12V or 6V Batteries - Which charge Better?

Ron,

You have an always-garaged immaculate Class C that is "your baby". You have it modified perfectly to your needs. Probably you will want to use it for maybe another 8-10 years.

Treat yourself and your rig special by putting one final set of batteries in it for 250 amp hours of a worry-free additional 8-10 years by treating it to a couple of these in parallel :C :

https://store.starkpower.com/12V-125AhStarkPower-UltraEnergy-Lithium-Ion-Battery-LiFePO-Energy-Storage-Battery_p_65.html

"Charge faster" is a relative term. So it takes me only 2 minutes to fill my Kia gas tank from empty to full - 8.5 gallons. My motorhome takes over 15 minutes. Is this because the pump is slower when filling the motorhome? NO!

So you are much better off with a pair of 6 volt golf cart batteries because they can accept a 35 amp charge for more time than a pair of 12 volt batteries. And the reserve water in a 6 volt battery is more likely to keep the battery cool and the plates are much less likely to warp.

What will degrade a battery? Warped plates can short out, causing instant death to the battery. Dry plates lead to warping and short life. I have had 13 years of service from a set of Trojan T-105 batteries, something that I never got from 12 volt batteries. And I could charge them at 45 amps for a while, without them getting past the "Warm" stage.

To fully charge my batteries, I always used the solar system. IT will slowly charge the battery bank, and keep the batteries from overheating or giving off to much water or gas.

I also used hydrocaps to recycle the leaving hydrogen and oxygen back into water, so that the cells did not need as much replacement water.

Many times battery charging is described much like a frog jumping 1/2 way towards the end of a log. It can take a long leap at first, while each additional leap has to be shorter and shorter to avoid going over.

So a battery charger can put out maximum amperage to a nearly dead set of batteries for about 30 - 45 minutes. Then it will reach it's set point voltage, and amperage will taper off, while voltage stays at say 14.4 volts.

If voltage is left at 14.4 volts more than about 2 hours, battery overheating and damage might happen, along with a lot of water loss. So most good chargers slow charge voltage and amperage to about 13.2 volts after a while to keep the battery stable. It can also reduce the charge amperage to less than about 10 amps.

So no point in running a 4,000 watt generator to put in 10 amps X 13.2 volts (about 150 watts into the charger). Makes more sense to run the generator and charger for only the first hour - twice a day. When you can put maximum amperage out of the charger - say it's 55 or 65 amp rating. Then after 1 hour shut off the generator, and use power for a while.

I would recommend running the generator at breakfast and dinner times. Fill from about 45% full to around 75% full. It will provide the most amperage to the battery with minimal generator run time. Filling from 80% full to 90% full can take about 1.5 hours (depending on converter output voltage) while charging from 90% full to 100% full can take an additional 4 hours. . .

Going below 45% state of charge can shorten the battery life, especially if not recharged soon. A battery left at 60% full or below for a couple of weeks can have perminate damage to it, that might be recovered by charging to 100% on shore power, but might never reach more than 95% ability - ever again.

Good luck!

Fred.

I recently installed a PD9245 converter/harger and two US brand 6 volt deep cycle lead/acid batteries in series in our 2004 Tioga. The US brand batteries were $99 apiece and were said by local Powertron battery shop owner to be "as good as Trojan T-105's" which were originals in our 2004 rig and lasted about 10 years. I also installed a Trik-L-Start device to keep the engine starting battery charged while rig is parked and on garage power,which works well. This setup should be OK for the average RV'er.

WOW, everyone has pilled on the data for me here. I did read through them all. Thank You!

pnichols, $2400.00 for a pair of Li-Ion batteries? I just couldn't do it given my financials. That is quite an interesting solution.

For the record to all, my situation is as follows
- class B+ motor home
- currently with two 12V batteries (always had 12Vs)
- 4000 watt Onan generator
- Three stage Tripp-Lite 2000 watt Invertor (takes too long to charge)
- I speed up charging while running the generator using this 3 stage charger setup


I am leaning heavily on the Duracell EGC2 (Group Size 230) batteries at Sam's Club at $112.68 per battery. CLICK HERE to see it. 6Vs would be my first experience with them. I have always had 12Vs to-date. I know there are better choices, but the lower cost is attractive. I figure it best to learn from these, then maybe upgrade when these are exhausted.

A solar panel comes to mind now and then but not sure how effective it would be when we seek shady sites all the time.

I agree that it would be nice to have a good battery monitor. Maybe I will look into that soon.

Looks like you've got the charger you need. If you have room for the 6v batts, do that and don't look back.

The above comments raise an interesting question: Is there any performance difference between using two 6V wet cell batteries versus using two 6V AGM batteries in an RV?

pnichols wrote:
The above comments raise an interesting question: Is there any performance difference between using two 6V wet cell batteries versus using two 6V AGM batteries in an RV?

I am actually answer that with specific experience.

The answer is YES. Can You afford it is another question.

Before the depression, I did a massive re-fit on a performance cruiser and the owner wanted to keep his existing house bank, but charge it more effectively. We did that (and some other things) and it all worked as expected. It worked well for a month and then a cell shorted. He (the owner) had a friend that did UPS stuff. Said friend got him a deal on a pair of AGMs with similar package and rating. The owner immediately reported shorter charge times at higher current (we had installed a very well instrumented charging system) and also longer run times before the low voltage threshold. This was interesting as we had not yet corrected the alarm for the AGM.

Matt

This is our 4th RV. I keep saying "when these batteries go, I'm getting AGMs". But each time we replaced the RV before the batteries went.

When these batteries go, I'm getting AGMs.
:)

pnichols wrote:
The above comments raise an interesting question: Is there any performance difference between using two 6V wet cell batteries versus using two 6V AGM batteries in an RV?

AGMs charge faster assuming you don't hit the limit on the charger.

Snowman9000 wrote:
This is our 4th RV. I keep saying "when these batteries go, I'm getting AGMs". But each time we replaced the RV before the batteries went.

When these batteries go, I'm getting AGMs.
:)

Mine went. I got AGMs.