Bigger EVSE than needed (HCS-60), or just right (HCS-40)?

Time to think about which EVSE to buy for home. Electrician comes next week to give me an installation estimate. It'll be in the attached garage, right next to the circuit breaker panel, in a home less than 10 years old, so I imagine installation will be easy.

Should I get an EVSE just the right size for the i3, or (assuming my panel will accommodate it) get something bigger on the theory that it'll become useful when I get my a new EV some years down the road?

My current plan is to get the 48A Clipper Creek HCS-60 for $899. Any reason not to do that? Anybody have this model and happy (or unhappy) with it?

If I went for 32A instead, I could do the Clipper Creek HCS-40 for $590. I know there are many other options at the 30-32A level. Clipper Creek seems to have a good reputation around here though.

I realize the 48A version costs 50% more than the 32A version, but Austin Energy will pay for half the cost (of the unit and installation).

I don't have any need to take this EVSE with me on trips so I have no problem with the hardwired installation that I understand a > 50A circuit would necessitate. I assume I can still uninstall it and take it with me if I move.

Thanks for your advice and opinions!

FWIW, a 48A output from an EVSE would require a 60A circuit, not a 50A one (80% rule, or multiply by 125% of a constant max load based on USA codes).

It is possible that with bigger batteries, vehicles may also come with bigger on-board charging packs, but that is not a given. A new vehicle can still be easily charged with a smaller EVSE, it will just take longer if they didn't also make the charging circuit more robust as well. As a comparison, the Nissan Leaf has about the same sized battery as the i3, but comes standard with a 3.4Kw charging circuit inside, 6.8Kw is optional...the i3 in the USA comes standard with a 7.4Kw unit. THe EVSE is essentially a fancy power switch...the charging circuit is in the car, at least for acv inputs.

Depending on the size of your power panel, dedicating a 60A circuit may be problematic, or maybe not...it entirely depends on how big your panel's supply is now, and the sum of your big power users (typically, things like electric stove, refrigerator(s), water heater, dryer, air conditioner(s), and maybe any large tools you may use - got a woodworking shop, big air compressor?). Even a 40A circuit in my panel was pushing it. SO, it depends.

If someone is going to subsidize the cost, and you're willing, it won't hurt, IF you don't also then need to upgrade your service, which could be quite expensive. Last thing you want is to trip the main breaker, or have all of the lights dim when you plug in your next EV and it can draw that max current! Could even be a major problem with the i3 and a 32A unit...my sister's old house has a 60A main service for everything!

I have the BoschEL51255. Works good...no problems. Amazon $552.

I bought a Clipper Creek unit...when available, a US built device has advantages to me.

rhead, is that a 30-amp unit? I could not find the Bosch EL-51255, but I found the EL-51254 and EL-51253 which are 30A units.

Jim, which Clipper Creek unit did you get?

Seems like most people get 30A or 32A units. To those who did, how did you arrive at that decision? Is it because you expect to drive your i3 for a long time so you don't want to pay extra for more amps that your i3 cannot use, or perhaps because you don't think EV charging technology will change much in the coming years? I have financed my i3 for two years, and I am hoping that in two years EVs with larger battery packs are available, and that onboard chargers will be correspondingly more powerful then in order to charge those larger batteries in the same or shorter amount of time, and I don't want to have to replace my EVSE at that time.

Sorry. 51253. The only difference is the length of the cord. 18 vs. 25 ft. I selected this one because it has the same/comparable specs as the BMW charger at 1/2 the price. My installer had experience with both and found no difference.

I've got a hard-wired HSC-40...it's rated at 30A - they tweaked them since I bought mine and now call them 32A units. If it didn't have a 3-year warranty, I'd probably open it up and adjust the pilot signal. But, my typical supply voltage is like 247vac, and at 30A, that's still about the max the i3 can use. Note, in Europe, a 32A units is functionally identical to our 30A units...they rate theirs at peak...the USA rates them as continuous. My guess is that the earlier CC units are identical to the current ones, with only the pilot signal adjusted a little higher. 32*1.25 still works out to a 40A breaker. If you want to buy it with a plug, you need a 50A circuit since there are no 40A plugs in the USA, and the HCS-60, there are no 60A plugs, so they only come hardwired, at least that I can see. Had mine installed since June 2014...works fine.

Installed our EVSE at the same time we upgraded our panel. Went with the HCS-60. I figure buy extra capacity now rather than buying another EVSE later for the next EV. Three months of use and happy with it. Now if only BMW would fix the repetitive charge and stop while preconditioning...

Say the next EV you buy has double the size battery pack. THey may not make the on-board charger bigger, so, the same EVSE would just take a bit longer. Unless the battery capacity AND the on-board charging circuits are increased, it makes no difference, since the EV won't be able to use it. Even then, say it was twice as big a battery pack, for most people, even double the time wouldn't be horrible, and hopefully, by then, CCS units will be more available, making the size of the on-board charging circuits somewhat irrelevant except maybe when home, and overnight would be a worst case.

Lots of people buy the Leaf with the stock 3.4Kw on-board charging circuit, and they have the same size 24Kw battery...just takes nearly 3x longer to charge.

So, bigger is better, but only if needed. IOW, the EVSE isn't going to become obsolete with larger batteries. You could always run larger wires now, then, the cost to upgrade later would not be as dear, and there'd still be value in the old one. The things are reliable, and probably repairable, but with larger wire in place to handle a new one, with the increased competition and volume, the prices may be lower, then, too.

I did exactly what you're planning. I got the HCS-60 over the HCS-40. I had enough headroom in my main panel to put in the 60A breakers, and even though PG&E does not subsidize, I felt that in the future cars will likely come with bigger chargers -- so given the fixed costs of installation (permits, electrician), i went with the larger unit. All good things to say about the unit (with the single exception that it's not the prettiest).

tezarc said:

Now if only BMW would fix the repetitive charge and stop while preconditioning...

Click to expand...

Has anybody heard anything more about BMW fixing this. Our EVSE is close to the bedroom and the dull thudding at 6am in the morning is getting old...

It's really hard to tell if the batteries are fully charged while you're pumping current into them. While their ability to accept power is a function of their charge state, when they near full, it is not entirely accurate. When you stop that, and monitor the voltage produced by the batteries, you can better assess when they are fully charged. I think, this is why it turns on and off when nearing full charge. It's the nature of battery tech, and if you want to achieve full charge (well, as much as the i3 allows), I'm not sure there is a different way. The alternative is a less than full battery, or one that has not had the cells balanced.

This is apparently a know issue from BMW, awaiting resolution. I was wondering if anybody had a more recent update: http://bmwiforum.bmwusa.com/thread/59/preconditioning-plugged-flakey

spoovy said:

All good things to say about the unit (with the single exception that it's not the prettiest).

Click to expand...

This seems to be a quality most EVSEs share...

ryandesign said:

Time to think about which EVSE to buy for home. Electrician comes next week to give me an installation estimate. It'll be in the attached garage, right next to the circuit breaker panel, in a home less than 10 years old, so I imagine installation will be easy.

Should I get an EVSE just the right size for the i3, or (assuming my panel will accommodate it) get something bigger on the theory that it'll become useful when I get my a new EV some years down the road?

Thanks for your advice and opinions!

Click to expand...

You're prepared to pay more for overhead and you understand the technical issues at hand. So what we're talking about the way I see it is "do I bet that materials science will move forward significantly in the next X years". And you pick your poison for X. I think the answer is a resounding "yes". FWIW I fully expect to be replacing my i3 battery pack in 10-15 years for a pack that will have at least 2x the energy density, better power capability on charge and discharge, better temperature and lifetime characteristics, and half the cost/kWh as the original.

With such a time horizon as 10 or 15 years though the question really is would you buy another EV within the lifetime of the EVSE (probably will last forever if you're handy enough to replace a relay when it wears out) that will be able to use more current. I would wager that probably within 5 years charge currents will routinely exceed 32A. Your "mean time to new EV" is something only you might be able to have an idea of.

And aren't Teslas already pulling a fair bit more current than 32A in their implementation and they have an option to double it up?

This might be helpful. As mentioned today both the RAV4 and Tesla can take advantage of the additional current in the HSC-60. I can imagine in the next 12-18 months, more vehicles will be able to do so.

Larger batteries for the i3 may not mean upgrading the internal charging units...they are two independent things. And, to significantly increase the capacity of the onboard charging circuits may also require replacing all of the associated interconnecting wiring. IOW, while higher density batteries are fairly easy to retrofit, making the corresponding (probably required) wiring and charging circuit upgrades to increase that recharging rate capacity as well would probably not be cost effective.

If I would not have had to upgrade my service entry wiring and panel, I might have considered a larger unit, but even then, in most cases, I have overnight to recharge, and it would not make any significant difference.

At least at this time, the majority of public EVSE's out there do not use the full advantage of the i3's onboard charging circuits, for similar reasons...increasing the infrastructure to allow for it is a major cost. Many of them are in the 6-6.5Kw range.

If I were to install a L2 EVSE in my home I would get the biggest baddest one my current home wiring/breaker box could support and that I could afford.

CMYK4Life said:

If I were to install a L2 EVSE in my home I would get the biggest baddest one my current home wiring/breaker box could support and that I could afford.

Click to expand...

I was about to post something similar. It is like buying a computer where you should buy the most you can afford. That way you can go longer before you have to upgrade. Which is what I plan to do as soon as I finish cleaning my garage so the electrician can do his job and I can park inside.