WTB: Standalone Eltek charger controller

[Scrappyjoe]

Hello,

I have an Eltek 3kw IP67 water-cooled charger. From what I can see, this is not supported by my Zombieverter. So, I am looking for a solution to get it working.

The ask:

What I want, at the end of the day, is to be able to plug my Eltek charger into a wall socket, leave it over night, and have my battery charged when I wake up.

Basic principles:

1. I'd like it to be as simple and stand alone as possible. Ideally a separate CAN line from the rest of my stuff, but if I need to integrate with other CAN connected components (IVT shunt etc) for proper functioning then I can put it on the main Zombie CANBUS.
2. I'd like to be able to adjust the charging parameters myself. This is because I am starting with a small, low voltage battery, but will move to a big, high voltage battery eventually.
3. [BONUS NOT ESSENTIAL] I actually have 3 of these chargers, so if I can control all of them that would be sweet, but it's not a main design goal. I just need one for now

What form will this take?

Well, it could be in the form of time (someone guiding me through how to implement this), or software (which I upload to an Arduino Due or Teensy), or and actual board which is shipped to me. If software or hardware is provided, I want the source code so I can maintain it myself going forward.

How much will you pay?

Hard to say, because I'm not sure how hard this is. Perhaps someone has something ready to go. I see johu charges EUR75/hr for support, and I don't think is particularly challenging for the right person, so probably between EUR 100 and EUR 150? You can let me know if that's unrealistic though.

[uhi22]

Hi,
I think it is unlikely that somebody develops a complete control unit in just two hours (aka 150 euros). If you are fine with studying of the data sheets and hacking some lines of code, I see the following ways:
- Add the necessary functionality to the Zombieverter project, supported by the forum. Or
- Use e.g. an Arduino with a CAN shield and adapt a CAN demo project for your needs.
It all starts with studying the data sheets, to understand how these chargers are controlled and what they require besides the CAN.
And then it is just your decision which hardware platform you feel most comfortable, and how well it should be integrated with the BMS. (From my PoV charging without BMS integration is a quite dirty workaround.)

[Scrappyjoe]

Thanks for your input uhi22. For sure, I wouldn't expect someone to go from zero to fully designed controller in two hours, but I thought this might be a nice way to pay someone for work they have already done for their own project.

I was speaking to tom91 via DM and he also advised me that it makes more sense to tackle this charge control issue once I've sorted out my BMS implementation. I was not aware that the BMS and charger are tightly integrated, at least for such a low power charger. I thought it could be done in a standalone manner but, as you say, it's a dirty workaround.

So, I will withdraw this WTB for now, and move my charger task to the end of my task list. Perhaps I'll circle back at the end!

[Scrappyjoe]

Not quite sure how to edit a title or delete a post, so, for anyone reading this, I have been shown that this is a premature request for my project, and withdraw it for now.

[uhi22]

Maybe we can just turn this discussion into an technical discussion about your Eltek, to collect data and ideas. Do you have data sheets, protocol descriptions or something like this which you could share?
And this maybe Johu could shift the thread into a more appropriate sub-forum.

[Scrappyjoe]

arber has done really good work on the Eltek, but I don’t how to join the dots - it’s a bit like reading code when you don’t know how to set up an IDE.

I will happily collect all that into a thread in the Volvo sub forum - I’ll make that a priority for tomorrow.

[arber333]

arber has done really good work on the Eltek, but I don’t how to join the dots - it’s a bit like reading code when you don’t know how to set up an IDE.

I will happily collect all that into a thread in the Volvo sub forum - I’ll make that a priority for tomorrow.

Uh what do you need then?
I developed arduino due board and code to work with Eltek charger on my cars previously.
Now i use esp32 chip to connect all my CAN items into a single control scheme.
If you want i can send you one control VCU... when i return from vacation in august?

If you read my blog you will notice Eltek uses voltage limit. So if you tell it to charge up to 388V it will taper off there and you can sleep soundly.
However i still recommend you use BMS to guard from individual cell failure.
There is an enable byte in Eltek CAN message that you can use with any BMS. This can disable charging on some condition. You would just need to adjust the VCU code...

[Scrappyjoe]

Hi arber333!

I'll PM you, I think, and we can make a plan. Hopefully I can get something together that can go into the wiki as a how to.

[Scrappyjoe]

Starting a thread on Eltek charger control here

viewtopic.php?t=5194