Maximum Level 1 current?

Hi,

Today I found a row of six, Huntsville utilities installed, 120 VAC outlets:



Our Level 1 EVSE is rated at 12A which limits the rate. However, the sockets appear to be NEMA 5-20R which should provide up to 20A, potentially a 66% increase in charge rate. So I'm wondering if anyone has a suggestion for a higher current, Level 1 EVSE?

I would like one that allows setting the current limit so it could provide more 'headroom' for the utility circuit breaker. For good measure, auto-step the current limit up measuring the dV drop to optimize loading on the circuit breaker.

So for dinner and a beverage, this is what happened at 12A:




Bob Wilson

Electrical code requires things like an EVSE not use more than 80% of the circuit, so if it were a 20A circuit, the max you could get legally, at least in the USA, on that type of device would be 16A. There are some out there that can do that. It has to do with a 'long-term' load, verses a short-term one. Things that are normally only on for a shorter period are allowed to use up to the maximum circuit capacity, but not an EVSE. Things would tend to overheat. FWIW, a typical CB has more than one trip curve: a fast response to a high load, and a much longer one for a longer-term, maximum load.

The reason why BMW chose to initially deliver the i3 with a 12A device is that 12A=80% of a typical 15A circuit very common in the USA. I've heard that the newest i3's come with a 10A one in the USA. More than one person has said that Clipper Creek is the supplier for EVSE's in the USA to BMW as delivered in the car.

Ask Emotorworks. Maybe they can build you an adapter so you can just bring your Juicebox down with you with an adapter:



https://emotorwerks.com/store-juicebox-ev-charging-stations/juicebox-accessories/54-juicebox-adapters-input-cables/category_pathway-39

The only offer Nema: 10-30, 5-15, and 14-30 on the store, but I bet they can make whatever you need.

jadnashuanh said:

Electrical code requires things like an EVSE not use more than 80% of the circuit, so if it were a 20A circuit, the max you could get legally, at least in the USA, on that type of device would be 16A. There are some out there that can do that. It has to do with a 'long-term' load, verses a short-term one. Things that are normally only on for a shorter period are allowed to use up to the maximum circuit capacity, but not an EVSE. Things would tend to overheat. FWIW, a typical CB has more than one trip curve: a fast response to a high load, and a much longer one for a longer-term, maximum load. . . .

Click to expand...

I agree that for a permanently mounted EVSE the load should be 80%. However, I'm a firm believer that this is something worth investigating including 'tickling the dragon.'

I found OpenEVSE has a 20A rated portable but it isn't clear that everything I would need is there.

The key technical question is whether or not the EVSE sets the current limit and the car complies. I know we can set Level 1 to three different levels: maximum, moderate (10A), and low and the car load adjusts appropriately. I also know setting the current limit on the Level 2 EVSE results in a lower charge rate which I suspect is set by the car in response to the EVSE. Having the EVSE limit the current would be 'ugly' but understandable.

Bob Wilson

I33t said:

Ask Emotorworks. Maybe they can build you an adapter so you can just bring your Juicebox down with you with an adapter:
. . .

Click to expand...

I appreciate the thought but first need some metrics. I'm not ready to risk my JuiceBox Pro (40) without some testing at home. Fortunately, I happen to have a NEMA 5-20 and can test at home first. In fact it is a split, dual-socket, NEMA 5-20 which might mirror what I found today.

Now if it turns out the utility company split the phases between adjacent power outlets, it would be trivial to make a 'two headed' to NEMA 14-50 adapter. But I would prefer not to go there, yet.

Bob Wilson

The EVSE sends out a pilot signal announcing how much current it can supply, then it's up to the car to decide how much it wants to use. Someone had tested the i3, and if I remember correctly, it will accept more on 120vac than the supplied EVSE announces it can provide. A 20A load on a 20A breaker, left on for a couple of hours is likely to trip the breaker, and then, you'd be far worse off than not trying to cheat, as it could trip anywhere after probably 15-20 minutes, but maybe more, depending on local conditions. So-called 'full load' devices are generally not on for very long; an EVSE is different and is not alone as a type where the 80% rule counts. Throw in the likelihood of maybe a less than perfect receptacle, and you're just asking for problems.

Do you know whether those outlets are designed to be used for charging EV's? If not, they might all be protected by a single circuit breaker that's not designed to have several EV's charging simultaneously.

bwilson4web said:

I'm not ready to risk my JuiceBox Pro (40) without some testing at home. Fortunately, I happen to have a NEMA 5-20 and can test at home first. In fact it is a split, dual-socket, NEMA 5-20 which might mirror what I found today.

Click to expand...

I can adjust the maximum current that our old JuiceBox kit will deliver using its wireless remote and the small LCD on our JuiceBox. But I don't know whether the maximum current can be adjusted on your JuiceBox Pro when it's not connected to WiFi. If it can function as a WiFi base station when not connected to a WiFi network, your smart phone could connect to your JuiceBox Pro and maybe allow you to adjust the maximum current that it would deliver. You would need to be able to adjust the maximum current to 16A to prevent tripping the circuit breaker protecting one of those public outlets.

The only real risk to your JuiceBox Pro would be vandalism or theft while it is lying on the ground by the outlet.

bwilson4web said:

Now if it turns out the utility company split the phases between adjacent power outlets, it would be trivial to make a 'two headed' to NEMA 14-50 adapter. But I would prefer not to go there, yet.

Click to expand...

I would never go there judging by the photos. You'd have to run a power cable across a sidewalk that would create a tripping hazard. You'd also deny another EV the ability to charge unless the owner unplugged one of your EVSE power cords.

Hi,

It turns out they have a "JuiceCord Pro 20", Level 1 EVSE. They are expected the end of this week and I spoke with them about the functionality:

• Needs WiFi connection back to their server for configuration options.
• Has a manual override pot for maximum current.

On the road, it maybe useful but I'm realizing the $300 doesn't make a lot of sense for what would be intermittently used.

Bob Wilson

I'm under the impression that the car will max out at 12A L1 current even if the EVSE is connected to a 20A outlet and reports 16A via the pilot signal. If the car will take 16A, I would try to modify the included charger using an OpenEVSE board.

The 12A figure comes from the typical supply and the stock OUC that comes with the car...in the USA anyways, the OUC has a plug designed for a 15A circuit, and 80% of that is 12A. As a result, the OUC couldn't send out a pilot indicating more than 12A as it has no way to know if it is plugged into a circuit with 20A available.

SOmeone else tested the i3 on 120vac, and the car did accept more current than 12A. You'd have to search the forum to find that series of posts, but I don't think I'm misreporting what was said. Personally, I have no easy means to test it out, and can't verify it myself.

I believe it was Tony Williams that did the testing.