House Batteries Question

[RoyS]

Recently read an article suggesting the use of (2) 6V golf cart batteries connected in series for a 12V house battery bank. This article (somewhat old) stated that Trojan T105 golf cart batteries were a good value compared to using a normal 12V deep cycle battery. Further investigation seemed to indicate that while this may have been true at the time that article was written it is no longer the case. Comparing the cost of two Trojan T105's at $129 each (ebay) to two Deka Marine Master deep cycle 12 Volt flooded batteries at $138 each (ebay) for a similar (225 vs 210) ampere hour capacity does not seem to justify the trouble. Total savings comes to $18. Am I missing something or has the cost of the golf cart batteries gone up.

 

[Garbonzo]

Lots of information on this subject, but mostly in the rv/campers forum. What you get with the Trojans is a much more robust package, not cheaper. The cell in the 6 volt versions are twice as large and have better plate structure. That will give you longer life, if you use them properly. Comparing the Trojans to the Dekas, is kinda like an apples to oranges deal.

 

[dlochner]

A couple of quick thoughts, you are comparing 2 different qualities of batteries. Trojans are more expensive than other brands (and less than some, like Rolls). A better price comparison is a Deka 12v to a Deka 6 GC. Since there is a bigger market for GC batteries than Marine Deep Cycle, there is more price competition on the GC batteries. East Penn (the company that makes Deka batteries) also brands their batteries for different businesses. Last I checked, East Penn make NAPA batteries and the cost there might be less than on eBay.

Golf Cart batteries are designed to be deeply discharged repeatedly where as traditional marine deep cycle batteries are not as robust, so you will get longer life from the GC batteries.

 

[jssailem]

YOU need to be sure that you are getting a "Deep Cycle Battery". One metric to examine is the battery weight. Trojan 105's weigh in at 62lbs a piece. The Deka battery I looked up (which might not be the same on you were seeing on E-Bay) weighed in at 53 lbs... Which one has more lead? As lead thick plates are a key element in the manufacture of "true" deep cycle batteries, which do you think is a True deep cycle capable of 700-800 cycles vs the lighter weight 200-300 cycles?

 

[jssailem]

You can find good 12 volt batteries that are deep cycle, but you have to look at the specifications not the marketing.

 

[Don S/V ILLusion]

Further investigation seemed to indicate that while this may have been true at the time that article was written it is no longer the case.

what leads you to that judgment?

 

[LeslieTroyer]

How many charge cycles can those Dekas do compared to the Trojans ?? Figure out your total cost of ownership over time and the 6 volt wins.

Les

 

[RoyS]

Thank you for your responses. I was using an incorrect part number for the Deka. The correct number for the Deka marine deep cycle group 31 flooded is DC31DT. The weight comparison is a good one and the two Trojans weigh 124 Lb.s. The two Dekas weigh 120 Lb.s. Using the correct part number, the Deka on ebay would cost $178, which is considerably more than the Trojan at $129. So I stand corrected; for similar capacity 225AH vs 210AH, using two batteries in either case, The Dekas would cost $98 more. The Trojan T105s golf cart batteries are a good choice. I will probably go that route. Thanks again.

 

[jssailem]

Having a way to make comparisons is a good tool to resolving choice.

 

[Gene Neill]

Roy, have you considered the Trojan SSG 06 290? Same size as the T-105, but offers 40Ah more capacity. Ten pounds heavier.

Specs on each:
http://www.trojanbattery.com/pdf/datasheets/T105_Trojan_Data_Sheets.pdf
http://www.trojanbattery.com/pdf/datasheets/SSIG_06_290_DS.pdf

 

[Maine Sail]

Recently read an article suggesting the use of (2) 6V golf cart batteries connected in series for a 12V house battery bank. This article (somewhat old) stated that Trojan T105 golf cart batteries were a good value compared to using a normal 12V deep cycle battery. Further investigation seemed to indicate that while this may have been true at the time that article was written it is no longer the case. Comparing the cost of two Trojan T105's at $129 each (ebay) to two Deka Marine Master deep cycle 12 Volt flooded batteries at $138 each (ebay) for a similar (225 vs 210) ampere hour capacity does not seem to justify the trouble. Total savings comes to $18. Am I missing something or has the cost of the golf cart batteries gone up.

You're not comparing apples to apples.. First you are comparing a premium Trojan battery to a Deka. Second, Ah capacity to $$ is only one very small part of the equation.... If you leave out cycle life you are simply cheating yourself. Also there are 12V golf cart batteries made, Trojan T1275, Trojan J150 or the Deka GC12, that yield about double the lab cycle life to the G24, 27 or 31 "automotive case" batteries. The link below covers all this is much more detail..

What is a Deep Cycle Battery (LINK)

.

 

[Maine Sail]

Roy, have you considered the Trojan SSG 06 290? Same size as the T-105, but offers 40Ah more capacity. Ten pounds heavier.

Specs on each:
http://www.trojanbattery.com/pdf/datasheets/T105_Trojan_Data_Sheets.pdf
http://www.trojanbattery.com/pdf/datasheets/SSIG_06_290_DS.pdf

For use on a sailboat I generally don't recommend a GC2 6V battery that exceeds about 225Ah's. Doing so just means the plates are a bit taller and you have less liquid covering them to deal with healing. Fine in an off-grid or stationary application but not as good as a 225Ah GC2 or smaller on a boat...

 

[Gene Neill]

For use on a sailboat I generally don't recommend a GC2 6V battery that exceeds about 225Ah's. Doing so just means the plates are a bit taller and you have less liquid covering them to deal with healing. Fine in an off-grid or stationary application but not as good as a 225Ah GC2 or smaller on a boat...

Well, fiddlesticks. There went 15% of the usable capacity I was planning on having in the Vega. I'm gonna miss those 40 extra Ah, but your advice is very much appreciated, as always. Better to learn this now than later.

 

[jssailem]

Or Gene... You could go thru with the purchase locate them on the boat have the 40 extra Ahr's and not heel the boat. Keep her flat on the water....
Nah. that is not a practical idea... Never mind.

 

[Gene Neill]

Or Gene... You could go thru with the purchase locate them on the boat have the 40 extra Ahr's and not heel the boat. Keep her flat on the water....
Nah. that is not a practical idea... Never mind.

Gimbaled battery box?? LOL ... nope.

 

[Justin_NSA]

I recognize that the thread title says "house batteries". Does it apply to the "start" bank as well? I'm faced with replacing 3 12v deep cycle batts. 2 House and 1 Start. Is there an advantage to use a different 12v battery for starting and maybe 4 6v GC batts for House? I have a Sterling Pro Charger Ultra 40 and I have a question out to the manuf to see if each output can handle different type batteries with their associated banks. They have not replied.

 

[LeslieTroyer]

I have a Sterling Pro Charger Ultra 40 and I have a question out to the manuf to see if each output can handle different type batteries with their associated banks. They have not replied.

The answer is sort of. You’ll need to purchase an add on for the batteries of different chemistry.

By itself your sterling can not have different charge profiles on the 3 output terminals.

https://sterling-power.com/products/multi-chemistry-battery-charging-module

 

[dlochner]

I recognize that the thread title says "house batteries". Does it apply to the "start" bank as well? I'm faced with replacing 3 12v deep cycle batts. 2 House and 1 Start. Is there an advantage to use a different 12v battery for starting and maybe 4 6v GC batts for House? I have a Sterling Pro Charger Ultra 40 and I have a question out to the manuf to see if each output can handle different type batteries with their associated banks. They have not replied.

Lots of us use GC for the house battery and a 12v for the start battery. A charger will simply see them as 2 12v batteries. Another option is to have all charging sources go to the House bank and then use an Automatic Charging Relay (ACR) to connect the two banks. This will charge both banks at the same time.

 

[Don S/V ILLusion]

For use on a sailboat I generally don't recommend a GC2 6V battery that exceeds about 225Ah's. Doing so just means the plates are a bit taller and you have less liquid covering them to deal with healing. Fine in an off-grid or stationary application but not as good as a 225Ah GC2 or smaller on a boat...

That seems contrary to the geometry of the system. If the batteries were wider, the heal angle would have a more pronounced effect. However, as they are taller rather than wider, the heal angle is irrelevant. The only exception might be in an absurd case where the batteries were many feet taller.

 

[Maine Sail]

I have a Sterling Pro Charger Ultra 40 and I have a question out to the manuf to see if each output can handle different type batteries with their associated banks. They have not replied.

Each battery bank gets the identical charge profile on most every "multi-output" charger. As long as the charging votlages are closely matched eg: within about 0.1V of each other for absorb and float it will work fine.