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Six 6 VDC Batteries Or Three 12 VDC Batteries


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#1 geraldlanc

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Posted 30 September 2013 - 09:32 PM

I have 6 6 volt house batts in our coach.  

 

When it comes time to replace them, would 3 12 volt batteries work as well?  We don't boondock at all and really don't even need such a large battery bank.

 

 The service advisor where we bought the coach suggested that using fewer batteries might do harm to other system components such as the inverter/charger.

 

Gerald


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#2 wolfe10

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Posted 30 September 2013 - 09:41 PM

Gerald,

 

Assuming the 6 6 VDC batteries are the common golf cart batteries (around 220 amp-hrs @ 6 VDC), your current battery bank is 660 amp-hrs @ 12 VDC.

 

Yes, you could choose to go with the same amp-hrs in 12 VDC (3 8D's), though in general quality 12 VDC batteries are more expensive per amp-hr than golf cart/6 VDC batteries.

 

As far as lower amp rating battery bank of either 6 or 12 volt batteries, the answer depends on how you will be using them.  My personal test is that my battery bank run everything I would expect to run overnight (say 12 hours) without needing a recharge and without discharging the batteries more than 50%.

 

Clearly the largest draw would be items using inverter power. 

 

You will have to tell us what size inverter you have and what electrical needs you expect for us to be able to suggest reducing the battery size (and the same answer would apply to either 6 or 12 VDC batteries).  In fact, just think of two 6 VDC batteries wired in series as a "12 VDC battery in two pieces".

 

Brett


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#3 geraldlanc

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Posted 01 October 2013 - 07:14 AM

The inverter is a pro sine 2500 and an overnight stay would mean using the water pump, minimal lights and my wife's cpap machine (it will run all night on just one 12 volt batt).

Gerald


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#4 wolfe10

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Posted 01 October 2013 - 08:01 AM

Gerald,

 

Indeed those are minimal needs.  So, minimum battery requirement would be more dictated by maximum amp draw from the inverter.  As an example, if you want to be able to run the microwave for 30 minutes and use a hair dryer without shore power or generator it will require more battery bank than if you know you will never want to do that. Do you have a residential refrigerator-- they also add quite a bit to electrical needs when dry camping?

 

Your present battery bank is sized to allow reasonable dry camping power.  If that is not how you use the coach, you may be able to scale back to, say 4 6VDC batteries or 2 8D 12 VDC batteries. That would save some money and about 120-150 pounds of weight.


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#5 geraldlanc

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Posted 01 October 2013 - 09:46 AM

Would the reduction to 4 batts and less amp hours have a harmful effect on the  coaches electrics such as converter/inverter/charger etc?  Four 6 volts  would provide ample power for an overnight stay for us.  Our fridge is not a residential and we don't need the microwave, ac, hairdryer, etc.

Gerald


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#6 wolfe10

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Posted 01 October 2013 - 09:51 AM

No harmful affect at all.

 

Just a quick re-program of the inverter/charger with the correct amp-hour capacity of the reduced battery bank.

 

This is in your ProSine owners manual.

 

Brett


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#7 Allegiance40x

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Posted 02 October 2013 - 09:45 AM

One thing to consider if going to 8D batteries...they are very big/heavy/expensive.


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#8 lpc2004

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Posted 02 October 2013 - 06:06 PM

I just did a change over from two 8D 12V batteries on my Monaco Dynasty to 4 6V deep cycle batteries and have had much better power with my inverter.  The 4 6V batteries weigh less than the two 8D's by about 30lbs.  And was less expensive to buy than the two 8D's.  And keep in mind that there is no real 8D 12V deep cycle battery made.  And that is from two battery vendors I was working with.  They will tell you there is but even the 8D gel or mat batteries are not deep cycle.  And by deep cycle they will not take being discharged and then recharged as will a deep cycle 6V battery.  So my suggestion is to maybe drop from 6 6V batteries to 4 6V batteries wired in a series, parallel.  That way if you do need to use the inverter for any extended period of time you will have the reserve power to do so.  On another note my brother just changed his RV from two 12 V batteries to 2 6V batteries and has noticed that he has more reserve power now and he and his wife both use their CPat  machines on 12 volt all night.  I hope this helps you make a decision as to what is best for your situation.   

 

Larry

 

PS I bought my 6V deep cycle batteries from Costco and they were 89.99 each.  The 8D 12V would have cost me just over 700.00 for two.  In the ten years I have owned my coach I have replaced the 8D's twice, this time I refused to, because they do not last as long as the 6V deep cycle batteries.  And I also installed a watering system that I can fill all the batteries at one time from a squeeze bulb and hose in a one gallon distilled water bottle.   


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