Friday, September 16, 2011

Electricity onboard.

There are many common misconceptions regrading battery capacity.

Deep cycle batteries are sold by capacity and are normally rated in amp-hours (Ah). It would be reasonable to expect a 100 amp hour battery to deliver one hundred amp hours – one amp for one hundred hours OR ten amps for ten hours.

Sadly this a long way from the truth. The number of amp hours you can extract from a given battery is dependent on the following factors:
  • The battery’s chemistry – for example – common lead acid batteries will deliver far less energy than AGM or GEL batteries for the same amp hour rating.
  • The batteries age – as batteries age they become less able to deliver the same capacity.
  • Your willingness to shorten the life of the batteries by deeply discharging the battery.
  • The chargers ability to fully charge the battery.

The following link goes to an online PDF from Victron Energy.

It's a must read as it describes all the different types of batteries and charging methods available for Yachts but this information and formula is equally applicable to any domestic application you may have.

It has chapters on why batteries fail and how to make them last longer, alternators and generators, power calculations and much more.

I won't reproduce the Victron report here for copywrite reasons, but click the link to check it out, A good read IMHO for anyone interested in Battery power and storage applications around the home, mobile homes and caravans or boats.