj281708 (Apr 29, 2014)

crackerjackz said:


> Just cut off the first traction pack and then turn on the second ... Thats what i was thinking of doing with a trailer system to go further sometimes ... All you need are two traction pack contactors and a security to make sure only one is on at all times ... Use a normally closed aux contact on each contactor and pass the opposites contactor coil by it ...


So does something like this for my second pack (http://elithion.com/traction_packs.php) get wired directly to an ECM and by-pass the battery modules existing inside the EV? Or does it work along side the existing EV battery...im guess separately since you said there should be a security...Do I have to use a contactor and not a relay because of the ampere? Do you have some links to appropriate primary or aux contactors blocks/security and what kind of ampere or voltage parameters you were thinking?

So, if I understand correctly, it works by me (the driver) stopping the depleted EV battery from running the motor, using a switch, and turning to the traction pack via contacters to provide power to the motor? Thanks for your help and insights on this, crackerjackz


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## crackerjackz (Jun 26, 2009)

sj281708 said:


> So does something like this for my second pack (http://elithion.com/traction_packs.php) get wired directly to an ECM and by-pass the battery modules existing inside the EV? Or does it work along side the existing EV battery...im guess separately since you said there should be a security...Do I have to use a contactor and not a relay because of the ampere? Do you have some links to appropriate primary or aux contactors blocks/security and what kind of ampere or voltage parameters you were thinking?
> 
> 
> 
> So, if I understand correctly, it works by me (the driver) stopping the depleted EV battery from running the motor, using a switch, and turning to the traction pack via contacters to provide power to the motor? Thanks for your help and insights on this, crackerjackz




Any ev supplier could sell you the appropriate contactors ... The strenght of the contactor is entirely dependent on what vehicule / motor combo you have ... 

But yes you understand what i mean by hooking it up ... As for the security you just have to get contactors with auxiliary normally closed contacts and youd be good to go ...


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## sj281708 (Apr 29, 2014)

crackerjackz said:


> Any ev supplier could sell you the appropriate contactors ... The strenght of the contactor is entirely dependent on what vehicule / motor combo you have ...
> 
> But yes you understand what i mean by hooking it up ... As for the security you just have to get contactors with auxiliary normally closed contacts and youd be good to go ...


Is that something I can wire myself? Where are the live and neutral wires coming from? The EV battery pack or the motor? How would you personally do such a thing? Thanks and I hope i'm not bothering you with constant questions


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## Ziggythewiz (May 16, 2010)

Even different AH can work fine together as long as they're connected/disconnected while at the same voltage. The voltage and approximate soc% will stay the same.


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## sj281708 (Apr 29, 2014)

Ziggythewiz said:


> Even different AH can work fine together as long as they're connected/disconnected while at the same voltage. The voltage and approximate soc% will stay the same.


So exactly should I connect the external batteries?


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## brainzel (Jun 15, 2009)

Could you tell more about your packs?
Are they both the same? Two Elithion 10 kWh, 30 Ah, 350 VDC ?

Voltage, AH, type of battery would be great.

I wouldn't take it too easy, if they should work together a long time.
F. ex. mixed chemistries (f.ex. pack 1 = LifePo4 / pack 2 = LiMn2O4) would behave not equal in discharging and voltage is not a good indicator for SOC.

I don't want to make it difficult but to make it reasonable, it's not just "put them all together" 

Michael


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## Duncan (Dec 8, 2008)

Hi Sj

I am a great believer in the DIY ideal - but if you are asking these sorts of questions you really should not be messing about with EV battery packs

Unless you tell us well enough in advance to get popcorn and good seats

Seriously a major fire or a lethal electric shock are possible here - you need to learn a lot more of the basics before you get to that


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> Does anyone know if I can wire a secondary battery to my existing battery for an EV or directly to a motor and flip a switch to draw power from it when my EV battery is out of juice?


If both batteries are onboard, it really doesn't make a lot of sense. The better move would be to create a single larger battery and use it all the time.



> So if I am in a remote area with no charger, and my car is a full EV, can I use a battery sitting in the backseat or trunk of my car to power the motor WHILE driving? How do you think these people did it? http://www.popsci.com/cars/article/...space-and-700-extra-miles-range-electric-cars


Well that's a beast of a bit different color. First off it's a trailer. Second it's a hybrid with its own engine. Third it's also a pusher meaning that it's self powered instead of being simply towed.

You really need to clarify your objectives. Let me rephrase your question in terms of a gas vehicle:

"So if I'm in a remote area with no gas stations. and my car is a ICE vehicle, can I use gas cans of gasoline sitting in the backseat or trunk of my car to power the ICE engine WHILE driving?"

Now clearly it can be done. But the average driver wouldn't be caught dead in a situation like that. So I question why would this need to be a constraint put on an EV when it's not one that a reasonable person would not put on an ICE vehicle?

That is an extreme EV situation. If this is an occasional thing, the best solution would be to carry or tow a gas generator to recharge your batteries.

If this is a normal spot for you, then currently an EV isn't the proper vehicle for the job. Look to a hybrid.

ga2500ev


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## sj281708 (Apr 29, 2014)

brainzel said:


> Could you tell more about your packs?
> Are they both the same? Two Elithion 10 kWh, 30 Ah, 350 VDC ?
> 
> Voltage, AH, type of battery would be great.
> ...


How about 53 amp-hours at 312 volts (16.5 kWh)? I dont have the elithion traction pack, just showing a link of it. I can't afford it haha.

I wasn't aware of the chemistry mismatching and uneven discharge (I learn new things all the time )...although I was aware the Voltage is not good to show SOC%. Can a normal lead acid battery (in series) be hooked/wired to give the 312 VDC a recharge when it is in need of charging? And can this be done while driving or does the car need to be stopped for that?

Thanks, Michael!


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## sj281708 (Apr 29, 2014)

Duncan said:


> Hi Sj
> 
> I am a great believer in the DIY ideal - but if you are asking these sorts of questions you really should not be messing about with EV battery packs
> 
> ...


I agree. And I'm trying to look around to learn more about it. I think I would let a mechanic with EV experience handle it, but I want to know options and learn more before I approach one. Thanks


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> If both batteries are onboard, it really doesn't make a lot of sense. The better move would be to create a single larger battery and use it all the time.
> 
> 
> 
> ...


I agree, but the slight difference to me between my EV situation and the ICE version, is that I would need to puncture a fuel tank and put a pike in there and manually tilt the gas container to pour it. I was thinking that for an EV's case, I'd just hook up wires that clamp to the pack/chassis/ECM...no spills, drilling etc.

So if I absolutely had to tow a electric car battery recharger, could I recharge the car while it is being driven/towing the generator, or would I have to sit for 4 hours for my battery to charge up? If it could be done while driving...where would I wire the generator's electro-chemical output to (i.e. to my ECM/EV battery pack)?

Thanks again for all your help guys! It is truly a learning discussion for me.


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## Ziggythewiz (May 16, 2010)

sj281708 said:


> How about 53 amp-hours at 312 volts (16.5 kWh)? I dont have the elithion traction pack, just showing a link of it. I can't afford it haha.
> 
> I wasn't aware of the chemistry mismatching and uneven discharge (I learn new things all the time )...although I was aware the Voltage is not good to show SOC%. Can a normal lead acid battery (in series) be hooked/wired to give the 312 VDC a recharge when it is in need of charging? And can this be done while driving or does the car need to be stopped for that?
> 
> Thanks, Michael!


If new to EVs 312v is not the best place to start. Most of us begin in the 144v or lower (generally non-lethal) ranges. 

A 312V lead pack would be rather counterproductive. I've heard of drag racers with high voltage lead, but they didn't need to go very far. 36 golf cart batteries would add enough weight to counteract most of the energy gained by adding them.

My car runs 2 parallel battery packs, of different size and chemistry, and it works great, but I carefully calculated (and experimented with) the charge/discharge curves and rates of each to play well together and have some controls in place to ensure the packs are within healthy ranges.


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## brainzel (Jun 15, 2009)

If you are planning your personal EV, than I would suggest to do some math.
How far do you have to go on a day?
Working, shopping, children to school and back etc.
Say f.ex. 50 miles.

Than estimate the consumption of the car.
If you can't do it, ask here.
Give some data in detail.
Lbs of the car, average speed, hilly environment etc.

Than you get some numbers to calculate.
If you aren't experienced in electric / electric vehicles, I would also suggest a lower voltage, like 96V.
*Everything above 120V DC is potentially fatal !*

Personally I would take a 320V pack, because higher voltage would bring the current down, but this seems to be too lethal for you.

So 50 miles with a mid size car and a 96V pack would be about 30 pcs. of >=130 Ah Lithium pack.

Is you take 30 batteries of f.ex. CALB 180Ah, you would have a great pack and a good range.
If you want to get more, take 200Ah or more.

Michael


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## ga2500ev (Apr 20, 2008)

brainzel said:


> If you are planning your personal EV, than I would suggest to do some math.
> How far do you have to go on a day?
> Working, shopping, children to school and back etc.
> Say f.ex. 50 miles.
> ...


This all makes sense for the onboard pack. What I was trying to determine is if the OP was really trying to do a battery trailer. It's the only logical setup for what he originally asked.

ga2500ev


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## sj281708 (Apr 29, 2014)

brainzel said:


> If you are planning your personal EV, than I would suggest to do some math.
> How far do you have to go on a day?
> Working, shopping, children to school and back etc.
> Say f.ex. 50 miles.
> ...


Imagine a 2010 Leaf, around 3500 lbs and going 70 miles a day usually. Sometime (30% of the time) I have to go to a hilly area, but not all the time. How much more range should the 30B Pack give me (is this what you had in mind? http://www.evsource.com/tls_lithium_calb.php). Now the question is...how is it wired? I will be sure to have an electrician do it, but I want to know it myself  Thanks so much!


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> This all makes sense for the onboard pack. What I was trying to determine is if the OP was really trying to do a battery trailer. It's the only logical setup for what he originally asked.
> 
> ga2500ev


No, actually I was just talking about an on board pack...


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## brainzel (Jun 15, 2009)

sj281708 said:


> Imagine a 2010 Leaf, around 3500 lbs and going 70 miles a day usually. Sometime (30% of the time) I have to go to a hilly area, but not all the time. How much more range should the 30B Pack give me (is this what you had in mind? http://www.evsource.com/tls_lithium_calb.php). Now the question is...how is it wired? I will be sure to have an electrician do it, but I want to know it myself  Thanks so much!


70 miles (110km) a day would not be an usual pack size.
About 20 -22kWh of energy should be installed, If you don't have the possibility to charge meantime.
If you want to go this hole range in winter and some hilly roads, you might take some extra kWh.

22.000Wh / 96V = 230Ah
The most common CALB CA series cells are 60Ah, 100Ah and 180Ah
So the common size of a single string pack would not match. .
You might parallel two/three/four strings, take a higher voltage or get some other cell manufacture like Winston Battery (WB-LYP260AHA).

f.ex. :
1 series string of batteries: 30 x CALB CA 400Ah (too big)
1 series string of batteries: 30 x Winston WB-LYP260AHA (match)
2 series string of batteries: 30 x CALB CA 100Ah (200Ah total) (too small?)
4 series string of batteries: 30 x CALB CA 60Ah (240Ah total) (match, but many connections)
…

If you really want to storage a trailer full of batteries in your garage to use it a few times to get somewhere >70miles or in hilly environment, it would be expensive!

The easiest way would be to double your pack and connect the two packs simple parallel, both charged, same capacity.
Then you could double (with a little weight and drag losses) your energy aka range.
In most cases this would be too much dollars to stay around (≈ $10.000).

You could take a smaller pack, same amount of cells, but lower capacity (Ah). Than you have to disconnect the second pack at the right time to protect it against undercharging while driving.
F.ex. 200Ah main pack, 60Ah trailer pack: count Ah while driving and disconnect the trailer pack at 50Ah.
If you get home, charge them separately with your normal charger.

Economically this wouldn't work well 

Perhaps you should look after a car that fits your needs directly (+100 miles on hilly roads).
Unfortunately most of the cars available do not match.
If you could afford it, Tesla would be the choice.
If not, look after a Chevrolet Volt as an affordable compromise.

Michael


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> No, actually I was just talking about an on board pack...


OK. Then to reiterate, it makes no sense to have two separate packs, which I believe was your original question.

Organize the largest capacity single pack that fits and that you can afford. Then optimize the car around that pack to get the range the range that you need.

Packs are organized around Volts, Amps (a percentage of amp hours), and watt hours (V*AHr). In very broad strokes:

The more volts you have, the faster the motor can spin.
The more Amps you have, the more torque you can generate.
The more watt hours you have, the farther the range.

Each of these have limitations. The first two are on the motors. Too many volts or too many amps will burn it up. Watt hours are related to space and cost because in general the more watt hours, the more space the pack will take and the more it will cost to build.

Use WHr/mile as a rough gauge of range. Be conservative. Use estimates from other EV's in the same approximate class/weight range. Refer to the rule of thumb earlier in the thread (weight/10 -> approximate WHr/mile estimate).

Remember that it's all a SWAG until you have a platform to gather some real numbers. So don't try to engineer an estimate to 20 digits of precision. It's OK to start working with a ballpark of the objective.

ga2500ev


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> So if I absolutely had to tow a electric car battery recharger, could I recharge the car while it is being driven/towing the generator, or would I have to sit for 4 hours for my battery to charge up?


Either is possible.


> If it could be done while driving...where would I wire the generator's electro-chemical output to (i.e. to my ECM/EV battery pack)?


To the charger for the battery. The charger really only serves two functions:

1. Make sure that the incoming charge is compatible with the pack (correct voltage, current).

2. Make sure that the battery doesn't overcharge.

Essentially this turns the EV into a hybrid, which charges while driving most, if not all, of the time.




> Thanks again for all your help guys! It is truly a learning discussion for me.


You are certainly welcome

ga2500ev


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> ... I can't afford it haha.


This is of course the first question. What is your budget? Without sufficient dollars all of this is simply pipe dreaming anyway...

ga2500ev


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## sj281708 (Apr 29, 2014)

brainzel said:


> 70 miles (110km) a day would not be an usual pack size.
> About 20 -22kWh of energy should be installed, If you don't have the possibility to charge meantime.
> If you want to go this hole range in winter and some hilly roads, you might take some extra kWh.
> 
> ...


Great! I think I get it now. I however would not need 70 miles on the extra pack....I just need the extra pack if for any reason I can't charge the existing pack. Meaning, I can get the existing pack to do 55, and maybe do 15 with the extra one you talked about. 

So, if I connect the extra pack in parallel to the car's existing charger (does it need to be wired differently, now that there is an extra cable(s) coming from the extra pack?) I can run both at the same time, and if the charge goes down...I can theoretically switch the extra packs (discharged) for charged cells and go on my way without stopping to plug in and wait to charge?

I drive back and forth between two cities, A and B. In City A, my home charger charges my extra battery and I put it in my car and I go on my way, using it when my EV pack depletes...in City B where I work, on my way back, I drop the discharged battery and pick up charged ones from B and I'm on my way back home again...will that work for same kind of batteries?

So if I am in City A with both full battery packs, and by the time I drive to City B and reach it, by extra battery is depleted, so then I pick up new charged battery in B, in exchange for the old discharged one, and use that to come back home in A.

Does that make sense?


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> OK. Then to reiterate, it makes no sense to have two separate packs, which I believe was your original question.
> 
> Organize the largest capacity single pack that fits and that you can afford. Then optimize the car around that pack to get the range the range that you need.
> 
> ...


The reason I said separate packs is because I want to switch batteries easily from discharged to new, charged ones. It will be too much of a hassle to unwire a pack and swap out old battery for the new, if I go for the bigger pack route. Please see my above response with City A and B, to see my plan. If I keep two battery chargers at two different locations, can I swab back and forth if those are my two destinations. I really hope I didn't confuse you.


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> Either is possible.
> 
> 
> To the charger for the battery. The charger really only serves two functions:
> ...


God bless folks like you who like to help lost souls such as me, knowing that I am a noob at this


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> To the charger for the battery.
> 
> ga2500ev



Does the charger allow for hookups/wiring for something like this, or would I have to tinker beyond limits? I did think that this extra pack would act more like an engine that chargers a battery like a hybrid. I'm guessing different makes have different incoming V and A, so could you tell me how the charger would be for a leaf, and for a volt, compared to a tesla or a ford EV?


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## brainzel (Jun 15, 2009)

sj281708 said:


> Great! I think I get it now. I however would not need 70 miles on the extra pack....I just need the extra pack if for any reason I can't charge the existing pack. Meaning, I can get the existing pack to do 55, and maybe do 15 with the extra one you talked about.


So I would recommend you a Leaf. Much easier and cheaper 



sj281708 said:


> So, if I connect the extra pack in parallel to the car's existing charger (does it need to be wired differently, now that there is an extra cable(s) coming from the extra pack?) I can run both at the same time, and if the charge goes down...I can theoretically switch the extra packs (discharged) for charged cells and go on my way without stopping to plug in and wait to charge?


My suggestion was to parallel the packs, because in my proposal, the packs would have the same voltage.
If you want to go through the charger, the charger has to be prepared for DC voltage input, like the SmartCharger.
But again, additional costs



sj281708 said:


> I drive back and forth between two cities, A and B. In City A, my home charger charges my extra battery and I put it in my car and I go on my way, using it when my EV pack depletes...in City B where I work, on my way back, I drop the discharged battery and pick up charged ones from B and I'm on my way back home again...will that work for same kind of batteries?
> 
> So if I am in City A with both full battery packs, and by the time I drive to City B and reach it, by extra battery is depleted, so then I pick up new charged battery in B, in exchange for the old discharged one, and use that to come back home in A.


Swapping battery packs is not so easy.
Only the cells would be about 200kg / 440lbs.
And it would not be in a few minutes.
For a DIY car … don't do this 



sj281708 said:


> Does that make sense?


Economically not. It would be a heroic mission for a DIY guy, even if it's not his first car ;-)

You wrote about a limited budget, so take a look at the costs and separate the options.
I guess you would end up with a Leaf or Volt.

Michael


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## brainzel (Jun 15, 2009)

btw: charging while driving

Yes it works. But actually you don't charge unless you stop, because a charger with an DC output f.ex. 20A would reduce the current, drawn out of your pack.

So if you are cruising down the road and consume 120A, 100A would come out of the pack, 20A out of the charger.

Michael


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> Great! I think I get it now. I however would not need 70 miles on the extra pack....I just need the extra pack if for any reason I can't charge the existing pack. Meaning, I can get the existing pack to do 55, and maybe do 15 with the extra one you talked about.
> 
> So, if I connect the extra pack in parallel to the car's existing charger (does it need to be wired differently, now that there is an extra cable(s) coming from the extra pack?) I can run both at the same time, and if the charge goes down...I can theoretically switch the extra packs (discharged) for charged cells and go on my way without stopping to plug in and wait to charge?
> 
> ...


That actually does help. Questions: How long will you be in city B?

Most EV folks would see this as you get enough battery to get from A to B and back if you have the permanent pack of the EV, plus the two swapped packs in A and B. So the question is what is the limitation of having a single pack that has the capacity of all 3 subpacks you describe? Will they not all fit in the vehicle?

ga2500ev


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> The reason I said separate packs is because I want to switch batteries easily from discharged to new, charged ones. It will be too much of a hassle to unwire a pack and swap out old battery for the new, if I go for the bigger pack route. Please see my above response with City A and B, to see my plan. If I keep two battery chargers at two different locations, can I swab back and forth if those are my two destinations. I really hope I didn't confuse you.


I do understand what you are trying to do. I think we're all trying to explain that this is the most expensive and complicated way to accomplish the goal.

Let me take another stab at it. You have two charging stations in two cities and enough battery to get the EV from one city to the other one way. You keep proposing to swap batteries and to carry/drag those extra batteries between the two cities.

The fact of the matter is that you really don't want or need the batteries. What you want/need is the charge that the batteries contain transferred to the EV in a timely fashion.

If you are going to invest this type of time/energy/money into this project, then the much better way to do is to develop a stationary quick charging station in each city (or at least in city B). The charging station would be a stationary set of batteries, a charger for those batteries (again stationary), and a quick charger that can dump the charge from the batteries into the EV.

So all you'd have to do is pull up, plug in, charge fast (30 minutes or so), and take off. The stationary charger can then take over the job of recharging the stationary pack of batteries.

You end up with approximately the same equipment (a charger and a pack in each city), but with nothing to attach to or swap with the EV.

Just a thought. Do a search for "Dump charger" for more information.


ga2500ev


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## sj281708 (Apr 29, 2014)

brainzel said:


> My suggestion was to parallel the packs, because in my proposal, the packs would have the same voltage.
> If you want to go through the charger, the charger has to be prepared for DC voltage input, like the SmartCharger.
> But again, additional costs



...and additional weight, so losses in rolling resistance too, i bet..




brainzel said:


> Swapping battery packs is not so easy.
> Only the cells would be about 200kg / 440lbs.
> And it would not be in a few minutes.
> For a DIY car … don't do this


Wouldn't each battery be around 12 lbs though? And together, 30 of them add up to 300-400lbs??

Thanks, Michael!


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> What you want/need is the charge that the batteries contain transferred to the EV in a timely fashion....
> 
> So all you'd have to do is pull up, plug in, charge fast (30 minutes or so), and take off. The stationary charger can then take over the job of recharging the stationary pack of batteries.


Got it.  but just curious...is it at all possible to not wait 30 minutes or charge from the station like a normal chargepoint? That's the only reason I wanted to carry these heavy and bulky charged cells to the point of them being discharged, and then dropping them off in the stationary charger in the next city. I keep asking if it charges while I'm driving because I just need to shave off as much time as I can. Sorry about that.

=ga2500ev;388255]
You end up with approximately the same equipment (a charger and a pack in each city), but with nothing to attach to or swap with the EV.

Just a thought. Do a search for "Dump charger" for more information.
ga2500ev[/QUOTE]

Cool! But I have an abundance of types of batteries and chargers from work and I want to do something like having the stationary charger and batteries, but I really do want to pick up those batteries and have them charge the EV pack or the on-board charger and not have to fast charge by plugging in at the station. I can deal with the weight, even though I understand that it would take a toll on my range and chassis...sorry for being repetitive...

Kinda like this: http://www.treehugger.com/cars/mira-plugless-plug-in-hybrid-car-has-removable-battery-packs.html

I know this is the only pack they have and they have been designed this way, but could something similar to this be done?


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> I do understand what you are trying to do. I think we're all trying to explain that this is the most expensive and complicated way to accomplish the goal.


Also, looks like others are asking similar questions: http://www.diyelectriccar.com/forum...ric-car-batteries-portable-battery-90840.html


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> That actually does help. Questions: How long will you be in city B?
> 
> Most EV folks would see this as you get enough battery to get from A to B and back if you have the permanent pack of the EV, plus the two swapped packs in A and B. So the question is what is the limitation of having a single pack that has the capacity of all 3 subpacks you describe? Will they not all fit in the vehicle?
> 
> ga2500ev


I wan't to spend as little time as I can in City B, because I'm passing through for a pick-up and should be on my way back to city A as soon as I have what I need. What if the cities are 200 miles apart, and the single pack (existing) does not go all the way from A to B, so I need the extra pack I am carrying to take me there. After I am done with B, and want to head back to A, I drop of the near-depleted one, and pick up the full one, and now I can be assured that I can travel all the way home with the EV pack AND the swapped full pack I picked up in B. They should fit in the vehicle...or I didn't understand the last part of your question...thanks, ga2500ev!!


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## onegreenev (May 18, 2012)

> What if the cities are 200 miles apart, and the single pack (existing) does not go all the way from A to B .....


Well then in this situation I would just jump into my trusty old Diesel and drive there and back on one fill up. Pretty simple actually. Might even be easier. My hybrid is two cars. One electric the other Diesel.


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> Also, looks like others are asking similar questions: http://www.diyelectriccar.com/forum...ric-car-batteries-portable-battery-90840.html


Yes. And the thread has two similar properties:

1. A newbie asked the original question.

2. The response pointed the newbie to dump charging.

ga2500ev


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> I wan't to spend as little time as I can in City B, because I'm passing through for a pick-up and should be on my way back to city A as soon as I have what I need. What if the cities are 200 miles apart, and the single pack (existing) does not go all the way from A to B, so I need the extra pack I am carrying to take me there. After I am done with B, and want to head back to A, I drop of the near-depleted one, and pick up the full one, and now I can be assured that I can travel all the way home with the EV pack AND the swapped full pack I picked up in B. They should fit in the vehicle...or I didn't understand the last part of your question...thanks, ga2500ev!!


Honestly, I think I'm agreeing with onegreenev on this one. If this is a regular trip, then the current infrastructure simply doesn't support an EV doing the job.

All of a sudden you changed the range requirements from 70 miles or so one way to 200. Yet there is no time available to do anything other than to swap packs?

Swapping packs and putting the depleted one on the charger in City B isn't going to be a two minute operation. You have to disconnect the extra pack, remove it from the vehicle, put it on the charger, get the charged pack into the vehicle, and reconnect it.

Think in about the same timeframe it takes to hook up or disconnected a trailer from a truck. Seems simple, but rarely is it a two minute operation.

With dump charging, you just pull up and plug it in. Depending on the range you may not even need to get back a full charge and be back on the road in a 15-20 minute timeframe.

The difference is that with dump charging, you can spend the extra time doing something else since there's nothing to move, change, or plug in. Think of it as a same kind of pit stop that is done when refueling.

What you propose is way more expensive and complex and way less reliable than simply recharging. I would agree with you that 4-8 hours of waiting would be unreasonable. But I really cannot see on how on a 2-4 hours trip how 10-15 minutes of extra time per trip really justifies the extra expense and complexity of battery swapping.

ga2500ev


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> Got it.  but just curious...is it at all possible to not wait 30 minutes or charge from the station like a normal chargepoint? That's the only reason I wanted to carry these heavy and bulky charged cells to the point of them being discharged, and then dropping them off in the stationary charger in the next city. I keep asking if it charges while I'm driving because I just need to shave off as much time as I can. Sorry about that.
> 
> =ga2500ev;388255]
> You end up with approximately the same equipment (a charger and a pack in each city), but with nothing to attach to or swap with the EV.
> ...





> Cool! But I have an abundance of types of batteries and chargers from work and I want to do something like having the stationary charger and batteries, but I really do want to pick up those batteries and have them charge the EV pack or the on-board charger and not have to fast charge by plugging in at the station. I can deal with the weight, even though I understand that it would take a toll on my range and chassis...sorry for being repetitive...
> 
> Kinda like this: http://www.treehugger.com/cars/mira-plugless-plug-in-hybrid-car-has-removable-battery-packs.html
> 
> I know this is the only pack they have and they have been designed this way, but could something similar to this be done?


You are at cross purposes in your goals. You want an EV. I presume you still want it to be cost effective (again I ask what is your budget?) But you also want to shave time off a trip that's outside the EV range of everything but a Tesla.

The time issue is going to kill this project. It's going to do so because time constraints mean that you are going to need more energy to move quickly on your route, and limited time to get your range extending energy on board.

Take a read of the range on the Mira packs: 15 miles in EV only mode. How long do you think it'll take to swap 15-20 cassettes worth of batteries from the back seat or trunk of your vehicle. You're not going to be able to have a single 200-400 lbs auxillary swap pack that you can easily get in and out and connect quickly from inside the car.

If swappability is absolutely the #1 goal at all costs, then the only effective way to pull this off is to use a trailer loaded with the extra battery pack. It'll still take about 10-15 minutes to swap, but it could be done. Essentially you can dump charge from the trailer by paralleling the trailer pack and the onboard one. The trailer pack would contribute energy to both the drive motor and to recharging the onboard pack.

This is the only way I can see meeting all the goals you have outlined. There's no way to pull this off in the timeframes you have specified with the swap pack onboard.

ga2500ev


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> You are at cross purposes in your goals. You want an EV. I presume you still want it to be cost effective (again I ask what is your budget?) But you also want to shave time off a trip that's outside the EV range of everything but a Tesla.
> 
> The time issue is going to kill this project. It's going to do so because time constraints mean that you are going to need more energy to move quickly on your route, and limited time to get your range extending energy on board.
> 
> ...


I agree with you wholeheartedly, I am just really interested in swapping...kinda like this (http://www.torquenews.com/1075/add-40-miles-driving-range-nissan-leaf-enginers-add-battery-pack) but the pack allows for the cells to be individually swapped and not charged...

Thanks for your answers, ga2500ev...I appreciate your time and for tolerating me


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> I agree with you wholeheartedly, I am just really interested in swapping...kinda like this (http://www.torquenews.com/1075/add-40-miles-driving-range-nissan-leaf-enginers-add-battery-pack) but the pack allows for the cells to be individually swapped and not charged...
> 
> Thanks for your answers, ga2500ev...I appreciate your time and for tolerating me


No problem. I'm just trying to get you to see the issues clearly. For example the link above. The smallest add on pack weighs 160 lbs, and offers an additional 20 miles of range. Honestly, how do you really expect to dead lift a bulky, heavy pack to swap it?

It's designed as a permanent installation in the vehicle.

I'm really not trying to be contrary just to be contrary. I just want to understand how you expect to swap a pack in the vehicle with any significant range capability in a shorter time frame than it would take to charge it.

As for the trailer idea, take a read here of essentially your idea.

ga2500ev


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> No problem. I'm just trying to get you to see the issues clearly. For example the link above. The smallest add on pack weighs 160 lbs, and offers an additional 20 miles of range. Honestly, how do you really expect to dead lift a bulky, heavy pack to swap it?
> 
> It's designed as a permanent installation in the vehicle.
> 
> ...


I am not thinking of getting this exact unit...I am thinking...why can't the batteries be the individual cells, like 10 or so lbs of laptop sized cells picking up and swapping 20 or so individually and not have to swap the 160lbs at once. Yes, time is against me, but why can't that be done? Michael talked about 180AH CALB cells that are like 12 lbs or something...

One last question...here is the installation and wiring of this; can you shed some light on how the DC,AC wires, relays and EV controller wires are being tapped into? These pictures are anything but self-explanatory. Thanks, as always!


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> I am not thinking of getting this exact unit...I am thinking...why can't the batteries be the individual cells, like 10 or so lbs of laptop sized cells picking up and swapping 20 or so individually and not have to swap the 160lbs at once. Yes, time is against me, but why can't that be done? Michael talked about 180AH CALB cells that are like 12 lbs or something...


Because it's complicated, time consuming, and unreliable. Cells have to be physically secured, wiring needs to be locked down, and there has to be monitoring equipment in place also.

You seem to be hellbent on in vehicle swapping to extend range. When given a more plausible way to extend range (dump charging), you stated that it was too time consuming. I suggest the trailer, which works in the timeframe you propose, and yet you come right back to in vehicle swapping, which honestly can only be done in the kinds of time frames it would take to do the dump charging anyway.

The types of range extenders that are out there are designed with these constraints in mind. The only reason to swap is to save time over charging. Swapping individual cells isn't going to save that time and is going to be the absolute most time consuming, complex, and unreliable way to get the job done.



> One last question...here is the installation and wiring of this; can you shed some light on how the DC,AC wires, relays and EV controller wires are being tapped into? These pictures are anything but self-explanatory. Thanks, as always!


I really haven't a clue. The Leaf isn't really relevant to the discussion unless you are actually planning on using one to do the job.

I think I've finally run out of steam on this. IMHO you simply cannot do what you want given all the constraints that you've given. And you really do not really seem to be interested in solving the problem (extending range in a timely reliable fashion) as opposed to implementing a specific solution that will not fit within the given constraints (in vehicle swapping).

So I wish you luck. I'm interested in seeing if you can figure out how to cut the Gordian knot.

ga2500ev


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## sj281708 (Apr 29, 2014)

ga2500ev said:


> Because it's complicated, time consuming, and unreliable. Cells have to be physically secured, wiring needs to be locked down, and there has to be monitoring equipment in place also.
> 
> You seem to be hellbent on in vehicle swapping to extend range. When given a more plausible way to extend range (dump charging), you stated that it was too time consuming. I suggest the trailer, which works in the timeframe you propose, and yet you come right back to in vehicle swapping, which honestly can only be done in the kinds of time frames it would take to do the dump charging anyway.
> 
> ...


I do appreciate your patience...and I will definitely consider dump charging...but I don't know how exactly that works, so I kept thinking that picking up and placing batteries is a lot easier than a powerful charger...

If you don't mind, one more question came up to me...I recently saw an article, which said: "Regenerative braking can be achieved adding a clutch to the alternator. The clutch engages when the vehicle is coasting or braking causing the alternator to help slow the engine as it charges the battery that powers the starter motor and other electric devices in the vehicle." Don't they mean electric motor, and not alternator?? I understand that I probably burnt you out, so if you don't respond...I'll be fine with that


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## onegreenev (May 18, 2012)

Dump charging. Is exactly just as it sounds. As an example, you take one full battery (a) which is 200ah in size and one empty battery (b) that is 100ah in size. You connect battery a to battery b and battery A will fully charge battery B. Or you take a large bank of batteries that can hold more ah than the one your dumping into but the same nominal voltage and you connect them together and one will charge the other. The empty battery bank will pull from the larger full pack until the one is charged. This kind of charging happens real fast. I can demonstrate with a small cell being charged with a large one. I can take a 100ah cell that is full and charge up a 2.5ah cell in seconds. The load bank must be much larger than the load being charged. 

This is the idea behind FAST charging. Have a huge bank of batteries that is charged by solar. Then when a car comes in you select your voltage level and plug into the car and let the power from the bank of batteries charge your pack. 


But then you run into the problem of only being able to fast charge at the location of that charge station.

The best solution to extended range is either use more batteries in your conversion and be sure it is matched to your needs or get another vehicle and just drive that when needed. If your daily range is always out of the range of your conversion then you have not built your conversion very well and you need a Hybrid. A Volt would come to mind. 

Remember, total electric is not for every situation. Use the appropriate solution for the situation. There is nothing more to be said. 

I'd offer you a suggestion. Completely mount your cells in your conversion. Mounted securely in the boxes and secured from coming out in case of an accident. Then take them all out again and then put them all back in again exactly the same way. Then you will experience how dumb the idea really is to do single battery swapping to save time.


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## onegreenev (May 18, 2012)

So if your pack is 120 volts nominal you will need at least 133 volts to charge your pack to 3.5 volts nominal with a 38 cell pack. So be sure to size your stationary pack to provide at least that level of voltage. You might even set it to dump at 138 volts. That would give you just under 3.65 volts nominal per cell. At that voltage your pack can't be over charged but it will charge fast as long as your bank has the capacity. 

So if you can set your bank to any voltage level you need you can fast charge any vehicle that comes in for a quick charge.


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## ga2500ev (Apr 20, 2008)

sj281708 said:


> I do appreciate your patience...and I will definitely consider dump charging...but I don't know how exactly that works, so I kept thinking that picking up and placing batteries is a lot easier than a powerful charger...


The charger is only powerful because of the batteries it is built from. The stationary battery bank can be recharged normally over an 8-10 hour period of time from a normal charger. The power comes from the ability of a pack to dump charge very quickly.

The real challenge in a dump charger is how to make it a bit smarter so that it can effectively charge quickly over the entire charging period. The caveman way of dump charging is simply to directly connect the big stationary pack to the smaller vehicle pack, with the larger pack at a voltage that causes charging. OnegreenEV describes this above in his post. However, the charging speed/current is based on the voltage differential between the two packs. So the closer together the packs come in voltage, the slower the smaller pack charges.

A smarter charger would follow a standard charging profile called a constant current/constant voltage profile. In short that charger provides the maximum allowed current, regardless of voltage, as long as the charging pack has not reached its target voltage. Once that occurs, the charger switches to constant voltage mode and holds the target voltage until the current drops to a cutoff.

To do this will require some smarts in the charger.




> If you don't mind, one more question came up to me...I recently saw an article, which said: "Regenerative braking can be achieved adding a clutch to the alternator. The clutch engages when the vehicle is coasting or braking causing the alternator to help slow the engine as it charges the battery that powers the starter motor and other electric devices in the vehicle." Don't they mean electric motor, and not alternator?? I understand that I probably burnt you out, so if you don't respond...I'll be fine with that


I'm only "burnt out" on swapping cells. It's not a viable option.

As for your quote from here:

You need to take into account the sentences that follows (emphasis mine):



> This type of regenerative braking is relatively inexpensive and easy to implement in *existing vehicles* An example of this technology is Mazda's i-ELOOP system. The i-ELOOP system stores the energy recovered by the alternator in a supercapacitor that helps to power the vehicle's 12-volt electrical system. Supercapacitors are used to perform this function because they can charge and discharge much more quickly than batteries.


In short the discussion is about a standard gas vehicle, not an electric one. So they are actually taking about an alternator.

ga2500ev


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