Efuel High Power Charging Questions

[Planehazza]

Also looking at the Revolectric site, while the PL8 has a max input current of 60 amps, it has a max output current of 40 amps. So anything more than 4 x 5000mah packs at 2C could take it over its limit (hopefully the software prevents this). If I was charging 6 x 5000mah packs, I personally wouldn't charge over 1C. That way, the psu wouldn't be running at full capacity either.

40A output is not necessarily 40A at input however remember.

[Grumpy]

Also looking at the Revolectric site, while the PL8 has a max input current of 60 amps, it has a max output current of 40 amps. So anything more than 4 x 5000mah packs at 2C could take it over its limit (hopefully the software prevents this). If I was charging 6 x 5000mah packs, I personally wouldn't charge over 1C. That way, the psu wouldn't be running at full capacity either.

No, you cant take the PL8 over it's limit. 40A on the output is the highest you can set and the highest it will deliver, it cannot 'go over it's limit'. As you say, it's software prevents it as it does on any charger.
As already mentioned in previous post, input current is not directly related to output current. You have to factor in voltage at input and voltage at output and charger efficiency. As a random example it's perfectly possible to have an input current of 20A and an output of 40A, or vice versa, depending on voltages.

The charger is however capable of exceeding the PSU's 50A limit and/or the PSU's 1200W power limit... so that's why you need to limit input current in the software.

[hedge]

You are right of course, I forgot to check the PSU after reading the 60A 12V comment in the first post.

HI All, just was not clear in the first post - sry - I was using a server 12v 100A 1200w PSU, the PL8 was set to draw a max of 60A at input and 12v. No matter it still blew up. So therefore I am not sure what is protected and what is not.

So once I blew one up and get that RMA'd I go buy the new 1200w 50a Efuel PSU to prevent this from happening again, only to find that the PSU wants you to limit the PL8 to 24v and 40a at input. My question is do I run the Efuel at 30v or set it to 24v EVEN THOUGH the PL8 is set only to draw 24v.

TBH Ive lost faith in the lot and will just run at a sedentary 24v/40a it appears neither of these top of the line bits of kit can actually perform to spec - poor show to both manufacturers, protect your kit! I will say this the 5yr old Revolutrix 10s charging off the same PSU as the PL8 at the same time just put itself in protection mode when the PL8 blew - why of why did revolutrix go backwards when producing the three times as expensive PL8!!!

[Grumpy]

If you set the PSU to 30V and the PL8 to 24V max then the PL8 will simply shutdown on over-voltage on supply side (because 30V exceeds 24V). If it were mine I'd set the PSU to 30V and the only limit I'd program into the PL8 is a 40A max current (to protect the PSU).

I think that you are jumping to conclusions when you say that the PL8 failed due to exceeding some limit. As I read it you don't really know why it failed, like any electronic piece of equipment components sometimes fail, even when operating fully within limits, or your old server PSU may have been faulty and providing an unstable supply... who knows?

[Mark_T]

Just out of interest, what were you charging on the PL8 at the time and at what rate?

[hedge]

Just out of interest, what were you charging on the PL8 at the time and at what rate?

6x6s 5000mah at 1C

[Mark_T]

6x6s 5000mah at 1C

I guess I'm going full circle then as you were trying to get over 750W @ 12V out of a PL8 which is only rated for 612W @ 12V.

I still would have hoped the PL8 would simply have shutdown rather than failing in the way that it did, but that was too much to expect it to handle.

The server PSU was obviously more than up to it though.

With your new PSU, if you still just want to charge those same packs at 1C then the recommended 24V/40A will cope with that so not a lot of need to go higher.

Personally I wouldn't try to pull 1200W out of a 1200W PSU and I'd suggest that the limit (24V/40A) or 80% of the rated output isn't a bad place to be for safety and long term life.

[Grumpy]

The PL8 wouldn't shut down. It would just reach the power limit (as result of 60A input limit) and charge at that reduced rate. Nothing 'dramatic' should have occurred.

Having said that 60A is a lot, it's far better to have a higher voltage PSU that wont need such high current..

[hedge]

With your new PSU, if you still just want to charge those same packs at 1C then the recommended 24V/40A will cope with that so not a lot of need to go higher

Thanks Mark, I agree and will settle for that. It would be nice though if

a) Specs listed by the equipment where under normal user conditions as opposed to lab conditions
b) the units would protect themselves- like my 10s did.

Anyway I will move on but thanks for the banter.

[myxiplx]

it appears neither of these top of the line bits of kit can actually perform to spec

That's a bit of a strong statement. You've experienced one failure, and while that's frustrating, if you look at the reputation of these units the vast majority of them perform over and over again for years.

Ultimately there's no way to know what actually caused the failure, you were certainly pushing it fairly hard, but definitely within the spec of the PowerLab. My guess would be something in the PSU triggering the failure, but without a thorough investigation you're not really going to know.

You've done your homework though, and know the safe voltage and current range to use with the new power supply, and the PowerLab has been replaced, so you should be good to go. Give it 6 months and hopefully this will just be a bad memory :-)