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I'm new to V2G: why with Boost is the unit only showing a charge at 2.1-2.2KWH and doesn’t having the 6.6kw charger on board make any difference?

  • 27 June 2020
  • 7 replies
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Userlevel 1

Hi All,

So Day 2 with my V2G - I’ve got a 30KW Leaf with a 6.6KW charger on board. Couple of questions - (1) why with Boost is the unit only showing a charge at 2.1-2.2KWH and (2) doesn’t having the 6.6kw charger on board make any difference?

 

Thanks

Sam

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Best answer by PurpleV8 30 June 2020, 00:18

Hi Sam,

In boost mode with a 30% battery, I would expect you would be getting a much higher charge rate than 2.2kw. 
As a next step, I would try to work out if the issue is the actual charge rate is only 2.2kw or is the charger really charging at a higher rate and the issue is only an error in the rate reported in the app.

To determine this, can you share how long it takes to charge a known percentage of the battery capacity. i.e. 50% of your 30kwh battery is 15kwh and would take just over 2 hours to charge at 7kw or close to 7 hours at 2.2 kw.

My V2G charger never shows over 5.4kw and often less on the app, but regularly charges the battery by 26kwh in 4 hours so actual average charge rate is 6.5 kw 

let’s see, once you get some measurements. 

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@Sam72 welcome to V2G. I had my installed a week before as well.

 

I have a similar set-up to you so I assume you’re using the chademo charger (left) which is rated 7kw and not the 6.6kw (right) charger which you might have been using with Rolec or similar charger.

My understanding is that whilst the V2G unit is rated at 7kw the boost is limited due to DNO restrictions. Trying to understand as well… 

Userlevel 1

Hi Sylm_2000, yes that’s correct, V2G cable into chademo charger on the left. I’m getting maximially 2.1-2.2Kw charge rate on boost - is that the same for you? Thanks Sam

Hi Sam

The on board charger is only used when the car is connected to an AC charging supply via the type 2 (right hand) connector and this rated at up to 6.6kw max, even if the supply is capable of supplying more current.

V2G is a D.C. charger, it uses the CHAdeMO connector on the right and is capable of 50kw and more on some versions if connected to a D.C. charger that is capable. 

The V2G charger is 7kw max, but there are 3 factors that may result in you seeing lower charging rates

The way the current monitoring feeds the app often under reads by 10-20%

The car will limit the charge rate as the battery gets towards fully charged. From 80% it slows down, then the last 10% can be down to 1-3 kw  I’m guessing this may be what you are experiencing?

Also the Kaluza platform can limit the charge rate, but I’m not sure this usually applies in Boost Mode. 

Hope this helps

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@Sam72 Yes agree with @PurpleV8 it could be due to trickle current when the battery is above 80% and that could be slowing down the rate of charge. You may find these two faqs on the Kaluza app helpful:

How quickly can it charge?

Unlike non-smart chargers, our charger doesn't always deliver the maximum possible power in order to maximise your battery's lifespan. It's maximum power output is 7 kW, so if it is charging at its highest rate, a 40 kWh battery will be charged in under 6 hours.

Why is my export rate limited?

In order to export at its full power of 6kW, we need to apply for permission from the local grid operator on your behalf. This process can take a long time, so in the interim we have limited the export power of your charger to 3.7kW (the highest export power before you need special permission).

Userlevel 1

Thanks PurpleV8, that’s a very helpful explanation - essentially having the 6.6KW option is not going to help me from the perspective of the V2G charger! But I should be still seeing 7KW or there abouts during charge with the V2G at some point? But, I’ve never seen charging beyond 2.2KW at anything from 30% to 90% battery charge? That can’t be right can it?

Slym-2000, my export rate is 1.2kw from 90% down to 30%!

 

Thanks

Sam

 

 

Hi Sam,

In boost mode with a 30% battery, I would expect you would be getting a much higher charge rate than 2.2kw. 
As a next step, I would try to work out if the issue is the actual charge rate is only 2.2kw or is the charger really charging at a higher rate and the issue is only an error in the rate reported in the app.

To determine this, can you share how long it takes to charge a known percentage of the battery capacity. i.e. 50% of your 30kwh battery is 15kwh and would take just over 2 hours to charge at 7kw or close to 7 hours at 2.2 kw.

My V2G charger never shows over 5.4kw and often less on the app, but regularly charges the battery by 26kwh in 4 hours so actual average charge rate is 6.5 kw 

let’s see, once you get some measurements. 

Userlevel 1

Hi PurpleV8,

You’re absolutely right, the car is charging around 20% in a hour, which would equate to around 6kw charge rate, not sure why the APP is showing a third of that rate!

Thanks!

Sam

 

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