iCharger calibration.... PSU supply problems...

[PaulJC]

I have an iCharger 306B that i think may be reading the input voltage slightly wrong :/

I have a 3 x 12v HP Server PSU setup, they output 12.6, 12.8 and 12.3 volts making for a combined 37.7v as measured by my DVM with no load, perfect for the iCharger 38v max input you would think (well that was the plan)...

However, the iCharger is reading the input voltage as 38.17 and shutting itself off with the 'input overvoltage' warning...

Now it is quite possible that the iCharger is more accurate than my DVM however i was wondering if anyone had experienced this before, with a charger potentially reading/calculating the wrong voltage?

And if so how was it solved, can the input stage be recalibrated, would this require the charger to be sent back?

There was i hoping to charge batteries tonight for a fly day tomorrow at the higher input voltage but now i'm left scratching my head over this problem instead....

Any thoughts?

[PaulJC]

OK, i have found instructions to calibrate the charger, apparently you can calibrate input voltage, output voltage including individual cell voltages, internal and external temperatures... HERE

I'm going to attempt to recalibrate the input voltage, i'm not going to lower it as far as 37.7 as i dont know how accurate my DVM really is so i'm going to try to drop it to just under 38v so the charger will operate...

[PaulJC]

I realise i'm talking to myself here but someone may find this useful in the future...

I recalibrated the input voltage, the charger was still unhappy with it set to 37.94 even though it should accept a 38v input and was shutting down with the over voltage warning however it is sat here now happily running with a 37.91 input voltage displayed on the screen

I guess we all just take for granted that these things are setup accurately, i'm not going to attempt to adjust the individual cell voltages but its kinda worrying that it could interpret higher than 4.20 as less, i think i'd want a fairly well calibrated or proven DVM before i attempted any adjustments on the output side of things though...

[MarkG_R1]

Stupid question maybe...........Why not run it at 25.?v like i do mine? with only 2 psu's

[PaulJC]

Stupid question maybe...........Why not run it at 25.?v like i do mine? with only 2 psu's

Thats what i used to do, but by running the higher voltage it will reduce the amp's going in to the charger for the same output and i will now be able to run 2 x 306B's flat out off this power supply without any problems

[MarkG_R1]

Fair enough I'm pretty sure my one would run flat out all day without complaining, but two makes sense

[PaulJC]

Oh yeah absolutely, i've had 2 of them for a year and they haven't missed a beat, they are used to running in serves 24/7 for ages so what we ask of them is nothing, i did rewire mine on this latest change so that the fans are temperature controlled and the load spread equally across the PSU's, no more jet engines woop woop lol

[MarkG_R1]

I did the variable fans from the start They hardly ever need to ramp up

[Varelco]

Nice find PaulJC i never realised you can calibrate the iCharger, I might check mine at some point.

Anyone know what the hell a '4 1/2' digital multimeter is? (taken directly from the instructions)

[PaulJC]

Anyone know what the hell a '4 1/2' digital multimeter is? (taken directly from the instructions)

No not a clue lol, and i know my meter is only cheap so i didn't go for 'accurate' and adjusted it just enough to get my combo working, i did quickly have a look around for a calibrated meter but they are not cheap... lol

[PaulJC]

"a multimeter which can read up to 19999 (plus an embedded decimal point) is said to read 4½ digits."

Thanks to google... So basically a very accurate one... lol

[xygax]

You could always turn the power supplies down a little to 12v each it will give you 2 v of headroom... and your meter one of these will do nicely Agilent 34401A 6.5 Digit Digital Multimeter - buy used refurbished or rent from Test Equipment Solutions

Steve

[PaulJC]

You could always turn the power supplies down a little to 12v each it will give you 2 v of headroom... and your meter one of these will do nicely Agilent 34401A 6.5 Digit Digital Multimeter - buy used refurbished or rent from Test Equipment Solutions

Steve

Complete bargain :/ lol

If i honestly thought they were producing over 38v then i would turn them down

[Mark_T]

If i honestly thought they were producing over 38v then i would turn them down

Sometimes you just have to be pragmatic and ultimately it is the charger that gets to decide what it believes , so turning them down would seem like the line of least resistance at this point.

[ghost2212]

Running them that close to their maximum input voltage is probably a bad idea IMO, The charger's will actually be doing more work and you'll probably use more power than if you were running them on two power supplies in series to get ~25V I assume you're charging 6s Packs?