AGM Battery 100Ah 12V — Motorhome Solar Boat | Electronicx
Why an AGM battery with 100Ah?
An AGM battery 100Ah 12V is the central energy source for anyone who needs reliable 12-volt power far from the mains. Whether in a motorhome, on a boat, in a solar system or as a backup – the combination of a high capacity of 100 ampere-hours and robust AGM technology (Absorbent Glass Mat) delivers exactly what mobile and stationary systems require: cycle-resistant, leak-proof and maintenance-free. At Electronicx, we offer you a wide range of powerful 100Ah AGM batteries for a wide variety of applications.
The nominal capacity of 100Ah (measured at the C20 discharge current over 20 hours) means: you can draw around 5 amperes of continuous current from the battery for 20 hours before the voltage drops to the end-of-discharge voltage (approx. 10.5V). In practice, such a battery easily supplies a typical motorhome electrical system with lighting, water pump, compressor fridge and USB charging ports over a whole weekend – without recharging. Thanks to extremely low self-discharge of only 1–3% per month, the AGM battery remains ready for use even during longer periods of storage.
Technical data and specifications of a 100Ah AGM battery
A high-quality 100Ah AGM battery is characterised by the following typical values. These figures refer to cycle-resistant (deep-cycle) models, such as those we stock at Electronicx, and may vary slightly depending on the manufacturer:
- Nominal voltage: 12 volts
- Nominal capacity C20: 100 Ah (at a 20-hour discharge rate)
- Cold cranking current (CCA): 800–1000 A (at -18°C according to EN standard)
- Internal resistance: typically 4–6 mΩ (fully charged)
- Maximum discharge current: 1000–1200 A (5 seconds)
- End-of-charge voltage cyclic: 14.4–14.8 V (temperature-compensated)
- Float charge voltage: 13.5–13.8 V
- Optimum operating temperature: 20–30°C (permissible -20 to +50°C)
- Self-discharge: <3% per month at 20°C
- Cycle life: up to 500 cycles at 50% depth of discharge (DoD) – at only 30% DoD even 1200+ cycles
- Weight: approx. 28–32 kg
- Typical dimensions (L×W×H): approximately 330×172×220 mm to 353×175×213 mm (depending on the casing)
- Connection: usually round terminal (M6 or M8 thread) or SAE cone
The extremely low internal resistance and the high current delivery capability make AGM technology particularly interesting for applications with short-term high currents, for example when starting generators or for inverters with a high inrush load. At the same time, the construction with sulphuric acid bound in glass fleece copes better with deep discharges than conventional flooded batteries – an invaluable advantage in the cyclic operation of solar or on-board power systems.
Possible uses – motorhome, solar, boat & more
Motorhome and camper
The 100Ah AGM battery is the most commonly installed leisure battery in motorhomes. It stores the energy from the alternator and solar modules and reliably supplies it to the fridge, heating, lighting and entertainment electronics. Thanks to its vibration resistance and sealed construction (VRLA), the battery can also be installed in the interior without hesitation – no acid escapes, no maintenance required. If more capacity is needed, simply connect two AGM batteries 80Ah or 100Ah in parallel and increase the storage to 200Ah or more. In our range you will find deep-discharge-resistant models specially designed for the camping sector with an optimised plate design.
Solar systems and off-grid networks
As a storage battery for off-grid photovoltaic systems, the 100Ah AGM shows its full strength: the high cycle life and low self-discharge ensure that the stored energy is not lost even on days with little sun. With suitable solar charge controllers (MPPT recommended), the AGM battery can be charged gently and kept at a state of charge of 50–80%, which can maximise its service life. A typical holiday home with a 200Wp solar module and a 100Ah battery covers the basic demand for light and 12V devices over many years with virtually zero maintenance.
Boats and marine
On boats and yachts, the AGM 100Ah is the established choice as a consumer battery. It copes with heeling angles of up to 45°, is completely leak-proof and handles the harsh, salty environment without complaint. Whether for bow and stern thrusters, anchor windlass or the complete on-board electronics – the AGM battery delivers the required currents within seconds and can be deeply discharged at the same time without being damaged. Combined with a shore power charger or a high-performance charge booster, the battery always remains at the optimum state of charge.
Further applications
Commercial vehicles with electric tail lifts, wheelchairs, cleaning machines, UPS systems and many industrial applications rely on 100Ah AGM technology. Even as an AGM car battery for vehicles with a start-stop system, a 100Ah variant (although starter rather than cycle-resistant batteries are usually used here) is a reliable choice. At Electronicx you will find both cycle-resistant deep-cycle and powerful starter AGM batteries with 100Ah.
Installation, charging and care of your 100Ah AGM battery
Installation is straightforward thanks to the leak-proof construction. Ensure adequate securing (lashing straps or mounting brackets) and protected routing of the cables with a cross-section of at least 16mm² for the usual distance of up to 3m to the consumer. Use acid-resistant terminal grease and tighten the terminal clamps to 6–8 Nm – too much force damages the casing feed-throughs.
To charge a 100Ah AGM battery, intelligent chargers with an IUoU characteristic curve that regulate the charging voltage depending on temperature are recommended. The ideal charging voltage in cyclic operation is 14.4–14.7V (20°C), and the trickle charge is 13.5–13.8V. Never charge at more than 20% of the nominal capacity current (i.e. max. 20A) in order to avoid gassing and premature ageing. Modern AGM chargers detect the battery condition automatically and adjust the charging phase. Further tips can be found in our 12 volt battery guide and the instructions on charging 12V batteries correctly.
The ideal storage temperature is 15–25°C. If the battery is taken out of service for a longer period, recharge it every 6 months to prevent harmful sulphation. A BMS (Battery Management System) or a simple voltage monitor reliably protects against deep discharge and overcharging.
AGM, GEL or LiFePO4? The comparison in the 100Ah class
Anyone facing a purchase decision wonders which technology is the right one in the 100Ah segment. We have compared the three most important types for you. A detailed comparison can be found in our article AGM vs. GEL vs. LiFePO4.
| Criterion | AGM | Gel | LiFePO4 |
|---|---|---|---|
| Usable capacity | 50–70% (recommended 50% DoD) | 60–80% (recommended 50% DoD) | 80–90% |
| Cycles at 50% DoD | 400–600 | 500–800 | >3000 |
| Cycles at 80% DoD | approx. 200–300 | 350–500 | >2000 |
| Weight (100Ah) | 28–32 kg | 30–34 kg | 12–14 kg |
| Charging efficiency | 85–90% | 80–85% | 95–99% |
| Max. charging current | 0,2C (20A) | 0,15C (15A) | 0,5–1C (50–100A) |
| Temperature range charging | 0–40°C | -5–50°C | 0–45°C (do not charge below 0) |
| Maintenance | None | None | None (BMS integrated) |
| Price range (100Ah) | 120–350 € | 180–450 € | 400–900 € |
| Installation position | any | any | any |
The classic AGM battery offers the best value for money if regular deep discharges are avoided and a moderate weight is acceptable. It is more robust against overcharging than gel and costs only a fraction of lithium systems. The gel battery scores with even higher cycle stability and suitability for extremely slow discharges, but is somewhat heavier and more expensive. LiFePO4 batteries are by far the lightest and most durable, but require sophisticated battery management and are significantly more expensive to purchase. For most campers, boat owners and solar installations, the 100Ah AGM represents the ideal compromise between cost, robustness and performance.
Buying advice – What to look out for when buying a 100Ah AGM battery
Not every 100Ah AGM battery is the same. The following points will help you choose the right model:
- Battery type: deep-cycle or dual-purpose. Pure supply batteries (deep-cycle) are optimised for regular, deeper discharges and use thicker plates. An AGM car battery, on the other hand, delivers high cold cranking currents but tolerates fewer cycles at deep discharge. For motorhome or solar operation, always choose a cycle-resistant model.
- Assess capacity realistically. 100Ah sounds like a lot, but because of the recommended 50% depth of discharge only about 50Ah is effectively available to you. Measure your daily consumption and dimension the battery generously accordingly. Two 100Ah batteries connected in parallel (=200Ah, 100Ah usable) are often the better choice than one battery that is constantly deeply discharged.
- Check connections and dimensions. Pay attention to the correct terminal type (round terminal M6/M8 or SAE cone) and the correct terminal arrangement (terminal 0 or terminal 1, depending on the vehicle). The external dimensions must fit exactly into the battery compartment – even a few millimetres can be decisive.
- Brand quality and technical data. At Electronicx we stock exclusively well-known brands with transparent data sheets. Pay attention to details on cycle stability (not just CCA), to the recommended charging voltage and to the year of manufacture. Fresh stock goes without saying for us, because AGM batteries age even when not in use.
- Order accessories at the same time. Suitable terminal adapters, battery mounts and a high-quality charger can significantly extend the life of your investment. Our service team will be happy to advise you.
The prices for a high-quality 100Ah AGM battery in our shop range from around 120 to 350 Euro depending on the version. Pure deep-cycle batteries with high cycle stability are usually in the middle to upper range, while simple starter AGM batteries with 100Ah are available more cheaply.
Frequently asked questions (FAQ) about the AGM battery 100Ah
Can I install a 100Ah AGM battery lying down?
Yes, AGM batteries are leak-proof thanks to the bound glass-fibre technology and can be installed in almost any position – including lying down. However, avoid overhead installation, as this can hinder gas venting through the valves.
How do I correctly charge a 100Ah AGM battery with a solar panel?
Use an MPPT solar charge controller with an adjustable AGM charging profile. The end-of-charge voltage should be set to 14.4–14.7V, the float voltage to 13.5–13.8V. Modern controllers detect the temperature and compensate the voltage automatically. Charge at a maximum of 20A to protect the battery.
How long does a 100Ah AGM battery last?
The service life depends heavily on usage. With regular discharge to 50% and immediate recharging, 400–600 cycles can be achieved, which corresponds to around 5–8 years with year-round operation. A new 100Ah AGM battery from Electronicx is suitable for long-term use. Deep discharges and overcharging significantly shorten the service life.
Can I connect two 100Ah AGM batteries in parallel?
Yes, this is easily possible and increases the capacity to 200Ah (usable approx. 100Ah). Make sure to use batteries of the same type, age and capacity and to connect them with equally thick, short cables. The parallel connection should always be made diagonally to ensure symmetrical current distribution.
What does CCA mean on a 100Ah AGM battery?
CCA (Cold Cranking Amperes) indicates the maximum current the battery can deliver at -18°C for 30 seconds without the voltage dropping below 7.2V. For pure supply batteries this value is of secondary importance; for starter or dual-purpose variants it is typically between 800 and 1000A. Even in deeply discharged states, the AGM battery can still start the engine – an extra safety benefit.
Can I use a 100Ah AGM battery as a starter battery in a car?
That depends on the type. A cycle-resistant deep-cycle AGM is optimised for repeated deep discharge, but not necessarily for extremely high starting currents at sub-zero temperatures – it often has lower CCA values. A 100Ah battery designed as an AGM car battery, on the other hand, delivers excellent cold starts and is perfect for vehicles with a start-stop system. So check the intended purpose carefully before use.
How do I dispose of my old 100Ah AGM battery?
AGM batteries are lead-acid accumulators and do not belong in household waste. Take them to a municipal collection point or back to the retailer. Under the German Battery Act, we as a distributor are obliged to take back old batteries. You can also drop off your old battery free of charge at our premises in Cleebronn (not by post, as it is hazardous goods) – simply contact us in advance.
Do you have further questions or need help with your selection? Call us on +49 7135 7194106 or write to [email protected]. Our specialist staff will advise you comprehensively and without obligation.
Electronicx GmbH • Hindenburgstr. 37A • 74389 Cleebronn • Germany • Managing Director: Andreas Emschanow • HRB 752730 (Stuttgart Local Court) • VAT ID: DE300176428
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