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Post by tonyqj on Nov 1, 2016 22:39:39 GMT
Acid is more conductive than water. Therefore as the acid concentration increases with higher SoC so the gassing voltage falls. However a higher voltage is required to remove the stubborn sulphate. Or wasn't that what you were asking? ISTR Gibbo saying it was the other way round. Maybe we can tempt him back, or else find an answer on t'interwebs. Once I had a Varta truck batt which lasted OK 9+ years on one boat with shore power charger 24/7, then new a but identical batt with same charger on a different boat completely died after 5 or 6 years. Only diffence I could see was that the first boat was moored below a weir so got constant movement in the winter. It was Gibbo who told me that.
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Post by tonyqj on Nov 1, 2016 22:43:18 GMT
Gibbo's exact words...
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Post by smileypete on Nov 1, 2016 23:41:19 GMT
Yeah seems to make sense.
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Post by smileypete on Nov 1, 2016 23:43:46 GMT
I don't think stratification was the issue. When the second set got down to 1/2 capacity after only 6 months I removed all the batteries onto the towpath and then gave them a right good tilting, swishing around and shaking (as well as one can shake a 25kg battery!), put them all back again with absolutely zero change! I then put them on an equalise charge for a couple of hours and they were reborn. For a while, then repeat every 3 - 6 months for the next 18 months until they went pretty weird and I got the Trojans. As to the gassing bit - no idea, sorry! Something else I just came across is something called 'passivation' where an insulating layer builds up on the plates, though it's not the same as sulphation: www.vershv.narod.ru/sdarticle.pdf
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Post by canaldweller on Nov 2, 2016 0:21:41 GMT
I don't think stratification was the issue. When the second set got down to 1/2 capacity after only 6 months I removed all the batteries onto the towpath and then gave them a right good tilting, swishing around and shaking (as well as one can shake a 25kg battery!), put them all back again with absolutely zero change! I then put them on an equalise charge for a couple of hours and they were reborn. For a while, then repeat every 3 - 6 months for the next 18 months until they went pretty weird and I got the Trojans. Been there, done that. From what I can tell it's not the stratification itself, but that the lower ends of the plates get sulphated due to excessive acid strength. So shaking the batts won't reverse the sulphation, and an EQ charge will mix the acid anyway. But in a car or lumpy water boat where there's constant motion, it should help prevent these problems. Over what sort of time period does it take? I once had a battery that was just water at the top of the cells that I thought was dead (I didn't know about stratification then).
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Post by JohnV on Nov 2, 2016 6:57:33 GMT
On Calcium batteries, I had a pair of 150 AH "Delcor" calcium batteries supplied with a new engine. Finding them physically too big to mount as close to the engine as I preferred they were swapped for a pair of smaller automotive batteries with high cranking ratings. I then installed them as my domestics. They had a fairly easy life running water pump, waste pumps, nav lights, nav equipment, some domestic lighting. Spending most of their life on shore power connected to a "Guest" 10 + 10 multistage charger.
Nominally "sealed" they were top-upable after removal of the label. One died of a shorted cell by which time the other's capacity had dwindled to microscopic. However this was in April 2014 ........ they were supplied October 2000.
If the Varta's I have replaced them with last half as long I will be very happy.
P.S. I have just bought my third set of el cheapo "starter batteries"
P.P.S. Battery charger now replaced with a pair of Vetus chargers
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Post by cuthound on Nov 2, 2016 11:33:44 GMT
I don't think stratification was the issue. When the second set got doxwn to 1/2 capacity after only 6 months I removed all the batteries onto the towpath and then gave them a right good tilting, swishing around and shaking (as well as one can shake a 25kg battery!), put them all back again with absolutely zero change! I then put them on an equalise charge for a couple of hours and they were reborn. For a while, then repeat every 3 - 6 months for the next 18 months until they went pretty weird and I got the Trojans. As to the gassing bit - no idea, sorry! Something else I just came across is something called 'passivation' where an insulating layer builds up on the plates, though it's not the same as sulphation: www.vershv.narod.ru/sdarticle.pdfPassivation is a phenomenon that affects batteries using calcium in the positive plates. it affects batteries used for standby, where they are kept on float charge for long periods without discharge, such a UPS or telecoms standby batteries. When the batteries are required to be used, the initial voltage drops and then recovers, something called "coup de foet". I first becamever aware of it in the early 80's, when critical loads were lost due to the voutage dropping below limits. Initially maintenance regimes were changed over include annual, or even monthly forced discharges, then more recently a move to pure lead batteries has eliminated the problem.
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Post by Deleted on Nov 2, 2016 19:47:54 GMT
I'm beginning to come to that conclusion too. I've got 2 newish 6v Trojans in series at the moment. They seem to struggle with coping with more than 50w a few hours after being fully charged. Might try 2 x 12v car batteries in parallel next time. Probably cheaper too. There maybe your problem, you are discharging them too far. How many days do they do? Have you any idea what the off load voltage is when the inverter screams? Sorry, I've got time to answer this properly now and after doing a little investigation. I beleive my perceived problem with the batteries is more to do with a change in my small invertor (Ring 120). The old Maplin one was much more forgiving with a low input voltage, the new one just cuts out when the input voltage drops below 11.2v. My battery voltage after settling down was about 12.7v (near 100%). If I run the Ring invertor with my small flat screen TV and satellite receiver (together rated at about 30 watts) the input voltage immediately drops to about 12.2v. The problem is that I don't have low wattage LED lighting, I have lots of filament bulbs which are rated at about 10 watts each. If I turn each one on, one by one, the input voltage drops by about 0.1 of a volt for each 10 watt bulb. What was happening later in the evening as the battery off load voltage dropped and got close to the min invertor input voltage (11.2v) all it took was a water pump activation to trip the invertor. So even though my off load battery was still close to 100% capacity, all it takes is 100 watts of lighting and few hours use to drop the input below the minimum invertor voltage. Once I remove the loads, the batteries eventually recover to around 90% so I know it's not so much an issue with the state of the batteries but more to do with the power they can deliver without dropping the supply voltage. This is probably the main disadvantage to running with 2 Trojans instead of 4. However the advantage is that it only takes a few engine hours to charge them back up close to 100% again (and when they do finally die I only have to buy 2 instead of 4!). Questions for you experts. Is a voltage drop of about 0.1 V per 10 watts load reasonable with my 2 6v Trojan T105-s? Would a different type of battery give me less of a voltage drop under load? Or is the only way to reduce the load voltage drop problem to add more batteries? My current thinking is to get some LED lighting and get a more forgiving invertor.
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Post by smileypete on Nov 2, 2016 20:03:01 GMT
Is it this one? www.ringautomotive.com/files/mydocs/RINV120%20MP120%20instructions.pdfIf so maybe get a replacement or refund, a decent inverter should work down to 10.5V or so. The Trojans will likely take a number of cycles (think someone mentioned 50) to get up to full perfomance. ETA: Just a thought, where are you reading 11.2V from, could it be there's excessive voltage drop in the wiring?
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Post by smileypete on Nov 2, 2016 20:06:57 GMT
Passivation is a phenomenon that affects batteries using calcium in the positive plates. it affects batteries used for standby, where they are kept on float charge for long periods without discharge, such a UPS or telecoms standby batteries. When the batteries are required to be used, the initial voltage drops and then recovers, something called "coup de foet". I first becamever aware of it in the early 80's, when critical loads were lost due to the voutage dropping below limits. Initially maintenance regimes were changed over include annual, or even monthly forced discharges, then more recently a move to pure lead batteries has eliminated the problem. Yeah that's my understanding too but I posted the pdf link as it says it can happen with prolonged heavy discharge followed by constant current constant, voltage recharge. Nick said his batts needed just 2 hours of EQ to make a big difference which doens't sound like heavy sulphation to me. Summing up is seems cheap leisures can be a mixed bag, sometimes batts need alloys and additives to work best but these can cost £££££ so the cheaper 'off brands' may skimp on them.
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Post by Telemachus on Nov 2, 2016 20:18:46 GMT
There maybe your problem, you are discharging them too far. How many days do they do? Have you any idea what the off load voltage is when the inverter screams? Sorry, I've got time to answer this properly now and after doing a little investigation. I beleive my perceived problem with the batteries is more to do with a change in my small invertor (Ring 120). The old Maplin one was much more forgiving with a low input voltage, the new one just cuts out when the input voltage drops below 11.2v. My battery voltage after settling down was about 12.7v (near 100%). If I run the Ring invertor with my small flat screen TV and satellite receiver (together rated at about 30 watts) the input voltage immediately drops to about 12.2v. The problem is that I don't have low wattage LED lighting, I have lots of filament bulbs which are rated at about 10 watts each. If I turn each one on, one by one, the input voltage drops by about 0.1 of a volt for each 10 watt bulb. What was happening later in the evening as the battery off load voltage dropped and got close to the min invertor input voltage (11.2v) all it took was a water pump activation to trip the invertor. So even though my off load battery was still close to 100% capacity, all it takes is 100 watts of lighting and few hours use to drop the input below the minimum invertor voltage. Once I remove the loads, the batteries eventually recover to around 90% so I know it's not so much an issue with the state of the batteries but more to do with the power they can deliver without dropping the supply voltage. This is probably the main disadvantage to running with 2 Trojans instead of 4. However the advantage is that it only takes a few engine hours to charge them back up close to 100% again (and when they do finally die I only have to buy 2 instead of 4!). Questions for you experts. Is a voltage drop of about 0.1 V per 10 watts load reasonable with my 2 6v Trojan T105-s? Would a different type of battery give me less of a voltage drop under load? Or is the only way to reduce the load voltage drop problem to add more batteries? My current thinking is to get some LED lighting and get a more forgiving invertor. Are you measuring the voltage right at the batteries with a meter, or somewhere else? All I can say is that when I put the 2000w kettle on (around 190A) the voltage of our 4 T105s (2 x 2 configuration) with reasonably well charged batteries, doesn't go below 11.5v as measured at the inverter. If we divide by 2 for your battery size that would be 95A. So that is roughly 0.01v per amp. Each 10W bulb is less than 1A so 0.1v per 10w is far too much. Again, where are you measuring it? i have found the T105s marginally worse at delivering high currents than leisure batteries (ie rebadged starter batteries) but not much. You are talking around 10A which they should shrug off easily. I'm suspicious that you are in fact dropping voltage in the wiring.
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Post by tonyqj on Nov 2, 2016 21:21:34 GMT
I've come to this a bit late but I agree with Pete and Nick that you may well be seeing voltage drop down too-small cables.
However, I'm unconvinced that the 12.7V you're seeing means that the batteries are fully charged. I suspect you're still seeing surface charge. If you run the TV for about 15 minutes then turn everything off, what's the voltage at the batteries then?
How do you determine the batteries are fully charged when you stop charging?
Tony
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Post by Deleted on Nov 2, 2016 21:27:44 GMT
Sorry, I've got time to answer this properly now and after doing a little investigation. I beleive my perceived problem with the batteries is more to do with a change in my small invertor (Ring 120). The old Maplin one was much more forgiving with a low input voltage, the new one just cuts out when the input voltage drops below 11.2v. My battery voltage after settling down was about 12.7v (near 100%). If I run the Ring invertor with my small flat screen TV and satellite receiver (together rated at about 30 watts) the input voltage immediately drops to about 12.2v. The problem is that I don't have low wattage LED lighting, I have lots of filament bulbs which are rated at about 10 watts each. If I turn each one on, one by one, the input voltage drops by about 0.1 of a volt for each 10 watt bulb. What was happening later in the evening as the battery off load voltage dropped and got close to the min invertor input voltage (11.2v) all it took was a water pump activation to trip the invertor. So even though my off load battery was still close to 100% capacity, all it takes is 100 watts of lighting and few hours use to drop the input below the minimum invertor voltage. Once I remove the loads, the batteries eventually recover to around 90% so I know it's not so much an issue with the state of the batteries but more to do with the power they can deliver without dropping the supply voltage. This is probably the main disadvantage to running with 2 Trojans instead of 4. However the advantage is that it only takes a few engine hours to charge them back up close to 100% again (and when they do finally die I only have to buy 2 instead of 4!). Questions for you experts. Is a voltage drop of about 0.1 V per 10 watts load reasonable with my 2 6v Trojan T105-s? Would a different type of battery give me less of a voltage drop under load? Or is the only way to reduce the load voltage drop problem to add more batteries? My current thinking is to get some LED lighting and get a more forgiving invertor. Are you measuring the voltage right at the batteries with a meter, or somewhere else? All I can say is that when I put the 2000w kettle on (around 190A) the voltage of our 4 T105s (2 x 2 configuration) with reasonably well charged batteries, doesn't go below 11.5v as measured at the inverter. If we divide by 2 for your battery size that would be 95A. So that is roughly 0.01v per amp. Each 10W bulb is less than 1A so 0.1v per 10w is far too much. Again, where are you measuring it? i have found the T105s marginally worse at delivering high currents than leisure batteries (ie rebadged starter batteries) but not much. You are talking around 10A which they should shrug off easily. I'm suspicious that you are in fact dropping voltage in the wiring. Yes that is a good point. I'm measuring it about 5 ft from the batteries where an old light was removed exposing a choc block with access to the old 2 wires to the lamp. I should really measure at the battery terminals. The other thing is that the small inverter is plugged in at the other end of the boat where the TV is. I have looked at the 12v wiring behind the 12v sockets and it all seems in good order and looks like the same rating as you would see behind 240v 13A sockets in a house. I presume inverters are normally connected close to the batteries and you have a 240v circuit running down the boat to 240v sockets. As an aside I actually have 2 x 240v circuits along with the 12v circuit. One connected to a 5kva generator which runs off the engine flywheel pulley via a belt drive (rarely use it due to noise). Another shore line circuit which I have never used as I'm a CC'er. I'll try to do some measurements at the battery terminals at some point but it does look like much of the voltage drop is down to the length of 12v wiring . The boat is a 58ft Les Allen BTW.
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Post by tonyqj on Nov 2, 2016 21:30:47 GMT
Wire about the same size as house wiring (2.5mm) is way too small to feed an inverter.
I'd still like to know the off-load battery voltage after 15 mins of TV.
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Post by Telemachus on Nov 2, 2016 21:32:17 GMT
Well there is your problem. The wiring is totally inadequate. Compared to 230v, you need roughly 20 times fatter cable for the same voltage drop at 12v. Put the inverter near the batteries and all will be sweetness..
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