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Yes - I’m getting about 3.6Kw throughput, so on the battery that’s 93.4 Kw it would take 26 hours to charge to 100% (from zero) or in more realistic circumstances, 25% to 85% (or 60% of 26 hours - so about 15.5 hours. Not ideal, but workable. I have 40 amp service so there’s no reason to have to live with such low throughput. I’ll look for a new EVSE.
question is your breaker 50 amps or 40 amps
if you have a 50 amp breaker - you can charge at 40 amps or 9.6 kW
if you have a 40 amp breake r- you can charge at 32 amps or 7.68 kW
the PMCC is adjustable via the LCD screen if you need to dial it down to 32 amps.
it would be unsafe to charge at a full 40 amps on a 40 amp breaker.
the _REAL_ issue for charging is _NOT_ the breaker - breakers can typically run at near full capacity no problem
but typically an qualified electrician will _MATCH_ the wire gauge to the breaker size - such that at full or nearly full load the wire is big enough to handle the electrical current - so the breaker is typically "indicative" of the capacity of the wire that is installed…
the breaker in this equation is somewhat irrelevant and is easily swapped - but it's the wire and it's gauge that is the _KEY_ safety concern
if your wire gauge is physically too small it will overheat when running high loads for hours on end and melt the insulation and potentially cause a short/spark/fire/disaster
wire that is too small for a given load is dangerous
wire that is too big for a given load is no problem
depending on length of run and local building codes - 50 amp circuits require 8/6 gauge wire (6 being physically "bigger" than 8)
cost of wire is typically dwarfed by the labor cost and actual effort to pull the wire so when pulling wire for an EVSE I recommend "over doing it" - because then later you can swap the breaker to a higher capacity breaker and the wire will be fine for the increased load
moral of the story if you're pulling new wire/breaker for your EVSE - over do it a bit so you can upgrade your EVSE later if you decide to increase capacity - the breaker easy/cheap/quick to swap - but pulling wire again is time consuming and expensive - so if building code requires 8 gauge wire, pull 6 or 4 gauge wire and you'll have head room to upgrade the breaker in the future and just slap a bigger/higher-capacaity EVSE on the other end - and reuse the over-capacity wire…
what I did was pull a 100 amp circuit to a sub panel - and then install wire/breakers off the subpanel in the garage for what ever EVSE I feel like running - makes swapping/upgrading and replacing EVSE's quick/easy and with 100 amp "feed" to the sub panel I have plenty of capacity to do what ever I want…
always consult a qualitifed electrician (which I am NOT) - the internet can be wrong
here is handy chart I found that gives you an idea what sort of wire gauge you want based on electrical loads - I think this should be accurate for runs of 75ft or less - smaller gauge wire is always better/cooler so there is no harm in running 40 amp loads on wire rated for 80 amps…
at the end of the day it's the wire and the electrical current that is the capacity we're targeting when doing an 8 hour marathon charing session - and the wire is the part that should not be "under spec" - as I said the breaker in this case is more of a proxy for the wire gauge - so it's important the the wire is rated to match the breaker or exceed the breaker's capacity.
one home I lived in had a 30 amp circuit in the garage - according to the breaker - and I wanted a 60 amp circuti for my EVSE - but apparently the the previous owner was a crazy engineer like myself - and when I inspected the circuit on both ends (breaker and NEMA 10-30 plug) I found that it had 4 gauge wire (rather than the expected 10/12 gauge wire for a 30 amp circuit) - given that the wire was already sufficient/overspec - a job that originally was estimated to be a new breaker and new wire pull (1 to 1.5 days of work mostly to pull the new wire) became a 20 min job to swap the 30 amp breaker to a 60 amp breaker since 4 gauge wire is more than sufficient to handle a 60 amp load…
moral of the story - it's the wire gauge stupid!!! - if the existing wire's good for the loads you are targeting the breaker is cheap/easy/fast to swap and you're done…but if the wire is under spec for the anticipated load you _MUST_ pull new appropriate gauge wire for legit safety reasons…
the _CORE_ issue here is wire gauge vs. AMP load - and there are known/scientific/predictable/reliable/consistent temperature a given gauge of wire will achieve running a given AMP load for a given number of hours - small/thin wire will overheat/metl - thick/ample wire will run cooler and not melt itself or the insulation - wire that is too thin for a given load _WILL_ fail (not may or if, WILL) and it will not be pretty - appropriate gauge wire is the CORE concern when running a 40/48/80 amp load for 2-11 hours to charge your EV…it is the most important thing!!
Once you have the correct wire gauge the rest is easy - and the breaker is almost an afterthought…the safety mechanism here _IS_ the wire gauge with the breaker being the proxy to indicate what the wire gauge should be- if the wire is appropriate and the breaker is equal to or less than the wire's capacity - the breaker will trip _BEFORE_ the wire would/should fail…
if you attempt to run 80 amp loads with an 80 amp breaker on 14 gauge wire (really really thin) the breaker is _NOT_ going to save you - 80 amps is too much current for 14 gauge wire - it will super heat, melt, fail and the breaker will _NEVER_ trip - but the wire will fail because it's the wrong gauge for an 80 amp load…
the breaker is ONLY a safety mechanism when the wire it's installed with is appropriate - if they are mismatched all bets are off…
so step one is to inspect the existing wire and it's gauge (normally stamped pn the insulation) - if the wire gauge is sufficient you may get lucky an only have to swap the breaker to move to a 50/60 amp breaker.
good luck!!
Last edited by daveo4porsche; 12-23-2023 at 09:38 PM.
12-22-2023, 09:46 PM
