DC85-12 Deep Cycle AGM Battery — 85Ah 510CCA 145RC

Q: What does deep cycle mean?
A battery built to be discharged to around 50% of capacity and recharged, repeatedly, without rapid loss of capacity. A deep cycle battery runs the fridge, the lights and the dash in a caravan or 4WD for hours and recovers charge from the alternator or solar. A starting battery, by contrast, is built to deliver a huge current for a few seconds then recharge immediately from the alternator.

Q: What is AGM and how does it differ from flooded lead-acid?
Absorbed Glass Mat. The electrolyte is held in a fibreglass separator between the plates rather than sloshing around as a liquid. That makes AGM spill-proof, safe to install at any angle, less prone to vibration damage, and faster to recharge. It's also sealed and maintenance-free — no topping up with distilled water.

Q: Can I use this as a starting battery?
It'll crank an engine in a pinch at 510 CCA, but it's not designed for daily cranking duty. Starting batteries have thin plates for maximum surface area and short current burst; deep-cycle plates are thicker and built for sustained discharge. If this is the only battery in the vehicle, buy a dedicated starter battery too.

Q: Does 85Ah mean 85 amps for one hour?
No. 85Ah at the C20 rate means 4.25A for 20 hours. Lead-acid batteries lose usable capacity when discharged faster, so pulling 85 amps for an hour will give less than an hour of runtime (closer to 48Ah per the C1 figure). Match discharge rate to the published capacity curve.

Q: What is the C20 rate?
The industry-standard discharge rate for stating battery capacity: discharge over 20 hours at a steady current until the battery hits a cutoff voltage. For an 85Ah C20 battery, that's 4.25A for 20 hours. C100, C10, C5, C3, C2 and C1 figures are the same test over different durations — published separately because capacity drops as discharge current rises.

Q: How do I charge an AGM battery?
AGM-aware smart charger or DC-DC charger set to 14.4-14.7V absorption and 13.5-13.6V float. A plain lead-acid charger at 13.5V float will slowly undercharge an AGM and reduce cycle life. The DC85-12 can take bulk charge current up to 35% of capacity (around 30A); larger charger current speeds up recharge but doesn't harm the battery.

Q: Can I install this inside the vehicle or caravan cabinet?
Yes. Sealed AGM chemistry produces no gas under normal operation, no ventilation is required, and the battery is safe at any mounting angle. Flooded wet-cell batteries by contrast must be ventilated to outside air — one reason AGM has taken over caravan and 4WD house-battery installs.

Q: Does it come with mounting hardware?
No. The battery ships bare and sits in whatever battery box, tray or clamp you already have. M8 bolts and cable lugs are standard automotive hardware and bolt directly to the TP08 brass terminal pattern. Torque to 7-9 Nm with a torque wrench.

Q: What warranty does it carry?
2 years general manufacturer warranty against defects in materials and workmanship. Fullriver extends this to 7 years when the battery is used exclusively in a residential solar or stationary renewable-energy application, charged per Fullriver's published AGM profile, and registered on install.