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Old 10-28-2006, 10:38 PM   #1
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Location: New Brunswick, Canada
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Default Homemade Portable Battery Packs

Ok, these are 'portable' if you can lift 60lbs!

I brought home eight 12v batteries from an APC UPS (Uninterruptible Power Supply). I got them for free from my job. We replace at 3 years. They are each 17ah. Total weight is 120lbs. They are sealed, maintenance free batteries. APC website gives the runtime of the entire bank in the actual UPS as 36 minutes using 1600 watts full load or 95 minutes at 800 watts half load at 48 volts. 100 amp fuses are on the batteries.

Maintenance-free sealed Lead-Acid battery with suspended electrolyte : leak proof
Charging voltage 14.4 to 15.0V.
Float charging voltage 13.50 to 13.80V.
Volts: 12
Maximum charging current 0.25C.
Charge Retention (Shelf Life) 1 Month: 97%
Charge Retention 3 Months: 91%
Charge Retention 6 Months: 85%
Life Expectancy/Cycle Use 100% Depth Of Discharge: 180 cycles
Life Expectancy/Cycle Use 50% Depth Of Discharge: 400 cycles
Life Expectancy/Cycle Use 30% Depth Of Discharge: 1200 cycles

The 8 batteries came with four 50 amp Quick Connects. I got lucky and found the exact same Quick Connects at a nearby marine store. It came with four 6 gauge terminals that fit in the Quick Connects.

I put a Quick Connect on the existing battery cables that come into the inverter/charger and also have two short pieces of 6 gauge coming from the inverter with a Quick Connect on the end. I will be able to choose the existing wet cells or these new sealed batteries to either power the inverter or get charged by it. You can choose between sealed or wet batteries on the charger.

I made two 68 amp hr battery packs that can be connected together using Quick Connects for a total of 136 amp hr. I can take none, one or both packs with me when I camp. The two boxes fit side by side directly aft of the inverter in a compartment. There is already enough space to pass the cable through. The batteries are paralleled together using five inch pieces of 10 gauge cable.

I use them to power my TV and DVD player.

The only change that I made to my existing RT wiring is putting a Quick Connect on existing battery cable that comes into the inverter/charger. The inverter is at the “end of the line”. All other 12v items will continue to run on the existing batteries as 12v distribution is split out before getting to the inverter.

The batteries are made by EnerSys/Yuasa and the model number is NP18-12B.

Intended Applications from the manufacturers web site:
Emergency Lighting
General Electronics
Uninterruptible Power Supply

From the Application Manual: Deep Discharge Recovery - NP batteries recover their capacities even after repeated deep discharges.

I use the built in van charger only.
Tripp Lite RV612UL inverter/charger
Includes selectable 11 / 45 amp DC charging system with selectable profiles for vented wet cell and sealed gel cell batteries. Built in charger shutdown protects battery against damage due to overcharge.

The rate of charge for these batteries is 25% of their capacity. I have configured them in parallel. 4 x 17Ah so I think that 17 amps is the maximum charging rate. I will use the 11 amp setting on the Tripp Lite with the sealed battery profile.

Project photos:

and photos taken when I tested them:

I have used these all year and am pleased with the results.
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Old 01-28-2007, 01:00 AM   #2
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I took a few photos of the battery packs fastened in place. You can see the quick connects etc.

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