Originally Posted by up2speed4
Hello, With all this battery knowledge I thought I would post this here. My problem: I will be camping without hookups for the first time in my new 20' Flagstaff and I was told my one year old 550 amp battery will power my water pump and 12v lights and occasional heater use for one or two days. Is this true or was the dealer trying to sell me additional batteries and generator I don't need?
First off, 550 CCA is not amp hours, it is "amp seconds."
30 of them to be exact. The CCA is then number of amps that battery, fully charged, can deliver in the cold for 30 seconds until dead.
There should be a "RC" (Reserve Capacity) number on that battery as well.
Post the model number. RC is used for how long the battery will last if your fan belt breaks before IT is dead.
These numbers being "on the battery" means it is most likely a dual purpose "Marine" type battery, used to start a boat's engine and run some boat items with the engine off. Not the best type for travel trailer house batteries that will never start an engine.
Amp hour rating is used to determine a deep discharge storage battery's capacity to deliver a reasonable house load over a long period of time "hours" not seconds.
The typical DP (Dual Purpose or Marine type) has between 60 and 75 amp hours capacity. 60 - 75 amps over 20 hours to discharge from "full" to 20% of initial charge remaining.
To determine "how long it will last" you will need to look at the discharge curve for your model battery. They are slightly different based on each manufacturer's construction.
Also due to something called the Peukert Effect, trying to pull more amps from battery than it is rated at (to drive an inverter or start a car) dramatically reduces the "amp hours" because the battery's construction has a hard time "serving up" electrons at that rate. Dividing that demand over several batteries means they ALL will last longer.