space efficient low power DCDC+charger?

[vwbrady]

So i'm working on converting a mk1 volkswagen, and thought i'd be able to fit an entire gen2 leaf tower under the hood. Turns out, without lowering the entire motor/trans assembly, it's not going to fit. This got me thinking that the gen 2 charger+DCDC converter isn't that space efficient for what it is.

This conversion will have manual brakes and steering, meaning the 12v loads will be lights and controls only. As well, it is just for fun so I'm not after fast charging or going very far, but i would like to use public J1772 chargers.

other reqs:
1. 350V nominal system
2. ease of Leaf BMS integration

Question is, what space and cost efficient charger+DCDCs are out there that can serve this purpose? Maybe separate components if it makes sense.

no charger + DCDC

[m.art.y]

Check out Mitsubishi Outlander charger & dcdc combo in one small package.

[johu]

I used a 62A Meanwell AC-DC for a while but there are some caveats:
- you need to add an output relay because it becomes a 12V load when unpowered (100 mA or so)
- in the long run it overloads the precharge resistor so needs also an input relay
- it's not waterproof and has a fan
I ran it for 8 months and it provided sufficient power even to the quite modern Touran. Just not after I added a PTC heater.

Well, not really what you're after, but in case you find a charger without DC-DC

[arber333]

If you need light DCDC check out Meanwell HEP-600-15. It is 600W and it works from 160Vdc up to 420Vdc. I use it in Mazda for 6 years now. Totaly enclosed IP65 and you can start it on demand with a remote wire. It was made for harsh enviroment like mining equipment. You can set it to 14V by a variable pot on its side.
https://eu.mouser.com/ProductDetail/MEA ... 45FQ%3D%3D

[Mouse]

Honda IMA 12V charger DC/DC converter modules are reasonably cheap and plentiful and built for the job?
I think there are two variants, the older on in a metal case and a newer one with a plastic case.
They have a large heatsink for forced air cooling and are not watertight no not suitable for in the engine bay without some modification. I've been looking at IMA stuff for a motorbike build and the inverter + DC/DC are often advertised with incorrect or misleading descriptions and I've seen some ebay sellers even mix the DC/DC and Inverters up in the descriptions.

Not sure exactly of the starting or and cut-off voltage from the main battery pack but I'm reasonably sure they are failsafe in operation, ie apply battery power and they give 12V (~14V) output, but please be sure of this before committing to it on my sayso.

Peter Perkins youtube channel goes into almost Damien level detail when reverse engineering them as part of his Honda Civic IMA performance hacking experiments and a good resource for information with many short concise videos.
There are other videos covering DC/DC converters but this is a good general one.
DC/DC from 1:20


[edit]
Just found this one looking into the max and min working voltages,
HCH2 90-220V Input versus CRZ 60-150V

[vwbrady]

thanks, Mouse! that actually look like a really good option. However, Peter says in his video that the civic one is only good for 160V. i hope to run @350V.

Ultimately it's looking like independent charger and DCDC is the best way to go here.

The Mitsubishi Outlander is not sold in the US so sourcing parts from them is difficult. The Tesla Gen2 charger is pretty cheap via eBay and with another EVBMW board this looks like a feasible option, though not super cheap overall. I really want to use J1772 charging, does anyone know if the Gen2 Tesla charger with board swap can do this?

[arber333]

Ultimately it's looking like independent charger and DCDC is the best way to go here.

Then you must go by the Volt gen2 route. I have made it sing and it made 1kW of 14V without cooling. I think with cooling it should be good for at least 2kW! viewtopic.php?p=15675#p15675

Volt gen2 Charger is also 3.6kW and is mentioned here... Both use simple PWM for control. I will soon get one sample to test control.
https://www.diyelectriccar.com/threads/ ... ost-972625

[vwbrady]

[/quote]

Then you must go by the Volt gen2 route. I have made it sing and it made 1kW of 14V without cooling. I think with cooling it should be good for at least 2kW! viewtopic.php?p=15675#p15675

Volt gen2 Charger is also 3.6kW and is mentioned here... Both use simple PWM for control. I will soon get one sample to test control.
https://www.diyelectriccar.com/threads/ ... ost-972625
[/quote]

yup, those are a great option! ordered the set on ebay. Thanks, Arber!

now here is a likely dumb question,
Is the Volt charger ready to hook straight up to a J1772 charge inlet?

[vwbrady]

shoot, just realized the Volt is a 300V pack and i will be running a 96S 350V pack. So that charger may not work for me unless i change my BMS

[arber333]

shoot, just realized the Volt is a 300V pack and i will be running a 96S 350V pack. So that charger may not work for me unless i change my BMS

No Volt is 96S.

[vwbrady]

No Volt is 96S.

yeah, i wasn't aware of that. I was looking for a 350V (96S) charger / DCDC, so I assumed. it's ok.

[arber333]

Is the Volt charger ready to hook straight up to a J1772 charge inlet?

Missed that question.
No only Outlander charger can tap directly to Cp signal from EVSE. But really it still needs separate control. For each and every one you need to have some sort of controler which tells it what voltage and current to use. Even the OEMs have that.

[vwbrady]

yeah, that makes a lot of sense.
As for voltage, i may just drop my system to 300V for now. But that could mean my Leaf BMS would have to lose 13-14 cells. I'm not sure how it will like that.

[arber333]

yeah, that makes a lot of sense.
As for voltage, i may just drop my system to 300V for now. But that could mean my Leaf BMS would have to lose 13-14 cells. I'm not sure how it will like that.

Why would you want to do that? Are you restricted by space?
Than i think you would want to find Mitsubishi charger/dcdc because it is really compact in that regard. And it works well.

[vwbrady]

im not really restricted by space. i was just thinking of utilizing the GM components that i hastily ordered off ebay

the mitsubishi parts are way harder for me to source and ordering from the EU makes them about 4-5x the cost of the Volt stuff.

[janosch]

Just picking up on this. I am looking for a cheap DCDC converter readily available in the UK. We have a Tesla Gen2 charger already.

Took our Mitsubishi Outlander PHEV charger apart today to see if we can take the DCDC unit out and use separately but it looks like a bit of a project.

How do you feel about these TDK ones:
https://www.mouser.co.uk/ProductDetail/ ... T1mw%3D%3D

The form factor is absolutely tiny, and they are cheap at £140, why I would really like to use them.
Go up to 600W, which we could make work. Or use two of them in parallel.
Although they would need some cooling fins and an enclosure, but shouldn't be too hard to make that happen.

Back of the envelope calculation at 12V:

• fans: 30A
• headlights: 16A
• elec windows each: 17A
• heated rear window: 25A

brings us to 88A
Our car was originally fitted with a 90A alternator.

[arber333]

Just picking up on this. I am looking for a cheap DCDC converter readily available in the UK. We have a Tesla Gen2 charger already.

Took our Mitsubishi Outlander PHEV charger apart today to see if we can take the DCDC unit out and use separately but it looks like a bit of a project.

How do you feel about these TDK ones:
https://www.mouser.co.uk/ProductDetail/ ... T1mw%3D%3D

The form factor is absolutely tiny, and they are cheap at £140, why I would really like to use them.
Go up to 600W, which we could make work. Or use two of them in parallel.
Although they would need some cooling fins and an enclosure, but shouldn't be too hard to make that happen.

Back of the envelope calculation at 12V:

• fans: 30A
• headlights: 16A
• elec windows each: 17A
• heated rear window: 25A

brings us to 88A
Our car was originally fitted with a 90A alternator.

Power steering?

For 600W I would use Meanwell HEP-600-15 ACDC. It can operate from 160Vdc to 420Vdc at 600W all day long.

[janosch]

Power steering?

Of course I forgot! And the brake pump!

[Dusty4]

Hey Arber, in the spec sheet for the hep-600-15 it states 390vdc for the upper voltage limit. Where do you get 420vdc from? I have also seen these 540w meanwell led drivers which operate up to 430vdc.https://au.mouser.com/ProductDetail/MEA ... 7BcQ%3D%3D

[arber333]

Hey Arber, in the spec sheet for the hep-600-15 it states 390vdc for the upper voltage limit. Where do you get 420vdc from? I have also seen these 540w meanwell led drivers which operate up to 430vdc.https://au.mouser.com/ProductDetail/MEA ... 7BcQ%3D%3D

I used to have 102S Lipo cells in my Mazda and i had it connected directly to my Pb battery. I charged to 4V/cell. In effect it operates night and day for 6 years now, despite i have 96S in Mazda now...
120~370VDC(390VDC operational), 10G vibration test.... I think i read about application in powering mining equipment... tough stuff.

[Dusty4]

That's good! Gives me confidence to put one in my conversion.