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Pipenslippers

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I've bought n installed my solar panels, the reading says 12.1 before bed then next morning reads 13.2 volts. So does this mean I've used 1

amp during day?

 

Unfortunately not no. Your before bed reading assuming batteries had time to settle for an hour or so with no load, suggests batteries were discharged below 50% of their present capacity. The 13.2 volts you are seeing now is a result of the solar panels charging the batteries, but that voltage suggests they have a long way to go before being fully charged.

 

The 1 amp you mentioned is an instantaneous unit of current so holds no relevance to the amp hours of battery power you may have used.

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It's like another language. The more I read the less I understand! Well and truly stood in the corner with a hat with a "d" on!

 

Sadly, L, it's not a straightforward subject. If you live aboard, it is well worth studying if you have a basic understanding of normal maths.

 

There are many beginner's DC power books on the internet, a 'google' is worth trying with just that in the search box.

 

It could be very rewarding though, and maybe save you lots of engineer's costs in the future, not to mention constantly having to replace your under-charged batteries if you've no idea what's going on.

 

Not a lot of help, I know.

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Thanks Loafer, very sound advice. I will follow up smile.png

 

You don't have to learn for years, either. You just need to know Ohm's Law, what Amps, Volts and Ohms mean, Lead-Acid battery charging and discharging information and you're there!

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I've bought n installed my solar panels, the reading says 12.1 before bed then next morning reads 13.2 volts. So does this mean I've used 1

amp during day?

 

If you're using a few lights then 12.1V is just fine.

 

The 13.2V just shows the batts are getting a little charge from the solar at the start of the day.

 

If you don't yet have an ammeter, an easy way to read amps is with a 'DC clamp ammeter' for £40 from Maplins or £25ish on Ebay:

 

http://www.maplin.co.uk/p/uni-trend-ut203-dcac-current-clamp-meter-n41nc (currently £30 - on clearance???)

http://www.ebay.co.uk/itm/MASTECH-MS2108A-Digital-Clamp-Meter-Multimeter-AC-DC-Current-Volt-Tester-UK-/231541729084

 

Bear in mind there are cheaper ones but they don't measure DC current so won't work for what you need. smile.png

Edited by smileypete
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If you're using a few lights then 12.1V is just fine.

 

The 13.2V just shows the batts are getting a little charge from the solar at the start of the day.

 

If you don't yet have an ammeter, an easy way to read amps is with a 'DC clamp ammeter' for £40 from Maplins or £25ish on Ebay:

 

http://www.maplin.co.uk/p/uni-trend-ut203-dcac-current-clamp-meter-n41nc (currently £30 - on clearance???)

http://www.ebay.co.uk/itm/MASTECH-MS2108A-Digital-Clamp-Meter-Multimeter-AC-DC-Current-Volt-Tester-UK-/231541729084

 

Bear in mind there are cheaper ones but they don't measure DC current so won't work for what you need. :)

Thanks, im using a 30watt 12volt tv for about 4 hours each night, 3watt led lighting, and intermittent pump use, mobile phone charging, no fridge at moment still using outdoor coolbox.

 

Ideally, what should the battery volts be going up to when full charged?

Im considering purchasing more solar

Thanks

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According to battery type, they should reach about 14.4 volts as the charging completes, this is an "on charge" voltage, that battery rested (no charge or discharge current) will sink to about 12.7 or 12.8 volts and be full.

 

Discharging causes the voltage to drop to about 12. 4 at 50% capacity and 12.0 at completely flat assuming that the current is little. If you draw a heavy current from the battery the instantaneous voltage may sink due to IR losses so a battery feeding a starter motor (big load for five seconds) will show as little as 9 volts under load but recover happily to it's resting voltage over the next 15 minutes (or more).

 

Possibly the best direct reading state of charge indicator is the "Smartgauge" it's about £150 and two wires and two screws to install. BUT no meter will give the entire picture with perfect accuracy all the time.

  • Greenie 1
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Thanks, im using a 30watt 12volt tv for about 4 hours each night, 3watt led lighting, and intermittent pump use, mobile phone charging, no fridge at moment still using outdoor coolbox.

 

Ideally, what should the battery volts be going up to when full charged?

Im considering purchasing more solar

 

For bog standard non sealed leisures, 14.4V at room temperature.

 

Also the current at that voltage should 'tail off' to a steady low level, usually less than 1 to 2% of batt capacity (hence 'tail current')

 

Sounds like your eleccy needs are quite modest, would have thought around 100W of solar would easily cover the basics (LED lights, pump, bit of laptop/TV) for most of the year. Only really needs a big solar setup to cover inverter use allowing the power hungry 240V stuff to be used.

 

Possibly the best direct reading state of charge indicator is the "Smartgauge" it's about £150 and two wires and two screws to install. BUT no meter will give the entire picture with perfect accuracy all the time.

 

Agreed, but a voltmeter and ammeter will give a the best indication when the batts are fully charged, which is when accuracy matters the most, as outlined in post #41 above.

 

Also 'resting voltage' will give a good indication of state of charge:

 

gallery_2174_346_64081.jpg

 

(originally posted by Alan de Enfield).

 

Even if a small load is on, a bit of guesstimating will get plenty close enough.

 

cheers, Pete.

~smpt~

Edited by smileypete
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According to battery type, they should reach about 14.4 volts as the charging completes, this is an "on charge" voltage, that battery rested (no charge or discharge current) will sink to about 12.7 or 12.8 volts and be full.

 

Discharging causes the voltage to drop to about 12. 4 at 50% capacity and 12.0 at completely flat assuming that the current is little. If you draw a heavy current from the battery the instantaneous voltage may sink due to IR losses so a battery feeding a starter motor (big load for five seconds) will show as little as 9 volts under load but recover happily to it's resting voltage over the next 15 minutes (or more).

 

Possibly the best direct reading state of charge indicator is the "Smartgauge" it's about £150 and two wires and two screws to install. BUT no meter will give the entire picture with perfect accuracy all the time.

 

That's good advice, another than the 14.4V in red, above. This applies very well to sealed batteries but not to 'wet' batteries with open cells. They need 14.8 in place of your 14.4. Greenie though, for a good summary.

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That's good advice, another than the 14.4V in red, above. This applies very well to sealed batteries but not to 'wet' batteries with open cells. They need 14.8 in place of your 14.4. Greenie though, for a good summary.

 

I would suggest that this is only true if you can and do top them up very regularly otherwise 14.4 is a fair compromise. Even lead-calcium batteries are likely to gas at a prolonged 14.8 volt charge so will need topping up while at 14.4 their gassing rate is far lower and is accommodated by the "spare" acid above the plates for far longer.

 

It can not be denied that 14.8 will better deal with sulphation than 14.4 though.

  • Greenie 1
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^^^ This

 

Been at least a couple of reports of boiled batts when non sealed leisures were charged above 14.4V : help.gif

 

battery panic-bubbling

Batteries nightmare

 

Could be OK or even helpful in deep winter, but more likey to result in boiled batts in high summer. ISTR reports that Beta engines used to supply 14.8V alts but changed because of a high incidence of boiled batts. mellow.png

 

Sealed calcium leisures are also a bit of a minefield, suppliers claim they can be charged OK at 14.4V but there have been reports of underperformance:

 

Still eatng batteries?

can I charge Numax sealed batts 14.9V?

 

Once nice thing about the big brands like Trojans is it's easy to find out from the horse's mouth (the manufacturer) exactly what the charge voltages need to be. smile.png

 

With the 'el cheapo' leisures it's difficult to trace who makes them, and relying on the advice of a charger manual (Sterling I'm looking at you rolleyes.gif) can lead to the problems above.

 

Bottom line is that charging needs to be properly monitored, which does need a bit of understanding on the part of the user. And leaving batts long term unattended on a high power charger may end in tears!

 

cheers, Pete.

~smpt~

Edited by smileypete
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Thanks for the replies, turns out there is a clamp meter on the boat, so what settings will i need to use?

Appreciate all yr comments

 

Sounds like you already have some sort of voltmeter, part of the solar panel monitor?

 

If it's reading no less than 12.1V or 12.2V before bed with little or few loads on, that's good. If on a sunny day the voltage reaches 14.4V for no less than a couple of hours or so then that's good too.

 

With the clamp meter just set it to DC amps then put the 'jaws' round ONE cable, say the red one from the solar controller to the batt bank. If the voltage is reading 14.4V on a sunny day and the amps drop to a steady low level of less than 1-2% of batt capacity in Ah, that's PERFECT, as the batts are FULLY charged. smile.png

 

Lastly, what sort of batts are they, bog standard leisures? And are they sealed ones or non sealed that you can top up? The above supposes you have bog standard leisure batts which need 14.4V, and the solar controller is set accordingly.

 

If it's a big budget type setup it'd be well worth spending £125 on a Smartguage which makes things easier, but still good to do a bit of hands on learning. cheers.gif

Edited by smileypete
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^^^ This

 

Been at least a couple of reports of boiled batts when non sealed leisures were charged above 14.4V : help.gif

 

battery panic-bubbling

Batteries nightmare

 

Could be OK or even helpful in deep winter, but more likey to result in boiled batts in high summer. ISTR reports that Beta engines used to supply 14.8V alts but changed because of a high incidence of boiled batts. mellow.png

 

Sealed calcium leisures are also a bit of a minefield, suppliers claim they can be charged OK at 14.4V but there have been reports of underperformance:

 

Still eatng batteries?

can I charge Numax sealed batts 14.9V?

 

Once nice thing about the big brands like Trojans is it's easy to find out from the horse's mouth (the manufacturer) exactly what the charge voltages need to be. smile.png

 

With the 'el cheapo' leisures it's difficult to trace who makes them, and relying on the advice of a charger manual (Sterling I'm looking at you rolleyes.gif) can lead to the problems above.

 

Bottom line is that charging needs to be properly monitored, which does need a bit of understanding on the part of the user. And leaving batts long term unattended on a high power charger may end in tears!

 

cheers, Pete.

~smpt~

 

The REAL bottom line is that NO-ONE has produced a charger for off-line use with a generator, except for those who's chargers have a 'custom' setting (where you can disable the EARLY drop in charge voltage to 'float')

 

Why not, Mr Charles Sterling? Get on the case! Make us a feckin offline battery charger!

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The REAL bottom line is that NO-ONE has produced a charger for off-line use with a generator, except for those who's chargers have a 'custom' setting (where you can disable the EARLY drop in charge voltage to 'float')

 

Why not, Mr Charles Sterling? Get on the case! Make us a feckin offline battery charger!

I don't understand the point? I am off line and use a generator to charge my batteries via a Sterling charger, albeit an inverter charger in my case

 

or Ave I missed something and you were being tongue in cheek?

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I don't understand the point? I am off line and use a generator to charge my batteries via a Sterling charger, albeit an inverter charger in my case

 

or Ave I missed something and you were being tongue in cheek?

 

 

Charging from a smart charger (like Sterling) is fine, but the absorption phase is always too short to get a 'proper' full charge. They reduce the charging voltage to 'float', around 13.4V, after an hour or two at 14.8. This is fine in a marina, where the batteries are then kept at 'float' for months on end.

 

Off-grid, it isn't possible to keep the battery voltage at float for hours and hours, because of diminishing returns as the charge current reduces and the increasing amount of petrol required. Therefore, wet-cell batteries (like Trojans, for example) benefit more from a longer time spent at 14 plus volts, until you turn off the generator.

 

The above figures only apply to wet-cell batteries, as the side-effect of higher charging voltages consumes water from the battery cells. The side-effect of not charging 'enough' is sulphation of the plates and early battery death.

 

Solar power helps keep the volts up and will result in less sulphation and longer life.

 

In conclusion, a charger that stays at bulk/absorption voltage, without dropping to float so early, is what I'd like. In my charger, I can achieve that by selecting the 'custom' battery type, and entering in 14.8V for both Absorption AND Float, so that the switchover from one to the other makes no difference to the charge voltage.

 

Summat like that anyway.

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In conclusion, a charger that stays at bulk/absorption voltage, without dropping to float so early, is what I'd like. In my charger, I can achieve that by selecting the 'custom' battery type, and entering in 14.8V for both Absorption AND Float, so that the switchover from one to the other makes no difference to the charge voltage.

 

Summat like that anyway.

 

Aha! Understood, and agreed!

 

I think Sterlings algorithm is such that Absorbtion will be a minimum of either 1 hour, or 10 times the amount of time to reach max voltage, (i.e. 10 x Bulk Phase time), with a max of 4 hours. So if the bulk phase is 6 minutes or less, you will only get an hour of Absorbtion... and to get the max 4hrs of absorbtion, you would need at least 24 minutes in the bulk phase.

 

I have recently taken to charging my Trojan T105s in Sterlings equalisation mode, which is 15.5V for a max of 4 hours. I never leave them unattended whilst this is going on, so am always able to restart the phase every now and then so as to exceed the 4 hours if necessary. This may not be the advised charging method, but I found 14.8V until Current < 2% capacity, with an occasional equalisation, was reducing the capacity significantly, (450Ah new last May - 250Ah last November).

 

My current regime seems to have increased to capacity up to 300Ah, where it seems to have stabilised for now. I'll keep a watchful eye on things now that Spring has Sprung, (has it?), and external temperatures will be rising.....

 

I think Sterlings latest Pro Ultra Chargers have a custom mode, so they may be able to accommodate what we are looking for.

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I think Sterlings latest Pro Ultra Chargers have a custom mode, so they may be able to accommodate what we are looking for.

 

Yes they do - I have one. It's a fiddle though!

 

Personally though, I would advise against TOO much equalisation, because voltages of 15.5 or so will start to degrade the plate 'foundations' and could cause early battery failure. It's a huge compromise.

 

If you want your batteries to last forever, don't use them!*

 

*Edited to add - that's not directed at you, Richard, it's just a generalisation.

Edited by Loafer
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The terminal charge voltage differs with different temperatures and types of battery IMO (and we may have to agree to differ) and 14.4v held for an hour or so will mean that most "fit and forget" batteries are adequately charged. For people who understand topping up batteries and have read the battery maker's data sheet for their battery may find better figures and temperature corrections quoted. For people with real fork truck deep batteries there will be the possibility of charging up to about 16v to force some gassing to actually agitate the acid to prevent stratification with the risk of the top layer actually freezing in winter, however these high voltages may be enough to kill on board electrical and electronic items.

 

Basically 14.4 is a good figure unless you have the makers preferred values to hand.

 

Overall a well maintained battery will accept charge and one that's been cooked dry may just get hot and fume and be most unpleasant.

  • Greenie 1
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  • 3 months later...

 

You don't have to learn for years, either. You just need to know Ohm's Law, what Amps, Volts and Ohms mean, Lead-Acid battery charging and discharging information and you're there!

And when you've got your head round that, spare a thought for Peukert's Law. If you're running an inverter and pulling high currents, you need to know about this. My honest practical advice would be, if you are using high-drain 230V appliances, such as a microwave or washing machine - run the engine on fast tickover while you're using them. Your batteries and your bank balance will thank you and they will both last longer.

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Since this thread has come back to life: having just fitted a set of Albion maintenance frees with calcium plates and given them a solid charging for a week with the Mastervolt running at 14.4 absorption and 13.4 float, I left them disconnected apart from the trivial drain of the two monitors (SmartGauge and NASA Clipper) and the Webasto controller for 36 hours.

 

I was surprised to see the resting voltage at 13.2, not the 12.8 I was expecting, but apparently that's what you get from calciums. Means those neat tables showing resting voltage against SOC need modifying for the increasingly common calcium cells.

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I was surprised to see the resting voltage at 13.2, not the 12.8 I was expecting, but apparently that's what you get from calciums. Means those neat tables showing resting voltage against SOC need modifying for the increasingly common calcium cells.

What battery type are you using on gibbo's device? 1 or 4? I have tried both with calcium batts but not really noticed a difference between the two.
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