Help!!! Did they sell us the wrong battery?

[lynne r]

Hate that our first post is a possible tale of woe. We have a new to us 2011 19ft and have camped about 3 times. Last trip our propane detector kept going off so we took it in to our local rv repair and they said we needed new batteries. We have the dual 6 volt system.
We left with Durcell Ultra 6 volt, part no. SLIGC125. They get all their batteries from Batteries Plus which is down the street.

It says 20 AH CAP and 132 min@ 75amps. I have no idea if this is the right battery and I am sorry to say that I have very little trust in RV shops....due to previous experiences.
Please tell me if we/they screwed up.

[Brian B-P]

Originally Posted by lynne r

We left with Durcell Ultra 6 volt, part no. SLIGC125. They get all their batteries from Batteries Plus which is down the street.

It says 20 AH CAP and 132 min@ 75amps.

The "20 AH" capacity value doesn't make sense, so perhaps it is just a typo. Batteries of this size should have a capacity of over 200 amp-hours (measured when discharging over a period of 20 hours, so at an average of 10 amps or more). The other capacity rating of 132 minutes at a rate of 75 amps does make sense: that's 2.2 hours times 75 amps, or 165 amp-hours; the capacity is lower in this test because you get less out in total if you pull it out at a higher rate.

The Batteries+Bulbs web page for the SLIGC125 says the capacity is "235AH at 20 hour rate", which is perfectly reasonable.

The Duracell SLIGC125 is a "golf cart" battery, which is the same general type as is normally used in dual-6V RV setups; it is at least approximately "the right battery".

[Brian B-P]

The Duracell site for this type of battery is not very informative, but the brochure covers the product line, and indicates that this is the highest-capacity model of the GC2 size, so it's probably a reasonable battery. "Duracell" is just a brand name in this case; the battery is actually made by East Penn, which is one of the big three or four lead-acid battery manufacturers

[lynne r]

Thank you, Brian!
The numbers 235 were over from the phrase 20 AH CAP on the top of the battery.

They first offered us a set of batteries that were $120 each and since we boondock frequently I asked for a better battery. So we upgraded to $180 per battery. Your link to Batteries Plus shows their online price at $119.00!
The batteries were not completely charged....the rv shop said this was normal. Our trailer lives in a storage place and we just tried to charge them up with our solar panel.
Going camping this week. Will see how they work.
Thank you for your help!

[rbryan4]

The Duracell SLIGC125 is advertised by Batteries Plus as a direct replacement for a Trojan T105. It's more than adequate. Most batteries like the Duracell are made by one of about 5 or 6 manufacturers, and just "branded" for the company they sell them to. The Duracell may very well be a Trojan or an Exide, but info on the actual maker is hard to find on the web. The specs are fine - it's a deep cycle, and has good amp hours.

[Brian B-P]

Originally Posted by rbryan4

Most batteries like the Duracell are made by one of about 5 or 6 manufacturers, and just "branded" for the company they sell them to. The Duracell may very well be a Trojan or an Exide, but info on the actual maker is hard to find on the web.

Right, but in this case the brochure has the actual manufacturer's name at the bottom of the page...

Originally Posted by Brian B-P

The Duracell site for this type of battery is not very informative, but the brochure covers the product line...
"Duracell" is just a brand name in this case; the battery is actually made by East Penn, which is one of the big three or four lead-acid battery manufacturers

Johnson Controls is the other big name in this business, in addition to Exide and East Penn. Trojan is big in commercial-grade batteries; the others build a wider range of lead-acid battery types.

[Brian B-P]

Originally Posted by lynne r

The numbers 235 were over from the phrase 20 AH CAP on the top of the battery.

That makes sense. The "20 AH" should be "20 hour": it means the capacity (measured as amps of current times hours of current flow) measured in a test that runs the battery down over a 20-hour period.

[cpaharley2008]

I'm curious why a 4 year old trailer with the original dual 6 volts would need replacement? Perhaps a better charging system? Were the batters check with a gauge for specific gravity? Seems odd, my alarm has gone off and I just recharged the battery in other trailers....

[thoer]

Jim - good point. My dual Interstates are over 5 years old and still perform and take the same charge they did when new.

But, I've also read that draining deep cycles lower than 50% levels often can seriously shorten their lifespan. As Lynne and David bought this one used there is no way to know how the first owner used/maintained the batteries.

[Greg A]

The 50% discharge should apply to 12v deep cycle. The 6v deep cycles should be able to go to an 80% discharge rate if I recall correctly. One of the big advantages to dual 6v systems.

[Brian B-P]

Originally Posted by Greg A

The 50% discharge should apply to 12v deep cycle. The 6v deep cycles should be able to go to an 80% discharge rate if I recall correctly. One of the big advantages to dual 6v systems.

While there are differences in construction between cheap multi-purpose batteries and proper deep-cycle batteries, the voltage doesn't matter. A 12V battery and a 6V battery of the same product series and same case size have the same lead plates - they are just connected in 6 cells (2 volts each) in the 12V battery, and three cells (always 2 volts each for lead-acid) in the 6V battery. This isn't about voltage.

The name "deep cycle" means that the battery can be more deeply discharged during each cycle than a "starting" battery (like the one in your car). A deep-cycle battery will withstand 80% discharge better than a starting battery will withstand a 80% discharge, but both will last longer if not discharged as deeply.

The first web page I found in a quick search for life versus cycle depth - TROJAN T-105 6V, 225AH (20HR) FLOODED LEAD ACID BATTERY - shows that the deeper your cycles, the shorter the life. A heavy-duty battery such as the Trojan T-105 featured in that web page lasts longer (more cycles) than a lighter-duty design from the same manufacturer, but in both cases repeated 80% discharges will kill the battery in fewer discharge/charge cycles than less extreme discharges. The "golf cart" GC2-sized batteries sold by Escape as an option presumably withstand deep discharges better than the "RV" batteries provided as standard equipment.

[Greg A]

Brian's correct in that the battery technically may last longer if you maintain shallower discharge rates, but even the Trojan site indicates that the true deep cycle battery won't suffer damage as long as the DOD (Degree of Discharge) doesn't fall below 20%. They just recommend that it will extend battery life at a 50% or better recharge cycle.

Most of the Marine 12V deep cycle batteries that are sold out there are not true deep cycles and it will damage the battery each time the DOD falls below 50% whereas the 6v true deep cycles will not be damaged if they go below 50% DOD. While shallower recharge cycles will maintain any of the batteries better, with the 6V deep cycles, you don't have to be as concerned if on a campout you fall below 50% and can push them farther if needed just don't do it all the time.

There of course are other factors that affect battery life and I know first hand the worst enemy of my auto and trailer batteries. Heat. In Phoenix, we don't worry about how long the battery is supposed to last, because even with the most conscientious battery maintenance you can cut the battery life in half.

[bisonbill]

Originally Posted by lynne r

Hate that our first post is a possible tale of woe. We have a new to us 2011 19ft and have camped about 3 times. Last trip our propane detector kept going off so we took it in to our local rv repair and they said we needed new batteries. We have the dual 6 volt system.
We left with Durcell Ultra 6 volt, part no. SLIGC125. They get all their batteries from Batteries Plus which is down the street.

It says 20 AH CAP and 132 min@ 75amps. I have no idea if this is the right battery and I am sorry to say that I have very little trust in RV shops....due to previous experiences.
Please tell me if we/they screwed up.

Back to the original problem. in addition to indicating a battery problem, the propane detector going off could indicate a bad propane detector. They have a life of about five years. There should be a born on date on the back. They also sometimes just don't work. Ours kept going off on the return trip from Chilliwack and ETI had them send a new one.

[lynne r]

Originally Posted by bisonbill

Back to the original problem. in addition to indicating a battery problem, the propane detector going off could indicate a bad propane detector. They have a life of about five years. There should be a born on date on the back. They also sometimes just don't work. Ours kept going off on the return trip from Chilliwack and ETI had them send a new one.

It was explained to us that the propane detector showed a code on the back after detaching it from the wall. And the code indicated a battery problem.
We were ready to buy new batteries as they did not appear to performing as well as we thought they should....And it is getting closer to time for boon docking in the desert.
The link provided by Brian BP provided me with an incentive to argue the price we paid for the batteries. The RV repair shop realized they overcharged us (in error) and refunded us $103.00! Thank you, Brian!

[Brian B-P]

Originally Posted by Greg A

Brian's correct in that the battery technically may last longer if you maintain shallower discharge rates, but even the Trojan site indicates that the true deep cycle battery won't suffer damage as long as the DOD (Degree of Discharge) doesn't fall below 20%. They just recommend that it will extend battery life at a 50% or better recharge cycle.

I haven't seen that - and I don't think it makes sense - but I do see a Battery Cycle Life Chart from Trojan which shows that every type of lead-acid battery suffers substantially shorter life (measured in number of cycles) if discharged more deeply.

This may not matter to many travel trailer owners if they get a good enough battery. Even the shortest-lived of Trojan's batteries (which are probably still pretty tough compared to cheaper brands) are claimed to go 300 cycles all the way down to 20% of full charge (80% depth of discharge), and that could be many years of camping for some people. If that's not enough, not-so-deep cycling means longer life, and there's nothing special about the 50% level... it's just a reasonable compromise for many users (the same shortest-lived Trojans are claimed to last 550 cycles at 50% discharge).

Originally Posted by Greg A

While shallower recharge cycles will maintain any of the batteries better, with the 6V deep cycles, you don't have to be as concerned if on a campout you fall below 50% and can push them farther if needed just don't do it all the time.

I agree - more robust construction and greater capacity both provide more margin for occasional severe use.

If you only cycle the batteries a few times a year, any decent battery not run completely flat, frozen, overcharged, or run dry will last quite a few years.

[kvermeulen]

Originally Posted by Greg A

The 50% discharge should apply to 12v deep cycle. The 6v deep cycles should be able to go to an 80% discharge rate if I recall correctly. One of the big advantages to dual 6v systems.

I understand that too be true, but thecresult of discharguing below 50% will reduce battery lifespan . I have read 3000 cycles vs 1500 cycles.
ken

[Brian B-P]

Originally Posted by kvermeulen

I understand that too be true, but the result of discharguing below 50% will reduce battery lifespan . I have read 3000 cycles vs 1500 cycles.

Trojan publishes charts that I have linked in a couple of forms; I'll upload a copy of the most extensive one to this post. Those numbers are on the chart - they depend on the product series, since not all batteries of the same size and general type are equally durable.

• A Trojan with life as long as 3000 cycles at 50% discharge vs 1500 cycles at 80% discharge would be their huge "Industrial Line".
• For a "golf cart" battery (a GC2-sized battery such as a Trojan T-105 in their Signature Line) life is more likely 1200 cycles at 50% discharge vs 800 cycles at 80% discharge.
• The lighter-duty batteries in the sizes that are used for a single battery, if purchased from Trojan, would be their other Signature Line set, with life is likely 500 cycles at 50% discharge vs 300 cycles at 80% discharge. By the time you get to this size, maybe lifespan matters...