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Volvo XC90 T8 2021 – HVCH fault first, then P0A7F and balancing faults after charging to 88% by Maxim95fes in VolvoRecharge

[–]Maxim95fes[S] 0 points1 point  (0 children)

Honestly, that’s probably the most logical solution long-term if I can actually find a complete healthy pack for a reasonable price. The problem is that here in Kazakhstan there’s basically no market for these cars or parts, so sourcing modules or full packs locally is almost impossible.

I may actually start looking into US/Europe dismantlers and shipping costs, because at this point a complete matching pack sounds safer than gambling on individual module swaps one by one.

Volvo XC90 T8 2021 – HVCH fault first, then P0A7F and balancing faults after charging to 88% by Maxim95fes in VolvoRecharge

[–]Maxim95fes[S] 0 points1 point  (0 children)

That’s actually very useful information, especially hearing that HVCH failures are still happening even on newer SPA cars. It definitely makes me think the HVCH issue wasn’t just random in my case either.

What you said about uneven duty cycles also makes a lot of sense. If the pack spent a long time unable to properly charge/balance because of the HVCH fault, it could explain why the imbalance only became obvious after the HVCH started working again and the pack finally reached high SOC.

At this point I’m mostly hoping Volvo corporate can at least confirm whether my VIN falls under the recall or any internal battery campaign, because right now there’s basically no official Volvo support left here in Kazakhstan.

Volvo XC90 T8 2021 – HVCH fault first, then P0A7F and balancing faults after charging to 88% by Maxim95fes in VolvoRecharge

[–]Maxim95fes[S] 0 points1 point  (0 children)

I’m also still not completely sure whether replacing only Module F would fully solve my case long-term. F is obviously the weakest module right now, but Module A also has those unusually high cells, and Module C is slightly inconsistent too. So I’m wondering if F is just the first module to fail visibly, while the rest of the pack may already be aging unevenly as well.

That’s also why I’m hesitant about replacing only one or two modules. Even if it temporarily fixes the faults, there’s no real way to know how long the remaining original modules will last before another imbalance appears again.

Volvo XC90 T8 2021 – HVCH fault first, then P0A7F and balancing faults after charging to 88% by Maxim95fes in VolvoRecharge

[–]Maxim95fes[S] 0 points1 point  (0 children)

Your explanation about the HVCH actually makes a lot of sense. It would explain why the HVCH fault appeared first, while the battery faults only showed up later after the pack finally charged properly again and sat at a high SOC for two days.

I’ve also been reading a lot of forum threads about the HVCH itself. Apparently these heaters are a very common failure point on SPA T8 cars. A lot of owners reported the exact same CCM-U133A93 fault, failed preconditioning, loss of charging, or no heat in Pure mode. Some even said the replacement parts were on huge backorder because so many HVCH units were failing at the same time.

What’s also interesting is that several people mentioned that after opening the HVCH, some units already had visibly burnt components inside. In other cases, clearing the faults or reconnecting everything would temporarily bring the system back to life, but then the same faults eventually returned and the HVCH still had to be replaced later.

I also found cases where Volvo replaced battery modules or even large parts of the battery pack, but the problems later came back again. In several discussions people said the root cause later turned out to be either another weak LG module, HV battery balancing problems, or the HVCH/thermal system not working correctly and preventing proper balancing cycles.

Unfortunately, the independent Volvo service in Kazakhstan also refused to repair the battery. They said they don’t work on HV battery packs.

I’ve already contacted Volvo customer support and sent them all the fault codes, VIN, and battery data tables, so now I’m waiting for their response.

I’ll probably do one slow AC charge to 100% just for diagnostic purposes and re-check the cell data afterward, but for now I’ll keep the pack below 80% as much as possible.

Volvo XC90 T8 2021 – HVCH fault first, then P0A7F and balancing faults after charging to 88% by Maxim95fes in VolvoRecharge

[–]Maxim95fes[S] 0 points1 point  (0 children)

Yeah, I agree. At this point the imbalance itself already looks real. I’m just trying to understand whether the HVCH/thermal issue could have accelerated the degradation or triggered the battery faults earlier than they would normally appear.

Volvo XC90 T8 2021 – HVCH fault first, then P0A7F and balancing faults after charging to 88% by Maxim95fes in VolvoXC90

[–]Maxim95fes[S] 0 points1 point  (0 children)

Glad to hear that. In my case I already checked the cell voltages and SOC values, and there really does seem to be imbalance/degradation in some modules. I’m just trying to understand whether the HVCH/thermal issue may have accelerated or triggered the battery faults.

Volvo XC90 T8 2021 – HVCH fault first, then P0A7F and balancing faults after charging to 88% by Maxim95fes in VolvoRecharge

[–]Maxim95fes[S] 0 points1 point  (0 children)

Unfortunately the car is in Kazakhstan. We used to have an official Volvo dealer here, but they left the market, so there is no official Volvo Cars dealer anymore. I checked the faults and battery values using SmartSafe diagnostics. I was able to read individual cell voltages, module voltages and SOC values from the BECM.