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Newbie...Trojan t105


Leon 12

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Having owned a boat for 2 years and a self renovation in that time. I have tried to fit the boat with as good equipment as I can. I currently have 6 x T105, BMV 701, Smartgauge . Also 3 x 100 solar via tracer 30 amp mppt. I use a Honda eu20i to charge via a sterling inverter charger. However the batteries don't seem to give many amp hours before dropping to 12.26 rather too soon in my opinion. I work all day and only use a couple of hours of tv every couple of days. All lights led. I understand that Trojans are at best 70% capacity when new also temperature at this time further reduces to up to 15% capacity. The smartgauge in my opinion just gives a voltage and places s.o.c at that voltage ie. 12.39 equates to 70% but the bmv has only gave out or used 28 amp hours since charge. Un beknown to myself my charger would go into float way before 100% is achieved. I didn't charge the batteries when I purchased them.........didn't know I had to so I don't really know what soc they are if I am honest. I don't use alternator for charging as its an old perkins 4108 45 amp which is too low and I'm looking for a suitable replacement ( any advice would be great). I am looking to move on more often virtually liveaboard so advice please .

Also I have no ideas what to import in the victron bmv to get the best results...... Tail, time to go etc

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Having owned a boat for 2 years and a self renovation in that time. I have tried to fit the boat with as good equipment as I can. I currently have 6 x T105, BMV 701, Smartgauge . Also 3 x 100 solar via tracer 30 amp mppt. I use a Honda eu20i to charge via a sterling inverter charger. However the batteries don't seem to give many amp hours before dropping to 12.26 rather too soon in my opinion. I work all day and only use a couple of hours of tv every couple of days. All lights led. I understand that Trojans are at best 70% capacity when new also temperature at this time further reduces to up to 15% capacity. The smartgauge in my opinion just gives a voltage and places s.o.c at that voltage ie. 12.39 equates to 70% but the bmv has only gave out or used 28 amp hours since charge. Un beknown to myself my charger would go into float way before 100% is achieved. I didn't charge the batteries when I purchased them.........didn't know I had to so I don't really know what soc they are if I am honest. I don't use alternator for charging as its an old perkins 4108 45 amp which is too low and I'm looking for a suitable replacement ( any advice would be great). I am looking to move on more often virtually liveaboard so advice please .Also I have no ideas what to import in the victron bmv to get the best results...... Tail, time to go etc

It sounds like you may have lost some capacity. I have the same number of trojans and from full charge to 50% will take two days with lots of telly use with sky box, microwave, hairdryer and other general use. Trojans do need to be charged fully and then on top of that regular equalisation charges. Your solar is not enough at this time of year to achieve this. First you need to charge to 100%. This will require something that in these cold temperatures will get the charge voltage up between 14.8 and 15.3 volts. You probably need to hook up to shorepower. Trying with the generator and or alternator will take many hours. To give you a rough idea, my 175 amp alternator will take five to six hours to get the SoC from 50% to 100%. The 240 watt solar will then continue to charge for at least another three hours before the tail current is below 2%. Once you have fully charged the bank you will almost certainly benefit from doing an equalisation charge, which in these temps means getting the voltage up towards 16 v (check Trojan website for exact values). As for the victron stuff I don't have any so can't advise but others will help.

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First, the Smartgage does much more than just mapping voltage to state of charge. You can prove this by applying a heavy load and watching the voltage rapidly fall whilst the Smartgage state of charge display will only fall at the correct slow rate. I suppose conceptually you are correct, it just works out what the off load voltage would be if the load was not present (the clever bit) and then maps this to soc.

 

Sounds like you have lost capacity due to sulphation due to persistent under charging. What voltage do you charge at? what is the tail current just before the charger goes into float? and when did you last equalise?

 

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

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I am moored with no shore power so the Honda is my only real source of charge, it kicks in at 611 to 650 watts around 47 amps building to 14.8 volts then slowly tails off to around 11 amps then goes to float. I haven't done many equalization charges and gravity readings were 12.75 today and 12.65 on the centre two batteries after a two hour charge. The sterling charges at 14.4 to 14.8 then 13.2 at float. Batteries seem a complex and annoying article. Just don't want to damage them.

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I'd say your batteries are badly sulphated by now and you need to research/learn how to desplphate them and what equipment you need.

 

I made much the same mistake when I first purchased my own set of Trojan clones. Capacity rapidly fell as I was only charging them to 100% according to the Smartgauge, and its fibbing when it says 100% charged.

 

For a start get yourself a decent hydrometer or refractometer so you can measure the specific gravity of the electrolyte. 1.277 means a fully charged and battery with no sulphation. As the sulphation increases with persistent undercharging, the maximum specific gravity achievable under normal charging falls too. Some of my cells were only getting up to about 1.240 IIRC before I embarked on some aggressive equalising.

 

I have equalised my (24V) bank at 31.6V for six hours and 32V now for a further six hours and the specific gravity of most of my cells is up in the 2.700 region. Capacity seems to have returned too.

Edited by Mike the Boilerman
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Also from reading on the forums, that even though the smartgauge gets increasingly more accurate it still can be between 5% to 10% out at 100% that seems to be quite a lot, the hydrometer I use is one with thermometer built in. All of this is a vast learning curve for me and I suppose a never ending one.

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Leon 12, on 05 Feb 2017 - 6:39 PM, said:Leon 12, on 05 Feb 2017 - 6:39 PM, said:

.........didn't know I had to so I don't really know what soc they are if I am honest. I don't use alternator for charging as its an old perkins 4108 45 amp which is too low and I'm looking for a suitable replacement ( any advice would be great). I am looking to move on more often virtually liveaboard so advice please .

Also I have no ideas what to import in the victron bmv to get the best results...... Tail, time to go etc

 

It will probably cost a bit but IME, you need a LARGE pullet ion the Pekins crankshaft (I had 10" on my old Beta) and the smallest I could get away with on the alternator.

V belts just don't cut it anymore at those ratios, but a Poly-V will.

I've no idea if you can fit - but Beta do a conversion for their engines that gives you a reasonable ratio - so that the alternator is running at 3000 rpm (or more) while the engine is not screaming.

 

Doubtless I'll get some flack.....

 

Edit - something like this:-

http://www.ebay.co.uk/itm/12V-COMMERCIAL-ALTERNATOR-160AMP-110-450-8LHA2057V-/311746910107?hash=item489590579b:g:TawAAOSw4GVYNbMI

(Its a bit more powerful - 110Amp would be a good start

Edited by OldGoat
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Sorry for being nieve but tail current befuddles me somewhat........

 

 

Tail current is the term used for the charge current when it stops falling. As you charge, the terminal voltage rises steadily and the charge current decays. Eventually it stops decaying and the steady final current is called the 'tail current'. On 'good' battery it will settle at about 1% of the nominal battery capacity so on a 400AH bank, expect the tail current to stabilise around 4A, at which point it is generally agreed the battery is 100% charged.

 

In my experience this point is reached about two to three hours after the Smartguage display reaches 100%. Not so smart at all in my opinion smile.png

 

Its a bit of a loose term however, as if you ramp up the charge voltage a bit, the tail current will rise and then fall a bit more. Even when eqalising at a constant voltage the current seems to fall slowly but continuously no mater how long one equalises for.

Edited by Mike the Boilerman
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Re the tail current. It is difficult to know when a battery is fully charged but the perceived wisdom is that once the charging current reaches 2 % of the banks capacity you have just about reached a full charge and the effort required to get even more into the batteries is not worth it.

 

The smart gauge seems to be a bit off whilst charging but is fairly accurate during the discharge phase. What I can say from my own bank which is the same as yours, when the SG states 100 the bank is not fully charged by a long way. The solar can continue for another 2 or 3 hours before the tail current reaches the 2%

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Wow...........and gulp..... So all along when I thought I'm at 100% I'm way down and always have been. I see that the smartgauge is a trusted piece of equipment but alas it's not in no way accurate. I understand that 100% is not achievable in a dynamic sense as usage constantly changes.

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I am moored with no shore power so the Honda is my only real source of charge, it kicks in at 611 to 650 watts around 47 amps building to 14.8 volts then slowly tails off to around 11 amps then goes to float. I haven't done many equalization charges and gravity readings were 12.75 today and 12.65 on the centre two batteries after a two hour charge. The sterling charges at 14.4 to 14.8 then 13.2 at float. Batteries seem a complex and annoying article. Just don't want to damage them.

You are consistently under-charging them.

 

I see that the smartgauge is a trusted piece of equipment but alas it's not in no way accurate. I understand that 100% is not achievable in a dynamic sense as usage constantly changes.

That's not strictly correct. Again, it's explained in the article which I linked to.

 

SmartGauge is around 3% accurate on discharge.

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What you said Phil made sense as the smartgauge read 100% in charge but then it dropped suddenly to 86% after stopping charge as i presumed it was full,when I looked over the evening, which threw me somewhat and thought the smartgauge wasn't very good

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You are consistently under-charging them.

 

 

That's not strictly correct. Again, it's explained in the article which I linked to.

 

SmartGauge is around 3% accurate on discharge.

 

 

I too am puzzled by this. How do we know it is 3% accurate? Is it that Gibbo said so, or is there a way to verify this?

 

I'd have thoughty 10% was equally possible, given there is no way of knowing!

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What you said Phil made sense as the smartgauge read 100% in charge but then it dropped suddenly to 86% after stopping charge as i presumed it was full,when I looked over the evening, which threw me somewhat and thought the smartgauge wasn't very good

As it explains in that link, the SmartGauge website and the manual (I think!) states how it is impossible for SmartGauge to measure the SoC of a battery under charge and you should do it by measuring charging current or by checking the relative density.

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I too am puzzled by this. How do we know it is 3% accurate? Is it that Gibbo said so, or is there a way to verify this?

 

I'd have thoughty 10% was equally possible, given there is no way of knowing!

See the specs from Cactus: http://www.cactusnav.com/merlin-smartguage-battery-monitor-p-11874.html

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Yep the learning curve is getting steeper........I have if am totally honest been undercharging for seven months with what I'm finding out piece by piece. I have just been looking at the equipment and what it does........ie charger goes to float so presumed 100%. The bmv says 100% so must be 100%. The smartgauge says 100% so it must be 100% ......answer no.lololol think I might sell up and buy a four man tent.

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