My DC/DC converter, please explain

spdas said:

Aloha, I have a Iota Dc/Dc DLS-75 converter and do not understand the specs. It says it operates at 108 to 132vAC 60HZ to 12vDC.
Specs also say it functions as ac input and dc input. Is it not one or the other?
Also it is hooked up to my battery bank of 158V and at one time it was hooked up to the battery bank when it was 228vDC.

What am I missing here? specs say input 108 to 132vAC and I am using it now at input of 158vDC. (I did not build my EV, I bot it and trying to understand the workings).

Please explain.

Francis

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If it's got a simple Bridge Rectifier on it, then you can connect DC, and it'll work just fine (As the bridge rectifier converts AC to DC). AC voltage is measured RMS (Root-Mean Squared), so an AC voltage that measured 300v peak-to-peak would be described as ~210v. So 132v AC is roughly 188v Peak-To-Peak.

What i do not understand is that it is run off my 158vDC pack not the vAC input that the specs say. Does my zilla hairball put out AC?


Francis

spdas said:

What i do not understand is that it is run off my 158vDC pack not the vAC input that the specs say. Does my zilla hairball put out AC?

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No, you're getting DC. But, as the first step of the converter is to convert the incoming voltage to DC, if you're already supplying DC you only use half the rectifier circuits (As it's already DC, and so doesn't need conversion).

See: https://secure.wikimedia.org/wikipedia/en/wiki/Diode_bridge

Anaerin said:

No, you're getting DC. But, as the first step of the converter is to convert the incoming voltage to DC, if you're already supplying DC you only use half the rectifier circuits (As it's already DC, and so doesn't need conversion).

See: https://secure.wikimedia.org/wikipedia/en/wiki/Diode_bridge

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Thanks for the explanation, it make sense to me now.

So, what do you think my DC voltage Input Range can be if the IOTA is rated 108 to 132vAC?
Would i use your example above of "132v AC is roughly 188v Peak-To-Peak" and meaning 42% higher converting ac to dc use? (But this converter was used at one time for 240vDC!!) which gives us about 170vAC specs.


thanks Francis

spdas said:

So, what do you think my DC voltage Input Range can be if the IOTA is rated 108 to 132vAC?

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I think it's only safe to use it for about 1.4 x 132 = 185 VDC.

(But this converter was used at one time for 240vDC!!) which gives us about 170vAC specs.

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My guess is that the input capacitor(s) is(are) rated at 200 VDC. It seems that this sort of capacitor will withstand a short term overload, but the life decreases rapidly when used over the rated voltage. Unfortunately the failure mode for electros that are overvoltaged is a bang, smell, and mess (which could corrode other components). So while you may get away with using it at 288 VDC for a short time, I would strongly advise against it.

You could replace the input capacitor(s) with say 350 VDC version(s), but the switching transistors and other components are likely also not rated for this. Semiconductors usually avalance (and melt) within microseconds of overvoltage, so maybe you'll get away with it, but the first spike on the pack voltage (e.g. back-emf from a contactor dropping out) could take them out.

Most devices made for 120 Vac operation can withstand up to 200 volts DC peak on the input because usually 200 volt parts are chosen. It is possible that Iota was using 250 volt parts on the input side. I wouldn't take it over about 195 volts peak voltage seen during charge.

228 amps 12v ~$200, easy to mod voltage

228 amps 12v ~$200, easy to mod voltage

six 12v rails at 38 amps each = 228amps

features voltage adjust knob.
11.8-12.6? we will see about that

http://www.evga.com/PRODUCTS/enlarge.asp?PN=100-PS-1200-GR&I=6
rebranded, i cant seem to find the original atm

Re: 228 amps 12v ~$200, easy to mod voltage

Tim_Fred_007 said:

228 amps 12v ~$200, easy to mod voltage

six 12v rails at 38 amps each = 228amps

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It seems to be a 1200 W supply, so that would be a maximum of 100 A @ 12 V. I'd say that might be peak, too, not continuous. But that should be plenty if you can get it to run on your pack.

I'd say each output is capable of 38 A, but not all together (since the front end has a power limit).