PSA: Fast Charging derating significantly on hot days

[NAVEWO]

I posted related content at the thread below. Dealer finding leaks on Max Tow package in Schroeder valves and replacing freon. See below.

https://www.f150lightningforum.com/...cion-after-dc-fast-charging.15668/post-413635

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[sd25]

Interesting. That's 2 data points (including mine) with a bad schrader valve for the Max Tow AC.

My dealer had trouble finding the leak initially, before finally locating it at the schrader valve. So for folks with low freon in the Max Tow AC system (which leads to the battery overheating during fast charging), might want the dealer to check/replace the schrader valves (my defective valve was on the high side of the AC system).

 

[NAVEWO]

Interesting. That's 2 data points (including mine) with a bad schrader valve for the Max Tow AC.

My dealer had trouble finding the leak initially, before finally locating it at the schrader valve. So for folks with low freon in the Max Tow AC system (which leads to the battery overheating during fast charging), might want the dealer to check/replace the schrader valves (my defective valve was on the high side of the AC system).

For my part my thanks to you and this forum for giving me the information to take to the dealer. The technician reported finding "oil" on the high side caps. They found the system to be "low" and said it was not that bad...of course since it was leaking...it was certainly not going to get better on its own. Thanks for your post!

 

[sd25]

Just wanted to add some updates...

TL;DR;
Another leak found in the HVB cooling system.

I had another instance of charge speed reduction during a road trip a few months ago.
Same symptoms as before. Around 30% SoC - fast initial charge rate 170KW+ then quickly drops below 100KW and keeps dropping. No alerts received. But didn't hear the noisy cooling fans running during charging. Only clear indication of an issue can be seen after unplugging - the battery temperature gauge is almost all the way to the right and available power is reduced.

The dealer at my destination found the refrigerant in the HV Battery cooling loop was completely empty again. They couldn't find the source of the leak so they just refilled the system.

Return trip was fine and fast charging seemed to work ok - 170KW+ initial rate for a few minutes then levelled off to around 105KW until 80% SoC. Luckily the return trip temps were milder so I'm guessing the cooling system didn't have to work as hard.

Once home I took it to my local dealer. They found that the refrigerant levels were normal and no evidence of a leak. I explained that the system seems to develop a leak after repeated fast charges in hot weather. So they decided to take a closer look.

They found evidence of a leak (uv dye) near the compressor seal on the low side. They said the way the seal was pinched, it may have been there since delivery. Dealer had to drop the HV battery to access the compressor and replace the seal.

Happy to report that after a completing a recent road trip with multiple charge stops during really hot weather (100F) the truck charged really well. 187KW peaks and held steady at 130KW until 80% SoC.

The only downside, now that the cooling system is running properly, is from the outside the truck now sounds louder than an ICE truck - but I'll take it.

 

[jetfixr1]

Just wanted to add some updates...

TL;DR;
Another leak found in the HVB cooling system.

I had another instance of charge speed reduction during a road trip a few months ago.
Same symptoms as before. Around 30% SoC - fast initial charge rate 170KW+ then quickly drops below 100KW and keeps dropping. No alerts received. But didn't hear the noisy cooling fans running during charging. Only clear indication of an issue can be seen after unplugging - the battery temperature gauge is almost all the way to the right and available power is reduced.

The dealer at my destination found the refrigerant in the HV Battery cooling loop was completely empty again. They couldn't find the source of the leak so they just refilled the system.

Return trip was fine and fast charging seemed to work ok - 170KW+ initial rate for a few minutes then levelled off to around 105KW until 80% SoC. Luckily the return trip temps were milder so I'm guessing the cooling system didn't have to work as hard.

Once home I took it to my local dealer. They found that the refrigerant levels were normal and no evidence of a leak. I explained that the system seems to develop a leak after repeated fast charges in hot weather. So they decided to take a closer look.

They found evidence of a leak (uv dye) near the compressor seal on the low side. They said the way the seal was pinched, it may have been there since delivery. Dealer had to drop the HV battery to access the compressor and replace the seal.

Happy to report that after a completing a recent road trip with multiple charge stops during really hot weather (100F) the truck charged really well. 187KW peaks and held steady at 130KW until 80% SoC.

The only downside, now that the cooling system is running properly, is from the outside the truck now sounds louder than an ICE truck - but I'll take it.

What charger brand were you using? My last trip to Florida was brutal. Temps hovering 85F+, the V3 Teslas only gave a max of 165 and would immediately throttle down to 100 after about 6 minutes.
Looking at carscanner, the truck was the one requesting the derated amperage the majority of times and the coupler temp was in the 130F range. I wasnt too pleased with the charging performance this trip but its probably the highest OAT ive encountered during a roadtrip. In the past ive had EA push out 185kw.

 

[sd25]

What charger brand were you using? My last trip to Florida was brutal. Temps hovering 85F+, the V3 Teslas only gave a max of 165 and would immediately throttle down to 100 after about 6 minutes.
Looking at carscanner, the truck was the one requesting the derated amperage the majority of times and the coupler temp was in the 130F range. I wasnt too pleased with the charging performance this trip but its probably the highest OAT ive encountered during a roadtrip. In the past ive had EA push out 185kw.

I've been sticking with Tesla chargers (and a 1 month Tesla membership) with pretty good success - also travelling to Florida. There was one bad Tesla supercharger site in Woodbridge, VA that had 4 out of 12 chargers down - but the rest of the stops were all good.

If you have the Max Tow package, and you don't hear the truck's cooling system get really loud when charging then the throttling behavior you're getting is similar to what mine was doing before getting the refrigerant leak fixed.

Did your battery temp gauge read high right after charging? That's another clue.

 

[jetfixr1]

I've been sticking with Tesla chargers (and a 1 month Tesla membership) with pretty good success - also travelling to Florida. There was one bad Tesla supercharger site in Woodbridge, VA that had 4 out of 12 chargers down - but the rest of the stops were all good.

If you have the Max Tow package, and you don't hear the truck's cooling system get really loud when charging then the throttling behavior you're getting is similar to what mine was doing before getting the refrigerant leak fixed.

Did your battery temp gauge read high right after charging? That's another clue.

It read within range, about halfway between 1/2 and 3/4. Carscanner was showing the pack around 115F after charging. Im probably going to test on an EA 350 charger to see if I get the full 500A on a "normal" temp day

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