Inverter Charging - Why is it so pathetic?

jtp100 · February 2013

I am quite familiar with off-grid solar systems and have been running one for the last 10 years. I have 850 amp/hrs at 12 volts in my batteries and try not to cycle my batteries too deeply (30% max) and like to get them back to full at least once a week.

I have an older Trace DR1512 modified sin-wave inverter that works well for what I need. My problem is with generator charging. Previously I had a hold Kohler generator which charged okay (but not great) but I recently purchased a Yamaha EF2600. I have been having a hard time charging my batteries through the inverter. For example, when the batteries are minus 150 amp/hrs I am only able to put in 10 amps/hr with the generator. If I turn a light on in the house while charging the charging amps drops to 5 amp/hr - suggesting it is related to a voltage drop? The generator doesn’t even sound like it is working, and I checked the voltage into the inverter and it is 123 volts. Also, I have confirmed many times that the charge rate is set to maximum on the inverter.

I have been reading some of the other threads, and wonder if this related to a poor power factor in the inverter? I find it hard to believe that a generator of this size can’t overcome this.

Anybody have any suggestions or experience in this area? If there is an old thread on this topic please let me know.

Thanks.

equis · February 2013

Re: Inverter Charging - Why is it so pathetic?

Unfortunately I cannot answer the question but I can confirm I have the same issue.

Batteries should take 60amp charge but only accept 10 or so.
My Generator says it is only at 20% output.

BB. · February 2013

Re: Inverter Charging - Why is it so pathetic?

Assuming I have the correct product (PDF download):

Maximum charge rate (adjustable) 70 Amps DC

Making some assumptions about the Inverter/Charger's AC/DC power specs:

70 ADC * 14.5 volts charging * 1/0.85 Charger Eff * 1/0.67 PF * 1/117 VAC input = 15.2 AAC

If your generator is rated over (117 VAC * 15.2 AAC=) 1,782 VA -- Then it should be able to power the inverter/charger.

I assume the inverter section is working OK. And the programming for the charger block makes sense (max AC & DC current, voltage set points, absorb timer, etc.)?

What is the voltage (at the DC power lugs of the Inverter/Charger) when charging?

In some of these type units, there are current sense transformers and I have read of folks here re-soldering the fine wires back to the PCB.

-Bill

NorthGuy · February 2013

Re: Inverter Charging - Why is it so pathetic?

I don't know about older ones, but in new Xantrexes there's a setting called "Breaker Size" for the AC line. They start do dial down the charging current, so that (load+charging) amperes would not exceed 80% of breaker amperes. If you had the breaker size set too low, it would cause exactly the problem that you describe.

boB · February 2013

Re: Inverter Charging - Why is it so pathetic?

The DR1512 charger is a triac light dimmer style charger with lots of harmonics with low PF. I think your new generator just may be too small
for the job. I suggest you get a newer inverter with power factor corrected charger.

boB

jtp100 · February 2013

Re: Inverter Charging - Why is it so pathetic?

Hello,

From reading this forum it appears that I am not the only one who has had this problem. I appreciate all the input you all have, and there is obviously a wealth of experience here.

Bill: I appreciate your math working through the expected output and what you say makes good sense. You have the right inverter model, but mine is a little older – but same model. As you suggested I measured the at the Trace DC output terminals/lugs as follows:
12.6 volts – prior to generator start-up
13.0 volts – several minutes after generator start-up
13.7 volts – thirty minutes after start-up where it remained.
Generator was run for 1 hour and put in between 6-7 amps/hr.
Not sure if these are the expected voltages?

I’m not exactly sure what you mean by “…re-soldering the fine wires back to the PCB”. Was this in reference to a defect or ‘a-fix’ discovered by users?

North Guy: Thanks for the information. On my model I don’t see a dial for the “breaker size”. All I have is a charge rate switch (now set to max), battery type, and battery size selector which are set appropriately.

boB: That is my sinking feeling that this inverter needs a very large generator. However, I still find it incredible that a generator of my size (EF2600) can’t overcome the inverter. The power factor must be terrible (ie < 20%)? I wonder if the newer designs of the same model are better?

As I side note, I do remember with my old generator (Kohler 3000W) that it never really charged very good and I always attributed that to it being very old. Just before it died the RPMs were running very high and during that period I was putting in impressive numbers of amps. Again, I wonder if that is because I had increased voltage temporarily?

Thanks everyone.

JTP.

BB. · February 2013

Re: Inverter Charging - Why is it so pathetic?

jtp100 wrote: »

Bill: I appreciate your math working through the expected output and what you say makes good sense. You have the right inverter model, but mine is a little older – but same model. As you suggested I measured the at the Trace DC output terminals/lugs as follows:
12.6 volts – prior to generator start-up
13.0 volts – several minutes after generator start-up
13.7 volts – thirty minutes after start-up where it remained.
Generator was run for 1 hour and put in between 6-7 amps/hr.
Not sure if these are the expected voltages?

Assuming the inverter/charger is set for something like 14.4 to 14.7 volts for bulk/absorb charging set point. And the AC maximum input current and/or DC max discharging current(s) are programmed correctly--Then there is no reason, that I can see, for the low charging current.

I have a Grid Tied system, so I am not any sort of expert programming any inverter/charger--But you should probably go through all the menus, write down the settings, and see that they all make sense... You can have conflicting programming settings--Like AC Breaker set point and DC Max Current... If the AC current approaches the AC breaker rating (if present in your unit) and you have a mix of AC loads and DC charging--The inverter/charger will reduce DC charging current to keep the AC current at less than rated input (as an example).

On rare occasions, reseting to factory defaults and reprogramming can "fix" a corrupted memory.

I’m not exactly sure what you mean by “…re-soldering the fine wires back to the PCB”. Was this in reference to a defect or ‘a-fix’ discovered by users?

On the AC side of the inverter/charger, they may have one or more small "current" transformers to sense the AC current flow through th unit. More than a couple folks have found the wires from the current sense transformers to PCB had broken and cause weired behavior (if you feel like popping open your unit).

North Guy: Thanks for the information. On my model I don’t see a dial for the “breaker size”. All I have is a charge rate switch (now set to max), battery type, and battery size selector which are set appropriately.

Try changing the charge rate to 1/2 the value (and/or try dropping/raising battery AH size by 1/2-2x and see what happens). Some units you program the values "you want"--Others do their own calculations based on the battery specifications.

boB: That is my sinking feeling that this inverter needs a very large generator. However, I still find it incredible that a generator of my size (EF2600) can’t overcome the inverter. The power factor must be terrible (ie < 20%)? I wonder if the newer designs of the same model are better?

Depending on how much generator charging you need to do--You may wish to disable the charger block and purchase an external AC Battery Charger--They are not too expensive for the "simple" ones... Certainly less than a whole new inverter/charger (if the inverter section is working fine for you).

-Bill

Blackcherry04 · February 2013

Re: Inverter Charging - Why is it so pathetic?

jtp100 wrote: »

12.6 volts – prior to generator start-up
13.0 volts – several minutes after generator start-up
13.7 volts – thirty minutes after start-up where it remained.
Generator was run for 1 hour and put in between 6-7 amps/hr.
Not sure if these are the expected voltages?

You don't think it jumped to Float real quick and you didn't see it ?? 12.6 is a high voltage on a 12 V bank to start a full charge routine. Some older chargers will switch kind of quick.

I looked at my manual and it won't trigger a full charge unless the voltage is below 12.5 Volts and that is subject to there being a calibration error of + / -. There at least 4 different versions on the controls on that Inverter, some analog and the newest is digital. I'd say the older it is the more slop it'll have in the control.

jtp100 · November 2013

Re: Inverter Charging - Why is it so pathetic?

Hello Everyone,

Sorry to pull this thread all the way to the top again, but I wanted to provide an update to my problem.

I tried many of your suggestions from resetting the inverter, to adjusting the charging settings and measuring the voltage of the batteries while attempting to charge with the DR1512 inverter.

In the end, I made no further progress and chalked up the lack of battery charging through the inverter charging as having a generator that is too small, and a inefficient charging inverter (I think the term I have read is Power Factor).

However, not all was lost as I just recently bought a IOTA charger as someone suggested. I mounted this on the shunt and it works beautifully! I didn't want to spend the money to upgrade the inverter and am very happy with the IOTA charger as an add on.

Thank you to everyone for your suggestions. This forum is full of helpful advice and knowledgeable people. The IOTA charger - so far - has been a great addition.

Thanks.

jcheil · November 2013

Re: Inverter Charging - Why is it so pathetic?

I like the IOTA charges also, but you will likely need to open it up and adjust the voltage with the small pot inside (with the little plug in the phone jack on the IOTA, but the IOTA NOT connected to your batteries) to get it higher than the factory settings which is too low for most batteries we use in RE.

Inverter Charging - Why is it so pathetic?

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