Parallel Configuration

BATTERIES

Connecting two batteries in parallel will double the amp-hour rating of the battery bank, while the voltage will be the same as each individual battery. Example, two 12 volt 105 amp-hour batteries in parallel will produce one 12 volt 210 amp-hour battery bank.

Note: It is not advisable to connect batteries of different case sizes or amp-hour ratings in the same battery bank.

Always use properly sized wire and terminals for your interconnecting battery cables. For size information refer to NEC

requirements or contact your local electrician.

BATTERY BANK RATINGS AND SIZING

Parallel

Parallel Increase Amp-hour Capacity

+	+	+
12V	12V	12VINVERTER
_	_	12VINVERTER
_	_	_
		_
EACH BATTERY		TOTAL BATTERY
CAPACITY:		BANK CAPACITY:
105		210
AMP HOURS		AMP HOURS
@ 12 VDC		@ 12 VDC

Only similar batteries should be connected together in one bank. Do not connect old and new batteries together or wet and gel cell batteries together. In the above drawing, the load is connected to the positive terminal of the first battery and the negative terminal of the last battery. This practice helps to balance the battery bank and is called cross-connectingthe battery bank.

Deep-cycle batteries are usually rated in amp hours. The amp-hour rating is based on a 20-hour discharge rate, therefore, a 100 amp-hour battery can deliver 5 amps for 20 hours. If the discharge rate is greater than 5 amps, the available amp hours are decreased. For example, if the load is increased to 100 amps, only about 45 amp hours will be avail- able at this rate of discharge.

Deep-cycle batteries can be discharged about 80% of capacity before damage occurs. Shallow cycling will result in much longer battery life. Calculating a battery bank size based on 50% discharge cycling is generally considered to be a good compromise between long battery life and size.