Re: Re: [VAC] Batteries

[donhorn@xxxxxxxxxxxxxx]

Wayne,

I have two Trojan T-105's and they weigh about 60 lbs each.  I paid $59 
each at a local distributor.  Most 12 volt batteries are rated at about 105 
amp hours (some may be higher), so that a pair in parallel would give you 
210 amp hours.  The T-105 is rated at 220 amp hours, so the two in series 
give you just that, i.e., 220.   Whether you use two or four batteries, the 
capacity is about the same, but the golf cart batteries are more durable.  
They may be heavier as well.  

For most people, 220 AH is plenty.  With a 200 AH battery bank and one or 
two 80-watt solar panels, you can probably dry camp indefinitely, if you 
have enough water and you're not in a fog zone.  

The guideline for efficient usage is to discharge to 50% of capacity, then 
recharge to 75-80% for regular usage in the field.  Above 80%, your charger 
is less efficient.  With a battery bank of 200 AH, this means that you'd be 
able to use 50-60 AH between charges.  A solar panel can supply 20-30 AH 
per day, which is well within this range.  

However, if you just want to go out and use your 12V for a week, and then 
come home and charge the batteries, you may need a bigger battery bank.  
You'ld also probably want to have a 120V charger rated at least 40 amps.  
You need to run the numbers on your daily usage, frequency of recharging, 
and amp hours available for charging, to determine the size battery bank 
you need.  

If you use solar panels, then that may not be necessary.  I have a 20-amp 
StatPower charger, and using my solar panel to keep the battery up between 
charges, it's actually very adequate.  My last trip I dry camped for a 
week, used my red chili pepper party lights about 4 nights for 4+ hours, 
and my 80-watt solar panel kept the batteries up well enough that it took 
less than 2 hours for the StatPower to bring them back to float stage.  It 
stepped down from 20 amps very shortly after turning on, so the batteries 
were in good condition.     

I know this is more than you asked, but I hope it helps.  

Don