New trojans

[daletournier]

So here's a little story for you.

Went to the shop that sold me the batteries yesterday to get one more cable made. They sell alot of these batteries , 100's in stock.

A guy came in and purchased approximately 20 6v trojans. Put them in the back of his truck and drove away. He then went around the corner to the industrial estate and purchased several iron roofing sheets.

What do you think he did with them?

Apparently you cant lay them across the top of 40 battery terminals! Not a good day for him and his employer.

[daveNZ]

> This puts the battery after discharge at about 35% SOC.

Compared to what? What gives you that idea? 10.5V at a low discharge rate is functionally **zero** SoC.

Thanks for your long response John, I understand all of the points you make.
To clarify, the V was over 11 V at one point during testing, then it dropped to 9.5 when I next checked, over the 2 hours I was away. I then left it for about 10 hours overnight to see what it came back up to , and it went up to 11.87 V
That is what I translate to 35%.

So, is it 'flat' because it went to 10.5V and below? or is it actually about 35% ?

These are sold as Endurant Industrial Deep Cycle batteries in NZ, and I was told by the NZ Sales Mgr that they can be discharged to 20% !!!, (with a 2 Year warranty)


apologies for large image!

Out of interest.....
Endurant (? brand) Standard (not industrial) 12V 130AH sells for about NZ$400 !!
Trojan T105 6V 225AH is about NZ$325

I agree this battery is toast !

Slightly annoyed though as BM history shows little use really.

Daily use is about 40-50 AH. (really only a small fridge/freezer, BD35 compressor)
We run the engine two hours most days, (usually 4 to 5 day trips) and there is a 40W solar panel and Genasun controller, for when its on the marina (no shore power).

I think:
1. panel is more like 30W (old)
2. panel can not push voltage up to absorbtion level, usually 13.5 to 14 (although panel V over 18V)
3. battery is in engine bay up to 35C when underway

Basically I'm researching, and will upgrade!

[john61ct]

Originally Posted by daveNZ

it went up to 11.87 V
That is what I translate to 35%.

So, is it 'flat' because it went to 10.5V and below? or is it actually about 35% ?

There is no way to accurately tell SoC from voltage or SG even after 72 hours rest, without calibrating against an AH counting BM.

I'm not saying the batts are toast, maybe you only lost some cycles off remaining lifespan.

Get them back to 100% Full (as per endAmps) and then do a proper 20-hour load test.

This time ensure stopping discharge at 10.5V and immediately start the recharge.

If capacity is over say 85% of rated keep using them.

[Maine Sail]

10.5V at a 3.8A load for 130Ah battery is 0% SOC.

The discharge load for a 130A battery, to determine SOH based on the original rated capacity, is 6.5A.

The fact that it was discharged to 9.5V, then left to sit there over night is going to negatively impact cycle life.. Once you hit 10.5V you stop discharging and begin recharging ASAP.

10.5V is you maximum allowable discharge voltage under load.

[daveNZ]

thanks again John and Rod,
and again I understand and accept all the points made. My Victron battery monitor is on the boat and I'm doing this in the garage, without enough equipment.
I've just done a higher discharge test at 20A with an inverter and lights, i.e. cycling at a higher rate to see if that breathes more life into the battery. Slightly caught out again as the inverter stops at 10.5 volts and even with 6mm x 1M cable there is a higher voltage at the battery (can't remember the difference, but not trivial). i.e. my test stopped a little early.

Curious that the inverter has a built-in alarm and stops at 10.5V What is it about 10.5V?
Is it just an accepted point based on research, an industry standard that equipment must function at or above, or some chemical behaviour at that voltage?

[john61ct]

Actually that is **such** a low stopping point that I have to believe that cutout is only intended to help protect the inverter.

You should **never** be allowing a bank to drop that low in normal usage.

Many battery experts have expressed disbelief that anyone in their right mind would even allow a bank to go that low for closely supervised maintenance and testing.

Doing so frequently would definitely cut a bank's lifetime to a small fraction of the potential cycles available restricting to the usual maximum 50% DoD.

Personally I think doing initial commissioning and benchmarking, then a load test every six months or so is worth the damage.

But going lower is not, and no reason to.

My bank-protecting LVDs are usually set at 11.85 for even "essential" house circuits, 12.05V for less important or heavier consumers.

[john61ct]

And yes afaik, 10.5V has always represented "dead flat 0% SoC" for lead chemistries, and going below that considered unnecessarily destructive.

Note with LFP, cutoffs should be no lower than 12V even under load. Letting them drop too low can cause immediate and irreversible destruction, aka scrap time for your thousand$ investment.

[john61ct]

Forget IMO about "breathing life" by heavy cycling, you're just further shortening its life if not actually doing damage.

130Ah ÷ 20 is 6.5A,

so after bringing it to 100% Full

( review for us your protocol for getting there?)

rest it fully disconnected, for 24 hours and ensure temps 75 - 80F

use an accurate DMM for voltage at the bank and start your stopwatch as you

hold a steady discharge at that 6.5A rate via an accurate ammeter,

record voltage changes every 30min

keep adjusting the DC load to maintain as close to that 6.5A rate as possible

and report back how many hours/minutes it takes to hit 10.499V

That will yield a go/no-go on whether it's worth messing with further.

Immediately recharging back to 100% Full, again at or close to that 6.5A 20-hour rate, followed by equalizing, get SQ the same across all 6 cells.

In any further such "restore cycles" never go below 11V, and in normal cycling 11.8 or so.

[Pete7]

Originally Posted by daletournier

I've just installed some Trojan T105's.

That is very brave of you coming on CF and posting that you have just installed flooded lead acid batteries rather than Dilithium Crystals or what ever this weeks fad is.

[Maine Sail]

Originally Posted by daveNZ

Curious that the inverter has a built-in alarm and stops at 10.5V What is it about 10.5V?

For lead acid batteries the LOWEST VOLTAGE UNDER LOAD is 10.5V. It does not matter if the load is 75A, 25A or the 10 hour or 20 hour or 100 hour rate the end point voltage or stop discharge point voltage is always 10.5V.

Again, if you want to know the SOH compared to the batteries rating then a 6.5A load (20 hour discharge rate) to a 10.5V cut-off is how you would do this. You don't need an Ah counter to do this, just a volt meter and a stop watch.

20 Hour Capacity Test:

#1 Fully charge battery, equalize if possible, then allow it to rest disconnected for 24 hours


#2 Make certain battery temperature is between 75F & 80F


#3 Apply a DC load that = Ah Capacity ÷ 20 (small light bulbs and/or resistors can work)


#4 Connect an accurate digital volt meter to the positive and negative battery terminals


#5 Start DC load and a stop watch at the same time


#6 As battery voltage drops, during discharge, adjust the DC load to maintain as close to the C÷20 rate as is humanly possible


#7 Immediately stop the discharge test when battery terminal voltage hits 10.499V


#8 Note the hours and minutes of run time on the stop watch and figure your percentage of 20 hours that it ran. This is your batteries Ah capacity or state of health as a percentage of the "rated" capacity. For example if a 100Ah battery ran for 16 hours it's testing at 80% of its original rated capacity. By industry standards lead acid batteries are considered “end of life” when they can no longer deliver 80% or more of their rating. They can still work beyond this point but are considered less safe and can be less predictable.



#9 Once you hit 10.499V recharge the battery immediately at the 20 hour rate. Once the battery is full, follow this up with equalization level voltage and measure specific gravity ensuring all cells match. (not for non-Lifeline AGM or GEL). A long slow recharge (20 hour rate) can have a slight reforming effect on batteries and can actually serve to recover some lost capacity. It is not uncommon for a battery to have more capacity after a 20 hour test than it had going into it.

[leftbrainstuff]

Originally Posted by daletournier

One more question mainsail, purely out of curiosity.

Obviously these batteries have self discharged whilst in storage. They have do. There were literally hundreds and hundreds of them on pallets. There's something like 3000 golf carts in the Seychelles (apparently).

Now I'm not sure how long they were sitting on pallets in the US then were sitting on ships now sitting in a warehouse in the Seychelles.

My question is, I assume this is normal? These batteries are already under full capacity due to sulphation from storage time and transit time therefore none of the traditional lead acid batteries sold are able to reach full soc as they are slightly damaged due to self discharge as a result of the sitting time?

As a bank once all connected (675amp hour) they measured 12.05v.

Once again thanks for your advice.

Expect a reduced life that broadly correlates with warehousing time. I like a discount when purchasing old stock batteries.

A build date older a couple of months is the max I like.

[daveNZ]

MaineSail again thanks for your time and notes. A perfect summary that I will refer colleagues to who are setting out in a new cat.
However, I do know that is the aim, but I am trying to do a cap. test without quite enough equipment. I will report results in a day or two, using my Victron BM.

Observation on Victron 700 battery monitor.
I don’t think it is spelt out in the manual, but Ahs counted, when discharging, appear to take the charge efficiency in to account. I thought Ahs were actual, across the shunt, and only SOC% used the charge efficiency factor, (and Peukert Factor)

I think this because....with:
Capacity set to 50 Ahs (for this test)
Charge efficiency set to .8
BM then synced, so Ahs = 0
After discharging approx. 6 hours at approx 6.5 A you have a discharge accumulation of about -40 Ah.
The BM actually showed an end result of ‘-50Ah’
In other words it calculated the Ah needed to recharge, ‘applying the charge efficiency factor’!!
Basic maths shows you need 50Ah as only 80% of it will count, which gives you 40Ah
Just nice to know what it is actually displaying! (I’m sure of these numbers but happy to be corrected if I’ve missed something.)

[daveNZ]

I think the Battery Capacity bring set to 50 is irrelevant and maybe confusing!
Just the Ah counting that is my point here.

[daveNZ]

Apologies. The Victron BVM 700 manual does spell out that Ah consumed is adjusted for the Charge Efficiency factor. It also contradicts this in an earlier chapter, saying 12A x 3 hours will be displayed as -36Ah (i.e. not adjusting for charge efficiency of < 1 )

If Charge Efficiency is not linear with respect to SOC, (as with FLA batteries) and you operate for several days in one part of the curve, e.g. from 50 to 80% , the Ah counter is going to have a serious error after 2 days!

Also...the cumulative Ah drawn from the battery is item ‘F’ in the BVM history. I wonder if that is also adjusted for Charge Efficiency. That would not make sense but for now I don’t trust it.

[john61ct]

That is the way it should be; don't expect a high degree of accuracy.

You can get precise with your defined 100% SoC when you end the charge cycle. As often as possible reset your BM there, that's what will help keep it (relatively) accurate.

Use your BM to prevent you drawing down too low, but leave a healthy margin of error there.

You will get **much** longer lifespan by keeping your cycling usage in the higher SoC range.

The lower SoC range is ideally used only when not actively cycled.