BZ MPPT250 25A,12V Charge Controller w/LVDWrite a review

I will buy any broken or non-working charge controller.

I found this controller to be adequate for my needs. I only have a micro solar system right now, and this controller has performed well for my needs so far. I could have gotten away with something smaller and cheaper, but this one will allow me to expand with more solar panels in the future. I have not noticed the clicking sound that the other reviewer mentioned. This is a good balance of price/performance for a MPPT controller. There are better ones for much more $$$, and cheaper ones with poorer performance. Probably good for first timers and small PV systems.

I don't understand why someone would write a review about a BZ MPPT 250 that he does not have and complain about the problems he had with an older BZ model 200. Specifically, he felt 14.4 volts was too high for a float charge. I agree. So does BZ. The manual for the model 250 clearly states:

"The float voltage of the MPPT250 is factory set to 14.1 volts. The float voltage is adjustable."

As for it not being a 3-stage controller. The truth is that 3-stage charging only really applies to PWM controllers although many MPPT manufactures like to say they are 3-stage as well because it sounds good and people expect to see the words "3-stage charging" in the specs. But the whole concept behind MPPT eliminates the first stage of "3-stage" charging. In 3-stage charging, Stage 1 is "bulk charge" done at a non-varying pre-set high voltage until the battery nears full charge, at which point Stage 2 "absorption" begins and varies the charge level to match what's happening in the battery as it finishes charging. But MPPT charging -- particularly when using a temperature probe like the BZ model 250 does -- eliminates the sledge hammer approach of the Stage 1 "bulk charge" and is *always* in Stage 2, always optimizing and varying the charge to the battery based on its current state and temperature and matching that to the varying output of the solar panels. So, by the nature of MPPT, it is a 2-stage controller: using optimized, variable charging until the battery is full, then maintaining the full charge at user-specified float level.

I don't have the MPPT250, but I had a MPPT200 until it quit working one day after about eighteen months of use. I wrote BZproducts and they wanted $10 for return shipping on a warranty item. This thing is about the size of a pack of cigarettes and would have cost $4 prioity mail to ship back to me.

So I decided to buy a C35 instead. Whoopee! Three stage charging. I had the BZ controller on a small system with four golf cart batteries and very occasional loads. About four months after I installed it, I went and looked at my batteries and I could see the tops of the plates! So I added water. Four months later, all the water is boiled out again. 12V batteries do not like a 14.4V float charge all day long every day.

These batteries literaly drank water until I figured out what was going on. Either give up absorbtion and ignore sulfation, or boil the crap out of them all day long. There is only one voltage to choosre from.

I've still got this busted BZ controller and an altenergystore reciept from 2004. I'll sell em both for five bucks if you want to deal with BZ on the warranty.

What looked like the best controller in my comparison of a dozen controllers turned out to be a mistake. At 5:30am the controller woke me up with a relay click every few seconds. This continued for quite a while as the sun came up. It was so annoying I had to unplug it.
Contacting their tech support was useless. After days and days of back and forth trying to find a solution, their final response was “that is normal operation”. It is clear what looked good on paper was horrible in actual use. I suspect no one at their company has every camped with one of these units. Otherwise they would have been screaming at the design staff the next day.
Having the MPPT feature is nice, but it is still a 1-stage single voltage charge algorithm. There is no absorption phase and no float option or setting. So your batteries will never be fully charged unless you set the charge voltage high enough to cause excess water loss all the time. Either way your batteries suffer.
Spend a few more dollars and get a good 3-stage charge controller even if it does not have the MPPT feature. Your batteries will thank you, and your sleep with thank you.
I would have rated it a zero if that was an option. Giving it the bottom rating of 1 seems too high.