Forum Discussion

DryCamper11's avatar
DryCamper11
Explorer
Jun 15, 2012

PD or Iota for my upgrade?

I'm thinking about a converter and battery upgrade. The batteries will be wet cell lead acid 6 volt Possible T-105s or the 230AH, EGC2 from Sam's club. I'll probably go for four. (Does nayone have recommended charging specs for the Sam's Club? The Trojan calls for 14.8 volts)

The converter will be installed within 3' of the batteries with 1/0 cable. I'd like to optimize charge speed with my Onan CCK generator. I'll probably buy a Trimetric 2025. I don't have solar, but may consider it later.

I'm leaning toward the PD9280 for these reasons:

1)The Charge Wizard lets me put it into boost mode or float mode. I like having control.

2)The Charge wizard is really simple - a single LED and a switch. I can integrate it into my existing control system and install one near the batteries and another near the monitoring station where my voltage monitor is now and the 2025 will be.

3) The patents for the PD 9200 series are extremely specific about circuit construction. There's enough there for repair or modification, which I'm interested in doing.

4) The design of the PD 9200 series makes sense to me from the patents and seems to be easy to control/modify. It uses the Unitrode UC3846 PWM current mode chip at its heart, which provides both constant current and constant voltage control on a pulse-by-pulse basis. It looks like it would be easy to change the current limit or the voltage output with a single resistor. I've read the patents several times.

On the down side, I know nothing about how the PD 9200 series converter performs, other than what I've read here (which is a lot, but I'm still working through it all). I've seen claims here that the Iota will perform better for fast charge from a generator when heavy cables are used and that the PD has a "bad design,", but I can't figure out why that opinion was expressed or what the design of the Iota is.

I know almost nothing about the design of the Iota, except that the boost/bulk mode voltage is higher. It looks like that voltage would be easy to adjust on the PD9200. It should be possible to adjust output voltage based on battery temp also. I'd love to know if anyone has modified the PD9200 series or if there is comparable information about the design of the Iota (a circuit diagram?).

I know there are more expensive converters that offer some of these features, but cost is important.

From some threads I've read, there can be dispute over the relative merits of these converters. I'm not looking for anything but friendly information.

Thanks for any comments or information you have.
  • time2roll's avatar
    time2roll
    Nomad
    Jun 15, 2012
    Either will perform well installed as you described.

    Since you want to modify the converter and the 9280 seems to lend itself to what you want the 9280 is what you should do.
  • BFL13's avatar
    BFL13
    Explorer II
    Jun 15, 2012
    The PD may suffer a bit (don't know how much) with a non-inverter type generator such as some Onans.
  • RoyB's avatar
    RoyB
    Explorer II
    Jun 15, 2012
    Someone was saying a couple weeks or so back that the IOTA has a better current regulator built-in then the PD does. i,e on my PD9260C if my batteries are close to 50% dischrage state the PD will throw a good 52AMPS of charge to my three batteries for maybe 5-10 minutes and than start droping back in current rate as the batteries start taking on charge. The post was saying the IOTA charger design would give out a good 50AMPS or better for the entire 14.4VDC two hour boost charging smart mode period and not drop back in current like the PD unit does... This porbably helps in charging the battery bank quicker.

    Maybe someone that knows what I am referring to will pop in here with a better description of what I might be referring to...

    I have had excellant performance out of my PD9260C now for over two years keeping my three 85AH (255AH total) battery bank re-charged. I just recently lost one of my 85AH batteries but at no fault to the PD-9260C unit. The battery was over 5yrs old and they wont last forever.

    One comment on getting an 80 AMP charger system you may run into a problem using a 2KW Honda type generator to run the converter/charger. My PD9260C really revs up my 2KW Honda generator in ECo mode when running my 30A trailer shore power connector direct connected to the Honda Generator using a RV30A-15A adapter. The 80AMP may be over the 120VAC output rating of the EU2000i Honda generator. Something to check first if that is what you was intending to use to operate your PD9280 series converter/charger when operating off the power grid. I dont have the specs here in front of me...

    NOTE: just Looked up the specs on the PD9280 and its 120VAC AC input is rated at 1300WATTS. The PD9260C is rated at 1000WATTS so your 2KW generator should be able to handle that I would thing. I believe 1800WATTS load is where the 2KW Honda generator starts thinking about not working for you.

    Nevertheless that is getting up there for loading down the EU2000i Honda Generator for a constant 3 hour or more generator run time...
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jun 16, 2012
    The 9280 is what I have on this rig (Well 9180 plus charge wizard) it is really just a bit big for a single pair of T-105/U-2200/GC-2 batteries (They really need a 70 amp or smaller converter) but to be honest, not all that much too big.

    It is a very good one.. And as it happens I'm partial to Progressive Dynamics products, (long story)

    From what others whom I respect tell me the IOTA with IQ4 technology.. Just as good.
  • Hybridhunter's avatar
    Hybridhunter
    Explorer
    Jun 16, 2012
    Without completely opening a can of worms, the IOTA cannot be forced into boost, and with wire size limitations, taht can be very irritating, and can result in a much slower charge.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jun 16, 2012
    Well Hybridhunter... Rather than a flame I will say Thanks,, I did not know that.

    So that is yet another reason for me to recommend PDI. Thanks.
  • time2roll's avatar
    time2roll
    Nomad
    Jun 16, 2012
    Hybridhunter wrote:
    Without completely opening a can of worms, the IOTA cannot be forced into boost, and with wire size limitations, taht can be very irritating, and can result in a much slower charge.
    Why speak in generalities? OP says 1/0 cable of 3' length. This will present NO issues for IOTA. Turn the IOTA off and back on to restart the charge sequence at max boost voltage.
  • Hybridhunter's avatar
    Hybridhunter
    Explorer
    Jun 17, 2012
    Or hit the manual boost button, oh wait.....
    j/k - The Iota might be a better charger in that instance. To me, the value of having the charge mode indicated, and selectable, negates the advantage of the theoretically faster charge from the IOTA. One other advantage of selectable modes that has not been mentioned, is the ability to trim converter output as desired, to accommodate generator loads, such as running A/C while charging. Allowing a slower, maybe all day charge, while hiding from the heat.
  • DryCamper11's avatar
    DryCamper11
    Explorer
    Jun 18, 2012
    Thanks for the comments and suggestions. The generator is a 4KW Onan. I'm going to get a DC current meter or a Trimetric or similar current monitor to check output.

    I spent some time reviewing the circuit diagram of the PD from the patents. I was surprised at how closely the patent shows the PD. It's nearly identical to the design being sold, all the way down to resistor values.

    The fundamental operation is relatively simple. There are lots of bells and whistles, but ignoring those, the system takes the AC voltage and runs it through a full wave bridge to produce 170VDC unregulated.

    It takes that voltage and chops it, sending the chopped voltage through a center tapped transformer to produce lower voltage AC that is sent through another bridge circuit to rectify back to DC and supply the output.

    The chopping is controlled by a Unitrode chip that has inputs from the output voltage and the output current. If the current gets too high, it cuts the output. If voltage gets too high, it does the same. It looks like it will be very easy to readjust the output voltage or the maximum output current to values that match the specs for my batteries.

    That's why I'm thinking about the large PD9280, even if I decide to go with smaller batteries initially. I can just limit the current to whatever I want.

    It sounds like the suggestions here match what I've been reading in the other posts from my research. The Iota may have an advantage for short cables, which I will be using, but I suspect that advantage comes mostly from the higher charging voltage it uses, and I can easily adjust the PD to that higher voltage if i want to. Increasing from 14.4 to 14.8, which is the highest I would go, is less than a 3% increase.

    Again, thanks for the comments.

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