DC to DC Battery Sizing Calculator2019-03-04T21:06:41+00:00

LifelineDC TO DC CALCULATOR

This calculator is designed to calculate DC loads to DC battery banks +/- a battery. To compute AC loads to DC battery banks, click here.

Input values below and click "Calculate" to populate other values on the page.

Load Voltage

Load Amperage

Measured by multimeter: Appliances, Inverters, Etc.
Amperage input at voltage rating chosen above.

Instant watt usage
— watts amps x volts

Hourly Amp Hours Used @ 12v
— ah

Daily Amp Hours Used @ 12v
— ah 24 Hours

Weekly Amp Hours Used @12v
— ah 7 days

Monthly Amp Hours Used @12v
— ah 30 days

This calculator computes the number of batteries needed for any application +/- a battery. System is set to +20% (ah X 1.2) to account for wire resistance, resulting voltage loss, heat, and other DC system inefficiencies.

For Critical Applications, battery sizing should be a starting point. Unusual circumstances call for an additional 100-500+ ah battery bank.

The computation does not account for losses of up to half ampacity for colder temperatures OR increased self discharge in warmer climates and on older batteries.

System does not account for amperages outside battery possible limits.

As a battery chemically transforms from fully charged to discharged, it’s voltage drops from 13.5 – 10.5 volts for a 12 volt battery. As the voltage drops this affects the amount of amps required to drive a load. (Watts law: amps x volts = watts)

13.5 volts x 10.00 amps = 135 watts
10.5 volts x 12.86 amps = 135 watts
As such, this calculator is for sizing purposes only. All systems should be thoroughly tested as they are installed to insure that the battery bank is appropriate for the load on site.

AGM Batteries are not harmed by high amperage charge and discharge so long as the input voltage is carefully regulated.

Charge 12 volt batteries at 13.2 – 14.4 volts
Charge 6 volt batteries at 6.6 – 7.2 volts
Avoid over charging and remove from charger immediately (or divert to other load – PV, renewable). Over charged batteries will have a unnaturally short lifespan. AGM batteries are not affected by higher current charging as GEL and Flooded batteries can be.

Lifeline Battery Part #Batteries Necessary for Reserve Power
@ 50% Depth of Discharge
LL-1257TBLL-1257TB
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
LL-1236TBLL-1236TB
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
LL-1228TBLL-1228TB
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-L16T-2VGPL-L16T-2V
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-6CT-2VGPL-6CT-2V
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-4CT-2VGPL-4CT-2V
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-31T-2VGPL-31T-2V
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-L16TGPL-L16T
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-6CTGPL-6CT
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-4CTGPL-4CT
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-U1TGPL-U1T
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-8DLGPL-8DL
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-8DAGPL-8DA
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-4DLGPL-4DL
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-4DAGPL-4DA
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-31XTGPL-31XT
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-31TGPL-31T
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-30HTGPL-30HT
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-27TGPL-27T
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1
GPL-24TGPL-24T
5 hour reserve:
—

12 hour reserve:
—

1 day reserve:
—

3 day reserve:
—

5 day reserve:
—

 Batteries, +/- 1