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Re: A peek at the Leaf's Charger

Posted: Tue Oct 09, 2012 5:45 am
by TimeHorse
TEG wrote:Will the ad-on charger follow the charge schedule of the on-board timer?
For instance, if you set to charge to 80%, stopping at 5AM, will both chargers stop charging at 5AM? ( I would assume so, but just checking. )
Bzz, sorry, wrong. What the LEAF really does when you ask to stop at 5AM is typically stop anywhere from 10 minutes to 2 hours before your target time. If you need more charge it could end up starting 2 hours before super-off peak TOU begins and ending 2 hours before it ends, a most unpleasant scenario. The miscalculation is proportional to the amount of charge needed so if you're only charging for 2 hours the offset isn't important but when you live in Virginia with a 4-hour window (I know you Californians get a 5-hour window but we only get 4) a 4:45 charge as is typical with my 70-mi per day 100% commute the offset could be as much as 90 minutes and so the timer will typically start (if set to the ToU SOP end of 5am) at 22:45 the previous night and finish at 03:30, by far not ideal. But if I just fake it and tell it finish by 06:30 (which would get it to finish about the right time under that scenario) and for some reason have a small charge required the night before I may end up charging 100% on-peak because peak begins at 6am (we're really tight on the ToU here in Virginia).

Point being with the 3.3kW charger I'm constantly doing very weird algebraic permutations of my charge timer to get it to finish before at least Off-Peak ended at 06:00. With that 6.7kW it's nothing but start at 01:00 (start of SOP) and by 05:00 and I'd always get a full charge by 05:00! Sigh.
TonyWilliams wrote:When would you need the 6.7kW charger on a timer? For overnight, for either 80% or 100%, just use 3.3kW. For midday, hit the override and charge at 6.7kW.
See my comment above.

Re: A peek at the Leaf's Charger

Posted: Tue Oct 09, 2012 12:54 pm
by DoxyLover
Since Phil hasn't piped up about details, I'll report what he told me. Any mis-information is probably my fault, not Phil's.

His charger is hooked into the CAN bus, listening to the BMS. The BMS turn charging on and off and also regulates the charge rate (power). Through most of the charge cycle, the BMS is requesting much more than the standard on-board charger can supply. The add-on takes the value supplied the the BMS, subtracts the 3.3KW supplied by the OBC, and supplies the remaining demand, up to its own limit.

As the battery nears full, the BMS tapers the requested power down to, and below the OBC's 3.3KW. As this happens, the add-on charger automatically tapers down and then turns off.

In addition, I believe he's monitoring the J1772 pilot signal and subtracting off the 16A draw from the OBC to limit the add-on so that both chargers together obey the pilot signal limit.

It's really clever and, IMHO, done right.

Re: A peek at the Leaf's Charger

Posted: Tue Oct 09, 2012 1:32 pm
by hgoudey
aries wrote:Who makes this charger?
Brusa, Swiss made. I'm not sure of the exact model, but it is something close to, if not exactly, this.

Howdy

Re: A peek at the Leaf's Charger

Posted: Tue Oct 09, 2012 1:47 pm
by TEG
The dashboard shows times to complete charge. It shows one value for 120V and another (shorter) time for 240V. I wonder if that time estimate will always assume 16A for 240V, or if adding another 3.4kW makes that number be less? Also, if you pick an end-time only for charge timer, it starts charging early enough to make sure to get to the target in time, also probably assuming 16A@240V (or 12A if it sees 120V available.)
I wonder if it would start "way early" with the add-on charger because it would be charging twice as fast, but the "time needed" caculation didn't take into account the double speed charging available.

Maybe just minor concerns of little consequence, but I am curious just how "fully integrated" it will be.

Re: A peek at the Leaf's Charger

Posted: Wed Oct 10, 2012 6:39 am
by TimeHorse
hgoudey wrote:Brusa, Swiss made. I'm not sure of the exact model, but it is something close to, if not exactly, this.
Shame that company doesn't make anything bigger than a 3.8kW unit. Seems to me although it may more than double the price it'd still be interesting to look at a 6.7kW to bring the LEAF up to 10kW. Sound like it'd never request more than that so a 15kW unit wouldn't do any better than 6.7kW but just curious about possibilities, that's all. I would love a 2 hour charge at home!

Re: A peek at the Leaf's Charger

Posted: Wed Oct 10, 2012 11:50 am
by FairwoodRed
Brusa's chargers are designed "modular" so that you can stack as many together as you need to get your desired charge rate.

Re: A peek at the Leaf's Charger

Posted: Wed Oct 10, 2012 12:40 pm
by DoxyLover
TEG wrote:The dashboard shows times to complete charge. It shows one value for 120V and another (shorter) time for 240V. I wonder if that time estimate will always assume 16A for 240V, or if adding another 3.4kW makes that number be less? Also, if you pick an end-time only for charge timer, it starts charging early enough to make sure to get to the target in time, also probably assuming 16A@240V (or 12A if it sees 120V available.)
I wonder if it would start "way early" with the add-on charger because it would be charging twice as fast, but the "time needed" caculation didn't take into account the double speed charging available.

Maybe just minor concerns of little consequence, but I am curious just how "fully integrated" it will be.
Just a guess, but I doubt Phil could control the estimate, so it will be off by a factor of about 2 and your end-only charge timer will trigger way early.

Re: A peek at the Leaf's Charger

Posted: Wed Oct 10, 2012 12:58 pm
by grommet
Phil told me at National Plug-in day that the LEAF itself has no clue the extra charger exists... so charge time estimates on the dash, timer, etc. won't change. No big deal.

Re: A peek at the Leaf's Charger

Posted: Wed Oct 10, 2012 10:05 pm
by Nekota
grommet wrote:Phil told me at National Plug-in day that the LEAF itself has no clue the extra charger exists... so charge time estimates on the dash, timer, etc. won't change. No big deal.
I suspect the BCM or what ever measures the current for coulomb counting see's the increase in current and reports it as amps. But I'm not surprised the charging time is hardwired to the 'expected' 3.3KW LEAF charger.

Re: A peek at the Leaf's Charger

Posted: Wed Oct 10, 2012 10:53 pm
by planet4ever
Nekota wrote:
grommet wrote:Phil told me at National Plug-in day that the LEAF itself has no clue the extra charger exists... so charge time estimates on the dash, timer, etc. won't change. No big deal.
I suspect the BCM or what ever measures the current for coulomb counting see's the increase in current and reports it as amps. But I'm not surprised the charging time is hardwired to the 'expected' 3.3KW LEAF charger.
Not completely hardwired, because the timer is aware of the capacity of the EVSE. The 120v aspect is obvious, but I'm sure it must also be taking the EVSE's amperage into its calculation. I have Phil's 12A upgrade, and use an end-only timer. If the timer assumed 3.84kW (the 16A max at 240v, enough for the charger output to be 3.3kW) and my EVSE could only give it 2.88kW, I wouldn't reach 80% by the cutoff time. But I always do, with lots of time to spare.

Anyone want to bet there is a CAN signal the timer is watching for that tells it what the charger capacity is?

Ray