Very poor after sales service from aurorra

[cjcj1949]

Its a convention that when a charger or power supply is in current limit that this is called constant current and that when a voltage limit applies that it is called constant voltage. My point is that these conventions obscure what is going on. There are two limits in operation all the time. One is a current limit, the other a voltage limit. In the early part of charging the current limit will hit first, as the volts rise to the end of charge value the current will need to be reduced to avoid exceeding this value. It looks like there are two distinct phases but in reality just two limits that are there all the time.

My comments are about lipo chargers in general and the way that terminology makes a simple process seem complex and magical.

Chris

[xygax]

So you feel that chargers actually change from one mode to the other.

Yes a constant potential charger will maintain its output voltage (potential) until it gets to its maximum current or the current you have programmed for the battery type you are charging.

I find this strange as my power supply using a current and voltage limit charges lipos and lead acid quite happily.

I would expect it to you can quite happily program a power supply to charge any chemestry correctly. Its knowing the maximum charge input current and the correct voltage per cell that enables a battery to be charged to its optimum capacity.

I'm even more interested in your mention of NiCd cells being charged in the same way. Did you mean that?

Yes. Wet nicad's are always charged by constant potential current limited chargers here is a tech manual for batterys from small to over 1000 Ah Sealed nicads can also be constant potential chargerd but its better to use the delta peak method
http://www.saftbatteries.com/doc/Doc...7ee4330f6c.pdf


How do your chargers switch from one mode to the other? There is a knee point where the voltage limit becomes dominant and takes over from the constant current portion of the charging curve its an analouge mixing from both the current and voltage amplifier that is fed to the charge controler. ohh and for a 1000Ah battery you need a 100A charger minimum.... so they are just a little larger than a BC 6 or a cellpro...

Chris

Jsut a few notes
Steve

[cjcj1949]

That constant potential charge is actually a voltage limit at the end of a current limited charge.

Please explain the function of your voltage, current amps and how that differs from a current, voltage limit.

Chris

[xygax]

That constant potential charge is actually a voltage limit at the end of a current limited charge.

Yes exactly CVCI effectivly the constant voltage takes precidence over current

Please explain the function of your voltage, current amps and how that differs from a current, voltage limit.

The voltage amplifier compares a proportion of the battery volatge to a very stable voltage reference. as an example we use a 2.5v reference for a 110v battery so if its not ultra stable then the battery charge voltage will fluctuate. we manufacture gear with a 30 year design life in continious service so the output mustnt vary over a very long period. The current amplifier can take many forms eithe the output from a current transformer or from a current shunt this is amplified and mixed with the voltage signal to produce the CVCI curve with a reasonably sharp knee point (<5%)

Chris

Steve

[cjcj1949]

I understand. I hadn't realized that you were talking about industrial chargers for wet nicds. They behave quite differently from the ones I've used. The correct terminology seems to be a constant current charge to a specified voltage. This explains why the chargers start to reduce current when a given voltage is reached. If people want to call it constant current, constant voltage as they do with hobby grade products then that is fine, so long as they know there is no mystery, just a current limit and voltage limit which apply all the time.

I know that when the current limit predominates that it looks like a constant current phase and that when the voltage limit predominates it looks like constant voltage. My argument is that if people think like that they then want to know how the charger switches from one state to the other, whereas there is no such problem, just a misunderstanding due to semantics.

I am not sure why your chargers are so complex, but I expect it is to do with regulations regarding reliability and longevity. It would be nice if we could use batteries that could last.

Chris

[Neilpearman]

Update regarding my charger which started this thread. FMA in the USA were very helpful replying straight back to emails giving me things to test on the chargers pcb and sending me a new component to fit, now I have a working charger hats off to FMA.
As for Aurorra they have lost any future business from me
Thanks to everyone that offered me assistance