Trojan T-105 vs Crown 235 and what's wrong with parallel?

[dharry]

I found this site last night and registered immediately because there's such good info here. I have been reading lots of posts and have two questions that I'd appreciate being pointed to answers if they are already discussed.

First Question:
The Crown 235 battery is identical in size but weights 5 lbs more than the T-105 (and has a better warranty) leading me to believe it has heavier plates and will outlast the Trojan. But, when I compare life cycles, the Trojan is better.
Here are the data:
Depth of discharge/#of Cycles T-105/C-235
100% T-105=750 CR-235=500
50% T-105=1600 CR-235=1200
40% T-105=2000 CR-235=1500
20% T-105=4000 CR-235=3000

All data supplied by the manufacturers. Do people here think these are good values that are to be trusted i.e., the T-105 will clearly outlast the Crown or is it possible that Crown reports conservatively while Trojan rigs the tests to give better than actual results? Why does the extra weight and presumably thicker plates of the Crown not translate into longer life?

Second Question:
I am putting together a 48V system to run a submersible pump and small shop. My usage can be tailored to coincide with good solar gain but I still wold like to have something like 400+ Ah of reserve.
I had planned 2 series of 8 6V batteries (240 Ah or so) in parallel to get to the magic 400+ but lots of posters say paralleling is a bad idea. I haven't yet found why they conclude that. Is there a "right" way to do it so it's OK? What about a parallel configuration is not good and shortens battery life?

I'm not trying to be argumentative, just trying to understand the physics of why parallel is a bad idea.

I appreciate the help, I am on a steep learning curve.

[Mike90250]

here's the bible on how to parallel batteries:

http://www.smartgauge.co.uk/batt_con.html

but it's really better to chose case/capacity that can do a single string (saves costs of fuses and such)

Sunking may chime in more about the brand vs lifetime question

[Sunking]

All manufactures fudge the numbers, and you will never ever see the numbers they claim. The way to tell what is really going on is by simply looking at the warranty. For example the standard T-105 not to be confused with their Renewable Energy battery the T-105RE (bet you did not know Trojan had RE batteries) has a 12/24 month warranty which tells you immediately it is a 2 year battery with TLC or 1 year battery if abused. With that said the T-105RE carries a 24/60 or a 5 year battery with TLC or 2 years if abused. FWIW the T-105 RE has 5 pounds more lead then the T-105.

Battery manufactures cycle test are done in a lab on a accelerated test platform under ideal conditions.

OK with that said if you need 400 AH then buy 400 AH batteries. There are quite a few 6 volt 400 AH and 4 volt 400 AH batteries to be had. Example a Trojan LR16RE-B is a 6 volt 370 AH battery and it carries a 24/60 warranty. Rolls S-600 is a 6 volt 450 AH battery and carries a 24/84 warranty.

[dharry]

All manufactures fudge the numbers, and you will never ever see the numbers they claim. The way to tell what is really going on is by simply looking at the warranty. For example the standard T-105 not to be confused with their Renewable Energy battery the T-105RE (bet you did not know Trojan had RE batteries) has a 12/24 month warranty which tells you immediately it is a 2 year battery with TLC or 1 year battery if abused. With that said the T-105RE carries a 24/60 or a 5 year battery with TLC or 2 years if abused. FWIW the T-105 RE has 5 pounds more lead then the T-105.

Battery manufactures cycle test are done in a lab on a accelerated test platform under ideal conditions.

OK with that said if you need 400 AH then buy 400 AH batteries. There are quite a few 6 volt 400 AH and 4 volt 400 AH batteries to be had. Example a Trojan LR16RE-B is a 6 volt 370 AH battery and it carries a 24/60 warranty. Rolls S-600 is a 6 volt 450 AH battery and carries a 24/84 warranty.

Yes, I had been looking at the RE as well (which incidentally weighs the same as the CR-235, 5 pounds more than the T-105 version as you mentioned) and wondering if the price difference was worth it. It seems that both battery companies would test their batteries under conditions to give the best results and that is why I am still not understanding why the extra weight of the Crown does not translate to extra lifespan, similar to the T-105RE.?

Other than the RE warranty, I don't find warranty info on the Trojan site. That info is not on the specific battery specifications/information page.

The Cr-235 is carrying a 24/48 but apparently that is a function of the seller not the manufacturer (according to Crown) so what does that mean?

Thanks to the poster for his link to the article from SmartGauge, that was helpful. I was planning on hooking up to opposite sides of the array but it's clear that is only a partial solution.

It seems to come down to unequal draw across batteries in parallel so at least I understand what the issue is now. I still don't know whether a Crown CR-235 will have a similar life expectancy as a Trojan T-105RE although it seems they should based on weight and dimensions.

Thank you

[dharry]

Get this, the Trojan T-105RE shows lower life cycle expectancy than the T-105 and is, according to Trojan's data identical to the Crown Cr-235, which makes sense because they weigh the same.

So, they must use different test protocol for RE batteries and that means the data across battery types and manufacturers do not appear to be directly comparable.

Any other interpretations?

[Sunking]

Here is the Warranty for all of Trojan product lines.

As for cycle life not sure where you picked up what you seen but here is the Trojan Cycle Life graph for all their product lines. Scroll down to page 7. RE or Premium Line is considerable longer than Signature Line. If you want Trojan best take a look at the Industrial Line.

[dharry]

Interesting. In answer to where I got my information it was from the Specifications sheet for each battery from Trojan's and Crown's sites. They have tabulated data for 20, 50, 60, and 100% discharge and I just graphed those data. I don't see where they identify the RE batteries on their graph but I guess they're part of the Premium line?

There seems to be a discrepancy between these charts and their data sheets.

I misstated the battery weights because I took those from teh distributor's websites rather than the manufacturer's. IT looks like the weights are"

T-105 62 lbs
T-105RE 67 lbs
CR-235 63 lbs

I have no idea any more which is likely to be the longest lasting. I can get the CR-235 for $126, the T-105 for $143, and the T-105RE for $165 so I really can't see any good reason not to go with the CR-235.

Thanks for the help

[Sunking]

Interesting. In answer to where I got my information it was from the Specifications sheet for each battery from Trojan's and Crown's sites. They have tabulated data for 20, 50, 60, and 100% discharge and I just graphed those data. I don't see where they identify the RE batteries on their graph but I guess they're part of the Premium line?

Yes it is the Premium Line for RE. Standard is the Signature line below the Premium Line. Industrial is the top line.

I have no idea any more which is likely to be the longest lasting. I can get the CR-235 for $126, the T-105 for $143, and the T-105RE for $165 so I really can't see any good reason not to go with the CR-235

. I answered that question for you in my last reply. The answer is the WARRANTY period. The battery with the longest warranty will last the longest.

[dharry]

. I answered that question for you in my last reply. The answer is the WARRANTY period. The battery with the longest warranty will last the longest.[/QUOTE]

I think warranty period is a little more complicated than you indicated. A company may choose to offer a longer warranty to help them sell more batteries. They may realize they will have some failures but they may decide it's worth it to increase sales volume. As posters here and elsewhere have noted, it's not always easy to get warranty coverage in the event of premature failure so the companies recognize that they won't have to honor some fraction of warranty claims anyway.

Finally, you say that if a battery is warrantied for 4 years, that is the maximum a user can hope to get out of it if it's treated very well. There are many postings where people get well beyond the warranty period (2x or 3x) so I don't what you base your conclusion on.

I do agree that warranty period can be an indication of the confidence a company has in its product. I just don't agree that it's as cut and dried as you state and that it should be the sole factor to consider when evaluating battery longevity.

[Sunking]

.Finally, you say that if a battery is warrantied for 4 years, that is the maximum a user can hope to get out of it if it's treated very well. There are many postings where people get well beyond the warranty period (2x or 3x) so I don't what you base your conclusion on.

I base my opinion on 25 years of electrical engineering experience building battery plants and working with every battery manufacture.

Laymens are uniformed or ignorant. Battery life is based on rated capacity and is what the manufacture bases its warranty from. A battery is considered expired when it can no long hold 90 and 75% of its rated capacity. So if you see a warranty of 12/24 the manufacture is telling you at 12 months the capacity should be roughly 90% of its rated capacity, and 75% after 24 months.

Catch is a laymen cannot measure battery capacity and has no idea what the capacity is. All they know is it does not do what it use to do. If the user abuses the battery and say discharges it 80% each day will wonder why it failed in a year or less when he was told it should last 3 years.

So if you want to know which battery will last longer, look at the warranty.

[dharry]

Laymens are uniformed

That's a great one! Thanks for the laugh!

Here is direct copy of Trojan's reply to my query to them about wiring in parallel. I asked them specifically about using 16 of their T-105 or 105REs in 2 parallel strings of 8 each:

Below is Trojan Battery's response:

As long as the number of parallel strings is 3 or less, this design is OK. If your battery bank requires more than 3 parallel strings, it is best to choose a higher capacity battery to avoid more parallel connections.


I guess they're not too worried about the parallel strings shortening the life of batteries meaning they'd have more warranty payouts.

[Sunking]

That's a great one! Thanks for the laugh!

Here is direct copy of Trojan's reply to my query to them about wiring in parallel. I asked them specifically about using 16 of their T-105 or 105REs in 2 parallel strings of 8 each:

Below is Trojan Battery's response:

As long as the number of parallel strings is 3 or less, this design is OK. If your battery bank requires more than 3 parallel strings, it is best to choose a higher capacity battery to avoid more parallel connections.


I guess they're not too worried about the parallel strings shortening the life of batteries meaning they'd have more warranty payouts.

Be my guest. Unless you have very good documented monthly records that include cell voltages, specific gravity, and cell temperatures good luck getting warranty replacements. Parallel is just fine for emergency standby systems on float, but asking for trouble in cycle service. You will find it is less expensive and less weight over all using just one single string of appropriate capacity. If you read between the lines Trojan is telling you parallel is not a good idea when they specify no more than 3 strings. As for me, I don't really care what you do. Happy Trails.

[ChrisOlson]

That's a great one! Thanks for the laugh!

dharry, Sunking is right on this. The manufacturers of "RE" batteries all base the end of their pro rata warranty on when the battery will reach 75% of its original capacity, based on 260 cycles/year @ 50% DoD. So if you want to know what battery lasts the longest, look at the warranty. It is designed to sell you a new battery at the time it expires.

And also be warned that getting any sort of warranty coverage on these batteries from any manufacturer after the full replacement period has expired is just about impossible without detailed logs from when the battery was new. Those logs even have to include how much water (in cc) has been added to each cell at service time, since a bad cell that necessitates a warranty replacement will show a history of excessive water use compared to the other cells. The warranty people at the battery manufacturers can tell in an instant if they're dealing with a neophyte or somebody that knows what they're doing.

On the parallel connection thing, there are reasons to use multiple strings such as one string not being able to deliver the amps to a load without excessive voltage "sag", so you use two or three (or sometimes more) strings. Another case would be where the highest capacity battery available does not provide enough capacity, so you need multiple strings to double or triple the amp-hour capacity. But when it comes to servicing, two strings has 48 cells and one string only has 24. So you have twice the cells to service, twice the chance that you will have a cell failure, and twice the chance that you will not catch the cell failure before you wreck an entire string. So from a service and monitoring standpoint, it is best to choose 400ah batteries in one string instead of choosing smaller batteries in two strings.

[Sunking]

dharry, Sunking is right on this. The manufacturers of "RE" batteries all base the end of their pro rata warranty on when the battery will reach 75% of its original capacity, based on 260 cycles/year @ 50% DoD. So if you want to know what battery lasts the longest, look at the warranty. It is designed to sell you a new battery at the time it expires.

And also be warned that getting any sort of warranty coverage on these batteries from any manufacturer after the full replacement period has expired is just about impossible without detailed logs from when the battery was new. Those logs even have to include how much water (in cc) has been added to each cell at service time, since a bad cell that necessitates a warranty replacement will show a history of excessive water use compared to the other cells. The warranty people at the battery manufacturers can tell in an instant if they're dealing with a neophyte or somebody that knows what they're doing.

On the parallel connection thing, there are reasons to use multiple strings such as one string not being able to deliver the amps to a load without excessive voltage "sag", so you use two or three (or sometimes more) strings. Another case would be where the highest capacity battery available does not provide enough capacity, so you need multiple strings to double or triple the amp-hour capacity. But when it comes to servicing, two strings has 48 cells and one string only has 24. So you have twice the cells to service, twice the chance that you will have a cell failure, and twice the chance that you will not catch the cell failure before you wreck an entire string. So from a service and monitoring standpoint, it is best to choose 400ah batteries in one string instead of choosing smaller batteries in two strings.

In addition to what Chris has said. parallel strings will mask problems in adjacent strings allowing them to go undetected until it is too late. That is a good thing for battery manufactures because they are in biz to sell you something. Chris and I are not here to sell you anything and could care less about your money or what you do.

I take a different opinion on parallel string to allow you to draw higher current discharge because of battery internal resistances and cable resistances. A single 400 AH string will have lower resistance than 2 parallel 200 AH strings and less to go wrong. It is really that simple. So believe what you want to hear, or listen to experience from unbiased engineers. Happy Trails.

[PNjunction]

Parallel is just fine for emergency standby systems on float, but asking for trouble in cycle service.

The simplicity of that statement just got burned permanently into my cerebral cortex. I might have to quote you on that later on...