antoinem
Posts: 1
Joined: Wed Sep 09, 2015 10:52 am

Additional pack

Wed Sep 09, 2015 11:37 am

Would it be possible to add additional batteries to the existing battery pack?

Don
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Location: Biloxi MS

Re: Additional pack

Thu Sep 10, 2015 7:46 am

Discussed here many times in previous threads - Nearly impossible to do because the car was basically designed around it's 88 cell battery pack. The charger, inverter and other systems (Air conditioning, heating etc) were designed for the voltage the pack came with. If you need a 100+ mile range EV, I would look elsewhere

Don
2012 iMiEV SE Premium, White
2012 iMiEV SE Premium, Raspberry Metallic
2012 iMiEV SE, White
2017 Chevy Volt Premier
2014 Ford Transit Connect XLT SWB wagon
2006 Itasca Navion Sprinter Motor Home

PV1
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Re: Additional pack

Thu Sep 10, 2015 8:21 am

An auxiliary pack would be possible and has been done before, but modifying the OEM battery pack so far does not look like it would provide additional range. A second, li-NMC battery pack could be constructed and wired into parallel with the existing pack to provide an immediate range increase. The pack would have to be 325.6 volts nominal, 88 cells or cell blocks wired in series, with automatic contactor connect/disconnect based on car's main positive contactor drive.

Even if larger capacity cells would fit and the car could be made operational, the BMU performs coulomb counting and would only use so much of the available capacity. The unknown factor would be if the i-MiEV would eventually perform a calibration and open up the unused capacity of the larger cells. You would not gain any range with this method until the point if/when the car performs a recalibration.

The bulk of this information and conversation can be found here:
viewtopic.php?f=14&t=1255
"Bear" - 2012 Diamond White Pearl ES with QC
"Koorz" - 2012 Cool Silver Metallic ES with QC
"Photon" - 2017 Bolt EV LT in Orange with QC
Solar-powered since 10/10/2013

Life with Electric Vehicles: https://lbry.tv/@PV1

siai47
Posts: 367
Joined: Fri Jun 14, 2013 5:54 pm

Re: Additional pack

Thu Sep 10, 2015 3:02 pm

I never ran it for a long time but adding an additional pack will work. The range meter starts out with a normal range (like 70 miles) regardless of how many packs are connected. The segments on the meter start to drop at a slower rate with two packs and the available range drops very slowly. Although the car reads current through the original pack, it doesn't read the current of the additional pack. Therefore, the car thinks it is using less energy (like driving down a mountain) because only 1/2 of the energy to run the car comes through the original pack and it's hall effect transducer. I didn't drive it to low battery cutoff or anything near to it because there was no monitoring on the external pack. However, the range looked like it would be nearly doubled. The additional pack (which was a standard I-MiEV pack with the steel bottom mounts removed) actually fit in the back of the car with the seats folded down. The rear weight bias and the higher CG with the pack in the back made the handling a little dicey. Plus it looked a little silly with a couple of large orange power cables going out the passenger side rear window and going into what looked like the gas tank door to other drivers.

Aerowhatt
Posts: 446
Joined: Wed Jan 28, 2015 1:52 pm

Re: Additional pack

Thu Sep 10, 2015 4:41 pm

siai47 wrote: Plus it looked a little silly with a couple of large orange power cables going out the passenger side rear window and going into what looked like the gas tank door to other drivers.


Just a quick question(s). You tied it in through the DCQC cable and manually Switched the DCQC contactors inside the battery pack under the car? The system did not lock out the drive with those contactors closed? How did you get the main contactors in the range extender battery pack to close? I'm truly sorry about your prospects for a Volt.

Currently working towards a Serial hybrid set up for the "i", so these questions help move that forward. I'm about half way there at this point. Having a serial hybrid option for the EV's would allow our household to not own an ICE automobile just EV's. So instead of a 30% -35% or so of the family driving done presently on gasoline it could approach zero at < 2% without having to worry about charging infrastructure issues and availability causing delays on longer trips.

Lousy of Chevy to pull the nationwide rollout of the 2016. They broke the golden rule of consumer based business (always promise less than you can deliver).
"stupid is as stupid does" Forest Gump

Aerowhatt
(July) 2014 cool silver ES, acquired new 4/2015 (40.9ah at ~34K miles)
(Aug) 2014 Labrador Black Pearl ES, acquired new 3/2016 (39.7ah at ~20k miles)

siai47
Posts: 367
Joined: Fri Jun 14, 2013 5:54 pm

Re: Additional pack

Thu Sep 10, 2015 5:55 pm

When I did this I was messing around with my first attempts at getting into the HV battery. The car was non QC and had a non QC pack in it, the second pack was from a QC car. I attached cables to a Anderson connector and routed them to where the QC port would have been located on the outside of the car. The other end of the cables were terminated at the inverter where the main power leads came in from the car's battery pack. This was a temporary setup to make use of a Manzanita Micro PFC-50B charger for quick charging. I wouldn't recommend this as a permanent solution as HV is available at the connector any time the car is in the ready position. The QC charge cables on the second pack were terminated with a mating Anderson connector. The HV contactors in the I-MiEV are all controlled by external 12v power fed through multipin connectors on the outside of the packs. Two wires were tapped into the wires that closed the main contactor in the original pack to provide power to close the QC charge contactor in the external pack. This way there was a way to allow the pre-charge contactor to sequence in the original pack before the main contactor closed and supplied power from both packs to the inverter. This also allowed for the car to be turned on and off in a normal manner without additional switching. The HV tie point of the second pack had to be outside of the original pack. This eliminates any power from the additional pack being read by the original packs hall effect transducer which would upset the charge/discharge calculation by the "range" meter. Like I said, this was a one time test to see if it could be done. I finally put the QC pack in the car and used the QC contactor to switch the Anderson connector for a connection point for my external Manzanita charger. All that being said, the I-MiEV IMO cannot safely handle the extra weight of an addition pack in the car. If I was to do it again, the pack would need to be on a external trailer towed behind the car. Even if you could carry the additional weight by changing rear springs, there is no way to lower the CG which really makes lane changing fun (exciting) :o ! BTW--both packs could be charged in this configuration by the internal charger but there was no cell balancing available to the external pack so this wasn't a real solution for a long term range extender.

JoeS
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Re: Additional pack

Thu Sep 10, 2015 7:56 pm

siai47, thank you very much for continuing to post on this forum and for sharing your insightful experiences. I find it gratifying that the external pack, injected into the battery power lines just before the controller, spoofs the iMiEV into thinking it's regen-originated energy and doesn't otherwise negatively affect the system. Agree with you about the weight placement and that a trailer with power pack would be a preferable solution (and one that could be quickly attached only when needed). Still need to repair my Enginer dc-dc as that will give me lots of options with all the 48v power packs I have lying around…
EVs: Two '12 Wht/Blu SE Prem., '13 TeslaMS85, three 156v CorbinSparrowsLi(NMC), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab96
Hybrids: 48v1kW bike
Mothballed ICE: Orig.Owner '67 Saab96V4, '88 IsuzuTrooper; '76 MBZ L206D RHD RV

Aerowhatt
Posts: 446
Joined: Wed Jan 28, 2015 1:52 pm

Re: Additional pack

Thu Sep 10, 2015 8:01 pm

siai47 wrote:When I did this I was messing around with my first attempts at getting into the HV battery. . . . BTW--both packs could be charged in this configuration by the internal charger but there was no cell balancing available to the external pack so this wasn't a real solution for a long term range extender.


Thanks so much for the valuable details. I'm looking at using the bolted main cable connections just inside the battery pack to piggy back another set of power cables. They would have their own contactor actuated by whether the genset was running, or not. That way the whole thing is disconnected from the main pack inside or directly outside the main pack if the genset is off. As with stock, all of high voltage would be terminated inside the pack by the main contactor when the vehicle is parked .

The current sensors inside the pack that talk to the system are battery bank side of the high voltage cable connections (at the battery pack) to the inverter aren't they? It looked that way from Martins pack cell replacement video. Is that correct from your experience?

I can use smaller cables since they will only carry genset amperage so waterproofing should be attainable. The car should see the whole thing much like it did your extra paralleled battery pack experiment. As reduced demand by the motor system and regen when genset output exceeds motor and systems power usage.

Of course the same type of connection could be done for a trailered XR battery (or smaller onboard one) with the XR battery contactors (one at each end) run by the presents or absence of system power from the cars existing system.

I've collected quite a bit of freeway cruising Canion data suggesting that as a serial hybrid the "i" should get between 50 and 58 MPG. Again, for EV purists the unit would likely be used two or three times per year burning less than 25 gallons of gas per year and replace the current need for a gasoline car in the household, burning hundreds of gallons per year. The rest of the time would be pure EV driving charged with in house solar. Sometimes the genset would be taken along for piece of mind but not needed and hence not used.

Aerowhatt
(July) 2014 cool silver ES, acquired new 4/2015 (40.9ah at ~34K miles)
(Aug) 2014 Labrador Black Pearl ES, acquired new 3/2016 (39.7ah at ~20k miles)

siai47
Posts: 367
Joined: Fri Jun 14, 2013 5:54 pm

Re: Additional pack

Fri Sep 11, 2015 6:23 am

I can't remember which side it is on but the hall effect (current sensor) is around the buss bar right at the end of the (I think) negative side of the HV pack right where the external cable connections are located. When you are dealing with internal pack wiring, the connection points on either side of the current sensor are switched via the main contactors. The contactors are really tough to get to which creates a connection problem if you want to provide an external source of energy to the pack as the connection will only be "hot" when the car in in the "ready" mode or connected to the EVSE. If you have a Chademo car (and don't wish to use the Chademo ever again) then the connection point is easy. When I installed the QC pack in my car I cut off the Chademo connector and soldered on a Anderson connector at that point. I put a switch on the dash to energize the HV contactor via a relay located under the back seat. For charging purposes (and I suppose it could be used for an external pack) the car had to be in the ready mode before I closed the switch to the external PFC-50 charger. Once the switch was closed, the charger could be energized and up to 10 KW could be sent to the pack. If the car was in park, nothing showed up on the energy use gauge. However, if the shifter was moved to drive, you could see the gauge move into the regen mode. If you looked at CANION data while charging in this manner, the data reported by the CANION (and the dash gauge) became increasingly inaccurate as the power input exceeded 4 KW and was about 40% low at 10KW. This inaccuracy doesn't really affect anything except the range calculation. BTW-for external charging purposes this is the only way it will work. You would think you could shut down the car and plug in the EVSE to start the charging process and close all the required contactors. I tried this and when the total power input to the pack exceeds about 4KW, the car shuts down the internal charger and opens the contactors---something the PFC-50 didn't like. I wired the switch for the QC contactor to 12v power that is only available with the car in the ready mode. This way the dash gauges work, CANION data is available, the DC-DC convertor is running and the BMS is functional. For driving with a range extender, this would not be a problem because the car is in the "ready" mode anyway. In summary, there are several ways to add external power to the car either though the existing pack or paralleling it. Each has it's own set of problems but it can be made to work.

PV1
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Re: Additional pack

Fri Sep 11, 2015 6:56 am

Aerowhatt, I've done the same, and found that I average 23-25 amps for 60 MPH driving. What stopped me from doing a generator was the fact that I couldn't find an affordable generator capable of producing 350 volts, and a converter such as Enginer isn't powerful enough to maintain speed until a tank of fuel was used up. I started doing some research on an electric pusher trailer made up of 3 LEAF batteries (or a crap-load of laptop cells), but couldn't figure out a way to get a powered trailer with that much battery light enough. If it could've been pulled off, then I could do the route from Pittsburgh, PA to Normal, IL without any gasoline or diesel with 3 or 4 stops at quick chargers.

It seems the best place to tie into the HV bus is inside the motor controller, with the auxiliary battery contactors driven by the main pack's positive main contactor (there is sequencing involved with the positive, negative, and pre-charge contactors that make the positive contactor the most suitable for aux. power interface). It's the last to engage at startup and the first to disengage at shutdown. If you tie onto the main negative contactor, then the condenser discharge circuit may try to discharge the aux. battery if it is voltage-based and not time-based. Plus, at startup, the aux. pack would engage before the pre-charge is complete (negative and pre-charge contactors engage first, then the positive engages as the pre-charge disengages).

The i-MiEV will shut down if it sees too much power going into the battery during a normal charge. This threshold is pretty close to the max output of the charger (4 kW threshold on a 3.3 kW charger), I guess to protect the charger from overload. My friend with a Ford Focus Electric has successfully added a secondary charger and CHAdeMO capabilities to his Focus. The Focus doesn't have as many safeties and protections and will allow him to inject an additional 3 kW during a level 2 charge for a total of 10 kW charging. Also, he can leave his car in READY and is able to use a CHAdeMO quick charger at full power. With a much more active thermal management system on the battery, it will cool or heat as necessary when charging and driving. But, that's a separate topic.

That is odd how the needle won't move into the Charge zone while in Park. If I hold the high beams on, the needle will move up a bit showing the extra load on the 12 volt system while in Park.
"Bear" - 2012 Diamond White Pearl ES with QC
"Koorz" - 2012 Cool Silver Metallic ES with QC
"Photon" - 2017 Bolt EV LT in Orange with QC
Solar-powered since 10/10/2013

Life with Electric Vehicles: https://lbry.tv/@PV1

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