xado1
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Delivery Date: 01 Oct 2013
Leaf Number: 003833
Location: Vienna/Austria

Re: Extra Battery, How to Integrate with 24kWh Traction Batt

Thu Apr 03, 2014 1:07 am

after checking all possible things,i will end up with a fuell cell.they are working on a plug and play solution.
when ordering more items,the price can drop to 8.000.-euro(11.000.-$)

http://www.anleg.de/
http://www.76937.de/iShop/pc/index.php? ... duct_id=52

for me it would be the best solution,so i can use the fuel cell in my electric boat,because here in euopr ,gasoline boat engines are not allowed in the most lakes.
2013 Leaf Tekna(SL) ,white,no solar,winter package,built in Sunderland-GB 8/2013

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drees
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Re: Extra Battery, How to Integrate with 24kWh Traction Batt

Thu Apr 03, 2014 9:43 am

valerun wrote:don't know - IMO 5kwh has near-zero utility. 100lbs would also be near-impossible with safe type of a battery. This illustrates a problem with battery-based range extension. Seems like a good idea until one actually runs the numbers.

What do you think the minimum capacity is in terms of utility? For me, anyway, lots of my day trips run the to 60-80 mile range and that's simply not possible without charging on a 3-year old LEAF unless it's flat and you can drive a constant 45-50 mph at most. Yeah, 5 kWh will be not be too usable, but 10 kWh would be (assuming ~8 kWh usable, good for about 25-30 miles of range).

It seems that with the design you are using, the smarts are pretty much vehicle agnostic. You just need to adjust the battery and perhaps tweak the smart-relay-box according to parameters.
'11 LEAF SL Powered By 3.24 kW Enphase Solar PV

valerun
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Location: Palo Alto, CA
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Re: Extra Battery, How to Integrate with 24kWh Traction Batt

Mon Apr 07, 2014 4:30 pm

xado1 wrote:after checking all possible things,i will end up with a fuell cell.they are working on a plug and play solution.
when ordering more items,the price can drop to 8.000.-euro(11.000.-$)

http://www.anleg.de/
http://www.76937.de/iShop/pc/index.php? ... duct_id=52

for me it would be the best solution,so i can use the fuel cell in my electric boat,because here in euopr ,gasoline boat engines are not allowed in the most lakes.


interesting. how much capacity do you get for $11K? (the second link gives 'The page cannot be displayed because an internal server error has occurred.' when I try to click it). Also, do you know what the round-trip efficiency is? Fuel cells are notoriously inefficient, with round-trip losses of up to 60%... (i.e. you get less than half of the electricity you put in it)
EMW - Creators of the Best-Selling 10-18kW JuiceBox EVSE: http://emotorwerks.com/, JuicePlug - a universal adapter to make any EVSE smart: https://goo.gl/dM29O7, and 12-50kW DC Charging systems: http://goo.gl/oOpBvq

valerun
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Re: Extra Battery, How to Integrate with 24kWh Traction Batt

Mon Apr 07, 2014 4:40 pm

drees wrote:
valerun wrote:don't know - IMO 5kwh has near-zero utility. 100lbs would also be near-impossible with safe type of a battery. This illustrates a problem with battery-based range extension. Seems like a good idea until one actually runs the numbers.

What do you think the minimum capacity is in terms of utility? For me, anyway, lots of my day trips run the to 60-80 mile range and that's simply not possible without charging on a 3-year old LEAF unless it's flat and you can drive a constant 45-50 mph at most. Yeah, 5 kWh will be not be too usable, but 10 kWh would be (assuming ~8 kWh usable, good for about 25-30 miles of range).

It seems that with the design you are using, the smarts are pretty much vehicle agnostic. You just need to adjust the battery and perhaps tweak the smart-relay-box according to parameters.


I think it should be around half of the existing pack or more. That's when you not only have some meaningful range but also get some benefits important for commercial viability of the solution:
* cost of associated hardware is amortized across a bigger pack and becomes a much smaller part of the total system cost. Your $/mile of range improvement goes down quite a bit.
* 50%+ lift in range starts to *feel* serious
* The car with 1.5x+ range of the original starts to become a different type of car - with different, not possible before use cases

For example, 80% range improvement we had with our RAV4EV has allowed us to (1) go on a 110-mile round-trip to visit some business partners, (2) use the car as an energy donor in our car-2-car charging experiments, (3) give the car to our employees and not worry about them running out of range, and of course (4) brag about it being a totally different car now ;-)

Of course, a 40kwhr battery is not cheap so it makes sense only for specialized cases like ours. For mass consumer applications, I would actually develop a hitch-mounted REX unit such as BMW i3's unit (not on the trailer - directly on the hitch - similar to the bike racks). I think that would be a commercially viable product but only with a RENTAL business model.
EMW - Creators of the Best-Selling 10-18kW JuiceBox EVSE: http://emotorwerks.com/, JuicePlug - a universal adapter to make any EVSE smart: https://goo.gl/dM29O7, and 12-50kW DC Charging systems: http://goo.gl/oOpBvq

miscrms
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Location: Phoenix, AZ

Re: Extra Battery, How to Integrate with 24kWh Traction Batt

Sun Oct 05, 2014 12:52 am

The main challenge to adding a PHEV pack to the original Prius was figuring out a way to trick the Battery controller into using more battery capacity. The Prius battery controller uses a current sensor to measure amps in and out of the pack, and calculates SOC primarily based on current flow integrated over time to get Ah in and out. This is commonly called coulomb counting, and is common in NimH and Li battery systems where voltage is a poor indicator of SOC. It knows how many the Ah the battery can hold, so be counting them as they go in and out, it knows what SOC should be.

If you injected current from the second battery on one side of the current sensor, the battery controller would "count it" as current coming out of the primary pack, and when X Ah had been counted as coming out of the primary pack it would assume min SOC had been reached and start recharging. It assumed a fixed battery pack size, and didn't care that you had added more battery capacity. It would still only use the amount of Ah it expected the original battery to be able to supply.

If you injected current on the other side of the current sensor, the battery controller wouldn't "see" it, and would only count the Ah actually going out of the original pack. So far so good. Unfortunately the HV controller also measures current at the inverter / motor end, and when it saw significantly more amps arriving at that end than the battery said it was putting out, it shut down the HV system assuming a fault had occurred. Not so good.

As a result there were two common approaches to PHEV conversions.
-The budget Enginer approach was to use a dc:dc converter to inject a controlled amount of current on the motor / inverter side of the battery current sensor, keeping it low enough to keep from triggering the fault/shutdown. When not being consumed by the motor / inverter the battery controller would "count" the supplemental current as regen topping up the original battery. The downside to this approach was limited instantaneous power, meaning it couldn't always supply enough current to keep the SOC of the original pack up.
- The more expensive kits generally tapped into the battery side of the current sensor, and required a custom add on controller to either replace the original battery controller, or spoof the right CAN traffic to get the HV controller to use the extra battery capacity.

I would assume the Leaf uses a similar coulomb counting scheme for managing battery SOC, and so could have similar challenges. In general the Leaf's BMS / controller seems quite a bit smarter though, as it seems like it has the ability to adapt to changing capacity over time to account for battery degradation. It would be really interesting to see if this capability extends to revising the capacity of the battery upwards :)

For example, as I understand it the BMS already manages 2 cells in parallel at every leg of the battery stack. What would happen if you simply added a third (or third and fourth) identical cell in parallel (being careful to match them first of course)?

If the Leaf uses simple coulomb counting and a fixed capacity (or is unable to revise capacity upward) on the next charge it would simply put in the right amount of Ah to fill the original pack, and leave the new expanded pack less than full. But if it uses some sort of adaptive technique (maybe particularly on a 100% charge?) that looks for some other markers of charge completion, its possible it might just be smart enough to revise the capacity of the pack up to account for the new cells :)

Maybe it would take multiple charge/discharge cycles to get it all, but that would be really cool!

Rob

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TonyWilliams
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Re: Extra Battery, How to Integrate with 24kWh Traction Batt

Sun Oct 05, 2014 11:17 am

miscrms wrote:For example, as I understand it the BMS already manages 2 cells in parallel at every leg of the battery stack. What would happen if you simply added a third (or third and fourth) identical cell in parallel (being careful to match them first of course)?


That's a great idea.

Thanks.

camasleaf
Posts: 602
Joined: Sun Sep 26, 2010 5:20 am
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Location: Camas, WA

Re: Extra Battery, How to Integrate with 24kWh Traction Batt

Sun Oct 05, 2014 12:15 pm

miscrms wrote:As a result there were two common approaches to PHEV conversions.
-The budget Enginer approach was to use a dc:dc converter to inject a controlled amount of current on the motor / inverter side of the battery current sensor, keeping it low enough to keep from triggering the fault/shutdown. When not being consumed by the motor / inverter the battery controller would "count" the supplemental current as regen topping up the original battery. The downside to this approach was limited instantaneous power, meaning it couldn't always supply enough current to keep the SOC of the original pack up.
- The more expensive kits generally tapped into the battery side of the current sensor, and required a custom add on controller to either replace the original battery controller, or spoof the right CAN traffic to get the HV controller to use the extra battery capacity.
Rob


I am wondering what aproach did Ingineer (Phil) used with his 30kW propane turbine trailer. I recall that the idea was you could drive and charge at the same time.
2011 SLe 06/17/11 Over 71000 miles, GID 213 49.88 AHr; 76%SOH; 16.5kWh
2015 SV 09/02/14, Over 15000 miles, GID 287; 61.12AHr; 98%SOH; 22.2kWh
5.7kW DC System:

hillzofvalp
Posts: 101
Joined: Thu Oct 30, 2014 10:59 pm
Delivery Date: 31 Oct 2014

Re: Extra Battery, How to Integrate with 24kWh Traction Batt

Thu Oct 30, 2014 11:56 pm

I think there is a very good chance (95%) that it will fine to parallel a high C rate pack (with Bms and dedicated contactors) with the leaf's pack. The leaf pack will likely be lower impedance than the aux pack, so generally speaking you are safe. Simple cutoff can be implemented.

I don't think it would be dangerous to charge the auxilary in parallel since it has it's own dedicated bms and contactor.

I have 10kW (112S currently, so will take down a little bit) I want to try. I just need help finding the best place to tap. It'll be important to use heavy gauge since it's going to see load from driving.

I don't think that this will fuss with the leaf bms at all.. because the leaf treats having an aux battery as if it's going down hill or you are on the moon. that's the simplest as I can put it. It's not counting energy consumed from both packs.

EDIT: I think a dc-dc charger makes the most sense... like vals

Bhhaahhb
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Sun Nov 22, 2015 1:29 am

Ok I am not an engineer and I might have missed this answer.

Is there possibly a safe way to link auxiliary power to the engine, so that the draw has to come through the auxiliary from the Leaf battery. Drawing power from the battery when there is not enough in the auxiliary power configuration? For example: take a cargo pod on top of the vehicle add 1 flat solar panel to the top of it. This unit is you auxiliary power with limited deep charge and power regulation. Link this into the power draw so that the Leaf pulls from here first and have the Leafs battery as the "back up" to the auxiliary. While it might not charge the Leaf battery it could extend range during lighted times. Perhaps grounding the Auxiliary through the car or even allowing excess charge to go to the 12 volt like in the SL's. I realize that by adding space you are reducing the perceived response time by the computer, but you are not messing with the regenerative monitoring or the battery in any other way. I am unsure how the computer responds to what it might label as a power leak, but I suspect it would respond as if the battery was wearing out and just keep on ticking.

I would really appreciate feedback on this. I am a new owner, but I drive a lot and the charging network in my city is far from adequate.

camasleaf
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Joined: Sun Sep 26, 2010 5:20 am
Delivery Date: 17 Jun 2011
Location: Camas, WA

Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Sun Nov 22, 2015 8:14 am

The Leaf monitors the DC power between the battery and the inverter. Only limited power can be injected there before the computer shuts down the whole car.
To use the auxiliary battery first, and bypass the DC sensors you will have to connect between the inverter and the motor. It will require another inverter. Even if you manage to sync them, I am sure that the original inverter will complain about it.

If my be easier to make the auxiliary battery power the rear wheels. you will have an all wheel drive Leaf.

Or just wait for the 60 kw battery.
2011 SLe 06/17/11 Over 71000 miles, GID 213 49.88 AHr; 76%SOH; 16.5kWh
2015 SV 09/02/14, Over 15000 miles, GID 287; 61.12AHr; 98%SOH; 22.2kWh
5.7kW DC System:

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