Posted by *Phil Cook* on October 27, 2003, 9:31 pm

Is the math below correct? I thought to run longer you had to increase

amp hours?

Most batteries express their capacity in terms of amp-hours at a

particular voltage. 2, 6, or 12V cells may be wired in series to give

higher system voltages.

Although the voltages double or quadruple, the amp-hour capacity of

the battery bank remains the same.

Why?

Volts x amps = watts.

Therefore, A single 6V 220 amp-hour cell produces 1320 watt-hours (1 x

6V x 220 amp-hours.) and 24V string of four 6V 220 amp-hour batteries

produces 5280 watt-hours (4 x 6V x 220 amp-hours).

However, using our equation volts x amps = watts, we can determine

that:

Watts ÷ volts = amps (watts divided by volts equals amps).

Using our figures from the 6V 220 amp-hour cell above:

1320 ÷ 6 = 220

Using our figures from the 4x6V 220 amp-hour cell above:

5280 ÷ 24 = 220

On the 6V 220 amp-hour cell, a 100 watt load could run for 13.2 hours.

On the 4x6V 220 amp-hour cell, the same 100 watt load would run for

52.8 hours, or four times as long.

Even though the capacity of the battery bank increased by 4 times, the

amp-hour capacity remains at 220 amp-hours.

Posted by *dbs__usenet* on October 27, 2003, 10:26 pm

To run longer with the same load, you need to EITHER increase amp hours

OR voltage. Remember, you are drawing 100 watts (6v at 16 amps or 24

volts at 4 amps) so the math still works. This assumes that you are using

a 100watt 24v bulb in one case and a 100 watts 6v bulb in the other case.

If you attach the same equipment (the 6v 100watt lamp) to each battery

bank, the 24v battery will supply 64 amps to the .37 ohm resistance and

probably blow a filiment :-)

I hope I didn't ness up the math. All values are approximate.

*> *

*> Is the math below correct? I thought to run longer you had to increase*

*> amp hours?*

*> *

*> Most batteries express their capacity in terms of amp-hours at a*

*> particular voltage. 2, 6, or 12V cells may be wired in series to give*

*> higher system voltages.*

*> *

*> Although the voltages double or quadruple, the amp-hour capacity of*

*> the battery bank remains the same.*

*> *

*> Why?*

*> Volts x amps = watts.*

*> *

*> Therefore, A single 6V 220 amp-hour cell produces 1320 watt-hours (1 x*

*> 6V x 220 amp-hours.) and 24V string of four 6V 220 amp-hour batteries*

*> produces 5280 watt-hours (4 x 6V x 220 amp-hours).*

*> *

*> However, using our equation volts x amps = watts, we can determine*

*> that:*

*> *

*> Watts ? volts = amps (watts divided by volts equals amps).*

*> *

*> Using our figures from the 6V 220 amp-hour cell above:*

*> *

*> 1320 ? 6 = 220*

*> *

*> Using our figures from the 4x6V 220 amp-hour cell above:*

*> *

*> 5280 ? 24 = 220*

*> *

*> On the 6V 220 amp-hour cell, a 100 watt load could run for 13.2 hours.*

*> *

*> On the 4x6V 220 amp-hour cell, the same 100 watt load would run for*

*> 52.8 hours, or four times as long.*

*> *

*> Even though the capacity of the battery bank increased by 4 times, the*

*> amp-hour capacity remains at 220 amp-hours.*

Posted by *allmailNOSPAM* on October 28, 2003, 12:56 am

Take a look at the web site. If you increase system voltage at the

bottom of the page the run times go up. Is that right?

http://www.solarsense.com/Spec_Your_System/Run_Times.html

On Mon, 27 Oct 2003 22:26:01 GMT, dbs__usenet@tanj.com wrote:

*>To run longer with the same load, you need to EITHER increase amp hours*

*>OR voltage. Remember, you are drawing 100 watts (6v at 16 amps or 24*

*>volts at 4 amps) so the math still works. This assumes that you are using*

*>a 100watt 24v bulb in one case and a 100 watts 6v bulb in the other case.*

*>If you attach the same equipment (the 6v 100watt lamp) to each battery*

*>bank, the 24v battery will supply 64 amps to the .37 ohm resistance and*

*>probably blow a filiment :-)*

*>I hope I didn't ness up the math. All values are approximate.*

*>> *

*>> Is the math below correct? I thought to run longer you had to increase*

*>> amp hours?*

*>> *

*>> Most batteries express their capacity in terms of amp-hours at a*

*>> particular voltage. 2, 6, or 12V cells may be wired in series to give*

*>> higher system voltages.*

*>> *

*>> Although the voltages double or quadruple, the amp-hour capacity of*

*>> the battery bank remains the same.*

*>> *

*>> Why?*

*>> Volts x amps = watts.*

*>> *

*>> Therefore, A single 6V 220 amp-hour cell produces 1320 watt-hours (1 x*

*>> 6V x 220 amp-hours.) and 24V string of four 6V 220 amp-hour batteries*

*>> produces 5280 watt-hours (4 x 6V x 220 amp-hours).*

*>> *

*>> However, using our equation volts x amps = watts, we can determine*

*>> that:*

*>> *

*>> Watts ? volts = amps (watts divided by volts equals amps).*

*>> *

*>> Using our figures from the 6V 220 amp-hour cell above:*

*>> *

*>> 1320 ? 6 = 220*

*>> *

*>> Using our figures from the 4x6V 220 amp-hour cell above:*

*>> *

*>> 5280 ? 24 = 220*

*>> *

*>> On the 6V 220 amp-hour cell, a 100 watt load could run for 13.2 hours.*

*>> *

*>> On the 4x6V 220 amp-hour cell, the same 100 watt load would run for*

*>> 52.8 hours, or four times as long.*

*>> *

*>> Even though the capacity of the battery bank increased by 4 times, the*

*>> amp-hour capacity remains at 220 amp-hours.*

Posted by *Tom Quackenbush* on October 28, 2003, 1:30 am

allmailNOSPAM wrote:

*>dbs__usenet wrote:*

*>>To run longer with the same load, you need to EITHER increase amp hours*

*>>OR voltage. Remember, you are drawing 100 watts (6v at 16 amps or 24*

*>>volts at 4 amps) so the math still works. This assumes that you are using*

*>>a 100watt 24v bulb in one case and a 100 watts 6v bulb in the other case.*

*>>If you attach the same equipment (the 6v 100watt lamp) to each battery*

*>>bank, the 24v battery will supply 64 amps to the .37 ohm resistance and*

*>>probably blow a filiment :-)*

*>>*

*>>I hope I didn't ness up the math. All values are approximate.*

<SNIP>

*>Take a look at the web site. If you increase system voltage at the*

*>bottom of the page the run times go up. Is that right?*

*>http://www.solarsense.com/Spec_Your_System/Run_Times.html *

As dbs_usenet said, yes. (in general; I didn't double check the

calculations on the web site). If power remains the same and voltage

increases, amperage must decrease. If amperage decreases and AH

capacity remains the same, run time is increased.

Once you decide the voltage you want for your system, that's it.

IOW, deciding to bump the voltage from 12V to 48V after you've bought

all 12V appliances is NOT a good idea. Adding batteries in parallel

then becomes you're only option to increase capacity.

R,

Tom Q.

Posted by *dbs__usenet* on October 28, 2003, 6:56 am

Yes, they are correct because they ask you to tell them the AH at the top.

When you draw power you are drawing watts, not Amp-Hours.

If you draw 100 watts from a 200 ah 6v system you get X hours.

If you draw 100 watts from a 200 ah 24v system you get X times 4 hours.

If you had 4 6 volt batteries in parallel to get the 200 AH 6v pack,

it would be able to provide the same number of watts as 4 batteries

wired in series to get a 50 AH 24v pack.

Daniel

allmailNOSPAM@consolidated.net wrote:

*> *

*> Take a look at the web site. If you increase system voltage at the*

*> bottom of the page the run times go up. Is that right?*

*> *

*> http://www.solarsense.com/Spec_Your_System/Run_Times.html *

*> *

*> *

*> On Mon, 27 Oct 2003 22:26:01 GMT, dbs__usenet@tanj.com wrote:*

*> *

*>>*

*>>To run longer with the same load, you need to EITHER increase amp hours*

*>>OR voltage. Remember, you are drawing 100 watts (6v at 16 amps or 24*

*>>volts at 4 amps) so the math still works. This assumes that you are using*

*>>a 100watt 24v bulb in one case and a 100 watts 6v bulb in the other case.*

*>>If you attach the same equipment (the 6v 100watt lamp) to each battery*

*>>bank, the 24v battery will supply 64 amps to the .37 ohm resistance and*

*>>probably blow a filiment :-)*

*>>*

*>>I hope I didn't ness up the math. All values are approximate.*

*>>*

*>>> *

*>>> Is the math below correct? I thought to run longer you had to increase*

*>>> amp hours?*

*>>> *

*>>> Most batteries express their capacity in terms of amp-hours at a*

*>>> particular voltage. 2, 6, or 12V cells may be wired in series to give*

*>>> higher system voltages.*

*>>> *

*>>> Although the voltages double or quadruple, the amp-hour capacity of*

*>>> the battery bank remains the same.*

*>>> *

*>>> Why?*

*>>> Volts x amps = watts.*

*>>> *

*>>> Therefore, A single 6V 220 amp-hour cell produces 1320 watt-hours (1 x*

*>>> 6V x 220 amp-hours.) and 24V string of four 6V 220 amp-hour batteries*

*>>> produces 5280 watt-hours (4 x 6V x 220 amp-hours).*

*>>> *

*>>> However, using our equation volts x amps = watts, we can determine*

*>>> that:*

*>>> *

*>>> Watts ? volts = amps (watts divided by volts equals amps).*

*>>> *

*>>> Using our figures from the 6V 220 amp-hour cell above:*

*>>> *

*>>> 1320 ? 6 = 220*

*>>> *

*>>> Using our figures from the 4x6V 220 amp-hour cell above:*

*>>> *

*>>> 5280 ? 24 = 220*

*>>> *

*>>> On the 6V 220 amp-hour cell, a 100 watt load could run for 13.2 hours.*

*>>> *

*>>> On the 4x6V 220 amp-hour cell, the same 100 watt load would run for*

*>>> 52.8 hours, or four times as long.*

*>>> *

*>>> Even though the capacity of the battery bank increased by 4 times, the*

*>>> amp-hour capacity remains at 220 amp-hours.*

*> *

>> Is the math below correct? I thought to run longer you had to increase> amp hours?>> Most batteries express their capacity in terms of amp-hours at a> particular voltage. 2, 6, or 12V cells may be wired in series to give> higher system voltages.>> Although the voltages double or quadruple, the amp-hour capacity of> the battery bank remains the same.>> Why?> Volts x amps = watts.>> Therefore, A single 6V 220 amp-hour cell produces 1320 watt-hours (1 x> 6V x 220 amp-hours.) and 24V string of four 6V 220 amp-hour batteries> produces 5280 watt-hours (4 x 6V x 220 amp-hours).>> However, using our equation volts x amps = watts, we can determine> that:>> Watts ? volts = amps (watts divided by volts equals amps).>> Using our figures from the 6V 220 amp-hour cell above:>> 1320 ? 6 = 220>> Using our figures from the 4x6V 220 amp-hour cell above:>> 5280 ? 24 = 220>> On the 6V 220 amp-hour cell, a 100 watt load could run for 13.2 hours.>> On the 4x6V 220 amp-hour cell, the same 100 watt load would run for> 52.8 hours, or four times as long.>> Even though the capacity of the battery bank increased by 4 times, the> amp-hour capacity remains at 220 amp-hours.