Auxiliary battery for Tesla FT438-U1R 12V 35Ah 438A AGM

Auxiliary battery Fullriver FT438-U1R Full Throttle Series 35Ah 438A 12V

Designed for the auxiliary network of cars with advanced Start-Stop and heavy electronics, the Fullriver FT438-U1R from the Full Throttle Series range stabilises the voltage with 35 Ah with AGM technology. It replaces the original battery without adaptation in vehicles with an auxiliary battery with a 196 × 131 × 192 mm format: same 35 Ah capacity.

• AGM technology: absorbed electrolyte, no spills, can be mounted at an angle.
• Stabilises the onboard network voltage.
• Sealed AGM: safe when installed in the cabin.
• Maintenance-free.

What the Fullriver FT438-U1R is for

As an auxiliary battery, the Fullriver FT438-U1R works alongside the main one; replace it when the vehicle reports a fault in the support network. Check that it matches your current battery in dimensions, terminals and hold-down: this reference has a weight of 11.30 kg and M6 + TP26 (SAE) terminals.

Size, terminals and hold-down of the Fullriver FT438-U1R

The Fullriver FT438-U1R is made in the 196 × 131 × 192 mm format and weighs 11.30 kg. It uses M6 + TP26 (SAE) terminals, the system that anchors and connects it in the vehicle. Before replacing it, measure your current battery tray: if all three dimensions and the terminal positions match, the swap is direct and needs no adapters.

Why choose Fullriver batteries

Fullriver specialises in deep-cycle AGM batteries for mobility, marine, solar and traction. Its DC and HC series are known for their tolerance to deep discharge and long cycle life. All the Fullriver batteries in our catalogue are genuine product, recently manufactured and covered by the manufacturer's warranty.

The Fullriver FT438-U1R: Full Throttle Series range and AGM technology

Within the Fullriver catalogue, the Full Throttle Series series groups the references designed for this use. The FT438-U1R is the 35 Ah model of that family, with the same performance as its siblings in other sizes.

In an AGM battery the electrolyte is absorbed in glass-fibre separators: there is no free liquid, it cannot spill and it can be mounted at an angle. That construction lowers internal resistance, speeds up recharging and multiplies cycle life compared with a conventional battery.

Usage and maintenance tips

The auxiliary battery works alongside the main one: if a support-network fault warning appears, check both. Charge with a charger that has an AGM mode: it limits the voltage and protects the glass-fibre separators.

Official warranty

The Fullriver FT438-U1R comes with the manufacturer's official warranty against manufacturing defects. If it fails through a defect within the warranty period, we replace it at no cost to you.

When you get it and how to return it

Order before 6:00 pm with stock available and it leaves today: mainland Spain and Portugal receive it in 24-48 working hours, the islands and the rest of the EU in 3 to 5 days. You have 14 days to return it if it has not been installed, with free collection on the mainland, and shipment tracking by email.