Charger to use with generator.

carilchasens · October 2016

The climate here does not always favor PV.. periods of heavy overcast and short days in the winter. Any recommendations for a charger to use with a generator for CC/CV charging on a 12V system? I would like to be able to get 55 amps bulking current (I do want to limit the current to around 55A), and to be able to absorb charge up to 100 percent.

arby · October 2016

Usually the inverter doubles as a charger on most systems.

BB. · October 2016

What genset do you have? Basically, AC Battery chargers can be difficult loads for a genset. AC battery chargers usually have poor Power Factor (use more AC current than they really need to) and not always very efficient. Plus for most residential gensets, you do not want to pull more than ~80% of rated VA (Watts) for hours at a time (typical battery charging).

So--For example, using "worst case numbers" for a Honda eu2000i 1,600 Watt/VA rated genset:

1,600 VA * 0.80 genset derating * 0.67 PF of charger * 0.80 charger eff * 1/14.5 volts charging = 47 Amps of charging current

Notice that the charger's PF can be a big "killer" in genset ability to supply enough AC current... If I use some more "nominal" numbers:

1,600 VA * 0.80 genset * 0.9 PF charger * 0.9 eff charger * 1/14.5 volts charging = 72 Amps of charging current

Matching your genset to the battery charger is important. And not all vendors list PF and Efficiency (hardly any do).

Iota has a new product line that should be PF corrected (better than 0.95 PF) and they have a 55 Amp model that should work (may) work on a Honda eu2000i: I take it back, from the specifications, the new Iota models do not appear to have Power Factor Correction. (not in business--Just from reading online specs. Update from -Bill B.).
https://www.solar-electric.com/iota-engineering-sdc1-120-12-55-battery-charger.html
https://www.solar-electric.com/lib/wind-sun/sdc1255spec.pdf
https://www.solar-electric.com/lib/wind-sun/sdc12man.pdf
But, I have not heard of anyone using this on a Honda eu2000i (I do not work for NAWS, I am just a volunteer here--So I only know what I read here about folks using the Iotas). You would also need the AL4 module to get high charging voltage bulk/absorb/float with this charger model (I think).

Battery chargers, because they can draw rated power for many hours straight--Are very difficult loads compared to typical appliances (pumps that have start up surge, microwave ovens that are used for a few minutes at t time, etc.).

Hmm... Reading through the Iota specifications and such--I am not sure that this unit is Power Factor Corrected.

Xantrex does make a true Power Factor Corrected charger in the 40 and 60 amp size (12 volt). In years past, the TC model had good recommendations--But the TC2 was way delayed in production and difficult to get (a few years ago)--And I have not heard anything about them since. You can take a look at the model and see if it is of interest to you (spec wise, the TC2 chargers are very nice--Even has a remote battery temperature sensor--Very few charge controllers seem to have this very needed option).
http://www.xantrex.com/power-products/battery-chargers/truecharge-2-2.aspx
Other options include inverter-chargers (Outback, Magnum, Schneider, etc.). Many of these units are quite programmable and have good efficiency/power factor.

-Bill

Marc Kurth · October 2016

I have been using 60 amp Xantrex Truecharge 2 chargers with my Honda eu2000i since Oct. of 2013. They play together perfectly even with the generator in Eco mode.

With the full 60 A DC output, the generator runs cool and has some capacity to spare.

BB. · October 2016

Thank our Marc! I am happy to hear from a an actual user--The TC2's looked like a killer product.

-Bill

carilchasens · October 2016

I have a honda eu3000i. Will be looking into what has been said.

BB. · October 2016

There is the Iota standard model and will work fine on the eu3000i:

https://www.solar-electric.com/ioten55amp12.html

Which has a jump on the side (jumper in, Bulk charging voltage)--Set for higher charging voltage and use your genset until battery is charged. Get the IQ4 control module if you have AC mains to automate bulk/absorb/float charging.

To be honest, from the specs, I am not sure which Iota is "better". The new model does not have PFC (and neither does the old model).

-Bill

Marc Kurth · October 2016

Bill, I chose the charger route in lieu of saving money with a converter-charger.
Temperature compensated charge voltages are important to me and I like the Xantrex charging algorithms for FLA, Gel and AGM.

carilchasens · October 2016

BB. said:

Get the IQ4 control module if you have AC mains to automate bulk/absorb/float charging.

-Bill

Bill, by AC mains, do you mean the approximately 110V 60Hz output from the generator? I will definitely be looking into these products.

BB. · October 2016

AC mains being utility power 24x7.

With gensets, you only run them for for a few hours, then shut them down. You really do not need a charger with full bulk-absorb-float stuff... Program/adjust the charger for bulk charging. Run the genset until the battery is charged (enough for your needs), then shut down.

The Float setting/mode is only needed when you have AC mains 24x7 (or a lightly loaded solar charged system with lots of sun) where holding bulk charging voltage for many hours/days/weeks at a time will overcharge the battery, boil the electrolyte (gassing), overheat, erode plates, and kill the batteries pretty quickly.

For folks that only run the genset for cloudy weather and the occasional shop tools--That is usually not an issue.

-Bill

carilchasens · October 2016

BB. said:

There is the Iota standard model and will work fine on the eu3000i:

https://www.solar-electric.com/ioten55amp12.html

Which has a jump on the side (jumper in, Bulk charging voltage)--Set for higher charging voltage and use your genset until battery is charged. Get the IQ4 control module if you have AC mains to automate bulk/absorb/float charging.

To be honest, from the specs, I am not sure which Iota is "better". The new model does not have PFC (and neither does the old model).

-Bill

Bill, It I use it jumper in, when it reaches 14.8V, will it cut out, or hold that voltage or what?
Thank you for your help so far.

BB. · October 2016

It will hold the voltage and the battery will naturally taper down in accepting current.

Ideally, you are doing one of two things... When the current starts to taper down, the battery will be ~80% state of charge (confirm with specific gravity measurement). At that point, you can turn off the genset and use solar to finish the charging (when gasoline gensets running at 50% or or less of rated power, their fuel flow tends to remain at 50%--So as power usage drops & fuel flow does not, it is less fuel efficient. With a variable speed inverter-generators, they tend to be pretty fuel efficient down to 25% of rated power).

If you left the genset running for many hours after the charging current dropped to a steady value (less than ~2% to 1% or less of rated AH of battery bank--Old flooded cell batteries near end of life can be 1-2% of rated current at tail of charging, new batteries and AGM can be as low as 0.01% of rated current at end of charging cycle)--The battery can over heat (even 2% rate of charge, if done for 1/2 a day or more can overheat a Lead Acid battery bank). (note: AGM batteries typically should be charged at ~14.4 volts maximum, GELs at 14.2 volts max).

If you still are running the genset and the battery is charged you can pull the jumper (or wire in a switch) and open the connection, the charging voltage will now be around 13.6-13.8 volts or so for float and can be left on for "unlimited" amount of time (there is a 10 turn pot in many/all(?) of the older generation of Iotas) that you can adjust the output voltage--But you have to pull the sheet-metal to access it--Not intended for field adjustment--But really needed for different battery types). The Iota will also supply DC loads at 13.x volts float and not let the battery discharge (kind of like a UPS solution--Uninterruptable Power Supply).

-Bill

carilchasens · October 2016

Sounds like a good solution: 14.8V with the current tapering down as the batteries charge. When the sun shines we bulk and absorb at 15V, 55Amax, and that seems to be working pretty well. The amps taper down to 5 or less at the end of absorb.. so far I have not been able to detect heating, inspecting the bank manually. Our bank is four Rolls S550s, 12V, 856AH. Usually use 10 percent or a little more in day.
Unfortunately, looks like the Iota has no display showing the current as it tapers down, would have to guess or add a heavyduty meter.
Finishing tha charge with solar should be a very good idea here.. this far north the days are short. Sometimes weather systems off the north pacific cause days of heavy overcast, so we do need to complete the absorb by genset..
appreciating your help, Caril
Whoah.. looks like the output is only 14.2...

jonr · October 2016

A switchmode power supply/charger can have a low power factor, but it is neither capacitive nor inductive. So there isn't wasted current sloshing back and forth and creating heat. So what happens when an inverter generator drives a SMPS in terms of de-rating - my guess is that typical SMPS non sinusoidal current waveforms create less heat in the generator's inverter and "will it trip based on the higher peak current seen" depends on the inverter circuit design.

So in this special case (inverter generator to SMPS), my guess is that you don't need a PF de-rating. Any actual data on these issues would be interesting.

carilchasens · October 2016

Marc Kurth said:

I have been using 60 amp Xantrex Truecharge 2 chargers with my Honda eu2000i since Oct. of 2013. They play together perfectly even with the generator in Eco mode.

With the full 60 A DC output, the generator runs cool and has some capacity to spare.

BB. said:

Thank our Marc! I am happy to hear from a an actual user--The TC2's looked like a killer product.

-Bill

I have ordered the Xantrex Truecharge 2 .... thanks folks

Marc Kurth · October 2016

They are not cheap, but my experience is nothing but stellar. My oldest unit is still my "go to" charger for 12v systems - in my shop and dragged out into the field. Because I'm in the battery business, my chargers often run 24/7- over and over again. I am very, very picky about charging algorithms.

I also own some very expensive specialized/FAA certified chargers for the aircraft industry and other chargers for 48v high output stuff. For 12/24v systems, the Truecharge 2 series has proven to be a reliable workhorse with the flexibility to properly charge FLA/AGM/Gel and specialized Calcium formulas. NO, I don't sell them. NO, there is no benefit for me to say these things.

I am only offering my experience with a good product!

Marc

Charger to use with generator.

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