6v vs 12v deep cycle... User Feedback?

[deplacent]

I am on the market for new batteries. I have pretty much decided to go with 2 6v "true" deep cycle batteries. The main reason I decided on the 6v is they have much thicker plates and will last much longer. Does anyone have experience using these? Is there any feed back or things I should consider before doing this? I assume once they are in series my charge controller and solar panel will treat them like any other 12v.

Thoughts?

[Triguy]

I put two Trojan 6-volt batteries (T-145) on my trailer and love the extra capacity. As you said, wire them in series and treat the bank as 12 volts for charging.

Here are some other thoughts for you...

These are big bateries so make sure that the space or battery tray has the room to fit them (and battery boxes).

While you are at it you might as well install a battery disconnect if you don't have one already.

Be aware of undercharging big 6-volts. It takes a long time to fully charge from 50% SOC so plan ahead. Also, know that some batteries, like Trojan's, require a voltage that is slightly higher than what the typical WFCO converter can supply. Just read up on the recommendations from the battery manufacturer that you buy from and make sure your charger can meet their needs.

[Mountainmanbob]

Originally Posted by deplacent

Does anyone have experience using these?

I assume once they are in series my charge controller and solar panel will treat them like any other 12v.

Thoughts?

I used the 2 sixes in the past
they do seem to be preferred by most over the twelve's
you should not be disappointed if you buy some quality ones

two sixes in series add up to twelve volts
so all should be good

Mountainman

[deplacent]

Thanks I'll look into to the voltage... are you talking the voltage output my charge controller provides to the batteries when connected to shore power? Also why would I want a disconnect? Should I be disconnecting them when not in use?

Originally Posted by Triguy

I put two Trojan 6-volt batteries (T-145) on my trailer and love the extra capacity. As you said, wire them in series and treat the bank as 12 volts for charging.

Here are some other thoughts for you...

These are big bateries so make sure that the space or battery tray has the room to fit them (and battery boxes).

While you are at it you might as well install a battery disconnect if you don't have one already.

Be aware of undercharging big 6-volts. It takes a long time to fully charge from 50% SOC so plan ahead. Also, know that some batteries, like Trojan's, require a voltage that is slightly higher than what the typical WFCO converter can supply. Just read up on the recommendations from the battery manufacturer that you buy from and make sure your charger can meet their needs.

[Herk7769]

Originally Posted by deplacent

The main reason I decided on the 6v is they have much thicker plates and will last much longer.

Plate thickness and surface area determines AH capacity.

Because there are only 3 cells in a six volt battery, they can have higher AH plates in the same footprint of battery. BUT YOU NEED TWO to get that AH capacity in a 12 volt system RV. Voltage doubles NOT AH.

A 12 volt battery has 6 cells so they have about 1/2 thickness of the plates and thus about 1/2 the AH capacity of a similar size and constructed 6 volt battery; BUT they are 12 volts and can be used "stand alone" if the companion battery gets damaged somehow. Two of them will give you similar AH as two 6 volt batteries of the same size and construction. Double the AH; NOT voltage.

The choice will be up to you. (You could also buy 6 2 volt batteries, etc)

Lots of good reading in the links I posted here http://www.forestriverforums.com/for...tml#post316221

[Triguy]

Originally Posted by deplacent

Thanks I'll look into to the voltage... are you talking the voltage output my charge controller provides to the batteries when connected to shore power? Also why would I want a disconnect? Should I be disconnecting them when not in use?

Yes, disconnect when not in use or during storage when not charging. Disconnecting a battery when not in use eliminates the parasitic draws in your camper that will deplete your batteries in a couple of weeks. Batteries like to be fully charged.

When connected to shore power, your converter/charger will charge your batteries. I don't know what unit you own but many FR trailers use a WFCO converter that has a three stage charge capacity. Mine is a WFCO 8955.

You can use your existing converter with a dual-battery bank. In your case, you are looking at two 6-volts wired in series. The converter essentially sees this as one big battery.

The WFCO's three stages are:

• Absorption Mode at 13.6 Vdc range
• Bulk Mode for when the converter thinks the batteries are less than 50% charged will give 14.4 Vdc for a maximum of four hours.
• Float Mode is a trickle voltage of 13.2 Vdc if the RV is not being used for approximately 48 hours.

You need to be aware of a couple of issues:

First, the WFCO doesn't really enter into bulk mode that easily or for long enough to adequately charge my two 6-volt batteries (Trojan T-145s). Also, many deep cycle batteries need a higher voltage than the converter can provide.

You can change out the WFCO, which is just a fair converter, for a PD or you can use a portable charger.

Since Trojan batteries need 14.8 volts and because I haven't changed out my WFCO, yet, I use a portable 40amp 3-stage charger from Stanley that hits the mark. I charge through the converter for convenience and when I am using the trailer, but use the charger when I am at home.

Second, sulfation occurs when a lead acid battery is deprived of a full charge, which will happen if the converter cannot charge to its recommended volts as explained above. Crystals form within the battery and eventually larger crystals reduce the batteries active capacity.

The WFCO 8900 series does not have the ability to de-sulfate the batteries so periodic reconditioning is recommended to maintain a battery's optimum performance and prolong its life.

On a healthy battery bank, reconditioning mode on my charger sends a series of electrical pulses to break up the crystalline form of lead sulfate and turn these chemicals into useful battery electrolytes.

[garbonz]

Regarding the charger (converter in your rig), the following example may illustrate what you are up against.

I have 2 6volt Deka batteries that I put in my camper and have a VERY high quality 3 stage 55 amp temperature compensating external charger that I have had for many years. After installing the batteries and letting them charge off the WFCO charger in my NEW camper, I put them on my "other charger" with a high quality battery monitor (my Fluke clamp meter) and estimate that I put another 50 amps in the battery before it was full.

That 50 amps is 25 percent of the capacity of the battery. Now, that 50 amp into the battery is not truly 50 amps that I will get out because of losses in the charge/discharge cycle, but does illustrate that you will get a better charge with a better charger than the cheap converter in your camper, most likely.

Rememering that you should not run you batteries below about 50% SOC then that means, approximately, you only have about 90%-40% range of usable Amp hours if you a stock charger and 100%-50% with a better one. For 200AH capacity battery pack that means about 20 AH less usable out of a potential of 100AH maximum, not a trivial amount.

IMO

[deplacent]

thanks guys that's very good info /suggestions. Sounds like an external charger may be the way to go. I have an 2002 827fls. I assume it does not have any super duper converter just the run of the mill factory installed converter. My trailer did however come with dual battery banks and a solar panel so perhaps mine is slightly different. I mostly plan on doing weekend camping so charging at home throughout the week with an external charger shouldn't be an issue. I am also not sure what brand of batteries I will get at this point. I am in Halifax, Nova Scotia, Canada and the selection around here is slim to none.

I think I will do some testing too to see what kind of voltage my converter is throwing out.

[acadianbob]

Originally Posted by Triguy

You need to be aware of a couple of issues:

First, the WFCO doesn't really enter into bulk mode that easily or for long enough to adequately charge my two 6-volt batteries (Trojan T-145s). Also, many deep cycle batteries need a higher voltage than the converter can provide.

Since Trojan batteries need 14.8 volts and because I haven't changed out my WFCO, yet, I use a portable 40amp 3-stage charger from Stanley that hits the mark. I charge through the converter for convenience and when I am using the trailer, but use the charger when I am at home.

Second, sulfation occurs when a lead acid battery is deprived of a full charge, which will happen if the converter cannot charge to its recommended volts as explained above. Crystals form within the battery and eventually larger crystals reduce the batteries active capacity.

The WFCO 8900 series does not have the ability to de-sulfate the batteries so periodic reconditioning is recommended to maintain a battery's optimum performance and prolong its life.

On a healthy battery bank, reconditioning mode on my charger sends a series of electrical pulses to break up the crystalline form of lead sulfate and turn these chemicals into useful battery electrolytes.

Right on the money! My WFCO has NEVER seen 14.4; no matter what. I bring along a Schumacher smart charger and run it from my generator. That really gets the job done. It also "equalizes" the battery.

When the trailer is in storage, I disconnect it and hook it to a Battery Minder to keep it topped off and for the anti-sulfation technology.

[deplacent]

so I decided to do some testing... I am using a single 12v deep cycle for test purposes because that's all I have right now. I ran it down to about 9 volts and plugged the trailer into shore power to see what kind of voltage I get to the battery. Mine seems to max out around 13v I haven't seen it go higher than 13.2 which seems a bit low to me. That will certainly charge the battery but not very quickly. Given that the battery is down to 9v I would assume the charge controller should see this as pretty much dead and put as much voltage as it can.

In a previous post it was mentioned that the charge controller should have 3 states. Higher voltage for dead, medium for semi charged and trickle for charged batteries. I wonder what the duty cycles are for each state is. Perhaps I need to check the voltage a few times in the first couple hours to see if it maybe starts off at a basic charge and then increases the voltage as it goes. Or perhaps it charges for a bit and then does little bursts form time to time?

Thoughts ?

[Herk7769]

All WFCO power converters are automatic three-stage switching power supplies. The converter senses which mode it needs to be in by checking the RV system voltage.

The three modes/stages of operation include:
Absorption mode/Normal operation

Nominal battery charge and supplies power to appliances

Bulk mode/Charge mode
Fast battery charge and supplies power to appliances

Float mode/Trickle charge
Trickle battery charge during storage

Absorption Mode:

During this mode, the converter output is in the 13.6 Vdc range. This is the normal operation mode. This mode provides the 12 Vdc and current required by the 12 Vdc RV appliances, as well as slow charging the battery.

Bulk Mode:

When the converter senses that the RV system voltage is less than 13.2 Vdc (equivalent to less than 50% of battery charge) the converter will automatically go into the “Bulk mode.” In this mode, the output voltage of the converter will switch to 14.4 Vdc for a maximum of four hours. If the converter cycles between “Absorption and Bulk mode,” there could be a shorted battery cell or other issues.

If the output voltage drops below 13.2 Vdc, the converter automatically changes to a “Bulk mode” 14.4 Vdc (unless the converter is in overload
condition).

There are two signs of an overloaded converter:

Low output voltage, and full converter fold back or shutdown. In both cases, the converter will automatically turn ON, once the complete load is removed. For low output condition, removing the extra (over the current rating) load will be sufficient. If it is impractical to remove all the load, resetting the main breaker will have the same effect.

Float Mode:
If the RV is not being used for approximately 48 hours, with a “no load” condition and the shore power is plugged in, the converter will automatically go in to the “Float mode.” In this mode, the converter is charging the battery with a trickle voltage of 13.2 Vdc. When the converter senses a demand (by turning on lights), the converter automatically returns to the “Absorption mode” 13.6 Vdc.