OPENEVSE charging on TT-30

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EnerGene

Well-known member
Joined
Aug 26, 2016
Messages
46
I think I asked this before but I can't fine my post.

I built an OpenEVSE Kit - Level1 & Level2 50A.

What do I need to do to charge on a TT-30 at 20A?

I recall GlennD posted something on this subject but for the life of me, I can't find it.

thanks
 
Force it to level 2 to use the L2 tables. I have tested my eGolf and at 120V it will draw 30A. The car's charger only cares about amps. Same for the Leaf's charger. I have heard Tesla chargers revert to 240V above 20A but I have not tried it. I no longer have a car with a Tesla drive train so I can not test it. I have tested my old Leaf and my current eGolf.
 
davewill said:
BTW, Unless there's some issue with the circuit, you should be able to go all the way to 24a on a TT-30.

The Tesla powered Toyota RAV4 EV, as well as Mercedes B-Class ED, and all Tesla Model S from model years 2012-2015 are limited to 20 amps at 100-135 volts. These chargers are limited to 40 amps maximum at 200-277 volts.

The 2016 and newer Model S and X and limited to 24 amps at 100-135 volts. These cars have chargers that are capable of 48 amps, or with a software change to 72 amps at 200-300 volts.
 
EnerGene said:
I built an OpenEVSE Kit - Level1 & Level2 50A.
What do I need to do to charge on a TT-30 at 20A?

Normally you would keep your OPENEVSE at "auto" for L1/L2 selection.

In the standard software that comes with the OPENEVSE this is defined:
// maximum allowable current in amps
#define MAX_CURRENT_CAPACITY_L1 16 // J1772 Max for L1 on a 20A circuit
#define MAX_CURRENT_CAPACITY_L2 80 // J1772 Max for L2

So if you want to take advantage of the amps available at the TT(travel trailer)30
there are 2 things you can do:

1) alter the (opensource firmware)
This is imo the best solution

Change the line in open_evse.h from
#define MAX_CURRENT_CAPACITY_L1 16 // J1772 Max for L1 on a 20A circuit
to
#define MAX_CURRENT_CAPACITY_L1 24 // Max for L1 on a TT 30A circuit

compile the software, upload it to the openevse cpu
From then on, you can increment L1 charging in increments of 2 Amps up to 24 amps.

2) alternative without programming
manually select L2 charging (instead of auto detect L1/L2)
That way you also will be able to select 20 amps, but the counting of kWh will be off since it will calculate with 240 volts instead of the real 120 volt.

If you want, I can compile a firmware image with the extra amps setting and upload it somewhere.
You would need a programmer like https://store.openevse.com/collections/frontpage/products/openevse-programmer (or one from ebay) to upload the new firmware to the openevse.
 
If you need a programmer with no support it is around $3 shipped from China on eBay. Chris sells the same programmer with US shipping and support for $20. The ones I have received from eBay work but to get around the nag message you need to upgrade the firmware. I assume that the ones Chris sells are upgraded. Since I am very cheap I will never know.
 
I see the eBay price has recently doubled. For $6.95 you can get a USBASP and a ten to 6 pin adapter. The last unit I purchased already was 6 pin and it was $3 shipped. They forgot to program it so it did nothing but since I planned to upgrade the firmware that was OK.

I have a batch file so it takes longer to install the programming jumper than to program the unit. I upgraded a couple for Phil Childs that way. If you just hold the jumper in place the unit looks unmodified and the upgrade is really fast.
 
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