Battery Bank Capacity

kVA is component of an AC system. There is no such rating for a DC source. The closest equivalent is kW.

1. Total capacity of your two 48 VDC, 300AH battery banks wired in parallel is 48 VDC, 600AH. That is because individual circuits in series accumulate voltage but do not increase the Amper Hourly capacity of each battery in the series set, thus it remains 300AH for each series circuit. Putting two circuits in parallel will not raise their voltage, however their combined capacity will accumulate, thus your parallel battery circuit has a capacity of 600 Amps for one hour, e.g. if you make a circuit to that load that consumes 6 amps at 48 volts direct current load; your battery should last about 100 hours. A 60 AH load would last 10 hours, etc. In reality, batteries loose efficiency at their lower discharge levels and one would expect a drop off of voltage somewhere past 85% of full discharge for Li-Ion batteries and 80% (as I recall) for Ni-Cad's, without a continuous trickle recharge also going into the batteries...

2. As an old, retired electrical technician, I don't have a clue WHY negative or positive is any better/worse than the other orientation on the engineering design end. As an old, retired technician I always appreciated knowing polarity so that I knew which lead to place where such that my multi-meter would not 'peg,' or be damaged on elevated voltage circuits, when placed backwards while trouble shooting. It's sort of expensive and not a little humiliating to have to replace a ruined multi-meter because of a "simple" mistake like that, I can attest. So having a circuit diagram show polarity, is a blessing. Sorry, that's the best I can do.

3. A bit of unasked for advice. If confronted with trying to raise Amper Hour capacity of battery sets by paralleling them, one must match the TYPE of batteries in each set. Lead Acid batteries in a series set should never be paralleled with a different type of series battery set such as Ni-Cad or Li-Ion. Their rates of discharge curves are different as they discharge their power. Experience has taught us that one or the other will be overheated by putting them into parallel with each the other.

Please visit my company web site: http://hbl.in everything explained in application notes.

1. I am guessing you want a kWh rating: 24 x 2 x 300 AH = 14.4 kWh per pack. 28.8 kWh total for the two packs.

2. This convention is explained in this thread.

Thanks for the link Blink. This has been a long time mystery to me, too. As I now understand it a Negative Voltage Electromotive force ( -ve ) connection as opposed to a +ve connection, reduces chassis corrosion issues, albeit it never interfered with being able to dope out circuit repair problems. Ney?

Ken,

I just read Sparky's explanation as to automotive battery connection.

Either I am losing it or the standard is different here than Australia where Sparky comments from.

Sparky says auto battery positive terminal is connected to the chassis.

Unless I am going nuts that used to be the way we wired cars here in the states but now connect the negative terminal to the chassis.

As well, every import car I have messed with in recent years also has battery negative connected to chassis.

Am I losing it or am I misunderstanding something.

j.

Cars the world over are negative ground. I think Sparky was confused on this point. Many cars many decades ago were positive ground, but the last of these were 1967 products from the UK.

Telco equipment is the other way around, but is also truly "grounded" (physically wired to an actual ground stake). In such equipment the polarity can make a difference in corrosion. (<< this is the same article I linked in the other thread)

I doubt that it makes any difference in cars, one way or the other, in terms of corrosion. I imagine the standardization had more to do with safety in jump starts, and (given the onslaught of electronic equipment going into cars starting in the 1970's) the need to avoid having different equipment according to manufacturer or national whim. In the late 60's, manufacturers probably got together and said, let's see... should we go with the standard used by Lucas, the prince of darkness, or should we go with the standard used by Bosch, Delco, and Nippon Denso, whose stuff seems to work so well?

Whoops

Important point to note is that battries capacity is always given in Ampere Hours AH KVA will represent the I and V flowing and not the capacity of your battries

battries in series add up the voltage but the capacity will remain the same .

each bank will give 2V X 24=48 v

AH will remain the same for each bank that is 300AH

total capacity will be 300AH X 2 =600AH at 48 V

Your second question is as above answered