120 Trickle Charge - How many amps?

[mitch672]

make sure the "friend" checks to see that 12AWG wire is used in that EVSE, or if it isn't, it will need to be replaced. 14AWG is only good for up to 15A, and I suspect as a cost cutting move (less copper), and to prevent things like this, the EVSE is wired with all 14AWG wire.

 

[wwhitney]

make sure the "friend" checks to see that 12AWG wire is used in that EVSE, or if it isn't, it will need to be replaced. 14AWG is only good for up to 15A, and I suspect as a cost cutting move (less copper), and to prevent things like this, the EVSE is wired with all 14AWG wire.

Standards for wiring outside of your walls (appliances, extension cords, etc.) are different from the standards for building wire. I'm fairly sure that 14 AWG copper wire in the EVSE cord or components would be fine for 16A continuous. [If you are worried, just don't leave any excess cord coiled up.]

Cheers, Wayne

 

[leaf561]

Lame question, would charging 24kWh battery require 24kWh of electricity? Is there a loss in conversion. I assume so, based on the additional amps requirement. If so, what is the percentage I should expect?

This would help me estimate how much electricity I might consume based on my driving pattern. And how it would affect my baseline tiered quota.

Thanks

 

[DaveinOlyWA]

all this makes me wonder if my Kill-a-watt meter is simply inaccurate.

the specs on my charger states max current of 12 amps "temperature adjusted" at 20º C.

tried again this morning and it went to max of 13.19 amps. i checked it after 20 minutes, it was at 12.55 amps. after an hour it was at 8.90 amps. i did a 5 mile RT, so generally full charge is about 90 minutes or so.

now as mentioned, the plug gets a little warm and has from day one. the actual cord does not; its 12/3.

i guess the only thing to do is plug in the Leaf and compare its onboard #'s with the Kill-a-watt and go from there

FYI; 24 KWH of charge requires more because there is heat loss from the extension cord, conversion losses from AC to DC (feel your charger when its plugged in. it will get warm and that power NOT going into your battery. the batteries will heat up a bit too but that will probably be minimal. most of it is the AC/DC conversion

 

[DarkStar]

Lame question, would charging 24kWh battery require 24kWh of electricity? Is there a loss in conversion. I assume so, based on the additional amps requirement. If so, what is the percentage I should expect?

Estimates right now are that the internal charger has about a 90% efficiency rating so you might need about 27 KWh in to get 24 KWh to the battery...

 

[garygid]

Good point on wire gauges, Thanks.
Possibly the "modified" EVSE would "specify" just 15 amps
instead of 16 (if the EVSE cord has the smaller 14g wires).

The Nissan L1 EVSE and cord is fairly heavy, so it MIGHT have
the heavier wires (12g instead of 14g).

Since the US, UK, and EU "included" EVSEs all seem to made by
the same manufacturer (Panasonic), and vary in ratings from
12 to around 16 amps (120 to 240 volts), it is quite possible
that all the cords are the same gauge, but ... maybe not as well.

In practice, for a TEST of the LEAF's capability to "eat" 16 amps at L1,
a 20-foot wire is not going to behave much differently at 15 or 16 amps.

The test is to find out what the LEAF will actually use (in L1 120v operation)
when it is offered (by the EVSE) more than it can use.

 

[leaf561]

Estimates right now are that the internal charger has about a 90% efficiency rating so you might need about 27 KWh in to get 24 KWh to the battery...

Thanks, it makes sense.

Does using L2/L3 make a difference?

And since it is all chemical reaction, should I expect any degradation over the period of time? Or should I just assume the battery capacity goes down, but the charging ratio remains the same.

Thanks

 

[johnr]

make sure the "friend" checks to see that 12AWG wire is used in that EVSE, or if it isn't, it will need to be replaced. 14AWG is only good for up to 15A, and I suspect as a cost cutting move (less copper), and to prevent things like this, the EVSE is wired with all 14AWG wire.

Mitch is right, 14 gauge wire simply cannot carry more than 15 amps, regardless of the length, if you try the wire will melt and cause a fire hazard. See ampacity chart here, http://www.cerrowire.com/default.aspx?id=46

I made a grave mistake once, in a project for a friend selecting the wire size for charging his batteries on his boat from a generator. I selected the wire size based on voltage drop calculations. But I didn't take into account the ampacity rating for the wire, and since it was a short wire it had a low voltage drop, but the ampacity rating was exceeded. The wire melted, and if he hadn't caught it in time it could have caused a fire and destroyed the batteries.

 

[DarkStar]

Does using L2/L3 make a difference?

It depends how DC Quick Charging is handled (technically there is no such thing as L3 yet). We aren't sure how the DC Quick Charge systems interface with the battery pack and that could affect the efficiency... L2 charging efficiency should be better than L1, but only by a percentage or two.

And since it is all chemical reaction, should I expect any degradation over the period of time? Or should I just assume the battery capacity goes down, but the charging ratio remains the same.

The ratio will stay exactly the same. As the battery pack decreases in capacity the time to charge and energy input should stay at the same ratio as when the car is brand new. The battery management system should be able to detect when each cell is at its maximum capacity and signal to stop charging.

 

[DaveEV]

Yes, the USA L1 EVSE "specifies" approximately 12 amps max.
Thus, that "maximum" would be used for most of the charging cycle,
but there4 is likely to be substantially less usage during the ending
hour or two (the "topping off" part) of the charge cycle.

I doubt that there will be much ramping down on a L1 charge - it's only 1440W max into a pack that holds 24 kW - that's a C/17 charge rate - the pack will hardly notice.

After all, if a L2 3.3kW charge takes 8 hours from empty to full is still very easy on the pack. It's not until you start getting to C/2+ charge rates that you have to start really thinking about ramping down as the pack is full.

What would be insightful would be knowing how long it takes to go from 0-100% full on a Level 3 50 kW charger. We already know that 0-80% will take 20-30 min... does it take another hour to get to 100%?

 

[DaveEV]

Mitch is right, 14 gauge wire simply cannot carry more than 15 amps, regardless of the length, if you try the wire will melt and cause a fire hazard. See ampacity chart here, http://www.cerrowire.com/default.aspx?id=46

It's not the wire that will melt (unless you are REALLY shoving power through it!), but the insulation that will melt. That's why there are different ampacity ratings for wire with 60*, 75*, 90* rated insulation (though it doesn't seem to matter much for the smaller wire gauges).

 

[DarkStar]

What would be insightful would be knowing how long it takes to go from 0-100% full on a Level 3 50 kW charger. We already know that 0-80% will take 20-30 min... does it take another hour to get to 100%?

When the DC Quick Charger was unveiled here in Portland I asked this exact question. Mark Perry stated that the Leaf would go from 0%-80% in 25 minutes and 80%-100% in an additional 15-20 minutes for a 0%-100% charge time of about 40-45 minutes.

 

[smkettner]

I doubt that there will be much ramping down on a L1 charge - it's only 1440W max into a pack that holds 24 kW - that's a C/17 charge rate - the pack will hardly notice.

After all, if a L2 3.3kW charge takes 8 hours from empty to full is still very easy on the pack. It's not until you start getting to C/2+ charge rates that you have to start really thinking about ramping down as the pack is full.

What would be insightful would be knowing how long it takes to go from 0-100% full on a Level 3 50 kW charger. We already know that 0-80% will take 20-30 min... does it take another hour to get to 100%?

This is even more true as you consider the top 10% is not even used. So even L1 is really only taking the battery to ~90%.

 

[garygid]

Cell equilization (balancing), if done, usually requires
substantially lower charging currents, maybe 1 or 2 amps
into the pack (3 or 6 amps from the L1 EVSE).

But, we do not know what the LEAF battery management will do
when nearing the end of charge (full useable capacity).

It is possible that the QC is just some kind of "brute force" charge,
without the "fine control" of the BMS moderation of the L1/L2 charger.
If so, trying to approach a 100% charge with the L3 (QC) might
be risky.

Or, the L3 charging might be substantially reduced at the end,
to the lower limit of the external QC "charger", but that might
not be low enough to allow for proper cell equilization.

 

[DaveEV]

What would be insightful would be knowing how long it takes to go from 0-100% full on a Level 3 50 kW charger. We already know that 0-80% will take 20-30 min... does it take another hour to get to 100%?

When the DC Quick Charger was unveiled here in Portland I asked this exact question. Mark Perry stated that the Leaf would go from 0%-80% in 25 minutes and 80%-100% in an additional 15-20 minutes for a 0%-100% charge time of about 40-45 minutes.

Yeah, so 20% charge in 20 minutes is a average rate of about 15 kW - far above L2 and L1 charge rates. There shouldn't be any noticeable ramp down at L1/L2 charge rates.

This is even more true as you consider the top 10% is not even used. So even L1 is really only taking the battery to ~90%.

Has anyone confirmed the actual full capacity of the LEAF battery?

The AESC site has 130 Wh/kg modules that weigh 3.8 kg - 48 of these would hold 23.7 kWh.

But I have read press releases claiming that the modules in the Leaf are rated at 140 Wh/kg - assuming that each module still weighs 3.8 kg, that would mean 25.5 kWh.

Others have claimed that the Leaf battery actually holds ~30 kWh - but Nissan doesn't seem to say anything other than that it will hold 24 kWh...

 

[DaveinOlyWA]

ok, so i know u all think i am crazy, so just snapped this pic. now this is from fully charged pack to a quick trip to Safeway and back. a total of 3.6 miles RT. rechecked it 15 minutes later and its now on 11.44 amps

now wondering if my charger is asking for 12 amps and i am losing the rest on the way?

 

[palmermd]

ok, so i know u all think i am crazy, so just snapped this pic. now this is from fully charged pack to a quick trip to Safeway and back. a total of 3.6 miles RT. rechecked it 15 minutes later and its now on 11.44 amps

now wondering if my charger is asking for 12 amps and i am losing the rest on the way?

It's unlikely that the charger that was installed in your car has any communication with an EVSE that is providing the power to it. The charger probably just takes what it needs up to its max capacity regardless of the source. If you plugged it into an outlet that was fed from a 5 amp breaker you'd likely just trip the breaker.

Who did your conversion. What type of cord are you using to connect to the outlet? If you are just connecting an industrial extension cable from the home improvement store to your car, then there is not any communication from the car to know how much power is available. That is the advantage of the EVSE that will become the standard for cars like the LEAF. The car will ask the EVSE how much amperage it can draw, and it will regulate itself to not draw any more than that amount.

 

[garygid]

What charger are you using?
What are you charging?
It apparently has a "habit" of drawing 13 then relaxing to 11 amps.

----------
With the EVSE, it "advises" the car to not draw more that it "says".
However, the "saying" is not exact, and the charger in the EV
can actually draw whatever current it chooses to use, until
the circuit breaker "trips" of a fuse blows.

The charger in an J1772-complient EV should "regulate" itself
to abide by the "advice" from the EVSE, as best as the charger
can interpret the "saying" that it receives from the EVSE.

But, being an amp over or under is quite possible, even with J1772.

 

[Coffee_Slurry]

I doubt that there will be much ramping down on a L1 charge - it's only 1440W max into a pack that holds 24 kW - that's a C/17 charge rate - the pack will hardly notice.

I expect to see a taper at the end of charge.

Once the first cell in a series pack of cells reaches maximum charge (4.2v or whatever), the charger has to stop putting current through that cell, while still charging the other cells in series. This is needed to balance the charge levels of the individual cells.

In practice, the bypass or bleed-off balancer for each cell can shed just a little current. Maybe an amp. My smaller chargers can balance at 250mA, for example. That's the limit of the per-cell shunts. If you charge at higher current than that, they can not bleed off individual cells, and you risk overcharging the first cell. Even if you could balance at higher current, it's less accurate, as you want the cells to get close to resting before calling them balanced in voltage.

So it's no so much that the battery can't handle C/17 to capacity, but that the balancing stage can probably handle much less.

 

[DaveinOlyWA]

the charger is called "QuiQ" by Delta-Q technologies this is on my Zenn which is a 72 volt DC electric vehicle.

the specs copied directly from the pdf. it is programmable but states this is true for all models (they run from 24-72 volts in 12 volt increments)

DC Output – see Operating Instructions
QuiQ Model: 912- 24xx 36xx 48xx 72xx
Voltage-nom (V) 24 36 48 72
Voltage-max (V) 33.6 50.4 67.2 100
Current-max (A) 25 21 18 12
Voltage-max (Vrms) 85 – 265
Frequency (Hz) 45 - 65
Current - max (Arms) 12A @ 104VAC
(reduced by 20%<104V)
Current – nom (Arms) 10A @ 120VAC / 5A @ 230VAC
AC Power Factor >0.98 at nominal input current
AC input connector IEC320/C14
(require 1.8m localized cord)
DC output connector OEM specific w/ 12AWG wire

although it states that voltage max for the 72 volt model is 100 volts, its programmable to go up to 90.6 volts (15.1 volts per battery) on the charge algorithm