Changing the LVC in a 72v generic controller

[Zenid]

But if all the controllers you got were marked as 72V controllers with 75V mosfets then you should submit a complaint against whomever you bought them {...}

What's to complain about? The controllers work, that's all that matters. What do you expect for $35-a-pop wholesale? I've had haircuts more expensive than that. If one breaks, I'll just chuck it in the bin and get another out the box.

If you don't want one then don't buy one.

[wesnewell]

But if all the controllers you got were marked as 72V controllers with 75V mosfets then you should submit a complaint against whomever you bought them {...}

What's to complain about? The controllers work, that's all that matters. What do you expect for $35-a-pop wholesale? I've had haircuts more expensive than that. If one breaks, I'll just chuck it in the bin and get another out the box.

If you don't want one then don't buy one.

What's to complain about? How about it's not built to specs! I don't care if it $5 or $500. It's out and out fraud. And don't worry, I won't buy one of those. The 2 I have now both have 100V mosfets. Just curious what voltage you are running them at, I run mine at 100V. Give that a shot for a while and let me know how it works out for you.

[The Mighty Volt]

Hua Tong makes lots of different controllers. They make 48V, 60V, 72V, and probably other voltages. One person said they had a 48V version that had 63V caps. I don't recall if he mentioned the mosfets on it. But if all the controllers you got were marked as 72V controllers with 75V mosfets then you should submit a complaint against whomever you bought them from since they can't be rated as 72V controllers with 75V fets.

I think that might have been me. I got my controller with a 48v 1500w rated Moped Motor, which is what Zenids Hua-Tong controller was feeding. It's a 15 Mosfet, 4410 spec, with 63v caps. The 4410 Fet's are 75v rated.

[Zenid]

Just curious what voltage you are running them at, I run mine at 100V. Give that a shot for a while and let me know how it works out for you.

I was running the thing with a 72V SLA bank for months with no problems, as do many other people. When I moved up to Lithium I overvolted one at 80-84V for a couple of weeks to see how far I could push it. It got hot enough to melt the grommets and silicone sealant, but still worked. I call that a good, working 72V controller.

As for trying to run it at 100V - why would I do a silly thing like that? It's a 72V controller, - okay below 80V, but overheats at above this. For a 100V bank I would use my Lyen's controller with the nice, IRFB 4110 MOSFETs. The quality one that I paid four times as much for...

[bobale]

As for trying to run it at 100V - why would I do a silly thing like that?.

Well, why not? I like pushing thing to their limits (sometimes beyond ), especially if they are cheap and/or easily repairable. Caps and FETs in ours HuaTong controllers are rated for 100V, so 100V would be pushing it really hard, but 90V would live you with a nice margin.

I run mine at 90V, and will run it like that as long as it holds up. It was only $37, so screw it. And just for the record, @90V it runs a lot cooler than stock 9FET Infineon @57V .

[Zenid]

Well, why not? I like pushing thing to their limits (sometimes beyond ), especially if they are cheap and/or easily repairable. Caps and FETs in ours HuaTong controllers are rated for 100V, so 100V would be pushing it really hard, but 90V would live you with a nice margin.

The ones in mine are only 75V rated, that's what this debate has been about.
Like I said, I like pushing thing to their limits too:
http://endless-sphere.com/forums/viewtopic.php?f=2&t=26306&p=466140#p465969
I overvolted one to 80-84V and it started to melt...
http://zenid10.wordpress.com/2011/09/03/meltdown/

[wesnewell]

That's what I'm talking about. A 72V controller shouldn't get that hot at only 84V. Mine runs cool as a cucumber on 100V. And for The Mighty volt, 4410 fets are rated for 100V not 75V.

[Zenid]

That's what I'm talking about. A 72V controller shouldn't get that hot at only 84V. Mine runs cool as a cucumber on 100V. And for The Mighty volt, 4410 fets are rated for 100V not 75V.

That's because it has 100V rated FETS and should therefore be runnable at 100V. Just like my Lyens controller.

A "72V" controller gets that hot at 84V because - as I ascertained from experiment - it is only suitable to be run at under 80V (at least this one from this batch).

Do you not understand that is NO SUCH THING as a "75V" or "100V" FET per se? These are just nominal ratings given based on their ability to run at these voltages while effectively dissipating heat. Quality of components varies. Some behave better than their rated values and others worse. If they perform well at higher voltages, someone stamps it with one little number, if they perform more poorly and get hot, they get stamped with another little number. But they are often exactly the same components, from exactly the same production process that SHOULD perform the same. That's the joy of statistical variation in quality: the whole thing is crap shoot.

You can "shoulda" til the cows come home, but at the end of the day you pay your money, you take your chances. Sometimes you end up with great stuff for near nothing, sometimes you pay big bucks and end up with shit. Get used to it.

And, again, "This is China!"

[The Mighty Volt]

@Wesnewell

I made a mistake. I have I407 Mosfets in mine, rated for 75v, in a 48v rated controller, which is acceptable.

The ratings are only nominal.

For instance, a 100v rated capacitor is rated to 100v, give or take 10volts.

So it could be 90 or it could be 110.

That's why a 72v controller has 100v capacitors, a 100v controller has 150v capacitors etc.

These controllers should be a cheap platform for us to work off.

Nothing more.

[wesnewell]

A "72V" controller gets that hot at 84V because - as I ascertained from experiment - it is only suitable to be run at under 80V (at least this one from this batch).

Do you understand that a 72V SLA battery pack in good condition will charge to over 80V? That's why it shouldn't be rated as a 72V controller using 75V fets. These aren't batteries, and the ratings aren't nominal ratings.

[Zenid]

Do you understand that a 72V SLA battery pack in good condition will charge to over 80V? That's why it shouldn't be rated as a 72V controller using 75V fets. These aren't batteries, and the ratings aren't nominal ratings.

In my experience, peak voltage of an 72V SLA bank settles quickly to around 78-79V. I've run experiments a couple of times taking regular readings during the discharge of a battery bank, then plotting it out to get a discharge curve. The discharge curve of a lead-acid cell typically goes something like this:



Though peak charge of a nominal 72V bank may just crack the 80V mark, voltage rapidly drops and plateaus, with most of the discharge spent somewhere between 78 and 72V (though obviously you can discharge them further if you really want). It therefore spends hardly any time in the 80-84V window that that my LiFePO4 occupies through most of its cycle.

I've already explained ad nauseam how ratings given to components are ultimately always nominal, because the rating always makes certain assumptions about how the component is being used, what the operating temperatures are, and countless other factors.

[Zenid]

@Wesnewell
I made a mistake. I have I407 Mosfets in mine, rated for 75v, in a 48v rated controller, which is acceptable.

The ratings are only nominal.

Yes. Exactly.

For instance, a 100v rated capacitor is rated to 100v, give or take 10volts.

So it could be 90 or it could be 110.

Yes. Exactly.

These controllers should be a cheap platform for us to work off.

Nothing more.

Yes. Exactly.

[auraslip]

well, the bad thign about wes is that he's not afraid to be wrong.

the good thing is that he's man enough to admit

[Gordo]

auraslip,
Is it possible for you to fix this link?
Thanks

So I ended up installing a 2.2k resistor rather than the SMD resistors. Some napkin math calculation says it should hit LVC near 37v (or 2.3v per cell for 16s).

I've tried to figure out how to do regen on this controller, but I've got nothing. I've figured out how to activate the brake through the high line. Seems a bit weird to run full battery pack voltage to the handle bars but what ever.

Here is the resistor wrapped in heat shrink.

[auraslip]

better?

[Gordo]

better?

The picture is perfect and by reading and reading and reading, one can finally figure out exactly which SMD you removed & which points you connected the resistor to. I thank you for all the work and now understand exactly what you have done. It would be great for the next newbee who stumbles onto this thread, if a summary was edited into the first post.

I am a bit concerned with the use of a pot on the board. You may be introducing unwanted L/C into the circuit? I don't have a clue if this is so, just wonder?
Thanks again,

[auraslip]

I posted the relevant part on the first post.

what is L/C?

[Gordo]

I posted the relevant part on the first post. what is L/C?

In my view, that makes this thread infinitely more valuable. You went to a lot of work figuring out how to lower the LVC and now the next fellow can take full advantage of your labour. Perfect. I wish all threads where in reverse chronological order, with the conclusion at the beginning.

L is inductance, C is capacitance. Every additional component induces some L/C. The length of the leads on the added resistor could make a difference to the functioning of the circuit, when compared to the SMD it replaces. I do not know if this has any negative effect on the controller, just a caution. It is just good practice to keep lead lengths to a minimum. Mounting the resistor vertically, by making a 180* bend in one lead, is an option.

[amberwolf]

I wish all threads where in reverse chronological order, with the conclusion at the beginning.

While it is not the default, you can do this if you wish:
ucp.php?i=prefs&mode=view
"Display post order direction:" change to "Descending"
and it will now display newest post in a thread first, with the first post in a thread on it's last page at the bottom.

[Gordo]

Perfect AW. Thank you very much.

I do think it is a great service to all to summarize the important points in one post as auraslip has done. Sometimes you can hunt a long time before you put the details together in to a meaningful whole.

[PeeHell]

Hey Auraslip, can you share with us some of your napkins math calculation ?
I want to run this cheap controller at 24s, so I'd like to increase the LVC to get the regen to work at higher voltage.

[Zenid]

Hey Auraslip, can you share with us some of your napkins math calculation ?
I want to run this cheap controller at 24s, so I'd like to increase the LVC to get the regen to work at higher voltage.

I wouldn't do that if I were you. These controllers use P75NF75 FETS, which are only rated for 75V and are already being slightly overclocked by a 72V SLA bank, which will run as high as 80V fully charged. If you run this controller on a 24s pack (mine is a LiFePO4, nominal 76.8V) it runs way too hot and this happens:


http://zenid10.wordpress.com/2011/09/03/meltdown/

I used my cheap controller for a few weeks while my Lyen 12-FET was being repaired. It lasted pretty well, but when it stuttered a couple of times I took a look at it and realised that it was starting to melt! Used gently you can just about get away with it, but they run very hot.

[wesnewell]

Not this again. Both my controllers had 100V caps and fets, and run cool with a 24s lipo pack at 100V charged. So it depends on which controller he has. AFAIK only the 2 headed wire bundle controllers had 75V fets. Of course one can check when they open the controller to change the lvc. I haven't changed lvc on mine and run 18s and regen works perfect on it. Looks to me like you just need to change the value of the 3 resistor bank to change lvc. Maybe put a pot or 3-4 poll switch across it with different value resistors so you can easily change it.

[Zenid]

Not this again. Both my controllers had 100V caps and fets, and run cool with a 24s lipo pack at 100V charged. So it depends on which controller he has.

I'm pretty sure he's talking about the cheap, Hua Tong controller that is the subject of this thread.

[wesnewell]

The original post was for the same controllers I have. You can see the 100v caps in the very first post. It's not the double headed one you had with 75v fets which is totally different looking even form the outside.