If you want a real 60 amps from a PD you better put in a 9280. ;)
My PD9280 puts out 84 amps at max. It varies from 80 amps at start (50% SOC) to 84A then down to about 75A before the battery has charged to within 0.2 volts of the max charge voltage, at which point the current is limited by the cable resistance and internal battery resistance. It's a perfect choice for me, as it can be easily modified to output 14.8 volts (Trojan recommendation) and I love the manual mode control, plus it wasn't expensive.
Mine has been modified, but the current output has not been changed.
On the negative side, it does have a low power factor, it loses max current at low voltage AC (<108 VAC) and it does not have remote voltage sensing or remote temperature sensing. It's output current is not as constant as I think it should be either. It should stay at near 80 amps, not vary up/down by 9 amps. For my application - rapid charging from my Onan gen of four 6 volt batteries, it's perfect, however for more money, there are other good choices that offer features I don't really need.
The current variation has only a minor effect on recharge time, the PF and voltage issues aren't a problem with my Onan gen, the remote voltage is addressed with thick short charge cables and the temp sensing is something I can deal with on a summer/winter basis.
Are you saying the IQ4 shuts off the charging current from the charger and then checks battery voltage while there is no voltage drop from current flow in the charge cables?No but it won't start the charging process until it does its check.
Ok. However, doing a voltage check at the start of a charge cycle won't tell the charger much about the status of the batteries, which is what it needs to know to decide where to pick up in its charge profile (i.e. whether to start in boost/bulk or in normal/absorption, and how long to stay in those modes).
The ideal method to make those decisions is to measure the specific gravity, and know the battery AH capacity. That's the only way to really know what the charge state of the battery is. However, that's not practical, so most chargers just make a guess, based on the initial voltage and then use time and/or voltage change to decide when to exit the boost/bulk mode.
How would it measure battery voltage without a separate wire?I believe the IQ4 uses a small amount of DC current. I think mine draws about .2A while taking the measurement.
Are you saying the IQ4 shuts off the charging current from the charger and then checks battery voltage while there is no voltage drop from current flow in the charge cables?
Fisherguy's PD9280, second graph
Note the first replies wrt the four hours.
Thanks. I appreciate the link. It looks like it shifted modes after about 3 hours. Perhaps Fisherguy was testing with the PD entering boost/bulk mode on its own, rather than from the manual button, as I tested. My battery bank is also about twice as large as the one he tested, so that may be why I haven't seen that auto-switching behavior.
It also looks like the PD being sold does not exactly follow the patent description of its charge profile.
One other comment on the Fisherguy plots:
He's got a 0.3 volt voltage drop on the charge cables at about 60A. With his limit of about 14.55 volts, he can't get the battery above about 14.25 volts without decreasing the current flow (to decrease the voltage drop in the cables).
He'd get a huge improvement from doing what I did - 1) using heavier gauge cables and 2) bumping up the voltage. I have about 0.1 - 0.15 volts drop in the cables and the higher voltage lets my modified PD take the battery to 14.65-14.7 before it has to cut back the current.
The current plots tell the story. The current pulse time for the Onan is almost twice as long as the Honda. That means the cap bank voltage drops a lot lower when powered by the Onan. Low cap bank voltage means converter goes out of regulation.
I don't agree that the "current plots tell the story" or that a longer current pulse shows any kind of problem. For example, a perfect converter/charger would have a power factor (PF) of unity and would draw current as soon as voltage rose above zero. An expensive PF corrected converter charger would have a sine wave shaped current pulse, producing the maximum possible width for each pulse.
Of course, I'm not saying that the PD has power factor correction, nor that the PD and Onan MicroQuiet combination works as well or better than the EU. It's just that the width of the current pulse alone doesn't seem to tell us much, other than that the charger is taking energy from the gen over a longer period of time - something that is usually good.
The total energy extracted from the generator during each cycle is what we'd really like to know, since that's the energy the charger/converter is sending out its output (minus some efficiency losses). To get that power number, we'd need to consider the shape of the voltage waveform, as well as the current waveform.
The pd, if triggered to 14.4 stays there for four hours.
Unless it gets the job done earlier--see Fisherguy's graph and tables.
I've never seen the PD leave bulk/boost mode in less than 4 hours when triggered manually. I'm not sure what it does when it enters that mode on its own. I tried to find Fisherguy's graphs again, but my recollection is just that they showed decreasing current as the voltage at the battery approached the PD's preset bulk/boost voltage limit (14.4 factory or 14.8 on my modified charger).
That's what all my graphs show, and I've recorded multiple discharge and recharge cycles. However, they were all made with the manual control forcing it into bulk/boost mode.
The pd, if triggered to 14.4 stays there for four hours.
That's what I see when manually triggering to boost mode and recording the output. It's also what the patent says it does (and IIRC, the manual says the same thing). However, I'm not sure what it does when it decides on its own to enter the boost/bulk mode. According to the patent, the controller keeps a flag indicating if the mode was entered by pressing the manual mode button. If that flag is not set, the patent says the charger/converter stays in boost/bulk mode for 8 hours.
Have you, or anyone else, seen how long it stays in boost/bulk mode when entering that mode on its own?
There's no guarantee Iota starts in bulk.
Unlike other converters, Iota monitors battery voltage when converter ac supply is off. Don't know where the threshold voltage is, but if battery is below (perhaps) 12.9V it will start in bulk.
OK. As a matter of interest, I've noticed that the PD also seems to be monitoring the battery when there's no AC power, although I don't know what it does with that info. The LED on the remote will flash according to the mode it's in, and you can force it into the different modes and it will switch to different modes automatically, even though there's no AC power being supplied.
2. If the battery requires bulk, the converter will charge at the specified current limit. As battery voltage rises, Iota's output voltage keeps pace, maintaining max current. As voltage within the converter reaches 14.6V, a 15 minute timer is initiated. Bulk mode will end after 15 min. During this time the output voltage can still rise up to 14.8V.
Thanks. That explains how it decides to switch into the absorption/topping/normal mode. I think the PD also uses a time measurement to decide when to switch, but I don't think it's based upon the time it reaches a voltage during charge the way the Iota's 14.6v for 15 minutes works. Based on something I read in the patent, I think the PD decides based on how long it's been in the bulk/boost mode and uses a different countdown time depending on if it entered automatically according to its programmed charge profile vs.being forced in via the manual switch. However, changing the charge profile is easy - just change the programming of the microcontroller, so they may have used a different method after the patent was filed.
At some point down the road, we can discuss our disagreement over the importance of SG measurement to making the decision to transition out of bulk.
Dry Camper, do you see this single mod with adding a pot /resistor to get 14.8 volts in bulk scaleable to other PD 92XX series chargers, so as to get a set of golf cart batteries up to 14.8V as Trojan recommends?
Yes. I believe they use the same control scheme for all 92xx (and 91xx models with the charge wizard.)
I've bought a 9245C and will mount it within 3 feet of the batteries, and again use some 4 gauge wire. Battery for starters will most likely be a trojan T1275 at 150 amp hours, later the 225 ah Trojan T105's, and it seems topping the charge off fully to the 14.8 to prevent sulphation is something that should be done a few times on a 3 week trip of boondocking.
Agreed. That's what Trojan recommends.
I've read this thread a couple of times now, and know just enough to be dangerous to my self. Have you looked inside your PD 9245,
I have the PD9280. I have seen inside a PD9245, but I didn't get a really good look and it was at a time when I was not that familiar with the circuit. Still, IIRC, it was nearly the same as the patent describes.
would the resistor values be the same to get a 9245 with pendant.
Possibly. You'd need to check. See what microcontroller it uses and we can compare to the way the PD9280 works. I strongly suspect you can find the resistor that needs to changed in the same basic location, but it may not be the same value. It's part of a resistor divider, and my mod just lowers the value on one side of the divider, which increases the output voltage.
Or am I just better off trying to adjust the PWM 10 amp convertor to finish off the battery daily with 14.8 volts out of a 120 watt portable solar panel? 6.5 amps is not a lot to work with on the solar panel to finish the charge, considering how much the resistance increases in the last 5 to 10% to finish charging.
I do think that using solar is the best way to finish off the batteries, but I don't have solar. I use the voltage mod to 1) get to the recommended 14.8, as that's the only way for me to get there, 2) speed up charging (it enters the asymptotic current decay later) and 3) to adjust charge voltage for different temperatures.
I don't know much about the Iota charge algorithm, but it would seem very odd to me if they drop to 14.2 at the start of the absorption stage. Usually absorption is constant voltage.The IOTA does indeed do this and the other converters do something similar.
Yes, you are right. I phrased my comment very poorly. I was trying to figure out what the Iota does when the current flow out of the charger is below the charger's current limit and the charger is still in boost/bulk mode at its maximum voltage.
When a charger is in bulk/boost mode and the battery is sufficiently discharged, and the cables are sufficiently fat/short, the charger will supply its full rated current at some voltage below its maximum rated voltage for that mode. As the battery charges, eventually, the charger will be unable to supply that full rated current (without increasing its voltage - which the charge profile does not allow).
All the charger knows at this point is that it can't supply full current. This is not necessarily a sign that the battery is ready to enter absorption mode. It would be an unusual design for a charger to immediately drop its voltage just because it can no longer supply its maximum rated current when in bulk/boost mode. Instead, chargers use some other method of deciding when to leave bulk/boost mode. Most use time. If they've been in bulk/boost mode for long enough according to the profile set by the charger designer, they switch out of that mode and enter absorption/topping/normal mode.
The criteria and method used by the charger designer to decide when to leave the bulk/boost mode and enter the absorption/normal/topping mode is one of the major differences between chargers.
I should have been more clear that I was talking about whether the charger uses the fact that it can't supply full current in boost/bulk mode voltage as a sign to enter the next mode. None do that, that I'm aware of. If you look at this:
you see two drops in current. One is the asymptotic decay in current at about 2 hours (dark blue current plot) due to the fact that the charger is not allowed to increase its output voltage. It is still in boost/bulk mode at that point. The other is the vertical drop at 4 hours where the PD enters the 13.6 volt absorption/normal/topping mode.
Sorry for the confusion.
The Iota with the IQ4 does bulk at 14.8 until battery reaches 14.6 (the "trigger") then after another 15 minutes it drops to 14.2 Vabs.
Hmmmmmm. I don't understand what it means to say that the IQ4 is doing 14.8 until the battery reaches 14.6. I did a quick search and didn't see anything saying the Iota has a remote battery voltage sensor, so we can't be talking about cable losses.
In the absence of that sensor, a typical charge profile will have the charger increase its voltage until it reaches a current limit. With the battery discharged, the current limit will be reached long before the charger voltage reaches 14.8. For example, with my PD, it takes about 3 hours from 50% SOC on the 460AH bank before the charger has to go to 14.8 to push in current at the current limit. During that entire time, the charger (and battery) are below 14.8 volts.
So what does it mean to say that the Iota does bulk at 14.8? If the Iota charger is really at 14.8, then the charge current will be well above 80A (at least on my batteries). That would burn something out if the charger isn't rated above 80A. If it's not really at 14.8, and it's at some lesser voltage to limit the current, and only charges until the battery reaches 14.6, then the charger would never reach 14.8 ???
Didn't I read that the Iota always starts in bulk mode (perhaps at 14.8 regardless of the battery voltage) and stays there for at least 15 minutes? If that's the case, are you saying it will go as high as 14.8 in that first 15 min window, then drop out if the voltage is 14.6 or above?
(PowerMax chooses to drop to 13.6 for Vabs instead which is even more "gentle." That's why I got in there and changed it to 14.6 (now at 14.8 recent change) on mine that has the internal voltage pot.
Aha - I see what you are talking about. You are referring to the voltage of the charger when it enters the longer term final charging mode (not the float/maintenance mode, but the actual final charging). I've seen it referred to as the "absorption" mode, the "topping" voltage/mode and (what PD calls it) the "normal" mode. PD uses 13.6v for that mode.
I have not modified that voltage, although I could. I was questioning what happens at the point where the battery has reached the output voltage of the charger, which is not necessarily the point at which the absorption mode should be entered.
Of course it depends on your charging rate what the SOC is when that happens.
Yes. And it's really SOC that determines when that mode should be entered, which can only accurately be determined from the specific gravity. Since our chargers can't measure that, they use another criterion. Most seem to use time or current as a proxy. If the current drops sufficiently and/or the charger has been in boost/bulk for long enough, the charger's preset charge profile will cause it to enter absorption/topping/normal mode.
From the reading I have done, the ideal charger would use constant current in the bulk mode, no matter how high the voltage rose. It would stay at constant current until it reached the desired SOC (as determined by the SG) and then it would switch to constant voltage for the topping/absorption, followed much later by float mode.
No chargers do this, since they have no way of knowing the true SG and SOC and thus, no way to know when to switch out of the constant current mode into the absorption mode. This isn't really a problem until the voltage at the battery has reached 14.4 or so, However, above that voltage, although it may be perfectly OK to supply the same current, it may not be OK. One can only tell from the SG/SOC, which is info not available to the charger.
Iota converters have their 14.8 but they say that is to get the batts to 14.6 before the Iota drops to 14.2 for the Iota Vabs.
I don't know much about the Iota charge algorithm, but it would seem very odd to me if they drop to 14.2 at the start of the absorption stage. Usually absorption is constant voltage.
The battery voltage will eventually be very close to converter voltage once batteries are full, but I meant that if you want battery voltage to be at 14.8 from the beginning of the Absorption Stage, then converter Vabs needs to be higher than 14.8.
Optimally, you would use a charger with a remote voltage sensor at the battery and stay in bulk until you reached 14.8 (or whatever the battery mfg recommended)at the battery. Using fat short cables is how we simulate that without having a remote voltage sensor.
It sounds like you are saying Iota tries to solve this issue by charging at 14.8 (at the charger = less at the battery), then dropping the voltage as it ends the bulk charge and goes into absorption, but I'm not sure how it would detect this point.
I an unclear if Trojan wants that or just for the batts to reach 14.8 by the time they are full and then go to Float.
They expect to charge to 14.8v at the battery each day - with either short/fat cables or a remote voltage sensor. Once that voltage is achieved at the battery (temp compensated), it is supposed to be held until current drops to the recommended level.
I use short fat cables converter-battery and you can see the spread between converter and battery voltages during Bulk and then during Absorption in those ugly graphs. I got the same with the Paramode converter I had. So I don't think it is some sort of wiring issue why there is such a wide spread in the voltages, but anything is possible in this business :)
Hmmmm. I need to look at your graphs more closely. If the cables are short and fat, there should be minimal voltage drop, unless the connectors are causing trouble.
Onan Microquiet is known to adversely affect PD performance.
Is the Onan Microquiet an inverter gen?
If so, do you know what the waveform looks like?
For non-inverter gens, one would expect a pure sine wave output. After all, the gen is producing the voltage by cutting magnetic field lines with a rotating rotor winding in a constant field produced by the stator (or vice versa) where the voltage should be proportional to the sine of the angle between the rotating rotor windings and the field lines.
Nonetheless, I've seen scope plots showing that's not the case in practice. My rotating armature Onan does produce a pretty good sine wave, but it has no voltage control module to control the field current. The field current is basically constant. In that design, the voltage is a function of rotor speed and the voltage should only drop if the load increases enough to slow the rotor speed. Fortunately the CCK is a cast iron design and the rotor has lots of mas, making it hard for a sudden increase in load to slow the rotor speed.
I believe the more recent rotating field Onans with voltage control modules will reduce the field strength during the part of the rotation when the low PF converter isn't trying to top off the cap voltage, then at the peak, when the charger tries to pull lots of current, the gen's voltage controller can't increase the current to the field windings quickly enough - so the peak of the sine output isn't as high as it should be.
Of course, that's just a guess about what's happening and why my CCK works fine when others report that rotating field Onans don't play well with low PF converter/chargers.
I was thinking if you wanted 14.8 battery, your PD9280 should be at 15? I find you need 0.2 spread at least as you see in those graphs I posted.
Perhaps I missed something in your graphs. Do you mind spelling it out - why you think it needs 15?
My graphs show that even at 84 amps, I'm only losing about 0.1 to 0.13 volts in the cables. I monitor both the voltage at the battery and at the charger and I've never seen a 0.2 volt difference. During that part of the charging cycle, the converter is current limited, not voltage limited, and the charger is simply holding the voltage about 0.1 to 0.13 volts above the battery voltage - enough to maintain the preset current limit.
During charging, as the voltage at the battery climbs to about 14.65 - 14.7, (with the charger at 14.8 and the current about 75 amps), the charger is prevented from increasing the voltage to hold the high current level by the voltage limit setting at 14.8. Thus, the current begins to drop. This is the transition point in those graphs from near constant current mode to near constant voltage mode.
The current reduction reduces the voltage loss in cables. By the time the batteries have become nearly fully charged, the current is down 10x to below 8-9 amps and the voltage drop in the cables has dropped to below 0.01 volts. The battery reaches 14.79+ volts, which is exactly what I want/need.
There is a slight issue with photos but that looks like one WELL BUILT device.
The photos came from my Photoshop notes on top of the photo, where I can blow up the vector text to read it when working. I saved as JPG, and checked that I could read the JPG, but somewhere the res was reduced.
One thing you can get off the photos is the pinout/connection for the remote. It's marked - LED, Switch and Ground. The LED lead goes to the positive lead of your LED and the other LED lead goes to the Ground lead . Your switch goes between Switch and ground. Shorting the Switch lead to ground causes the PD to change modes (brief goes into Boost mode, 3 secs goes to normal and longer than 6 goes to float) and the LED will flash to indicate the mode you are in. It uses modular connector (phone handset).
Motorcycle carrier is way more important. I never leave without my Yamaha XT225. I added 2 extra 1 1/4" hitches to stabilize the cycle carrier. It made a huge difference in keeping the cycle from bouncing around.
We have the Yamaha XT200 that we usually carry for dual fun, an IT200 enduro when I want to play alone in the woods, and an XT 350 that's a bit too heavy for the bumper. The carrier has been there since 1986, and is only off now because it needs to be modified to fit the septic hose carrier I'm adding now.
The Jeep goes behind with the kayak and Canoe on top.
IF PWM controlled, you can adjust the feedback circuit to change (increase) the duty cycle which will in effect, increase the supplied current. However, I am just guessing without looking at the schematic and feedback loops.
The duty cycle is controlled by the UC3xxx chip (forgot the number it is posted in this thread), which is designed specifically for this job. It has a voltage limit input and a current limit input. They should produce constant current up to the voltage limit. However, there are some other inputs to that chip (short circuit protection, etc.), and the PD design may have some crosstalk between the voltage produced by the current sensing input and the voltage input to the duty cycle control. That was what drove my mods 2 and 3. I fooled the chip into thinking it was running at lower current, and then reduced the current limit in the hopes of reducing potential voltage based current/voltage crosstalk resulting from the circuit in which that chip was embedded.
Posting a short msg from my phone:
The transformer can be replaced or turns ratio modified, but we agree, that's not the easiest solution. I remain unconvinced that is the problem - it may just be control related. It's annoying, as I have the stuff needed to test it, but I just can't do it yet. I'm in the middle of several other RV projects now (remote water pump switch and waste hose storage and motorcycle carrier and cargo carrier), and don't want to drop those to scratch this curiosity itch. I will eventually, as I'm pretty sure the itch won't go away. :)
We agree on the issues in regards to the PD. I don't however believe you can fix the problem by modifying the PD front end. "By "front end", I presume you mean the capacitor peak charge circuit. I believe the transformer is at fault. It doesn't have enough turns-ratio to output 14.4 at minimum cap bank voltage.
The minimum ac voltage the converter is supposed to supply full current is 105Vrms. That translates to a cap bank voltage of:
V_cap = 105Vrms * sqr2 - 2 * Vd = 152V - 2V = 150Vpeak
You want to operate at least 20V below peak voltage.
The minimum transformer turns ratio is:
N_min = (V_cap - 20V) / V_reg
N_min = 130V / 14.4V = 9
If you look at the PD patent, I bet you'll find the transformer turns ratio is higher than 9.