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Victron Inverter/Charger voltage too high


Peregrine

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My boat has a Victron MultiPlus 12/3000/120 inverter/charger. My new SmartGauge alerted me that my new sealed Numax batteries (4x110) had been subject to a voltage "too high for their type". I found the meter showing 14.7 volts with the Victron indicating it was in absorption phase (though by rights it should have been in float phase since it's on a landline and the batteries are pretty much 100% charged).

 

The manual says the Victron's default battery type is an Exide gel type, and the settings for this are pretty much what you'd want for a sealed battery – absorption voltage of 14.4 and float of 13.8/13.2. I took my life in my hands, read the manual, opened the unit, found how to read the settings via a combination of DIP switches and LEDs, and confirmed that the unit is indeed on its default. So it should have been applying a maximum of 14.4 volts. Not the 14.7 shown by the meter.

 

I don't know whether this is something recent or not. I have also just fitted a solar panel with a Tracer 30Amp charge controller, in parallel with the other charging systems (the Victron unit, and a Sterling alternator-battery unit). The meter for the Tracer shows the panel and controller behaving themselves – they also are set for sealed batteries and the charging measurements seemed spot on when we disconnected the landline and just used solar for a few hours.

 

So I wonder whether the Victron is troubled by having a second charging source in parallel with it. But I am especially troubled by the fact that it is exceeding its stated absorption voltage for the battery type to which it is set. Any comments on this behaviour?

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The 14.4v is the nominal voltage at (usually) 25 degC. If the battery temperature is lower the charge voltage will be higher. I forget how much but it is quite conceivable that an extra 0.3v will be a result of the temperature compensation for cold batteries.

 

What battery type do you have the Smartgauge set to. Should be type 1 I think, in which case the over-voltage alarm is at 15v.

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The 14.4v is the nominal voltage at (usually) 25 degC. If the battery temperature is lower the charge voltage will be higher. I forget how much but it is quite conceivable that an extra 0.3v will be a result of the temperature compensation for cold batteries.

 

What battery type do you have the Smartgauge set to. Should be type 1 I think, in which case the over-voltage alarm is at 15v.

Mine is the old type smartgauge but sealed calcium / calcium batteries on this unit are to be set as type 6. I regularly get the same E03 over voltage alarm with both Victron charger and also alternator so suspect the smartgauge alarm voltage is set a bit lower than 15v. My Victron absorption voltage is currently 14.7 - canal water and swim are still very cold.

 

This has been discussed on earlier sealed battery threads and temperature compensation on the charger was chief suspect. Also not everyone agrees with Numax and smartgauge about the 14.4 charge voltage.

 

Paul

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14.7 volts on your Numax sealed lead calcium batteries will do no harm whilst charging, in fact will be beneficial. Important that they are not left indefinately at that voltage though, so ensure the Victron does eventually drop to the much lower float voltage.

 

FWIW I have been using nominal 14.8v absorb setting on both chargers and alternators for several years with same battery type. Same regime on previous boat as well.

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Nicknorman, PaulD, by'eck,

 

Thanks for these responses. I'd not realised that the effect of the temperature coefficient would be that powerful, and hadn't taken it into account. I eventually found in the Victron's manual a graph of voltage against battery temperature for the units default setting, and it does rise to 14.7 at about 10˚C. The manual doesn't seem to give an actual coefficient, but the manual for my new solar stuff does, and the calculation shows the 0.3v rise to be perfectly normal, as nicknorman says.

 

The battery type is set to 6 on the SmartGauge, but there seems no way of adjusting the voltage at which the E 03 error kicks in. I see I can turn it off if it becomes a distraction.

 

Thanks again for the comments. Odd things after fitting new gear are always a bit worrying!

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Nicknorman, PaulD, by'eck,

 

Thanks for these responses. I'd not realised that the effect of the temperature coefficient would be that powerful, and hadn't taken it into account. I eventually found in the Victron's manual a graph of voltage against battery temperature for the units default setting, and it does rise to 14.7 at about 10˚C. The manual doesn't seem to give an actual coefficient, but the manual for my new solar stuff does, and the calculation shows the 0.3v rise to be perfectly normal, as nicknorman says.

 

The battery type is set to 6 on the SmartGauge, but there seems no way of adjusting the voltage at which the E 03 error kicks in. I see I can turn it off if it becomes a distraction.

 

Thanks again for the comments. Odd things after fitting new gear are always a bit worrying!

Alarm voltage is certainly higher for type 1 than type 6. After fitting the sealed batteries it was sometime before I got round to setting the smartgauge to type 6. The E03 errors started with the new setting.

 

An occasional charge at 14.8 - 15v seems to be necessary to maintain capacity with sealed batteries. Numax insist on 14.2 - 14.4v max so you have to make your own decision. I certainly wouldn't worry about 14.7v for short durations.

 

Paul

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Nicknorman, PaulD, by'eck,

 

Thanks for these responses. I'd not realised that the effect of the temperature coefficient would be that powerful, and hadn't taken it into account. I eventually found in the Victron's manual a graph of voltage against battery temperature for the units default setting, and it does rise to 14.7 at about 10˚C. The manual doesn't seem to give an actual coefficient, but the manual for my new solar stuff does, and the calculation shows the 0.3v rise to be perfectly normal, as nicknorman says.

 

My experience with the Victron Inverter Chargers (mainly with the 12/3000/120) is that the battery temperature compensation system is not really suited to an installation in an English canal narrowboat. My suspicion is that it was originally intended for different boats used in altogether warmer climes and vehicle applications. What I have experienced is that when used it tends to let the voltage go a bit higher than necessary or useful, particularly when the weather is cold.

 

My advice to my customers is to leave this function disconnected on a normal installation, the Inverter Charger will work perfectly well without it. It is an on balance bit of advice though and not always appropriate.

 

Hope this helps...

 

Arnot

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My experience with the Victron Inverter Chargers (mainly with the 12/3000/120) is that the battery temperature compensation system is not really suited to an installation in an English canal narrowboat. My suspicion is that it was originally intended for different boats used in altogether warmer climes and vehicle applications. What I have experienced is that when used it tends to let the voltage go a bit higher than necessary or useful, particularly when the weather is cold.

 

My advice to my customers is to leave this function disconnected on a normal installation, the Inverter Charger will work perfectly well without it. It is an on balance bit of advice though and not always appropriate.

 

Hope this helps...

 

Arnot

So what is the downside of the voltage being "higher than necessary or useful". The battery manufacturers specify temperature compensation for charging voltage, the charger manufacturers include temperature compensation in order to meet the battery manufacturers' specs, which increases the cost of their product, and yet you have decided to ignore both these. What is your justification for doing that?

 

The optimum charging (not float) voltage is a compromise between warding off sulphation and avoiding excessive gassing / loss of water. Bother of these issues are temperature dependant.

Edited by nicknorman
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The downside is that if the charging voltage is too high (for the application) then the battery(ies) slowly convert the water in the electrolyte to gasses and the level falls. This then leads to premature failure if they are not topped up regularly with high purity water. I accept that in an ideal world this is what should happen but it isn't an ideal world. I did day that this was an "on balance" bit of advice and stand by this.

 

The problem seems to be that depending on what software an inverter charger has in, in almost every case it uses the charge current to determine when to reduce the voltage to the "float" level. If it senses when despite being on float, it is having to supply a current well above the threshold it used to reduce the voltage it then increases it for a while. Of course, inverter chargers have no way of knowing that the current they are supplying is not being used for battery charging but running lights, pumps and other gubbins. If that current draw then stays above the float threshold then it stays at the absorbtion voltage for longer than is ideal for the batteries. This leads to electrolyte depletion.

 

In the case of a boat used for pleasure (i.e. occasionally) this isn't a problem in practice providing the inverter charger they have has a maintenance mode. However, in the case of a live aboard boat that is almost permanently on a shore line, it does become a problem. A lot of solar systems have similar shortcomings and they do impact pleasure cruisers.

 

Most of the battery manufacturers specifications don't refer to temperature compensation but of course some do and it should be taken into account for the rest. The absorbtion voltage is not so much a compromise between sulphation and gassing as between charging time and gassing, sulphation is unlikely to be a problem at either absorbtion or float voltages or for that matter the newer (and lower) maintenance voltage. I suspect that the inverter charge manufacturers actually don't worry as much about battery manufacturers recommendations as getting a bad reputation for killing batteries prematurely. Elon Musk once said “The battery industry has to have more BS in it than any industry I’ve encountered,” and I have to agree...

 

Another thing to take into account is that when the manufacturers of both inverter chargers and batteries issue their instructions and recommendations they have no way of knowing where they will be used and the conditions can be quite extreme. Death valley has a completely different set of problems to Alaska. An English Canal Narrowboat, generally has its batteries located new the bottom of the hull and in an area that is not heated so the thermal inertia of the steel/water combination and the lack of direct heat or airborne heat means that the battery temperature doesn't tend to vary to either extreme. Of course there are exceptions...

 

On a more empirical note, I have been dealing with inverter chargers and battery systems for about 45 years now and have some experience on them. Not that I claim to know it all, on the contrary, the more I know, the more I realise I don't know. The advice I offer is based on this experience. I am sure that some people will downright disagree with me and some will quote examples where the advice would clearly be inappropriate but it doesn't alter the experience.

 

I do suspect that were I able to alter the thresholds, limits and slope of the temperature compensation rate then I might give different advice but I can't...

 

Still, in the final analysis, it is up to the boat owner to take the decision, I can only advise and when required justify this advice which I am happy to do.

 

Does this answer your query?

 

Regards

 

Arnot

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The downside is that if the charging voltage is too high (for the application) then the battery(ies) slowly convert the water in the electrolyte to gasses and the level falls. This then leads to premature failure if they are not topped up regularly with high purity water. I accept that in an ideal world this is what should happen but it isn't an ideal world. I did day that this was an "on balance" bit of advice and stand by this.

 

The problem seems to be that depending on what software an inverter charger has in, in almost every case it uses the charge current to determine when to reduce the voltage to the "float" level. If it senses when despite being on float, it is having to supply a current well above the threshold it used to reduce the voltage it then increases it for a while. Of course, inverter chargers have no way of knowing that the current they are supplying is not being used for battery charging but running lights, pumps and other gubbins. If that current draw then stays above the float threshold then it stays at the absorbtion voltage for longer than is ideal for the batteries. This leads to electrolyte depletion.

 

In the case of a boat used for pleasure (i.e. occasionally) this isn't a problem in practice providing the inverter charger they have has a maintenance mode. However, in the case of a live aboard boat that is almost permanently on a shore line, it does become a problem. A lot of solar systems have similar shortcomings and they do impact pleasure cruisers.

 

Most of the battery manufacturers specifications don't refer to temperature compensation but of course some do and it should be taken into account for the rest. The absorbtion voltage is not so much a compromise between sulphation and gassing as between charging time and gassing, sulphation is unlikely to be a problem at either absorbtion or float voltages or for that matter the newer (and lower) maintenance voltage. I suspect that the inverter charge manufacturers actually don't worry as much about battery manufacturers recommendations as getting a bad reputation for killing batteries prematurely. Elon Musk once said “The battery industry has to have more BS in it than any industry I’ve encountered,” and I have to agree...

 

Another thing to take into account is that when the manufacturers of both inverter chargers and batteries issue their instructions and recommendations they have no way of knowing where they will be used and the conditions can be quite extreme. Death valley has a completely different set of problems to Alaska. An English Canal Narrowboat, generally has its batteries located new the bottom of the hull and in an area that is not heated so the thermal inertia of the steel/water combination and the lack of direct heat or airborne heat means that the battery temperature doesn't tend to vary to either extreme. Of course there are exceptions...

 

On a more empirical note, I have been dealing with inverter chargers and battery systems for about 45 years now and have some experience on them. Not that I claim to know it all, on the contrary, the more I know, the more I realise I don't know. The advice I offer is based on this experience. I am sure that some people will downright disagree with me and some will quote examples where the advice would clearly be inappropriate but it doesn't alter the experience.

 

I do suspect that were I able to alter the thresholds, limits and slope of the temperature compensation rate then I might give different advice but I can't...

 

Still, in the final analysis, it is up to the boat owner to take the decision, I can only advise and when required justify this advice which I am happy to do.

 

Does this answer your query?

 

Regards

 

Arnot

 

I'll certainly have to give you credit for a well formed answer, even if I don't totally agree with it. I just wonder how many folk you have encountered with sealed wet batteries whose batteries have expired as a result of running out of electrolyte. In my personal experience modern wet "leisure" batteries, whether sealed or open, seem to be able to tolerate surprisingly high voltages without any significant gassing due, presumably, to a relatively high proportion of calcium. On this forum most problems seem to occur as a result of sulphation caused by inadequate charging - sometimes lack of duration but also quite often lack of sufficiently high finishing voltage. Unless there has been a regulation issue I can't remember a thread where the batteries had died from loss of electrolyte. Although my own "leisure" (calcium-rich) batteries, when I had them, were open type, I found that despite charging to say 14.8v and relatively frequent bursts of 15.5v for equalisation, they used very little water and although I did top them up once or twice, if I hadn't done so they would not have run out of electrolyte before needing replacement.

 

You mention 45 years experience etc but I just wonder if you are not basing your advice on batteries of yore which tended to have much less calcium and thus were more prone to gassing at lower voltages.

 

On the point about chargers remaining in absorption due to current being taken by the boat's services, this is of course correct but in practice surely the charger is likely to go into float overnight and even during the day when not much power is being used. A fridge, for example, seems insufficient to take a charger out of float and back into absorption. So even if night-time TVs and lighting will take the charger back to absorption, this will in reality not last long as once the occupants go to bed it will revert to float.

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I looked at my (non-sealed of course) calcium-rich Varta leisure batteries recently, using a variable voltage supply. Varta publicly quote 14.4v as the maximum charging voltage. At the usual voltages there was no gassing at all. Ditto at 15v, and 15.5v; at 15.8 there was just the faintest hint of gassing, and at 16v there was noticeable but slight gassing. Increasing to 16.1 gave about the same amount of gassing as an old-fashioned (ie calcium free) battery on an old-fashioned non-intelligent charger. It wasn't until 16.3v that the amount of gassing was enough to even begin thinking about fluid loss.

 

This was in response to Varta's private suggestion that on a narrow boat a monthly charge at 16v or more was needed to prevent sulphation or stratification.

 

From this and the pathetic performance I've seen from sealed Numax CX31s when they were charged at the recommended 14.4v, I'd say that even sealed batteries would benefit from regular charging at 14.8 with an occasional boost towards 15.5

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The important word there is "occasional" Sulphation and stratification are helped by charging to gassing, but battery life decreases as the electrolyte goes down due to prolonged overcharging. Far too many boats hide the batteries out of sight, out of reach and then they don't get what little care they need.

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I take your point about lead calcium batteries and agree. However in practice unless well maintained (when they do very good service) sealed wet batteries do have their issues. The problem is that the electrolyte can't be checked apart from the little magic eye thing on the top. And this is difficult to see on a lot of boats where the batteries are tucked in the side if the engine well under the deck. So; often if there is a problem with the charging, the first indication comes with a bill for new batteries as well. And, as you mention, they do tend to prefer a slightly higher voltage to achieve full charge.

 

No I'm not basing my advice on batteries of yore but it's also true that I'm not basing it on calcium batteries. Maybe I'm unusual in this respect but a lot of boats I work on have traction cells and semi traction blocks which are both lead antimony. Actually a lot of my experience in batteries is on very modern cells. In fact there is one type that gives significant improvements in CCA that hasn't even hit the market yet as far as I know. Ever seen a 24Ah battery with a 1200A output?

 

Regards

 

Arnot

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