Smartgauge and Smartbank

[Rich]

I think you mean that they should never be discharged below 50%, This is true, however even amongst the experts you will find that there are different opinions on charge/discharge regimes and equipment used to achieve optimum battery life.

 

In addition it's not simply battery life that's the issue for boaters but also battery bank size, engine or generator running times, etc. Unfortunately these things are not simple and optimum performance involves balancing a whole host of variables.

 

If you read the posting I was replying to you should see that I meant exactly what I said. This statement re discharging to 50% has been made to me more than once.

 

Richard

[Rich]

SG compensates for Peukert

 

 

I'm amazed. It was Gibbo who told me that when the SG read 100% it wasn't necessarily so because of the Peukert effect.

 

Richard

[nb Innisfree]

I'm scratching my head (or rather shaking my head) at some of the comments on this thread.

 

It's an accepted fact that the SG is the most accurate state of charge battery monitor on the market. I also have a BEP DC monitor and it doesn't compare even though it cost a lot more. It gives me amps in/out and voltages on 3 banks so that's all I use it for - the SoC is a waste of time.

 

The problem with using a voltmeter to monitor your batteries is that it's not accurate unless you wait for 24 hours after any charge or discharge. Clearly that's impractical on a boat.

 

In our case though we have a SG it isn't accurate, this is because our batteries have lost more than 50% of their capacity at which point SG is ineffective, so we only have voltage and amperage readings left to go on. Yes voltage needs 24 hours to be really accurate but 8 hours overnight gives pretty near as dammit accuracy, definitely ok for practical use. Ok I hear you say our batteries need replacing but as we have eight of them there is enough capacity left for us to be able to still get by on two hours charging per day.

[MikeV]

I'm amazed. It was Gibbo who told me that when the SG read 100% it wasn't necessarily so because of the Peukert effect

I think you either misheard or misunderstood. It is true that when the battery charger or alternator is charging the batteries the SG can only estimate the SoC as it's unable to read the actual battery status because the terminals are being driven by the charger/alternator. It states this clearly in the manual:

 

During charging this is not possible due to the presence of the charger preventing SmartGauge ever getting an opportunity to actually measure the charge status. In effect, if it tried, it would be attempting to measure the charge status of the charger. During charging, SmartGauge only shows the calculated charge status as does an amp hours counter however SmartGauge, because it operates on a different principle, calculates a charge status that is much more accurate. For this reason, it is possible that, during the charge cycle, the charge status displayed may not be totally accurate. It will be within 10% of the actual battery charge status. This may seem like nothing (and is infinitely more accurate than an amp hours counter may show which could be literally hundreds of amp hours adrift), but it can have certain consequences.

 

Peukert's Law comes into play during the discharge cycle when higher discharge rates reduce the effective capacity of the battery.

[Keeping Up]

There are some chinese digital panel volmeters out on Ebay that work out at about a fiver including post. The digits are black on a blue backlit display about 3" x 1" operating 7 to 20 or 30 volts They take their power from the supply being measured. So I found them cheaper and more accurate than car type analogue volt indicators for portable generators.

Yes they are more accurate but they can't display the pattern of movement in the way that an analogue meter can. The movement of a a less accurate analogue meter can tell you far more than the most accurate digital meter can on its own. My choice of analogue meter is dictated not by price but by preference.

 

Disagree, discharging to 60% SoC is better than 50% AGREED - 70% better than 60% AGREED - 80% better than 70% etc etc. AGREED But 90% is better than 95% DEBATABLE. 100% is best DON'T AGREE.

As stated earlier, there is always more than one answer. It is generally accepted however that at least a small degree of discharge is beneficial to the life of the battery.

[Rich]

I think you either misheard or misunderstood.

 

 

Possibly, down to deafness or senility but I don't think either is an big problem just yet, so I'll stand by what I said.

 

Richard

 

As stated earlier, there is always more than one answer. It is generally accepted however that at least a small degree of discharge is beneficial to the life of the battery.

 

My original post read "OK. Batteries should always be discharged to 50% before recharging for optimum life. Note the "always". Not sometimes, now and again, occasionally etc."

 

So, should batteries always be discharged to 50% before recharging? Surely there are only two possible answers, either yes, or no.

 

To say that the less discharge the better means NO, they should not always be discharged to 50%.

 

Richard

[Keeping Up]

My original post read "OK. Batteries should always be discharged to 50% before recharging for optimum life. Note the "always". Not sometimes, now and again, occasionally etc."

 

So, should batteries always be discharged to 50% before recharging? Surely there are only two possible answers, either yes, or no.

 

To say that the less discharge the better means NO, they should not always be discharged to 50%.

OK. No. Pendant.

[Rich]

OK. No. Pendant.

 

And proud of it. Mind you, I don't seem to have many friends

 

Richard

[blackrose]

If you read the posting I was replying to you should see that I meant exactly what I said. This statement re discharging to 50% has been made to me more than once.

 

Richard

 

Well in that case I disagree with you. As I understand it discharging your batteries by any amount reduces their overall lifespan. The notion that discharging keeps them maintained is a very old myth that was dispelled on this forum years ago.

 

At least that was what Gibbo told me.

Edited March 7, 2010 by blackrose

[MikeV]

So, should batteries always be discharged to 50% before recharging?

Only if you want to shorten their lives versus discharging them less.

 

Every discharge/charge cycle shortens the life of a battey. The deeper the cycle, the more the life is shortened. There is no benefit, as far as battery life is concerned, from always discharging to 50%. There may be be some benefits from having to run the generator/engine less often.

 

Not discharging below 50% is a rule-of-thumb that is compromise between being able to use a reasonable proportion of the battery capacity while at the same time not unduly shortening their life.

 

In general most batteries are damaged (have their useable lives shortened) from either being discharged to deeply or not being fully charged regularly i.e. they are not charged long enough to bring them truly to 100% SoC.

[Nickhlx]

At the risk of being pedantic, should the criticism of of Rich being a pendant, be a pedant ? :lol:

 

:lol:

 

Nick

 

....coat... ( and hat and gloves ? )

Edited March 7, 2010 by Nickhlx

[alan_fincher]

My original post read "OK. Batteries should always be discharged to 50% before recharging for optimum life. Note the "always". Not sometimes, now and again, occasionally etc."

 

So, should batteries always be discharged to 50% before recharging? Surely there are only two possible answers, either yes, or no.

 

I have no doubt the answer is No.

 

50% from my understanding is the absolute minimum they should ever be discharged to, and if you actually tried to do that, can you really sure you are not going even lower.

 

Going regularly to 50% must shorten the life of lead acid batteries, and doing it deliberately only means you will buy new batteries sooner.

 

Which lasts far, far longer ? Your domestic batteries, regularly run well below 100% charge, or your starter battery, which remains at virtually 100% all of the time. OK, it's more complex than that, I freely admit, but batteries kept towards a high SOC must last better.

 

Advice about heavy discharge may have been fine for old Nicads, but sounds completely wrong for lead acid batteries to me.

 

Clearly not all agree, but I'm convinced.

[Nickhlx]

I have no doubt the answer is No.

 

50% from my understanding is the absolute minimum they should ever be discharged to, and if you actually tried to do that, can you really sure you are not going even lower.

 

Going regularly to 50% must shorten the life of lead acid batteries, and doing it deliberately only means you will buy new batteries sooner.

 

Which lasts far, far longer ? Your domestic batteries, regularly run well below 100% charge, or your starter battery, which remains at virtually 100% all of the time. OK, it's more complex than that, I freely admit, but batteries kept towards a high SOC must last better.

 

Advice about heavy discharge may have been fine for old Nicads, but sounds completely wrong for lead acid batteries to me.

 

Clearly not all agree, but I'm convinced.

 

Me too - The higher the depth of discharge to me means a shorter life, the higher the rate of charge (and discharge) also to me means a shorter life, and time spent on overcharge or at low states of charge also means a shorter life (to me)...

 

Naturally a battery has a job to do though and that means work. However, if it works less hard (by perhaps sharing the load with one, two or three others) and the charge to replace the lost energy is not hammered in too fast and without any more delay than can be avoided, you should be able to make your expensive investment last another season or two...

 

Nick

[Keeping Up]

At the risk of being pedantic, should the criticism of of Rich being a pendant, be a pedant ? :lol:

 

:lol:

 

Nick

 

....coat... ( and hat and gloves ? )

Well, actually thereby hangs a tale ... a very long tale ... involving a certain Mole of this Forum

[colin stone]

The great advantage of SG/SB is that enables 2 different types of batteries to be charged by the same system. I have sealed engine start batteries and flooded domestic batteries. SG disconnects on low/high voltages, enabling the flooded batteries to be charged at higher voltages without damaging the sealed batteries. SG also has a relay, so one can relatively easily modify alternators with diodes to charge at higher voltages until a voltage is reached, and then the voltage drops back to a float type voltage. See the Alt Mod here

 

Excellent kit, but perhaps quite advanced to use once one gets past the basic display and bank connection business.

[Rich]

Well in that case I disagree with you. As I understand it discharging your batteries by any amount reduces their overall lifespan. The notion that discharging keeps them maintained is a very old myth that was dispelled on this forum years ago.

 

At least that was what Gibbo told me.

 

 

If you go back and read the previous posts on this subject you will see that your latest post doesn't make a lot of sense.

 

Richard

[Rich]

Only if you want to shorten their lives versus discharging them less.

 

Every discharge/charge cycle shortens the life of a battey. The deeper the cycle, the more the life is shortened. There is no benefit, as far as battery life is concerned, from always discharging to 50%. There may be be some benefits from having to run the generator/engine less often.

 

Not discharging below 50% is a rule-of-thumb that is compromise between being able to use a reasonable proportion of the battery capacity while at the same time not unduly shortening their life.

 

In general most batteries are damaged (have their useable lives shortened) from either being discharged to deeply or not being fully charged regularly i.e. they are not charged long enough to bring them truly to 100% SoC.

 

 

Oh dear, oh dear, oh dear. The statement about discharging to 50% before recharging was in response to Blackrose's statement that there are always more than two answers to a question. I queried the use of always and he said yes, always. I then made the statement which is causing such much problem because people start posting without reading the previous messages. I was suggesting that this could be a question with ONLY two answers, either yes or no. So then it was suggested that the less the discharge the better for the batteries. Or to put it another way,no.

 

I accept that the less the discharge the better (but before someone steps in I know that nil discharge is not good). I am not suggesting that down to 50% is good although last week I was informed by someone at a very well-known marine electrics company that it was most definitely was the case and I have been told this on a number of occasions. But I know it is incorrect. Please believe me, I don't discharge below 50%. I don't normally get anywhere near that figure.

 

Richard

[nb Innisfree]

Oh dear, oh dear, oh dear. The statement about discharging to 50% before recharging was in response to Blackrose's statement that there are always more than two answers to a question. I queried the use of always and he said yes, always. I then made the statement which is causing such much problem because people start posting without reading the previous messages. I was suggesting that this could be a question with ONLY two answers, either yes or no. So then it was suggested that the less the discharge the better for the batteries. Or to put it another way,no.

 

I accept that the less the discharge the better (but before someone steps in I know that nil discharge is not good). I am not suggesting that down to 50% is good although last week I was informed by someone at a very well-known marine electrics company that it was most definitely was the case and I have been told this on a number of occasions. But I know it is incorrect. Please believe me, I don't discharge below 50%. I don't normally get anywhere near that figure.

 

Richard

 

If you stop trying to be a clever clogs with words then people will respond positively, we're trying our best to help you.

 

Nil discharge is ok, less than 5% isn't, read the posts properly.

Edited March 8, 2010 by nb Innisfree

[Rich]

If you stop trying to be a clever clogs with words then people will respond positively, we're trying our best to help you.

 

Nil discharge is ok, less than 5% isn't, read the posts properly.

 

 

I find your post offensive.

 

I am not being "a clever clogs" with words, I am simply fed up with people coming in half way through a thread and miss-reading my posts. It is not difficult to understand if you read the previous posts. I didn't ask for any help regarding the charging of batteries. I ask for help with removing a SmartBank and possibly a SmartGauge. All the rest has sprung from that.

 

What you could help with, and I would be very grateful, is to explain how I can achieve nil discharge on a liveaboard connected to a shoreline.

 

Richard

[nb Innisfree]

I find your post offensive.

 

I am not being "a clever clogs" with words, I am simply fed up with people coming in half way through a thread and miss-reading my posts. It is not difficult to understand if you read the previous posts. I didn't ask for any help regarding the charging of batteries. I ask for help with removing a SmartBank and possibly a SmartGauge. All the rest has sprung from that.

 

What you could help with, and I would be very grateful, is to explain how I can achieve nil discharge on a liveaboard connected to a shoreline.

 

Richard

 

You accuse people of not reading posts but you misread one regarding zero discharge which is the best condition for a battery. Just discharging a small amount down to 5% isn't good.

You can achieve nil discharge by disconnecting batteries and just using shoreline, ok batteries will naturally self discharge anyway so zero is perhaps not the ideal term.

[Rich]

You accuse people of not reading posts but you misread one regarding zero discharge which is the best condition for a battery. Just discharging a small amount down to 5% isn't good.

You can achieve nil discharge by disconnecting batteries and just using shoreline, ok batteries will naturally self discharge anyway so zero is perhaps not the ideal term.

 

If I disconnect the batteries how do I run the 12v lights, water pump and fridge? This is a genuine question, not an attempt to be "clever".

 

Richard

[nb Innisfree]

If I disconnect the batteries how do I run the 12v lights, water pump and fridge? This is a genuine question, not an attempt to be "clever".

 

Richard

 

Ok, then keep batteries on charge 24/7 with a '4 stage charger' or instead make sure batts are running a small bulb or similar to ensure batts don't overcharge? Or connect charger via a timer and keep topping up regularly. All this is a bit risky if there is a shore power cut though as your batts will die if you are absent and the fridge is left on. If all that is a bit involved/risky cycle batts down to, say, 90% and recharge, still a bit involved and you would need to turn fridge off if left for any time but that's the nature of things unfortunately.

[sociable_hermit]

Re. the fridge, if you are stationary for the vast majority of the time it would pay to buy a mains fridge and run it off the shoreline. For the few weeks of the year your supply is disconnected because you're boating, run it off the inverter. The batteries will get charged up by the engine every day anyway, when you're out and about.

 

Obviously there are a lot of variables (size of fridge, size of battery bank, alternator rating) but it's what I do and it works for me.

[Rich]

Ok, then keep batteries on charge 24/7 with a '4 stage charger' or instead make sure batts are running a small bulb or similar to ensure batts don't overcharge? Or connect charger via a timer and keep topping up regularly. All this is a bit risky if there is a shore power cut though as your batts will die if you are absent and the fridge is left on. If all that is a bit involved/risky cycle batts down to, say, 90% and recharge, still a bit involved and you would need to turn fridge off if left for any time but that's the nature of things unfortunately.

 

Sorry to have to say this, more clever clogs stuff, but four stage chargers do/don't exist. Anyway I don't have one.

 

I will do as you suggest and discharge-charge by turning on and off the charger. This is exactly what I have been doing for the last nine months.

 

Richard

[GUMPY]

What you could help with, and I would be very grateful, is to explain how I can achieve nil discharge on a liveaboard connected to a shoreline.

 

Buy a decent charger and leave it connected 24/7/365

Then if the charger has the facility, do an equalistion charge every 6 weeks or so.

If it does not have that facility, many don't, turn the charger off once a month and do a timed absorption charge.

Do NOT be seduced by a charger that does adaptive charging it doesn't work.

There is NO SUCH THING as a 4 stage charger despite what the manufacturers say.

 

That all there is to keeping batteries in good condition if you have a shoreline it becomes far more complex if you don't.

 

There is another way, that I do with my heating, and that is use a charger that is also able to be a Power supply and disconnect the batteries then it all runs off the charger all the time instead of the batteries. Then you have to be aware of self discharge as you could after a few months find that the batteries are down to 60% and need charging before you use them again.

 

Sorry to have to say this, more clever clogs stuff, but four stage chargers do/don't exist. Anyway I don't have one.

 

What charger do you have?

Edited March 8, 2010 by idleness