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Battery charger an solar


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Do I need to disconnect the solar panel if I need to run the battery charger? And yes yes I know with solar I wont need to run the charger but I did have to.

 

Also a mate was told to disconnect his solar panel when he starts the engine. Any idea why that would be? We certainly dont. Am I doing it wrong?

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No on both counts. No need to disconnect panels or charge regulators for any normal reason.
There should be back current/surge protection built into the reg unless it is a realy nasty cheap piece of crap.
And when ever other charge source/s are connected, the one that puts out the greater regulated voltage ends up causing the other regs to back off and the greater charge voltage becomes sole charge source. This is a real pain in the A when you want the greater charge current to be the primary charge source. Someone needs to design a single charge reg that combines all source currents and feeds that as a single regulated output.

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I turn off my panels when running engine so the alternator is the sole provider of charging current.  I assumed the charge voltage of the solar charging would limit the current from the alternator as the reg would see the high voltage?

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If the voltage is high, the batts will only accept a small charge. No need to turn any regulated charge source off. As wheels said, the reg with the highest voltage setting will win. Otherwise, if the batts volts is low, all sources will charge until they reach their cut off voltage.

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This is a real pain in the A when you want the greater charge current to be the primary charge source. Someone needs to design a single charge reg that combines all source currents and feeds that as a single regulated output.

Apparently the guys at Wakespeed are working on a device such as this right now, how long until it gets to market could be another thing entirely. Their WS500 alternator reg is very good though.

http://www.wakespeed.com/

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 This is a real pain in the A when you want the greater charge current to be the primary charge source. Someone needs to design a single charge reg that combines all source currents and feeds that as a single regulated output.

 

The batteries resistance dictates charge acceptance and ohms law would cause a higher current if available to be the primary source.     

 

You could easily combine multiple different output voltages into a single static output voltage using  buck boost regulators and feed the single regulated voltage to a single Mttp controller that could handle the combined amperage.   I would exclude a wind generator from this though. 

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The batteries resistance dictates charge acceptance and ohms law would cause a higher current if available to be the primary source.

 

You don't understand how these regs work. First of all, you cannot use ohms law to calculate the charge current into the battery. Your comment would be correct if it were simple single stage current regulation. But multistep charge regulators don't work that way. They are changing modes from Voltage regulation to Current regulation and then Voltage regulation again. They sense the voltage level, placing then into their different modes or steps of regulation depending on the Voltage sensed and depending on the trigger points of the steps. Of which, some regs can have those trigger points manually set. For instance, the bulk charge voltage can usually range from 14.1V (nominal is 14,4V) to 14.8V. The float charge can range from 13.3V to 13.8V. So while bulk charging, all regs are poking in current. As soon as a reg senses the trigger voltage, it's output drops to float level and no longer charges due to the other reg/s continuing to supply the greater bulk charge. If you have a sophisticated reg that does a 3 step regulation producing an absorption charge, then that reg no longer pushes current into the battery. It is like a tandem bike and one regulator is not trying hard peddling letting the other do all the work.

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While that is true Wheels, normally they all work while in Bulk, which usually gets the batts to about 80%. Its not called bulk for no reason, it's where most of the charging happens. After that, then any sources will drop off one by one, the one with the highest voltage settings last. Once lead acid batts are over 80%, the charge accepted drops away pretty quickly, and the fuller the charge, the lower the charge rate, so as you approach full you don't need a huge charger, as the batts wont accept it anyway.

Of course, none of that means you should not think about this, and set up your sources to get the best possible benefit - which, by the way, is not just fast charging, but maintenance resulting in healthy, long lived batts.

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 First of all, you cannot use ohms law to calculate the charge current into the battery.

 

Easy.   Batteries resistance [at its current state of charge - this changes as it charges] / voltage = Current.    I = R/V is ohms law and this is a prefect example of how it works.   A battery changer can not rewrite the laws of physics.

 

I am very aware of how these chargers work but they are mostly a triumph of marketing over technology. 

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.... What about the battery EMF which is increasing as the battery charges? You can't say that the resistance is the charging voltage/charging current. The battery internal resistance will be (charging voltage - battery EMF)/charging current.

I'll be generous and suggest I=R/V is a typo on your part.

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Easy.   Batteries resistance [at its current state of charge - this changes as it charges] / voltage = Current.    I = R/V is ohms law and this is a prefect example of how it works.   A battery changer can not rewrite the laws of physics.

 

I am very aware of how these chargers work but they are mostly a triumph of marketing over technology.

When in regards to a very simple power supply, as in a Transformer and Rectifier (simple non regulated battery charger) yes simple Ohms law, (or resistance), would be correct.

But for a properly designed/controlled multistep charger, the Battery resistance does not apply.

And yes, there are some chargers out there that are more about marketing hype than actual "smarts", but there are also many chargers that are truly very sophisticated computer controlled charging devices. 

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Id suggest that its a good idea to keep the details provided on a public forum to the most simple explanations and name conventions. EMF (Electromotive Force). Battery EMF is battery voltage.

Fair cop IT. I was in full on mobile phone typing mode, which takes up about 90% of my brain power just to maintain legibility.

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When in regards to a very simple power supply, as in a Transformer and Rectifier (simple non regulated battery charger) yes simple Ohms law, (or resistance), would be correct.

But for a properly designed/controlled multistep charger, the Battery resistance does not apply.

And yes, there are some chargers out there that are more about marketing hype than actual "smarts", but there are also many chargers that are truly very sophisticated computer controlled charging devices. 

 

Wheels no and sorry, I do not want to disrespect you as you are very knowledgeable in so many technical areas and have taught me tons about repairs and other little golden musings while reading your posts on this website......but without being a load the battery can not be charged.   Also,  because a battery heats and gases, this proves the battery is a resistive load to the charger. Ohms law applies to every circuit..always.

 

Multistage chargers are made out to be super technical devices and they really are not.  Some of them that are running FPGA's [Field programmable gate array's - for IslandTime] where firmware can be updated and they can integrate with other systems are getting quite clever.  But the charge circuits themselves do a relatively straight forward job and are not complicated.  The stages are labeled so they sound fancy, 3 or 5 or 7 stages,  they describe the stages that the battery is at.  There really are only two stages of a multistage charger and that is charge and float.  The rest is a description of what the battery is doing and what the marketing department use. 

 

Luigi - EMF / Electromotive force is going to describe changing another type of energy into an electrical energy and describe its potential for work [in volts]  ie: a wind turbine will convert wind energy into electrical energy,  is where you would use emf in your example/description.  A cell in a solar panel would be another great example.

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Luigi - EMF / Electromotive force is going to describe changing another type of energy into an electrical energy and describe its potential for work [in volts]  ie: a wind turbine will convert wind energy into electrical energy,  is where you would use emf in your example/description.  A cell in a solar panel would be another great example.

MCP,

Battery EMF is the correct term and has been since I did my electrical technical education, many years ago. On technical matters, that is how think and speak. However, I.T. (Matt) is correct and terminology needs to be appropriate for the forum and discussion subject.

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Wheels no and sorry, I do not want to disrespect you as you are very knowledgeable in so many technical areas and have taught me tons about repairs and other little golden musings while reading your posts on this website......but without being a load the battery can not be charged.   Also,  because a battery heats and gases, this proves the battery is a resistive load to the charger. Ohms law applies to every circuit..always.

You are correct and this is more about how we are viewing the topic I guess. Yes there is a resistance and that resistance is needed for the circuit to work. But they do not take into their calculations the resistance of the battery to set a charge current. That is a factor of Voltage. In fact these smart chargers often will not work at all if the battery has no Voltage (total 100% discharge). The resistance state will be max and would normally take a non regulated charger to max current for a short time. For the smart charger, but there must be a voltage present to kick the charger off. No voltage, no work. In fact you can short the leads together and nothing will happen. That would be max resistance.

So in regards to your original comment, what I am saying is that the resistance is not a factor of how a smart charger charges. For instance, if you think about this, for a plain PS type charger, the charge current is constantly reducing as the charge is accepted and thus battery resistance decreasing. These type of chargers need a higher OC voltage so that via simple ohms law, they produce a current into the resistance. Which is what you are saying.

 But for a smart charger( the clever ones), the charge current remains constant. These chargers use algorithims and the temperature of the battery is sensed and adjusted for buy calculation. The algoritims are complex and is why these chargers tend to be so darn expensive.

When a battery is charged or discharged, only the reacting chemicals, which are at the surface of the Plates, are initially affected. This is called Surface or interface charge. This charge enters the depth of the plate by diffusion only and that is a factor of time. This also in a way happens in reverse when discharging and is why Purkets Law is used to caculate correct dishcarge states of the battery.

Raising voltage above normal charge points is what causes gassing. In an equalisation charge, the voltage is lifted substantially and current dropped substantially to compensate. This causes the gas by electrolysys which stirs up the elctrolyte. If the voltage was increased against pure resistance, then the resulting current would simply boil the electrolyte in very short time. Heat kills batteries.

 

 

 

 

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Electro Motive Force (EMF) is the Force  (voltage) of the electrons as they flow (current) through a circuit. That circuit can be as simple as a wire passing through a magnetic field (generator).

 

*sigh*     That would be Electro "Magnetic"  Force

 

MCP,

Battery EMF is the correct term and has been since I did my electrical technical education, many years ago. On technical matters, that is how think and speak. However, I.T. (Matt) is correct and terminology needs to be appropriate for the forum and discussion subject.

 

 Yes,  there is a chemical reaction at the electrodes isn't there?   It does not describe voltage,  voltage only describes its potential.  

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You are correct and this is more about how we are viewing the topic I guess. Yes there is a resistance and that resistance is needed for the circuit to work. But they do not take into their calculations the resistance of the battery to set a charge current. That is a factor of Voltage. In fact these smart chargers often will not work at all if the battery has no Voltage (total 100% discharge). The resistance state will be max and would normally take a non regulated charger to max current for a short time. For the smart charger, but there must be a voltage present to kick the charger off. No voltage, no work. In fact you can short the leads together and nothing will happen. That would be max resistance.

So in regards to your original comment, what I am saying is that the resistance is not a factor of how a smart charger charges. For instance, if you think about this, for a plain PS type charger, the charge current is constantly reducing as the charge is accepted and thus battery resistance decreasing. These type of chargers need a higher OC voltage so that via simple ohms law, they produce a current into the resistance. Which is what you are saying.

 But for a smart charger( the clever ones), the charge current remains constant. These chargers use algorithims and the temperature of the battery is sensed and adjusted for buy calculation. The algoritims are complex and is why these chargers tend to be so darn expensive.

When a battery is charged or discharged, only the reacting chemicals, which are at the surface of the Plates, are initially affected. This is called Surface or interface charge. This charge enters the depth of the plate by diffusion only and that is a factor of time. This also in a way happens in reverse when discharging and is why Purkets Law is used to caculate correct dishcarge states of the battery.

Raising voltage above normal charge points is what causes gassing. In an equalisation charge, the voltage is lifted substantially and current dropped substantially to compensate. This causes the gas by electrolysys which stirs up the elctrolyte. If the voltage was increased against pure resistance, then the resulting current would simply boil the electrolyte in very short time. Heat kills batteries.

 

 

 

 

 

 

Wheels,  you know an awful lot. No question!   Some of what you are saying above is 100% correct but some of the links you are drawing and examples you are giving sound plausible but but are not correct in physics and that is ultimately the test for anything electrical. 

 

I think if you and I got together with a whiteboard and some beers, we would soon easily understand what each other is saying.  But continuing this on a forum is pointless as we are looking at this from different levels. 

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The way I read both your posts are that you are both right.

 

If I interpret correctly, Wheels is saying that the more advanced chargers don't just change the voltage by set rules, but also monitor current, and in some modes change settings because of the current, not the voltage.

 

Which is right, even though to change the current you must change the voltage , according to the laws of physics, as you cannot directly change the resistance of the battery, although that will, of course, change as the batts charge!

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