Charging directly from DC

EV Chat ⚡️💬 Charging
#1

HI, Can anyone tell me if it is possible to charge from a DC source without inverting the signal? We have a DC source operating nominally at 120V, we can purchase a DC-DC transformer but for various reasons DC to AC conversion is not an option. Any help would be very much appreciated!

Thanks!!! :sunny:

#2

Sorry not something I’ve come across

How do you convert 120v to around 60 . And why can you not convert to AC?

#3

Hi Osbrook, Thanks for replying! One possibility is to use an Outback MPPT DC-DC charge controller - I understand that these can and have been used to step down from 120V DC to 60V DC. I already have one so would want to re-use. Can you conceive of any way to charge from DC (e.g. directly connecting to the twizy batteries)?

Thanks again!

#4

i have an outback mppt controller on my boat it is the 200volt 79amp version it does set itself to the battery voltage but not sure if it does lithium ion batteries would have to look at the blurb

#5

All looks good in theory. Its just I don’t know enough to say exactly where to connect the DC input. It must be between the charger/inverter. However need to monitor the charger some how.

#6

My understanding is that the charge controller will sweep to find the maximum power point at any given moment, the bulk or float phases on charging will depend on the battery voltage and the set-point. Which from previous posts I understand to be 60V. The questions I have are how/where can I connect to the battery and what the tolerances are wrt DC characteristics: max voltage, max noise etc…

#7

I’ve been thinking about this for a while myself, I would have thought that if the DC charger is capable of monitoring the battery voltage and shut off at the correct point I would of thought a direct connection to the battery would work. If the charger isn’t capable of monitoring, I would suggest that it would need to be placed in between the inbuilt inverter and the inbuilt charger matching the normal output from the inverter (what every that is!)

#8

Sounds about right. However where is that? No one has stripped the Charger down and certainly not provided details of the various parts. If you could find the point between the AC/DC converter and the Charge controller it should be easy enough to do. This would mean you keep the main Twizy Battery controller in place making things safer and should be easier.

So who has the details of the charging unit?