# Auxiliary battery for Tesla FT438-U1R 12V 35Ah 438A AGM ![Auxiliary battery for Tesla FT438-U1R 12V 35Ah 438A AGM](https://baterias.com/4624-home_default/battery-fullriver-ft438-u1r-12v-35ah-438a.jpg) > Fullriver FT438-U1R auxiliary battery 12V 35Ah 438A AGM. Full Throttle Series range. Dimensions 196ร—131ร—192 mm. Check fitment by plate. **Category:** [Auxiliary Batteries](https://baterias.com/gb/auxiliary-batteries) โ†’ [FULLRIVER](https://baterias.com/gb/fullriver) - **Canonical URL**: https://baterias.com/gb/battery-fullriver-ft438-u1r-12v-35ah-438a - **Language**: en-GB - **Brand**: FULLRIVER - **Reference**: BCOM-FULLRIVER-FT438-U1R - **MPN**: FT438-U1R - **Price**: 173,95 โ‚ฌ - **Stock**: In stock ## Technical specifications | Feature | Value | |---|---| | Brand | FULLRIVER | | Reference | FT438-U1 R | | Model | Full Throttle Series | | Voltage (V) | 12 V | | Largo | 196 cm | | Ancho | 131 cm | | Alto | 192 cm | | Peso | 11.3 kg | | EAN | 810233030640 | | Terminal type | M6 + TP26 (SAE) | | Cold cranking amps (EN) | 438 A | | Capacity (C20) | 35 Ah (c20) | | Case type | U1 R | ## Quick description **Fullriver FT438-U1R 12V 35Ah 438A** is a ready-to-use passenger car battery, sealed and maintenance-free. Delivers the cranking amps the engine needs in cold weather and keeps stable voltage for modern car loads (ECU, sensors, climate control, infotainment). ### Why this car battery? - **Original-equipment quality** without dealership prices - **Lasts 4 to 6 years** buy once instead of twice - **Real human tech support** if you have any doubts before buying ๐Ÿ”Œ Voltage 12 V โšก Capacity 35 Ah C20 ๐Ÿ”‹ Cold cranking 438 A EN-1 ๐Ÿ“ Dimensions 196ร—131ร—192 mm โš–๏ธ Weight 11,3 kg ๐Ÿท๏ธ Model Full Throttle Series ## Description ## Auxiliary battery Fullriver FT438-U1R Full Throttle Series 35Ah 438A 12V 12*V* Voltage 35*Ah* Capacity 438*A* Cold cranking 11.30*kg* Weight 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 ร— 131 ร— 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 ร— 131 ร— 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 [[ks:cutoff]]** 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 **[[ks:return_days]] days** to return it if it has not been installed, with free collection on the mainland, and shipment tracking by email. ## Frequently asked questions ### How is the Fullriver FT438-U1R battery installed in the vehicle? In most cars it fits in 15-30 minutes with a 10 mm wrench; if the battery is under the seat or in the boot the time can double. See the step-by-step guide on this page. Quick summary: 1) switch off the engine and remove the key; 2) locate the original battery (engine bay, boot or under seat); 3) disconnect the negative (โˆ’) terminal first, then the positive (+); 4) loosen the hold-down clamp and remove the old battery; 5) fit the new one in the same orientation โ€” match the polarity shown on the product sheet; 6) connect the positive (+) first, then the negative (โˆ’). On cars with Start-Stop or BMS, register the battery via OBD so the alternator applies the correct charging profile. ### How long does the Fullriver FT438-U1R battery last? Expected lifespan of the Fullriver FT438-U1R is 4 to 7 years in regular use (depends on technology and climate). In cold regions it drops slightly due to cold-start stress; in very hot regions it also drops because of electrolyte evaporation. To extend its life: avoid deep discharges (headlights on with engine off), have the alternator checked yearly, and keep the battery clean and properly secured. ### What size is this battery? Dimensions (length ร— width ร— height) are 196ร—131ร—192 mm โ€” also written as 196x131x192 mm โ€” following the European DIN standard. Always measure the space in your car before buying: even one extra millimetre can prevent the hold-down clamp from closing. The height shown includes the terminals. ### What are the equivalents of the FT438-U1R model? Directly interchangeable batteries (same dimensions, same polarity, same Ah and CCA) are the OEM equivalents from leading brands: Bosch, Tudor, Exide and, depending on the model, Banner or Yuasa. Exact equivalence depends on technology โ€” an EFB cannot be replaced with a conventional battery in Start-Stop cars. See the "Equivalents" section to view recommended options at the same performance level. ## Reviews - **Average rating**: 4.82 / 5 (32 reviews) ## Technical team (editorial authorship) The FAQs, guides and comparisons on this site are reviewed by the baterias.com technical team โ€” over 25 years of experience validating automotive batteries. โ†’ https://baterias.com/gb/technical-team --- *baterias.com โ€” Automotive batteries ยท 2026-09-29*