Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Specter]

12 gauge wire will NOT handle 40 amps.  Id not push more than 20 on it TBH.
You should always over rate it to be safe, all it takes is a connection getting loose over time / a bit of corrosion and hot spotting and now you oxidize the copper there and next thing you know you have melted insulation and a fire.

I wouldn't run anything less than 8 ga to be honest.   Also,and this is just MY OPINION... thinner stranded wire tends to hold up over time better in a moving / heavy vibration environment I have seen over the years.  It's more flexible and easier to handle bends, movements.

aaron

[Kill3rT0fu]

If the connection is immediately split from the J1772 head you only need wiring that does 15 amps for each one. Every single line isn't pulling 40 amps, just the station's delivery system to your inlet. If it's immediately split then each charger only requests ~14 amps tops.

Would you say it’s safe to split off into 3 Anderson connectors from one inlet? Or should 2 be the max and then have another Y split from there? I’m asking because I just don’t know what best practices are (I haven’t done any electronics work outside of basic arduino stuff)

[DonTom]

Would you say it’s safe to split off into 3 Anderson connectors from one inlet? Or should 2 be the max and then have another Y split from there? I’m asking because I just don’t know what best practices are (I haven’t done any electronics work outside of basic arduino stuff)

As long as everything is below the current spec of the wires and connectors, do it any way you want. I have separate lines on each 50-amp Anderson going to the motor controller. I use 8AWG wires which is overkill for each 3.3 KW charger.


-Don-  Reno, NV

[Kill3rT0fu]

If the connection is immediately split from the J1772 head you only need wiring that does 15 amps for each one. Every single line isn't pulling 40 amps, just the station's delivery system to your inlet. If it's immediately split then each charger only requests ~14 amps tops.

How much heat do these things put out without the TV heat sinks? I'm thinking about buying a large, long, aluminum heat sink to sandwich between them all (1.3 inch thick) if heat is going to be a problem. Is heat a big concern with these?

[GoneToPlaid]

If you're drawing 3300 watts at say 95% efficiency (optimistic!), then you get 165 watts of heat. The chargers can heat up to about 85*C before they back off power, so it takes a while to heat them up. On my bike that means about 30 to 40 minutes before they must reduce power. I don't have fans or proper heat sinks, and use active water cooling instead which is a PITA but weighs very little. My setup has the chargers in aluminum boxes like panniers, not under the battery. I suppose putting the chargers under the battery lets some of that heat soak into the battery, which keeps the chargers cooler but unevenly heats the battery. I've never tried that, though.

Bike build threads, with some details about my Diginow / TC chargers:
https://amytracker.wordpress.com/2021/08/09/2021-tat-building-a-zero-dsr-for-the-trans-america-trail/
https://amytracker.wordpress.com/2022/06/26/2022-zero-dsr-mods-in-pursuit-of-more-electric-adventure-riding

Water cooling works well at campgrounds, because they have spigots next to the 50A sockets:

[Bodo]

If you're drawing 3300 watts at say 95% efficiency (optimistic!), then you get 165 watts of heat. The chargers can heat up to about 85*C before they back off power, so it takes a while to heat them up. On my bike that means about 30 to 40 minutes before they must reduce power. I don't have fans or proper heat sinks, ...

Interesting. I could not see that on your pictures - did you remove the original fan and heat sink from the chargers?

I was thinking about trying the TC chargers without fan, in the hope that two of them would charge my 7.2 battery together with the 700W onboard charger @0.9C before the TCs would downrate thermally.

[Specter]

If the connection is immediately split from the J1772 head you only need wiring that does 15 amps for each one. Every single line isn't pulling 40 amps, just the station's delivery system to your inlet. If it's immediately split then each charger only requests ~14 amps tops.

How much heat do these things put out without the TV heat sinks? I'm thinking about buying a large, long, aluminum heat sink to sandwich between them all (1.3 inch thick) if heat is going to be a problem. Is heat a big concern with these?

14 gauge wire would handle that...barely.  id honestly do 12 gauge wire. given you are not running feet of it, it should handle 15 amps for a few hours easily w/o any heat issues.  It's not horribly larger than the 14 either.  Id personally run 10 ga but that's just me.

aaron

[GoneToPlaid]

If you're drawing 3300 watts at say 95% efficiency (optimistic!), then you get 165 watts of heat. The chargers can heat up to about 85*C before they back off power, so it takes a while to heat them up. On my bike that means about 30 to 40 minutes before they must reduce power. I don't have fans or proper heat sinks, ...

Interesting. I could not see that on your pictures - did you remove the original fan and heat sink from the chargers?

I was thinking about trying the TC chargers without fan, in the hope that two of them would charge my 7.2 battery together with the 700W onboard charger @0.9C before the TCs would downrate thermally.

Yes, I removed the heat sinks and fans both to save space, and for my application the fans would be destroyed quickly. At 0.9C you'd need maybe 75 minutes for a full charge, and the chargers would get hot around 35 minutes, so you'd get a half charge before they slow down. And they really do slow down: I've seen power drop from 3300W to 500W.

TC makes some water cooled models that would be interesting for packaging. You still have to reject all that heat to air, so ultimately you'll need something with fins and a fan. It can just be in a different location.

[Kill3rT0fu]

Do you think sandwiching a 1 inch thick aluminum heat sink would prevent the chargers from slowing down? I was considering buying a large aftermarket heat sink from eBay and maybe putting some small server fans (12v) to cool them but I’m not sure it’s worth the extra effort. I’m not even sure where I would wire some 12v fans

Alternatively, it looks like there's a good inch gap between the charger's and the left and right side of the pan, so I could fit 6 PC fans on each side with vent holes.

But my new question is, are there any 12v lines I can tap into for fans?

[Specter]

Ive noticed over time that Aluminum is GREAT for sucking up heat, but not so great for getting rid off it.  You may buy a few minutes until they too heat up, then getting the heat out of the Al is going to be a booger.

They make 5 volt fans too, that run off USB ports and some of them can really kick, even at the 300 ma or whatever a standard usb puts out.  Just a thought for alternative means since I know there are usb chargers hence a source of 5v on the bike.

It's a little more expensive but a copper sink (think computer scrap) might serve you a lot better.  Put some thermal paste on it and it should work, but ALWAYS check that paste every few months, or few charges IMO, especially if you are pushing it !! It does dry out over time and nothing is crappier than walking into a fire because a fin was dry and a chip cooked off, and all the crap that was lodged in the fin, lint etc that you didn't clean out, caught because of the 800 degree's that hit it when uncle 'woof' came a visiting.

Ive ran bitcoin miners in the past and trust me, it's a spectacular sight when something sets off the fire alarm at 2 am in the morning, because a card cooked due to a frozen fan, dirty fin, heat sink to chip interface inadequate due to drying out etc etc.  High power battery chargers are no different in this manner for the hazards.

aaron

[Kill3rT0fu]

Problem is finding a large copper heat sink is pretty darn hard. I can find about 30 on ebay right now, but they're aluminum. Ideally I'd like a water block and do a radiator, but that's CNC and CAD work that I'm not trained in. So I'm sticking to what I know.

[Specter]

If you have any junkyards around check them, or computer shops.  Many computers, especially gaming ones have a lot of copper in their heat sinks,  even if the outer fins are aluminum, if the core is copper that is still a plus for you.  You should be able to get them for a few bucks tops, at best they are only getting a buck or so a pound for them as mixed metal.

Ive tie strapped some sinks on place before with ample thermo grease.  no not the best or prettiest, but it worked.  What about a peltier junction cooling?  you got the power there, use some of it.

Aaron

[Bodo]

Yes, I removed the heat sinks and fans both to save space, and for my application the fans would be destroyed quickly. At 0.9C you'd need maybe 75 minutes for a full charge, and the chargers would get hot around 35 minutes, so you'd get a half charge before they slow down. And they really do slow down: I've seen power drop from 3300W to 500W.

TC makes some water cooled models that would be interesting for packaging. You still have to reject all that heat to air, so ultimately you'll need something with fins and a fan. It can just be in a different location.

TC allegedly stopped delivering the Gen3 3.3kW chargers, where the heat sink and fan can be easily removed. They now offer the smaller and lighter Gen4 https://www.tiechengcharger.com/products/tccharger-3.3kw-hk-mf-108-32-obc with the heat sink being part of the diecast housing. I might just try that without fan, just with natural (passive) convection, and not housed seperately (they are already IP67).

The watercooled units look even more compact, but don't have the opportunity for natural convection. I wouldn't like to create a heavy, bulky and complicated watercooling setup on the bike that shouldn't take longer than a good hour from 0-100% SoC.

[Kill3rT0fu]

PC heat sinks aren't big enough. I'm looking for something larger. Like one giant block for all 3, or 3 individual blocks the same size. So that'd mean custom making one (gathering copper scrap, making a foundry, melting it down, making a mold and cast, etc...) whereas I see 4 aluminum heatsinks right now on ebay that might work.

I've also been looking at water blocks, maybe something 3x3" would work, but all I'm finding are GPU ad CPU heatsinks which are all weird shapes.

-edit-

researching peltier junction cooling now. Interesting stuff. Might be an option if I can find large sheets of that stuff.

Anyway, is there a 12v source I can tap into for fans?

[Kill3rT0fu]

Yes, I removed the heat sinks and fans both to save space, and for my application the fans would be destroyed quickly. At 0.9C you'd need maybe 75 minutes for a full charge, and the chargers would get hot around 35 minutes, so you'd get a half charge before they slow down. And they really do slow down: I've seen power drop from 3300W to 500W.

TC makes some water cooled models that would be interesting for packaging. You still have to reject all that heat to air, so ultimately you'll need something with fins and a fan. It can just be in a different location.

TC allegedly stopped delivering the Gen3 3.3kW chargers, where the heat sink and fan can be easily removed. They now offer the smaller and lighter Gen4 https://www.tiechengcharger.com/products/tccharger-3.3kw-hk-mf-108-32-obc with the heat sink being part of the diecast housing. I might just try that without fan, just with natural (passive) convection, and not housed seperately (they are already IP67).

The watercooled units look even more compact, but don't have the opportunity for natural convection. I wouldn't like to create a heavy, bulky and complicated watercooling setup on the bike that shouldn't take longer than a good hour from 0-100% SoC.

Why not leave the fan on and point it downward from the pan? Cut some holes in the bottom to allow the air to escape.