Specifications
| Brand | EXIDE |
|---|---|
| Part number | EM900 |
| Voltage (V) | 12 |
| Capacity (C20) | 42Ah (c20) |
| Technology | AGM |
| Length | 230.00 cm |
| Width | 173.00 cm |
| Height | 206.00 cm |
| Weight | 15.80 Kgs |
Exide EM900 12V 42Ah 700A is a starting battery for boats and motorhomes, with a case reinforced against the vibration of mooring and cruising. All its energy is designed to crank the engine reliably, not to run long loads: for that, fit a separate service bank.

The Exide EM900 with AGM technology is a marine battery with 42 Ah and 700 A of cold cranking current (EN) for motor and sailing boats, both for engine starting and onboard services. Measuring 230 × 173 × 206 mm, it is the direct replacement for boats fitted from the factory with a 42 Ah battery of this format.
The Exide EM900 is designed for motor and sailing boats, both for engine starting and onboard services. If it is your starter battery, run the services from a separate battery; if it is a service battery, avoid routinely discharging it beyond 50%. Check that it matches your current battery in dimensions, terminals and hold-down: this reference has a weight of 15.80 kg, SAE M 3/8"- 5/16"&stud terminals and B7 hold-down.
The EM900 is part of the Exide Marina Start AGM range. Choosing the right reference within the series comes down to capacity, dimensions and terminals: technology and quality are common to the whole family.
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.
The Exide EM900 is made in the 230 × 173 × 206 mm format and weighs 15.80 kg. It uses a B7 hold-down and SAE M 3/8"- 5/16"&stud terminals, the system that anchors and connects it in the vehicle. Checking the three dimensions and the terminal position before buying avoids the most common mistake when replacing a battery.
With more than a century of history, Exide Technologies manufactures automotive, marine, motorcycle and industrial batteries in Europe. Its presence as original equipment on assembly lines vouches for the quality of every reference. We guarantee that every Exide arrives new, charged and with the manufacturer's full warranty.
As a service battery, avoid routine discharges below 50% to extend its cycle life. At the end of the season, charge the battery fully and, if possible, keep it on a charger over the winter lay-up.
The Exide EM900 comes with the manufacturer's official warranty against manufacturing defects. Deep discharge from winter lay-up without charging is not covered.
Same-day dispatch from our warehouse for in-stock orders placed before 6:00 pm: 24-48 working hours in mainland Spain and Portugal, 3 to 5 days in the islands and the rest of Europe. Returns are accepted for 14 days if the battery has not been used (free collection on the Iberian mainland). You will receive tracking by email.
Data sheet
Specific References
| Brand | Exide · see all batteries Exide |
|---|---|
| Manufacturer range | EXIDE MARINA START AGM |
| Manufacturer reference (MPN) | EM900 |
| EAN-13 barcode | 3661024036030 |
| Dimensions (length × width × height) | 230 × 173 × 206 mm (230x173x206) |
Guide to replace a marine battery (cranking or house) in 20-30 minutes. Moisture and vibration in marine environments require reinforced hold-downs and sealed copper terminals.
Park on a flat surface, switch off the engine and remove the key. Make sure all lights and electrical accessories are off. Wait 1-2 minutes before starting.
Usually under the passenger bench, engine room or a dedicated ventilated compartment. Verify the compartment is dry and well ventilated before opening.
Use the 10 mm wrench to loosen the negative cable nut (black, marked −) and remove the cable from the post. Move it aside so it cannot touch any bodywork.
Repeat with the positive cable (red, marked +). Important: never let a terminal touch metal of the car while the other is still connected.
Marine batteries are heavy (15-50 kg). If it has rope handles, use them; otherwise have a carry strap ready. Secure the new one with metal hold-downs (not plastic) to resist sea-state vibration.
Place the battery in the same orientation as the old one (positive terminal on the same side). Tighten the hold-down clamp firmly.
Connect the positive (+) terminal first, then the negative (−). Tighten the nuts with the wrench until each terminal does not move. Apply anti-spark grease if you have any.
Apply dielectric grease on terminals to prevent salt-air corrosion. Check the engine charging circuit delivers 13.8-14.4 V at 2,000 rpm.
Yes. The EM900 from Exide uses AGM (Absorbent Glass Mat) technology: a sealed lead-acid battery where the electrolyte is absorbed in a glass-fibre mat. It withstands more charge/discharge cycles than a conventional one, handles heat better and is the required technology for boats with advanced Start-Stop and regenerative braking. Expected lifespan: 5-8 years under normal conditions.
In most boats 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 (−) 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 — match the polarity shown on the product sheet; 6) connect the positive (+) first, then the negative (−). On boats with Start-Stop or BMS, register the battery via OBD so the alternator applies the correct charging profile.
Expected lifespan of the Exide EM900 is 5 to 8 years in mild-climate boat use with Start-Stop. 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.
Dimensions (length × width × height) are 230×173×206 mm — also written as 230x173x206 mm — following the European DIN standard. Always measure the space in your boat before buying: even one extra millimetre can prevent the hold-down clamp from closing. The height shown includes the terminals.
Three options to confirm: 1) enter your number plate in the finder (DGT/DVLA/KBA auto-detect your model and engine); 2) check the "Compatible vehicles" tab on this page, where we list every vehicle verified by our technical team; 3) if you cannot find your model, message us on WhatsApp with brand, model, engine and year — we reply during business hours (Mon–Fri 10:00–13:30 and 16:40–18:00 (Spanish time, CET)). The EM900 typically fits a wide range of European vehicles thanks to its standard DIN case format.
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 — an EFB cannot be replaced with a conventional battery in Start-Stop boats. See the "Equivalents" section to view recommended options at the same performance level.
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