Ready to go w/ 2 6v batteries: converter/wire question

[bgrasspkr]

After a couple years in a big TT, then a 5th wheel, I made my first motor home purchase last year. I found a 2008 Gulf Stream Super C, with only 5k miles,kept inside in the winters, literally like new condition.

I've learned a tremendous amount regarding battery use and charging techniques on this forum the past couple years. The MH now has a 2 12V Marines, which I would like to replace with two 6v Trojan T-105's. Fortunately, I have room on the tray for these, AND I have a PD 9160 converter, rather than the WFCO(?)s that were in my last two rigs.

The MH has an onboard Onan 5500 Watt gen, and I have a 2k Champion Inverter that I sometimes bring along. I plan on purchasing the Charge Wizard for the converter when I get the new batteries. No plans for solar at this time, just not in the budget with the cost of the batteries.

It is a substantial run of wire from the converter, mounted under the rear bed, to the battery bay in the front of the rig right behind the driver cab. It looks thick, but I can't tell the wire gauge just by looking. The charts that I looked up give pretty similar diameter measurements between 0, 2, 4 etc, so I think I need to measure it to be sure.

Question is this: After purchasing 2 new bats, and the charge wizard, will I be able to get enough voltage across the bats with the existing wiring? How thick does it need to be for the converter to work properly in bulk mode. If my wire is not substantial enough, the thoughts of rewiring, or adding wire, or moving the converter just stresses me out!!

Any help from the extremely knowledgable battery experts on this forum appreciated.

[DrewE]

bgrasspkr wrote:
f you really find that you want more voltage on the battery... get the PD9260-14.8 at bestconverter.com

Will that give me more voltage than the pd9160 with the wizard?

Yes; the 9160 with the wizard (and also the standard 9260) have 14.4V set as the boost output level.

[Lwiddis]

"I would like to replace with two 6v Trojan T-105's."

T125s have fifteen more amp hours (240) and are the same size as T105s.

[bgrasspkr]

f you really find that you want more voltage on the battery... get the PD9260-14.8 at bestconverter.com

Will that give me more voltage than the pd9160 with the wizard?

[time2roll]

Good to go, no issues. Yes you can use a portable charger at the same time if you think it is needed. Not sure I would run the portable in jump-start mode. Max normal should be fine.

If you really find that you want more voltage on the battery... get the PD9260-14.8 at bestconverter.com

[bgrasspkr]

If I'm not getting enough voltage during bulk mode due to wiring issues, can I use my car smart charger on jump start mode ( 75 amps)for a little while? Read only a couple posts about this. Not sure it is safe or practical

[SoundGuy]

donn0128 wrote:
CA 675
RC 180
CA 845
This is the ratings of a single GP27 battery. So take it as you will. Two T105s like everyone try to tout as the best will have what once you have them hooked to give you the required 12VDC?

Forget so called RC - Reserve Capacity - it's a deep cycle battery's 20 HR rating that is the most useful reference. A 6 volt GC-2 deep cycle battery like the Trojan T-105 will have a 20 HR rating of about 220 AH but because 6 volts are wired in series to create 12 volts the AH rating remains the same - about 220 AH. A 12 volt G31 is typically 20 HR rated around 105 AH to 110 AH so two in parallel will be rated around 210 AH to 220 AH, the same territory as a pair of GC-2s. Smaller G27 12 volt jugs are typically 20 HR rated around 85 AH so two of those in parallel would be 20 HR rated around 170 AH. As for cost a pair of GC-2 flooded batts are most often the best deal around because so many of them are manufactured and sold every year. I should know - this spring I replaced my aging G27 flooded with a new G31 AGM and it was anything but inexpensive. :E

[Tom_M1]

RC(Reserve Capacity) is not the same as AH(Amp Hour). Dividing RC by 2 will give you an approximate AH rating.

[Boon_Docker]

donn0128 wrote:
CA 675
RC 180
CA 845
This is the ratings of a single GP27 battery. So take it as you will. Two T105s like everyone try to tout as the best will have what once you have them hooked to give you the required 12VDC? Compared to two 12VDC batteries at the above rating. Comparing the cost, again, the T105s 30 dollars for what ammounts to one 12 volt battery, vs about 225 dollars for two 12 volt batteries.

It always come down to homework. Now if the OP were installing 4 golf cart batteries and did a fair ammount of boondocking I would be first in line to say go for it. But he is installing two golf carts, and that simply does not make sense dollar wise.

Someone has given you some bad misinformation.

Two - GP27 = 180 AH
Two - GC2 = 225 AH

[bgrasspkr]

I think I'll order the wizard, bring the bats I have now down to 40-50 percent. Start it up and see what voltage I have at the batteries. That will determine where I go from there. Maybe the wiring is fine! ( crosses fingers)

[MEXICOWANDERER]

End to end on a thirty foot long run, the outside diameter of converter to battery wires should roughly be as big around as the knuckle on your index finger. Not not even a smidgen thinner.

Running new wire the length of the rig is a pain. I have had to do it professionally and did not like it at all.

The wire was pulled through lengthwise slitted 3/4" garden hose then passed forward through a frame rail. Be absolutely certain to use decent bussman breakers at both ends.

I have as an option used ARMORED 12/3 cable (wire inside a metal sheathed semi flexible outer covering) to move a converter somewhere distant. The hole in the deck must be insulated to do that.

RV manufacturers consider every penny they spend on electrical stuff (except for plastic chandeliers) to be squandering possible profit. Good luck with your project.

[donn0128]

CA 675
RC 180
CA 845
This is the ratings of a single GP27 battery. So take it as you will. Two T105s like everyone try to tout as the best will have what once you have them hooked to give you the required 12VDC? Compared to two 12VDC batteries at the above rating. Comparing the cost, again, the T105s 30 dollars for what ammounts to one 12 volt battery, vs about 225 dollars for two 12 volt batteries.

It always come down to homework. Now if the OP were installing 4 golf cart batteries and did a fair ammount of boondocking I would be first in line to say go for it. But he is installing two golf carts, and that simply does not make sense dollar wise.

[bgrasspkr]

I'm not plugged in all the time. I could do the test, when I get the wizard, just wanted to know what to expect; whether or not I will have a big project on my hands

[Boon_Docker]

donn0128 wrote:
First thing first. Why do you want to cut your available power by a third? Two 6V golf cart batteries will be barely more than one 12V. Second, you you really need golf carts? Do you boon dock? It really makes little sense to me to go backwords.

That would have to be be one awful big single 12 volt battery to match a pair of 6's in amp hours.

[SoundGuy]

donn0128 wrote:
Why do you want to cut your available power by a third? Two 6V golf cart batteries will be barely more than one 12V.

What in the world are you talking about? :h A pair of T-105s in series will be 20 HR rated around 220 Amps, half of which is usable at a 50% depletion rate, a pair of G31 12 volt batteries wired in parallel will be similarly rated.

[wolfe10]

If you are plugged in most of the time, the answer is yes, no problem.

The only time the smaller gauge wire/longer run will limit voltage (due to resistance) is at higher charging amps.

Now, if you do a lot of dry camping where you are paying fuel to run a generator and desire a quick charge for deeply discharged batteries, absolutely, consider larger gauge wire. Another option is to ADD another wire to "supplement" the smaller than desired wire.

This is pretty easy to verify: With batteries discharged (below 12.2 VDC which is 50%) plug in/start the generator. You should be at maximum charge amps. Check voltage at the converter and compare to that at the batteries. This will give you the maximum difference. As batteries charge, you will notice that the voltage at batteries more closely matches voltage at the converter.