Do any battery chargers actually do it all right?

williaty · September 2012

As a point of reference, this is for my home system that just provides a backup for basic stuff, not the EMCOMM system I was asking about before.

Due to the absurdities of my living situation, I can't permanently install my 900W of PV panels outside. They have to be stored inside and taken outside when the power looks like it's going to be out for an extended period. :grr The rest of the time, the batteries are just going to be sitting around inside, so I need something to both float them and to recharge them if they've been used for a number of hours (but not so long as to justify setting up the solar system). I would like to get a grid-powered 3-stage charger to recharge and maintain the batteries on a "normal" basis when plugged into the wall, plus be able to recharge the batteries via a generator in the winter if we get one of our famous "It's Ohio in January and the sun won't be back for 3 months" weather events. I've been looking at a number of chargers, and I'm appalled that they all get something wrong! Many of them don't run through the 3-stage charging sequence properly. The biggest problem seems to be that many of them begin to reduce current during Bulk long before the voltage has risen to the Absorb setpoint. If I'm charging from the genny, this is a deal-breaker. Even if they do run the 3-stage algorithm properly, they don't have user-adjustable voltage settings that happen to work for my battery bank (UPG Universal Power batteries, requires 29.4V Absorb and 27.4V Float). Most chargers have a setting for FLAs that is too high and a setting for AGMs that is too low. There's some offerings from Samlex that look like they do what I'm wanting except the voltages a preset.

So, what I'm looking for is basically a grid-powered version of a Midnite Solar Classic! Here's what I really want out of it:

1) Properly executes a 3-stage charging profile to allow the quickest possible charging while not risking the batteries
2) Allows user customization of voltages to actually match what the battery manufacturer suggests for their batteries
3) Functions both from the grid and from a Yamaha inverter generator (I've read some chargers and some generators don't play well together)

Is there such a thing out there, or am I chasing a unicorn?

BB. · September 2012

Re: Do any battery chargers actually do it all right?

This thread discussed picking the "optimum" AC battery charger for a small (1.6kW) genset (long thread, lots to read):

Question about battery charger selection with EU2000 generator.

Stevek did find a charger that was a good match for his genset--which also appears to be a pretty good charger in its own right:

The answer (for Steve) was the Meanwell (1,000 watt charger available in 12/24/48 volt models):

http://www.jameco.com/Jameco/Products/ProdDS/1954341.pdf

-Bill

stephendv · September 2012

Re: Do any battery chargers actually do it all right?

Victron Phoenix chargers do all of the above: http://www.victronenergy.com/chargers/phoenix-charger-12v-24v/ they also do an adaptive absorb charge which bases the absorb time on the bulk time, so if it was a shallow discharge, the battery doesn't spend too much time in absorb.
Another nice feature is that in addition to float they also have a "storage" mode which is slightly lower than float and prevents corrosion of the positive plate. This usually isn't an issue for solar chargers because they don't spend a lot of time in float, but for marine applications where a system could be plugged into shore power for many months, too high a float voltage can damage the batt.

williaty · September 2012

Re: Do any battery chargers actually do it all right?

The Meanwell charger looks really cool, but it has the same major flaw several other chargers have: the Absorb voltage is too low and fixed (non user settable).

The Phoenix charger looks awesome, actually, but... $800 for a charger?!? The only thing I can do with that is curl into a ball and cry! Even the 24/16 that's a little too small for my bank is still $600. Man, I hope I turn up something else the works because that would be very difficult to afford.

williaty · September 2012

Re: Do any battery chargers actually do it all right?

Hmm, from the other thread, this interests me:

SteveK wrote: »

I just got off the phone with Iota. They confirmed the DLS-27-25 can be switched into higher voltage mode via a jumper. The output voltage would be ~29.5V while reducing the charge current to compensate the compliance wattage of 680W.

That's a useable voltage for me and seems to imply that the peak charging current would be around 23A, which is a little low (I'd like 30) but I'm starting to get to the "I'll take what I can get" stage. Are Iota known for tight voltage regulation? 29.6V is the upper limit for charging of my batteries. I'd hate for it to wander up a few tenths and cook the batteries. However, it's still $310 with the IQ4 unit, which it looks like I'd need. While a great savings, for that much money, I'd like to be excited about what I'm buying. Is the Iota a good unit?

EDIT: Nope, won't work. It'll bulk to 29.6V, but drops down to 28.4V for Absorb. That's not useful

vtmaps · September 2012

Re: Do any battery chargers actually do it all right?

williaty wrote: »

Nope, won't work. It'll bulk to 29.6V, but drops down to 28.4V for Absorb. That's not useful

Williaty, you realize that Iota does not use the terms 'bulk' and 'absorb' the same way we tend to use them on this forum. Many battery manufacturers use the terms the way Iota does. The charging profiles that are common in the RE industry (Midnite, Outback, Morningstar, etc) are different from what most battery manufacturers use. The battery charger industry tries to produce what the battery manufacturers want.

read this: http://forum.solar-electric.com/showthread.php?14738

I have been reading about the Xantrex Truecharge2 battery chargers. They now have a 24 volt version. On paper it looks like what you (and I) want. I don't know enough about their field performance to recommend for or against them.

--vtMaps

Blackcherry04 · September 2012

Re: Do any battery chargers actually do it all right?

IOTA's and all the rest of the " Power Converters " came from the RV industry. After the RV business folded they began selling them as " Battery Chargers " . They all have added some controlling charging algorithm to them. The IOTA is available in two flavors, with or without IQ4 built in, Without the IQ4 built in you have the plug in Jack for the 2 stage plug and you can buy the IQ4 as a separate module for around $25.00 and have 3 stage charging.

They do have quirks though, The Absorption phase is for 7 Hours before it will drop to float. You can short cut it by unplugging the IQ4and plugging it back in, you cannot do that if it's built in.

If the voltage is not what you want, you can change it with a pot located inside the case. When you do that it changes both the " bulk and absorption phase " and the 1 volt difference stays the same and at the same ratio.

For me the best solution was the crank them to their highest voltage and run them through a Xantrex C-35 charge controller where I can control their output to my liking and have the ability to Equalize .

halfcrazy · September 2012

Re: Do any battery chargers actually do it all right?

Simply said you could take 120vac from the grid or the Generator and rectify it and stuff it into an MPPT charge controller that will handle the 190 ish VDC you end up with. I have seen this done with a Classic 200 and it does work but there are some gotchas. If the grid is used it is super stiff and if you use a mode like Solar it will try to drag the grid down to the battery voltage during a sweep and fail. (Usually with smokey results)

If you used a Classic (Realizing this is an UNSUPPORTED function) you could use Hydro mode and set a minimum input voltage to eliminate this issue. Realizing at this time this is an unsupported function (Although we are looking hard at it at the moment and may support it at some point) I would start with a real high Input voltage limit as well as a low Output current limit and sneak up on the spot I wanted to run at. Remember every grid and generator connection will act differently.

The one thing I have noticed is with a single phase of AC rectified it has a lot of ripple and I added some filter caps to the output of the rectifier. It did not appear to bother the controller but seemed to make the lights settle down.

Ryan

williaty · September 2012

Re: Do any battery chargers actually do it all right?

halfcrazy wrote: »

Simply said you could take 120vac from the grid or the Generator and rectify it and stuff it into an MPPT charge controller that will handle the 190 ish VDC you end up with. I have seen this done with a Classic 200 and it does work but there are some gotchas. If the grid is used it is super stiff and if you use a mode like Solar it will try to drag the grid down to the battery voltage during a sweep and fail. (Usually with smokey results)

If you used a Classic (Realizing this is an UNSUPPORTED function) you could use Hydro mode and set a minimum input voltage to eliminate this issue. Realizing at this time this is an unsupported function (Although we are looking hard at it at the moment and may support it at some point) I would start with a real high Input voltage limit as well as a low Output current limit and sneak up on the spot I wanted to run at. Remember every grid and generator connection will act differently.

The one thing I have noticed is with a single phase of AC rectified it has a lot of ripple and I added some filter caps to the output of the rectifier. It did not appear to bother the controller but seemed to make the lights settle down.

Ryan

I had not considered using the Classic that way. I had assumed I'd need to get a AC>DC power supply and feed DC to the Classic. If I got, say, a 36V 45A DC power supply, would the Classic happily "digest" that source?

Cariboocoot · September 2012

Re: Do any battery chargers actually do it all right?

williaty wrote: »

I had not considered using the Classic that way. I had assumed I'd need to get a AC>DC power supply and feed DC to the Classic. If I got, say, a 36V 45A DC power supply, would the Classic happily "digest" that source?

There isn't much point in doing that as the Classic 150/200/250 could take 120 VDC input. No sense stepping the line Voltage down, then rectifying it, then stepping it down again inside the controller.

Ryan has already mentioned that this isn't a supported function (meaning guarantee invalid) and that there could be issues with the AC ripple. That last one has been a problem with previous attempts to use MPPT controllers in this manner; the DC is no place near as 'clean' as the output from PV's. This could cause problems with the MPPT function.

He and boB (et alia) know more about this than I do by far. I'll only say that if it worked it would be great, but rather expensive. There's a lot of function in the Classic that would not actually be needed in an AC powered battery charger, but you have to buy it anyway. So far.

williaty · September 2012

Re: Do any battery chargers actually do it all right?

I have to admit that the idea of having the Classic there to be the charge controller for both the solar array (when set up) and the grid-powered charging is very appealing. However, I'm not sure I feel I know enough electronics to get it charging from the grid without letting the magic smoke out.

inetdog · September 2012

Re: Do any battery chargers actually do it all right?

williaty wrote: »

I have to admit that the idea of having the Classic there to be the charge controller for both the solar array (when set up) and the grid-powered charging is very appealing. However, I'm not sure I feel I know enough electronics to get it charging from the grid without letting the magic smoke out.

I think that one of the biggest problems would be if you have to switch the operating mode of the Classic depending on whether it is current getting input from the grid or from the panels.
(I have a mental image of the CC doing its best to find the MPP of the grid, and it alternates between hilarious and sad. It reminds me of the old arguments against using generators to supply power to a utility load: "Since the maximum power will be obtained from the generator when the load resistance equals the internal resistance of the generator, the generator will just melt down." Only in this case it would be the load melting down!)
I can't tell from the response whether Hydro mode with voltage limits would still be able to do some MPP tracking with panels connected instead, as long as the string Vmp matched the rectified grid voltage fairly closely. My impression is that to do it right there would have to be two separate inputs to the CC with different modes associated, and some logic to deal with simultaneous operation.

boB · September 2012

Re: Do any battery chargers actually do it all right?

We just need a decent stand alone AC powered battery charger that does what the customer needs instead of make-shift doo-hickies.

I know of a company that has been working on one for years now (not MidNite)... Given enough time and still no decent
alternatives, I would hope that MN Solar would make one. PF corrected, fully adjustable and networked of course.

I am liking how newer energy equipment products these days have somewhat open communications that will allow systems
from different manufacturers to fully integrate into a good and properly working installation.

boB

Cariboocoot · September 2012

Re: Do any battery chargers actually do it all right?

williaty wrote: »

I have to admit that the idea of having the Classic there to be the charge controller for both the solar array (when set up) and the grid-powered charging is very appealing. However, I'm not sure I feel I know enough electronics to get it charging from the grid without letting the magic smoke out.

That probably isn't a likely scenario, but I know what you mean. The rectifiers and filter caps have to be able to take the Voltage and current levels expected. The thing that gets tricky is that the output of a charge controller is based on Amps @ Voltage, where Voltage can be 12, 24, or 48 but Amps remains the same. Therefore 60 Amps @ 12 Volts is 720 Watts in but 60 Amps @ 48 Volts is 2880 Watts in (more or less). So you have to plan the input accordingly as you would with solar.

And since I haven't done any circuit design/building in literally 30 years I am not the guy to ask about this!
But it'd make a really interesting thread in the Advanced section, eh?

westbranch · September 2012

Re: Do any battery chargers actually do it all right?

Another pricey choice is the TSB Omni-charger with the add on to do custom charge settings via a computer...

niel · September 2012

Re: Do any battery chargers actually do it all right?

for the record, a 36V 45A DC power supply would work as long as the battery bank is 12v or 24v being charged from the classic. the power supply would already have its own ul or other certification and would act as a clean dc source of power for the classic to utilize, but don't do it without midnite's ok on it.

with the battery chargers you have to watch and would violate the classic warranty as there's not always the same quality of power present and most would need the filtering too before it would work. i did bring this thread to ryan's attention because of your need and the fact that you mentioned using a classic. you have a need that isn't being met by the chargers out there and i did not want to advise you to connect anything up to a classic that is beyond it intended sources of power that would void the warranty. anything done with the classic in this regard would need their ok on it.

most controllers really are sophisticated power supplies without the ac component being present as they are meant for a range of select dc input voltages only.

Blackcherry04 · September 2012

Re: Do any battery chargers actually do it all right?

I have been using two charge controller's for a couple years now, but they are both PWM type, both Xantrex C-35's. One on a 24 V IOTA and one on a PowerMax 12 V. The IOTA is cranked up to 31 V output and the PowerMax to 15.5 V. They seem to be happy being used this way.

The C-35 is limited to 32 Volts and 35 amps so they fit in fine. Both of these Chargers / Power Converters are not all that smart and have limited control circuitry or it might not work and would fight with the controller and cut their output back. Thats something to consider before you waste you money trying. Also I had to old controllers in scrap anyway.

Just being able to have Equalize Charge voltage available is a big plus when they are used together like this.

Do any battery chargers actually do it all right?

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