Random thought about RV batteries

[chainblu]

Bear with me. As indicated in the thread title, this is just a random idea that I wanted to run by. I have a Travel Trailer and I'm in a few groups and about camping and "boondocking" in general. Many people report that 2 (or more) - 6 volt golf cart batteries, mounted in series (or series-parallel) is a better set-up than traditional RV batteries.

My golf cart uses 8 volt batteries. So, (hypothetically) lets say I used 2 - 8 volt batteries, which I know would give me 16 volts, BUT, once the initial charge is drawn down, my on-board converter will only bring it back to 12 (or so) volts.

My thought was: Would the bigger plates or whatever that makes the battery produce 8 volts give the battery extra capacity than a regular 6 volt battery?

 

[old1]

If I am not mistaken, what makes a battery 8 volts instead of 6 is the fact that it has 4 cells instead of 3 like a 6 volt, or 6 like a 12 volt.

 

[fsdork]

Your 8-volt batteries are likely designed to operate in a small voltage range just above 8 volts. As a comparison, the linked table shows voltage of a 12 volt battery relative to state of charge percentages. For that reason, I can't see how you could discharge your 8-volts (16 volts in series) to get them in range of your 12 volt travel trailer equipment. Not to mention the fact that the charger you presumably have built into your converter wouldn't charge the batteries properly based on the voltages it would see from them.

As for capacity of the batteries, that should be rated in amp-hours by the manufacturer, usually displayed on the sticker.

 

[fsdork]

Forgot the link:

https://electronics.stackexchange.com/questions/401414/calculate-battery-state-of-charge-percentage

 

[mk378]

They won't charge at all. And many of the devices in the RV will not like being hit with 16 volts (actually about 18 when fully charged). So stay with a 12 volt system, which can be done with two 6 volt in series.

If you have the space for extra batteries, two 12 volt in parallel is also an option.

The stored energy per weight or volume is about the same no matter how you divide up the cells between separate battery cases.

 

[eljefino]

Originally Posted by fsdork
Forgot the link:

https://electronics.stackexchange.com/questions/401414/calculate-battery-state-of-charge-percentage


To jump on this, you'd be in the land of 90-95% discharged when it's within your appropriate 12 volt range. So you'd only have 5% of the batteries' capacity. And it's the part that's not good for them, at all.

 

[chainblu]

Thank you to all that replied. Every post was helpful. My curiosity in this matter has been answered.

 

[ragtoplvr]

The 8 volt was originally made for old 6V systems,, the regulator could be adjusted to 8, and the dim bulbs worked fine on 8. Then it was used for other functions. It was common for a time in race cars to get hotter point ingition and faster starters.

 

[MasterSolenoid]

Maybe this may help -
Edit: Oh, I see your question is answered.

 

[JHZR2]

Do not use 8v batteries where 6/12v are specified. While it woukd work for a 24v nominal system, because it's a common factor, it won't work properly if at all for a 12v system.

 

[Linctex]

.
Sadly....

many RV'ers do NOT realize that the "on-board charging system" NEVER gets the voltage high enough to equalize the cells in the battery....

That's why you hear about RV batteries dying after just 2 years - - they are ALWAYS slightly undercharged, at all times.

Bringing those "12 volt" batteries up to the full 14.82 volts every 3 months will dramatically increase their lifespan!!

(actually, Trojan battery data says you must reach 16.20 volts for a brief period to do an ACTUAL equalization)