Multiple onboard chargers

[Kohler Controller]

Valerun,
I assume you have captured the charging algorithm from the on board charger (i.e. max current until XXX Volts before current tapers). Can you tell me what constant voltage the on board charger hits towards the end of charge when set on Standard Charge setting? Is it 428V?
What about the extended charge setting, is it 444V?
Thanks.

Kohler -

CV point for Extended charge mode is 381.5V (at least according to my AMPROBE). Charge profile can be seen at http://emotorwerks.com/cgi-bin/JuiceBox/JB_data.pl?ID=28117872904738883433501998325314421251172647325&timeunit=1 (bottom) - report from my JuiceBox

I will post CV point for Standard tomorrow.

Thanks,
Valery.

Thanks Valery. With that information, I would assume the standard charge mode will stop charging (with no taper) when the voltage hits 368V then. Looking forward to the info.

 

[snoltor]

Simple question here: How many amps the Rav4 EV can handle as sold? Perhaps I missed it, but I read through this thread. Wondering because a 208V 70A Tesla Roadster station at a shopping plaza in my area was recently fit with a J1772 connector.

 

[miimura]

Simple question here: How many amps the Rav4 EV can handle as sold? Perhaps I missed it, but I read through this thread. Wondering because a 208V 70A Tesla Roadster station at a shopping plaza in my area was recently fit with a J1772 connector.

The on-board charger will pull up to 40A from the J1772 inlet. The car should pull about 8.3kW from that station. I've used one of those at a Rabobank location.

 

[snoltor]

OK, thanks.

8.3kW from that station.

 

[valerun]

Standard mode cutoff - 369.5V. There is no current taper - 10kW charging all the way.

@Tony - I have also seen 386V in documentation as the CV point for Extended charging mode. My CV measurement was 381.5V - perhaps it's dependent on temperature etc...

Conditions for measurement of Standard mode cutoff were very close to the measurement of the Extended mode. So ~12V difference (~3%) corresponding to 20% of capacity.

 

[Kohler Controller]

Standard mode cutoff - 369.5V. There is no current taper - 10kW charging all the way.

@Tony - I have also seen 386V in documentation as the CV point for Extended charging mode. My CV measurement was 381.5V - perhaps it's dependent on temperature etc...

Conditions for measurement of Standard mode cutoff were very close to the measurement of the Extended mode. So ~12V difference (~3%) corresponding to 20% of capacity.

Thanks Valery. From that information, I expect our battery is arranged in a 92S49P configuration (i.e. 92 in series, 49 in parallel; total 4508 cells).
This corresponds to charging up to 4V per cell for 80% capacity (Std Charge), and 4.15V per cell (with taper) for "full capacity". Technically, that is ~95% SOC to the cell, because they leave some headroom to allow for early regen acceptance.

386V would be 4.2V/cell which would be the highest the pack could ever be charged to, even though they don't. I think that rating is more for first responders (i.e. the voltage could never be above this value)

I believe they keep 3-4 kWh out of reach on each end (top of charge and bottom of charge), which leaves 41.8 kWh usable in the middle. This means our 331V (nominal) pack is rated at ~150Ah total, with ~125Ah accessible.

In other news, I get to use the cyclers until mid March, which means I'll be able to capture up to 95k miles of testing on the cells. Graphs will be posted to this forum second half of March.

 

[valerun]

386V would be 4.2V/cell which would be the highest the pack could ever be charged to, even though they don't. I think that rating is more for first responders (i.e. the voltage could never be above this value)

And we have also found out that BMS will initiate an emergency disconnect around 390V. 12V battery disconnect required to clear the resulting fault...

 

[TonyWilliams]

386V would be 4.2V/cell which would be the highest the pack could ever be charged to, even though they don't. I think that rating is more for first responders (i.e. the voltage could never be above this value)

And we have also found out that BMS will initiate an emergency disconnect around 390V. 12V battery disconnect required to clear the resulting fault...

Awesome news!!! Keep posting all these "quirks", because we can use them to smoke out the appropriate CAN message.

 

[valerun]

386V would be 4.2V/cell which would be the highest the pack could ever be charged to, even though they don't. I think that rating is more for first responders (i.e. the voltage could never be above this value)

And we have also found out that BMS will initiate an emergency disconnect around 390V. 12V battery disconnect required to clear the resulting fault...

Awesome news!!! Keep posting all these "quirks", because we can use them to smoke out the appropriate CAN message.

Hey Tony - I remember you were going up here (SF Bay Area) in March... Is that still in plans? Would be great to meet. V

 

[TonyWilliams]

Hey Tony - I remember you were going up here (SF Bay Area) in March... Is that still in plans? Would be great to meet. V

It looks like it will be April some time. Currently in Dubai, UAE.

 

[valerun]

another fun don't-do-this-at-home RAV4 hack from EMotorWerks - a 38kWHr additional pack in parallel with the main battery. Confirmed no-error operation in all modes. Will see what the onboard computer recalculates as the resulting range

PS. Batteries will be covered, of course ;-)

 

[Airton]

Now that is one heck of a range extender!

 

[Kohler Controller]

You are having too much fun Valerun!

Can you also measure the current from the main pack as well?
It'd be interesting to see the current sharing between the two packs. (all depends on the resistance of the two packs of course).

How do the rear springs hold up? Does it look like a low rider?
I bet you could peel out for over a block with traction control off and the front end slightly lifted like that.

 

[smkettner]

Is this the reason the charging starts so early on the RAV4? Charging seems programmed for ~80kWh battery

 

[Kohler Controller]

another fun don't-do-this-at-home RAV4 hack from EMotorWerks - a 38kWHr additional pack in parallel with the main battery. Confirmed no-error operation in all modes. Will see what the onboard computer recalculates as the resulting range

]

What voltage aux pack did you use, 340VDC?
If so, did you use 106 LFP 110Ah cells at 3.2V each? I only see ~72 in the picture.

 

[valerun]

another fun don't-do-this-at-home RAV4 hack from EMotorWerks - a 38kWHr additional pack in parallel with the main battery. Confirmed no-error operation in all modes. Will see what the onboard computer recalculates as the resulting range

]

What voltage aux pack did you use, 340VDC?
If so, did you use 106 LFP 110Ah cells at 3.2V each? I only see ~72 in the picture.

109 cells. At 3.5 CV, this is 381.5 - or my observed Extended charge CV point. So CVs are matched. On the bottom, we have observed ~310V when the range gets to 10 miles. This would translate roughly to 2.8V per LFP cell. So the bottom matches, as well. But leaves very little room for balancing errors. So we are planning to add a couple of cells to total count of 111 - this way I sacrifice some capacity on top of the curve for LFP but get 2.9V bottom. Alternatively, we could just connect the BMS to a contactor that would break off the pack once the lowest cell hits 2.8V. The latter is probably the best solution overall. We will likely implement both at the same time.

V

 

[TonyWilliams]

Valery,

How about you become a sponsor for our electric rally, BC2BC-2014, www.AllElectricVehicleRally.org, and we put this battery pack to good use?

Tony

 

[valerun]

Valery,

How about you become a sponsor for our electric rally, BC2BC-2014, http://www.AllElectricVehicleRally.org, and we put this battery pack to good use?

Tony

maybe. PM me with your benefits package description.

PS. we have just become an official sponsor of this forum, as well. Mike does a great job across the whole network.

V

 

[valerun]

first real test of that extender pack yesterday - trip to Santa Cruz and back - total of 108 miles at 75-80mph (well, more like 60 on rte 17 ;-). With 70 miles remaining according to the guessometer. JuiceBox-metered charging says ~55kwhrs went back into the packs -

The first ramp is native battery recharging (~20kWhr), the second is aux pack (~35kWhrs). The AUX pack was largely depleted at the end of trip. 20kWhrs remaining in the main.

PS. now outfitted with simple BMS (top-balancing).

Need to adjust rear suspension, though ;-)

 

[Kohler Controller]

Val,
Do you normally charge each pack separately, or did you just do it this time to capture individual pack recharge capacities?