Newbie...Trojan t105

[Leon 12]

smartgauge hit a steady 82% but had used 38 ah which in comparison is 15 ah more than the same stage before charging 2 days ago. looks promising and given time I will see a marked improvement.

[Leon 12]

Someone mentioned using the equalization charge 15.5 volts. Does it still build up to 15.5 volts or is it instant.? Would it be wise just to use the charge setting on the sterling?

[WotEver]

Someone mentioned using the equalization charge 15.5 volts. Does it still build up to 15.5 volts or is it instant.? Would it be wise just to use the charge setting on the sterling?

It would still build up. However Nick pointed out that the 15.5V is probably current limited (I think you said it never went above 10A) in which case you'll be better off charging at 14.8V until the current drops to sub 10A. Then switch to 15.5V. This is purely to save time, not to do with battery care.

[Richard10002]

It would still build up. However Nick pointed out that the 15.5V is probably current limited (I think you said it never went above 10A) in which case you'll be better off charging at 14.8V until the current drops to sub 10A. Then switch to 15.5V. This is purely to save time, not to do with battery care.

On my Sterling inverter charger, if I set it to equalising setting when the batteries are depleted, it ramps up to 80A, with the voltage building up to 15.5V, just like normal.

[WotEver]

On my Sterling inverter charger, if I set it to equalising setting when the batteries are depleted, it ramps up to 80A, with the voltage building up to 15.5V, just like normal.

Brilliant if that's the case

[Leon 12]

Update on battery capacity.........

 

Performed charge today. The smartgauge read C69 and had consumed 79 ah according to the BMV that was a 20 ah change from the previous drop to C69 on the smartgauge. The voltage was still 12.45..... So it held ok.

 

I charged withe normal setting first for 30 minutes then changed to the equalization setting for a further two and a half hours. So what that means in terms of capacity I have no idea. If it takes 3 hours to charge from 31% DOD then what will 50% take?? The sterling ultra charge is the way to go 60 amp which has a user setting so I can input the correct trojan settings also it has a temperature connection so it will compensate high or low temps.

[Leon 12]

Multiple parallel battery strings are only good up to a certain point. 1 string is ideal. 2 strings are okay. 3 strings are tolerable. More than 3 strings is just BEGGING for trouble! Tiny resistance differences between strings are unavoidable, and electrons being the supremely lazy things they are will always try to take the route of least resistance. With 2 or 3 strings battery string imbalances can usually be kept within control. But with more than 3 strings it’s inevitable that some strings will end up doing all the work, and some will do next to nothing. Neither condition is good for battery life expectancy.

[Leon 12]

How Can You Squeeze More Years (Cycles) Out of Your Battery Bank?

This starts with the design. Minimize the number of strings of batteries by using higher Ah 6V or 2V batteries. Having fewer strings can help distribute the charge equally across the battery bank. Make sure your battery connections are at opposite corners of the battery bank. This will also help equalize the charge and discharge distribution across the battery bank. The last tip involves rotating your batteries within the series strings can help with more evenly distributed charges between cells. Use this opportunity once a year for your Saturday exercise routine and not only will you be in better shape, but you will save some money by extending the life of your battery bank. (Ok, we threw in the exercise part in to see if you were paying attention.)

[Leon 12]

The ideal battery bank also is the simplest, consisting of a single series string of cells that are sized for the job. This design minimizes maintenance and the possibility of random manufacturing defects. Suppose you require a 700‑amp-hour (AH) bank. You can approximate that with a single string of 700 AH industrial-size batteries, or two parallel strings of 350 AH (L-16 style) batteries, or three strings of 220 AH (golf cart) batteries. The diagram below shows these three variations.

 

A common blunder is to buy the smaller batteries because that approach is less expensive up front. The problem is that when current splits between parallel strings, it’s never exactly equal. Often, a slightly weak cell or terminal corrosion will cause a whole battery string to receive less charge. It will degrade and fail long before other parallel strings. And because partial replacement aggravates inequalities, the only practical solution is to replace the entire battery bank. One way to reduce or avoid parallel battery strings is to use the highest DC voltage standard that is practical. The same batteries that would form two strings at 24 V can be wired all in one string for a 48 V system (now a common standard). The quantity of energy storage is the same, but the layout is simpler and the current at critical junctures is cut in half.

 

If you must have multiple battery strings, avoid stacking cable lugs at the battery terminals to make parallel connections. Instead, bring wires separately from each string to two bus bars outside the battery box. This reduces corrosion potential and helps create electrical symmetry.

[dmr]

Lets look at this a different way.

 

I had two strings of Trojans (4 batteries), it was ok.

 

I now have 3 strings, I know they are a bit out of balance cus I configured the extra pair as a semi split bank.

So are my original 4 Trojans going to wear out any sooner.....no they are not because they are working less hard than they used to.

Are the new pair going to self destruct....well no because they have a tiny bit more resistance so should be fine????

 

and also.....

I propose that batteries are largely self balancing so small resistance differences are not critical, If one is working a bit harder on discharge its voltage will fall a little more and so the others will begin to take on more of the effort till its all suitably shared. It is not like just putting resistors in parallel.

 

Putting power transistors in parallel is a different kettle of worms altogether....they go bang.

 

.................Dave

[Leon 12]

The surest way to ruin batteries within a year or two is to keep them at a low state of charge (SOC) for weeks at a time. Active battery material will crystallize, covering the plates, which will become permanently inert. We call this “sulfation.” Ideally, batteries should receive a 100 percent full charge about once a week for good longevity, and more frequently is better. If this takes a full day of backup charging with a generator, do it! Use your monitoring system to know when full SOC is reached. If you don’t have an amp-hour meter, watch for the voltage to reach maximum and the charge current to drop to a low level. This means the batteries are unable to accept much more energy, and are accepting only a “finish” charge.

 

In winter, some people run their backup generator for an hour a day—just enough to prevent the system from shutting down. Bad idea! It may be better to run it for ten hours, once a week, or whatever it takes to fully charge the batteries, instead of partially charging them more frequently.

 

Finish-charging a battery bank with an engine generator is an inefficient use of fuel, and results in extremely long generator run times. As a result, generators are typically shut down once the absorption charging stage is finished. But at this point in the charging process, the battery bank will only be at about 85 percent SOC. Since regular, full battery charging is important for battery longevity, make sure that your RE sources are topping off the battery bank after the generator has done the bulk of the charging. Relying on your PV system to provide the finish charge may be difficult during winter months. Another option is to set the inverter–charger to equalizing mode (see below) during generator charging about once a month to ensure that the battery bank is getting fully recharged.

 

The extreme of undercharging is called “overdischarging.” Voltage should never, and I mean never, be drawn below about 11 V (for a 12 V system), or 22 V (24 V system), etc. System controls and inverters usually include a “low voltage disconnect” (LVD) function. If you have DC loads connected directly to the batteries without LVD, you are asking for trouble. It’s better to lose power than to squeeze out another watt-hour and damage your batteries. Metering is vital here, because if you wait for the inverter to shut down or the lights to go dim, it’s already too late—batteries will likely have lost a portion of their capacity and life expectancy.

 

Finally, flooded batteries need to be equalized at least four times a year. Exactly how often depends on several factors, including the size of the battery bank in relation to your charging sources and the average depth of discharge during cycling. During normal battery discharging/charging, the individual cells of each battery will stray from a common and consistent cell voltage. Equalization can be thought of as a controlled overcharge of the battery bank that serves to both equalize cell voltage, and provide an aggressive and necessary mixing of the battery electrolyte. Equalization charging can be done with your PV system if your array is large enough, or with an engine generator or the grid. Most PV charge controllers and inverter­­­­–­chargers have battery equalization functions.

[cuthound]

Some people swallow a dictionary, others an American battery manufacturer's manual.

 

I have worked with batteries in critical applications for over 40 years, and there is nothing wrong with multiple strings, provided reasonable care is taken to ensure cable lengths are about equal and all terminations, clean, and correctly torqued. Indeed parallel strings (usually four) are standard practice in critical applications because it allows one string to fail without affecting the critical load. However each string is protected by a fuse or circuit breaker.

 

Edited to correct autowrong.

Edited February 12, 2017 by cuthound

[Leon 12]

As a newbie any information is good from an understanding point of view and to determine how things work. Not that you take all info as gospel but give you insight into looking after equipment. All of us were at some point in the same boat excuse the pun. Since joining this forum I have changed the way I charge my batteries,looked at my maintainence schedule and hopefully leads to a good lifespan of an expensive purchase.

[mrsmelly]

As a newbie any information is good from an understanding point of view and to determine how things work. Not that you take all info as gospel but give you insight into looking after equipment. All of us were at some point in the same boat excuse the pun. Since joining this forum I have changed the way I charge my batteries,looked at my maintainence schedule and hopefully leads to a good lifespan of an expensive purchase.

 

Or you could buy a battery bank for £ 280 every 2/3 years that works out at between £2.70 and £1.80 per week as a full time liveaboard off grid. We charge every day for between 2 and 4 hours depending on what we did the day before. We always have enuff leccy for all our needs lights/pumps/tv/fridge/laptops etc etc etc. I buy sealed wet so I never need to top them up or even look at them and as the layout is quite low I dont worry too much about them as I would if I had paid lots for them. Batteries are very much horses for courses and are just as disposable as diesel.

[peterboat]

I have said this before but will repeat it

When I first joined the ARMY I was an electrician driver in the Royal Signals part of my job was battery maintenance, we used to every couple of years empty batteries flush them out and refill them with electrolyte they were tested and stamped with the date batteries used to last about 20 years. Det commanders used to check batteries to make sure they were fully charged and records kept.

Over the years the above wasnt deemed as important and when I left the forces, batteries were doing only a few years before they were failing and had to be replaced.

Given that a unit battery shop had a staff of 3, and most electrolyte was recycled after being filtered and brought to the correct strength, and the soldiers if not looking after equipment were doing what? Which idiot of a civil servant thought it would be a cost saving to do away with battery shops and change batteries every couple of years against maintaining them?

Answer not a very clever one

[ditchcrawler]

I have said this before but will repeat it

When I first joined the ARMY I was an electrician driver in the Royal Signals part of my job was battery maintenance, we used to every couple of years empty batteries flush them out and refill them with electrolyte they were tested and stamped with the date batteries used to last about 20 years. Det commanders used to check batteries to make sure they were fully charged and records kept.

Over the years the above wasnt deemed as important and when I left the forces, batteries were doing only a few years before they were failing and had to be replaced.

Given that a unit battery shop had a staff of 3, and most electrolyte was recycled after being filtered and brought to the correct strength, and the soldiers if not looking after equipment were doing what? Which idiot of a civil servant thought it would be a cost saving to do away with battery shops and change batteries every couple of years against maintaining them?

Answer not a very clever one

The GPO use to do the same thing

[WotEver]

Update on battery capacity.........

 

Performed charge today. The smartgauge read C69 and had consumed 79 ah according to the BMV that was a 20 ah change from the previous drop to C69 on the smartgauge. The voltage was still 12.45..... So it held ok.

 

I charged withe normal setting first for 30 minutes then changed to the equalization setting for a further two and a half hours. So what that means in terms of capacity I have no idea. If it takes 3 hours to charge from 31% DOD then what will 50% take?? The sterling ultra charge is the way to go 60 amp which has a user setting so I can input the correct trojan settings also it has a temperature connection so it will compensate high or low temps.

Who knows? A lot more than 3 hours. The only guide whilst charging is charge current - what was it reading at the end of the 3 hours?

[nicknorman]

On the number of parallel battery strings thing, we had 4 110AH batteries in parallel, with 70mm^2 interconnects. We also charge and discharge at up to 200A. But whilst charging hard, or discharging hard (2kw electric kettle) I could never detect any difference in the current distribution between the batteries using a clamp meter. OK so the clamp meter isn't super accurate but if one battery was giving 51A and the other 49A - so what!? It is not going to cause a battery meltdown.

 

All this stuff about battery imbalance is spouted by people who read it somewhere but have never actually tried to measure it.

 

Of course if you installation is poor with undersized interconnects and dirty connections, maybe it could be an issue, but the solution is to fix the interconnects!

[dmr]

On the number of parallel battery strings thing, we had 4 110AH batteries in parallel, with 70mm^2 interconnects. We also charge and discharge at up to 200A. But whilst charging hard, or discharging hard (2kw electric kettle) I could never detect any difference in the current distribution between the batteries using a clamp meter. OK so the clamp meter isn't super accurate but if one battery was giving 51A and the other 49A - so what!? It is not going to cause a battery meltdown.

 

All this stuff about battery imbalance is spouted by people who read it somewhere but have never actually tried to measure it.

 

Of course if you installation is poor with undersized interconnects and dirty connections, maybe it could be an issue, but the solution is to fix the interconnects!

 

I do see some differences between the batteries and this includes between the two "chains" that are correctly and symmetrical wired. Its got a bit worse over the last year. (maybe I should check the connections but they all look ok). I am assuming that this is due to cell variability rather than wiring.

When first charging I observe the biggest difference (still only maybe 15 to 20%) but as the current starts to fall they come into almost perfect balance.

 

Ive only got 35mm wires but I also have less amps flowing than you, max charge is about 110 amps split between 3 batteries (where two Trojans=1 battery )

 

My point is ... if one battery sees 15% more current than another does it actually matter....and my answer is "not much".

 

If it gets worse I might worry/investigate.

 

.................Dave

[WotEver]

My point is ... if one battery sees 15% more current than another does it actually matter....and my answer is "not much".

I think you Nick and I are all in agreement over this with the single caveat being that with decent interconnects and correct configuration any imbalance is more likely to be a few percent rather than the 10-15% you mention.

 

A poor charging regime will do way more damage than having an extra battery in parallel.

 

Copying and pasting info from an American website doesn't achieve much either unless it's applied to a specific question and used in context

[dmr]

Copying and pasting info from an American website doesn't achieve much either unless it's applied to a specific question and used in context

 

There's a lot of good stuff on the www, some spot on, some a bit suspect, and some just totally wrong. The skill is to select the good stuff.

Liveaboard boating is a somewhat unusual and extreme use of batteries so all the theoretical advice needs to be adjusted by varying amounts to suit our needs.

This could be a moment for that lovely quote "there is a difference between knowing the path and walking the path".

 

.................Dave

[smileypete]

Best thing for the SmartG may be to use it to buy some time to get to grips with correct charge voltage and tail current.

 

Thereafter use it for convenience in preference to a voltmeter.

 

'Once a week to 100% plus 2-3 hours' might be an OK compromise for off-grid live a boards in the meantime.

 

With chargers that drop into float too soon, one workaround is to cycle to charger power when this happens.

 

AFAIK SmartG was initially designed for the military.

Edited February 15, 2017 by smileypete

[Leon 12]

Your right there, a glorified voltmeter...

 

Performed charge and after hitting 100% on Smartgauge, it took four hours to reach tail current of 4.75 amps,then a further 2 hours equalization charge and finally all specific gravities read 12.85...... 19.2 ah taken out over night....tv etc. Smartgauge 87% .... the voltage read 12.63 on the Bmv and 12.65 on the Smartgauge. The Smartgauge dropped 3% in 0.4 ah..Come on that's unreal.

[Alan de Enfield]

Have you actually done any testing to quantify your CURRENT battery capacity rather than the theoretical 'as new' capacity ?

[mross]

19.2 ah taken out over night....tv etc. Smartgauge 87% . suggests remaining capacity around 200Ah