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My 2022 F350 has two batteries in it. I had to replace the one that drives the starter as it wasn't holding a charge anymore. There was a substantial amount of corrosion/acid damage on the terminals and bracket - It took a couple hours to clean up.
I went back in to it a few hours after to reinstall the bracket (after the paint dried), and I noticed the other battery was "hissing" and there was sporadic bubbling out of the top of the battery (see image).
Thoughts on causes, concerns/issues and what repairs would be needed?
I would start by changing them in pairs, not just one at a time. I would also bump up to AGM’s. Many of us went with the Walmart brand with good success.
Last edited by chadstickpoindexter; Jun 21, 2026 at 09:18 PM.
replace the batteries in pairs so the weaker one doesn't put extra strain on the new one and reset the BMS when you replace the batteries so the truck isn't using the charging rates from the old aged batteries
replace the batteries in pairs so the weaker one doesn't put extra strain on the new one and reset the BMS when you replace the batteries so the truck isn't using the charging rates from the old aged batteries
FLA shouldn't outgas rapidly enough to push the electrolyte out of the vents. The regulator should follow the charge profiles and the BMS should I don't know where the regulators are on this truck but perhaps it's integrated into the alternator. Do you have dual alternators?
The OP's understanding of how the two batteries are wired is wrong; they are wired in parallel. The weaker battery is going to draw basically unlimited current from the good battery till they are equalized. BMS has nothing to do with it.
To rectify, replace the other battery. If you're lucky you did not kill the one you already replaced and it can just be charged.
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