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Discussion Starter · #1 ·
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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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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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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Discussion Starter · #4 ·
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.


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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Discussion Starter · #5 ·
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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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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Discussion Starter · #7 ·
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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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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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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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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Discussion Starter · #13 ·
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
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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Discussion Starter · #14 ·
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
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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Discussion Starter · #15 ·
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.



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
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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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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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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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
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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Discussion Starter · #19 ·
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
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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Discussion Starter · #20 ·
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...:D
 
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