BZ Products MPPT 250 controller problem?

James · October 2007

Hello Friends

I received a 250 unit back from BZ which was sent in for service.

Before taking the unit out to my friends place to install, (long drive), I thought I would set up a test on the unit.

So here are the results:

Set up Kyocera 120 watt panel in full sun.
Before hook up to the 250, I measured current output with two diffirent meters.
Both meters read 7 amps.

Hooked up 250 to 12 volt battery,
Noted battery voltage at 11.9 volts.

Hooked up PV panel.
Switched 250 panel switch to current setting

waited for unit to cycle up.
initial current reading was 6.4amps...
it then dropped to 1.4 amps and held at that reading.
Battery reading was 13.6 vdc

I then disconnected unit and started hook up procedure once again, but this time inserted and analog currect meter in positive output line to battery.

The meter reading matched the 250 meter reading of 1.4 amps.

This is the same condition noted before returning unit to BZ....
So here is the question.....

Why do I get only 1.4 amps out of the 250?
I would expect at least about 7 amps, if not more due to the MPPT feature.
Should I expect more output amps considering the somewhat low battery voltage?

The unit is simple to hook up and I doubled checked connections polarity as I hooked it up.

Can you offer any explanation as to why this is happening?
Am I misunderstanding the operation of the 250?

Please advise of what I should do here, as I cannot afford to absorb the cost of the 250 unit for this system i'm installing.

I should note that I installed a temporary controller, a Xantrex C40, which is working just fine.

Thanks again for your help

Solar Guppy · October 2007

Re: BZ Products MPPT 250 controller problem?

Sounds like the unit went to float mode

make sure you have a discharged battery that can provide a load to stay in bulk charge mode to verifiy the mppt.

mike95490 · October 2007

Re: BZ Products MPPT 250 controller problem?

put a load on the battery, like an inverter with a 200 - 300 watts of load, that should lower the sensed voltage, and drop it out of float, and you will have a nearly full battery afterwards

What is BZ Products home page (just courious)

crewzer · October 2007

Re: BZ Products MPPT 250 controller problem?

http://www.bzproducts.net/

HTH,
Jim / crewzer

James · October 2007

Re: BZ Products MPPT 250 controller problem?

hi ,
i have already contacted bz (frank) with no reply.

I will try test setup once again this time with a load.
Regarding the float mode comment,
i may be wrong, but isn't 11.9 volt a bit low for the unit to switch into float mode?
I should mention that the 6.4 amps was only displayed for about a half second before dropping to 1.4 amps

BB. · October 2007

Re: BZ Products MPPT 250 controller problem?

Yes, 11.9 volts is probably too low for float mode...

But first, check your meter calibration. At least one time here, a bad DVM (that seemed to be work--but gave very weird results for various current/voltage tests) caused lots of back and forth posts. Ideally, your meter needs to be accurate to about 0.01 volts at 12 vdc...

Next, check your installation... If there are bad connections, improper use of sense leads, etc., can cause the charger to miss-read the battery voltage (battery may read low, but up at the charger, the battery voltage reads OK because of wire/connection resistance raising apparent battery voltage).

And, you need to check the battery manual from the manufacturer and the current battery temperature. The controller should be temperature corrected--so it will very a few 0.1's of a volt... But you should be closer to 14 volts +/- rather than 12v...

You could have a bad controller, but it is just as likely that there may be some wiring issue too.

Don't let your battery sit too long deeply discharged... If you can, you may wish to use a standard battery charger to get the battery fully charged again... Then work on the charging issues with the solar controller.

-Bill

Solar Guppy · October 2007

Re: BZ Products MPPT 250 controller problem?

James wrote: »

waited for unit to cycle up.
initial current reading was 6.4amps...
it then dropped to 1.4 amps and held at that reading.
Battery reading was 13.6 vdc

You hooked up the panel, mppt controller put out high current, battery voltage went up, unit went to low current, battery voltage @ 13.6v ( not 11.9 as you just posted )

The controller is not regulating the current, its regulating the voltage and your battery @ 13.6v is only enough load to for 1.4 amps.

My best guess is your battery is not doing well and when the voltage quickly rises with even a small current, indicating high resistance or bad plates or it could be fully charged.

Regardless of the battery, to test the Mppt controller, you need to have a load that will allow the controller to source its maximum current without the voltage going over the bulk/absorb set points. Hook up the battery and a 100-200 watt load and perform the test again

James · October 2007

Re: BZ Products MPPT 250 controller problem?

Checked with different meters...same results.

Hooked up a DC motor to battery as a load. Current output from 250 unit increased to 3.4 amps. I should note that the motor pulls 12 amps unloaded.

Therefore, it still seems to me this unit is not operating correctly.
Still no reply from BZ Products.

???????

niel · October 2007

Re: BZ Products MPPT 250 controller problem?

in rechecking to be sure of all connections it sounds defective and if under warranty i'd send it back to either get another controller other than bz or the money.

mike95490 · October 2007

Re: BZ Products MPPT 250 controller problem?

What's your location, anyone nearby that could look at your setup before you bail on it ?

System2 · January 2009

Re: BZ Products MPPT 250 controller problem?

I have one of these units I bought used, there is a variable resistor on the back of the main board used to adjust float voltage, which is supposedly factory set at 14.1 volts. It's adjustable from about 13.8 to 15.7 volts, you can download the data sheet from BZ. You may want to try that, I had to adjust mine. Also temp probe varies the float voltage.

Russ

BB. · January 2009

Re: BZ Products MPPT 250 controller problem?

Russ,

This thread is over one year old... Since then found that (some, many, all?) BZ controllers have some major design flaws and, generally, do not function correctly.

-Bill

BB. · January 2009

Re: BZ Products MPPT 250 controller problem?

Russ,

By the way, I am very sorry if my above reply sounds curt. It was not my intention.

Thank you for supplying some information about the BZ controllers, and I hope that it is working well for you.

We have a few people here that have tried them (and looked at them on a lab bench), and found them to be wanting in major areas.

Please feel free to ask/supply information and participate here in the forums.

Sincerely,
-Bill

tvengineer · February 2009

Re: BZ Products MPPT 250 controller problem?

WOw...

Sure wish I had found this forum before I purchased the darn thing.

Nothing technical to add.. but I replaced a Morningstar PWM controller with the BZ three days ago..

Before that the morningstar charged batteries and ran a fixed load for MONTHS even during stormy weather... the batteries never dropped below about 80 percent.

In three days with the BZ using the exact same setup and load.. the batteries are near dead.

Oh.well
live and learn.. glad I found this forum..

Louis

BB. · February 2009

Re: BZ Products MPPT 250 controller problem?

Louis,

Truly sorry to hear of your problems--if you can get your money back--run, don't walk, back to the retailer.

There are a lot of "BZ" threads here... This one includes a look at the unit by Solar Guppy--a design engineer that specializes in solar products (charge controllers, inverters, etc.).

Solar Guppy wrote: »

I'll be more direct, having just done some competive data analysis with a new in box BZ 500. ( also phil's older unit )

Don't buy one,
If you know of someone thinking of getting one, tell them not to buy one.

The Mppt doesn't work, its a total mess. The array voltage is in a ~second random movement/ramp from -2 to -13 volts from the true vmp. The testbed in this case had a verified vmp of 38 volts, the bz was going from 25V to 36V non-stop .. averaged with a yokogawa about 12% off true vmp.

The unit has no heat sink and could never ever support 45amps.

Its has other design issues as well, clearly produced by someone that lacks basic power supply design skills.

I know I've written this in the other thread, but its so bad, I feel it warrants posting the info here. If anyone thinks it works OK, they aren't doing any meaningful measurement to quantify that thought and are doing a dis-service to recommend the unit to anyone.

If you have any questions, or answers, please feel free to jump in!

-Bill

tvengineer · February 2009

Re: BZ Products MPPT 250 controller problem?

Yes.. I found that thread too...

:-(

For my BZ.. it looks like it is putting out about exactly what the Morninstar PWM controller would do.. So no GAIN at all from MPPT that I can tell, in bright sunlight.

The bigger problem seems to be that it shuts down.. thinks for about 20 seconds.. then the relays click and the charge current slowly begins to ramp up... after a minute or so the charge current suddenly drops down to 0.0 and the relays drop out and the cycle begins again..
So all in all it is only charging about 1/2 of the time, wasting the energy the panels could be making while it resets.

I may or may not have a bad unit.. but after finding this forum it is not worth trying to find out.

Thanks
Louis

kenputer · February 2009

Re: BZ Products MPPT 250 controller problem?

I have one of the BZ 250 and it works great. I must be one of the lucky ones by the sounds of others.
ken

icarus · February 2009

Re: BZ Products MPPT 250 controller problem?

Ii have one too,, from Phil S. ( thanks Phil!) Works great,,,,, as a wall ornament, or paperweight, or small (really small) boat anchor, or door stop.

I wouldn't plug it into a battery however. Does have a pretty cool ammeter,,, wish I could figure out how to yank it out and use it for something else!

Tony

PhilS · February 2009

Re: BZ Products MPPT 250 controller problem?

icarus wrote: »

Ii have one too,, from Phil S. ( thanks Phil!) Works great,,,,, as a wall ornament, or paperweight, or small (really small) boat anchor, or door stop.

I wouldn't plug it into a battery however. Does have a pretty cool ammeter,,, wish I could figure out how to yank it out and use it for something else!

Tony

GEEEZZZ Tony! I forgot I still have another one of those (after sending two away for "evaluation").

So if you figure out how to use any of the pieces/parts (like ammeter) be sure an pass it on. Otherwise I'll still try and remember it when/if I need a cool little equipment box.

Phil

icarus · February 2009

Re: BZ Products MPPT 250 controller problem?

Phil,

Every once in while, while perusing Ebay I see how much these controllers are selling for, I am tempted! Then my better angel says no! If you ever see one on E-bay with my name on it,,,, shoot me!

Tony

PhilS · February 2009

Re: BZ Products MPPT 250 controller problem?

icarus wrote: »

Phil,

Every once in while, while perusing Ebay I see how much these controllers are selling for, I am tempted! Then my better angel says no! If you ever see one on E-bay with my name on it,,,, shoot me!

Tony

Yeah, Tony, I was checking out eBay yesterday trying to find a cheap small controller and saw some BZs listed. They were over $200 each. I had considered dumping them on eBay but, like you, dismissed that idea.

I ordered a Steca Solsum 6.6A controller from Wind-Sun. The price of that controller wasn't much different than the cheapest I found on eBay. Of course, the biggest advantage is knowing who I'm dealing with.

And I must add: there were some 'scary' looking controllers there for sale.

This controller will be hooked to one 65W panel that I have put on the roof of a garage to keep a Ford diesel truck's batteries fully charged. The pickup doesn't get driven much and has a high enough phantom drain that it won't start after a few weeks of sitting. I've had the panel up for a couple of weeks now and even with all the cloudy days, the batteries are now always 12.6 or better. So I'm figuring when the sunny season starts again, without a controller I'd cook 'em.

Phil

BZ Products MPPT 250 controller problem?

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