RE: Silicone brake fluid
For another opinion, at http://www.valvoline.com/car-care/automotive-system/brakes/ccr20081001v4 it says "DOT 5 doesn’t play well with DOT 3, 4 or 5.1, as well as some original-equipment brake system components. Consider it a track-racing-only fluid." And there are lots of warnings from brake fluid manufacturers to not use DOT 5 fluid in ABS systems.
RE: How does an RV receptacle work?
I understand some of the inverter type generators actually supply two 60 volt supplies out of phase with each other to get to 120 volts. This is a several year old myth that just won't die. It's perpetuated by users who know enough to use a meter, but not enough to understand what they're measuring. They simply jump to a reasonable sounding but incorrect conclusion based on the measurements.
RE: WFCO 8955 Charge Test & Question
If the issue is "which charger is better"?, then someone will have to assemble a test comparing all available chargers and charge the same bank of batteries with the same wires in the same temperature under the same conditions and we will have the winner. And all of these ridiculously long threads will stop.I pretty much agree about the head-to-head comparison issue, but it will not stop the long threads. There will always be somebody who thinks they know better, or who thinks there is a serious flaw in the process, who will assertively make an incorrect statement. If it's not rebutted, it appears to be true. Sometimes after many long threads a consensus builds and a 'truth' is generally agreed on. I think a good example of this is a general agreement that the WFCO converters, while they look good on the surface, don't perform well as installed in RVs. We can debate if it's WFCO's fault, or the RV makers fault, but the bottom line is that it's not a good combination.
But some issues will never have a consensus. For instance some think the PD converters are the best choice because of the manual mode control that's available, while others think they are idiots for thinking they can do better than the automatic mode control provided by the converter manufacturer. Converters, inverters, and generators seem to provide the most endless long threads in this forum.
RE: Accuracy of Displayed Voltage for PI EMS-HW30C
Since the Champion doesn't output a perfect sine wave I'd suspect that has something to do with what you're seeing. You're not going to be able to close in on the answers without more opinions, like a reading from a different meter and/or another PI-EMS. If you haven't done this, one thing that could give a clue is to add a pure resistive load (like a 100 watt or greater light bulb or portable heater) to the generator output and see if the meter readings are closer. If they are, that's a pretty big hint that the waveform is behind the differences. I'm trying to be careful to not imply which of the readings is the "wrong" one.
RE: WFCO 8955 Charge Test & Question
Harsh words.
I just assumed that using the words from the original post would be acceptable.
If this sensing of the output voltage at the converter terminals give the converter equivalent zero resistance, how do you explain the drop from 14.4V to 14.1V when under the load of 50A.OK, I'll accept being nailed on this. It's always a struggle to decide whether to post every detail and lose most of the lurkers, or to summarize, assuming those that care about the details will make the 'correct' underlying assumptions. So the long version: When operating in its constant current mode, a switching converter will maintain a constant voltage at its output because that's where it samples the voltage, thus being the equivalent of a zero-resistance constant voltage source. The PD converters unfortunately won't deliver their advertised current when operating at 14.4 volts, which leads to all sorts of debates and misunderstandings in the forum discussions. Making comparisons even tougher is that the PD output capability is very dependent on the AC input voltage. From a few data points I took it looks like the PD's maximum power output varies about 1% with every one volt change in the AC line voltage. If it's powered by a small conventional generator, the converter output can be hit significantly because of the aprox. 0.7 power factor load confusing the generator's AVR. I haven't noticed the data we've seen presented tracking the AC line voltage, making that an unknown variable in the comparisons. A PD9160 output at 14.4 volts and 60 amps would be 864 watts. Mine will in fact produce this with a 120 volt input, but it's 64.5 amps at 13.4 volts (into a dummy load), and it can't maintain that as the converter's temperature rises. Perhaps if the current regulation were more precise and it could dissipate more heat, the 9160 could attain the goal of full advertised power at the boost voltage.
RE: Some AWD now requiring all new tires if one blows?
Basically, I would say that if your OWNERS MANUAL or the service manual doesn't state that all tire must be replaced at once, then the tire dealer is scamming you.The OWNERS MANUAL? What kind of man would read the Owner's Manual? That's as bad as asking for directions when you're lost! But just for curiosity, my wife tells me this is what mine says:
"For safety reasons, tires should be replaced in pairs and not individually. The tires with the deepest tread should always be mounted on the front wheels".
"All four wheels of the vehicle must have tires of the same size, construction, and tread type. Different tires on the front and rear wheels may impair vehicle control and will damage the all wheel drive because of the constantly different wheel speeds".
"The proper function of the system is not affected by unevenly worn tires".
This of course applies directly only to my make, model, and year of car. But the other claims in this thread for "all" AWD cars would seem to be false. But here's the kicker:
"We recommend that you have your tires changed by an Audi dealer", so a shop that says they're following the manufacturer's instructions can't change them at all!
RE: Shopping for Electric Heater-need advice
In all of the bashing and supporting of the oil-filled heaters nobody mentioned what I consider their most important feature: no fan noise.
RE: WFCO 8955 Charge Test & Question
Have you highly qualified people heard of an INTERNAL RESISTANCE? Every source of electricity has it. It is responsible for a voltage drop on the terminals of the source when under load. When a charger has open circuit output voltage on terminals 14.4V, it is guaranteed (and perfectly normal) to have lower terminal voltage when under load. Due to the internal resistance of the charger!!! To which I'd respond, have you heard of sensing the output voltage at the converter terminals, giving the converter an equivalent zero resistance? Any modern converter that doesn't do this IMO is junk. I'd be pretty surprised if there is any switching converter that does not sample at the output terminals.
RE: Some AWD now requiring all new tires if one blows?
Just as a data point I have an AWD Audi and I replace the tires as-needed by the pair. So I'm always matched on an axle, but pay no attention that the front and rear axles are matched. At 210,000 miles I have not a hint of any drivetrain problems. Most hard core Audi enthusiasts are totally grossed out by what I do, and predict dire consequences. If the matching is so important for the drivetrain I wonder how AWD cars survive on the track, always turning mostly in the same direction.
RE: WFCO 8955 Charge Test & Question
Why won't somebody call the tech lines of the manufactures and debate THEIR ANSWERS?For what purpose, I wonder? If it's based on the assumption that one would get correct or complete information, I'd disagree with that premise. I've seen at least 2 different technical descriptions of the charging cycle published by PD. They disagreed with each other, and both were laced with unstated assumptions about things like battery type, SOC, temperature, etc. Critical information was selectively omitted to make the product appear to be ideal in all circumstances, instead of the best case circumstance that was documented. Why would the information from the tech lines be any more complete or accurate than an official technical publication?
For the PD operation I have chosen to trust what is stated in its patents, and my own measurements under controlled conditions. For other brands I have come to believe trust measurements made by others. I wouldn't be able to do the same for some tech line response.
RE: WFCO 8955 Charge Test & Question
Where the microprocessor comes into play is deciding when to change states. In the case of the PD, the Charge Wizard (I'm assuming) has a small microprocessor to control when it switches between the different voltage levels. I am also assuming that the converter itself, not the Charge Wizard, contains the actual current limiting (regulating) and voltage regulating circuits. The reason I assume this is because without the Charge Wizard, it still limits the current and the voltage is regulated at 13.6v.
All correct assumptions. The Charge Wizard sends an analog level down the cable to control the converter's output voltage. It could easily be replaced by a voltage adjustment pot. The current limit level is fixed.
RE: Calculating "Battery Short Circuit Current Rating"
So if you have 50 amps flow during a short the fuse may open but not stop the flow of current.
I'm curious how this would work. I always thought the failure mode would be something like the fuse exploding or catching fire, but I never imagined it wouldn't stop the current flow.
RE: Grounding Generators
Another "interesting" anomaly occurred when connecting my MAXX 3,000 watt inverter to the transfer switch (disconnect generator then connect inverter). The inverter would internally shut down just as the switch made the transfer. This would happen even with no load attached. My 1,500 watt Xantrax inverter would work through the switch perfectly. The higher end Xantrex MSW inverters have a floating output, while the lower end ones don't. I don't know if the Maxx 3000 is floating or not, but if it's not floating and you have a downstream grounded conductor, and if the inverter has protection circuitry, that would explain the shutdown. If it didn't have a floating output, and a downstream ground, and no protection circuitry, it would go up in smoke. This is the situation with lower end Xantrex and Maxx models. I don't know your setup so I'm just throwing out a few pieces of info that may or may not help explain things.
RE: Do Electronics Need Surge/UPS Protection with Generator?
I asked a friend who has a Phd in electronics, if the generator could hurt any of the equipment and his answer was, the generators do a good job by themselves but if you want insurance have a light bulb lit at the same time. It would help with surges should there be any.
Absolutely good advice. The voltage regulators in the non-inverter generators go into stupid mode with a bad power factor load, or after a substantial load change. The pure resistive load of the light bulb reduces the voltage regulator's exposure to these undesirable load characteristics. This advice will make things worse, however, when incandescent bulbs become illegal in the next few years. The CF bulbs are about the worst loads that exist.
RE: Calculating "Battery Short Circuit Current Rating"
Try this link to the manual for the inverter..
http://www.xantrex.com/web/id/627/docserve.aspx
IMO to the manual is messed up. On page 3-8 it gives 3 steps to determine the fuse size (my summary, not quotes):
1. Determine the short circuit rating of the battery.
2. Pick the fuse size based on the short circuit rating.
3. Choose a 150 amp fuse for this inverter.
Items 2 and 3 are in conflict. My best guess is that they meant to say use the fuse size from step 2 or 3, whichever is less.
This is followed by another careless statement: "Fuses can be bought at any marine supply store, RV supply store, or electrical products store." And there's no mention of the fuse type. Maybe the manuals are being written in China now, too.
RE: WFCO 8955 Charge Test & Question
Don't confuse current regulation as being the same as current limit. Current is only limited at the top of the rating.Doesn't the current limit provide the current regulation? Most RV converters have both a current and voltage limit, and at any given time are operating in either constant current or constant voltage mode.
RE: WFCO 8955 Charge Test & Question
For context, I don't have the advantage of having Barre's book available, and everything I think I know about the Xantrex charger is what I've read on the forum.
He shows with a chart (fig 5-2) how on discharge the voltage and battery state of charge decrease linearly. But on recharge, while the SOC rises linearly, the voltage makes an immediate jump (which he speculates is due to surface charge) before settling in. He says the voltage regulator "senses" this increase in voltage and reduces charger output. IAW it drops its amps too soon.
Which RV converter works this way? Certainly not a PD which reacts at a minimum of 4 hours after sensing the voltage increase.
During the bulk stage, the multi-stage charger produces a constant current; (emphasis mine) THE AMPERAGE IS KEPT AT A HIGH RATE until the gassing voltage is reached
In other words, the charger puts out its max current, allowing its voltage to rise until the voltage limit is reached. Same thing a PD converter or a fixed voltage converter does.
.....THIS IS UNLIKE A CONSTANT VOLTAGE CHARGER, which reduces the charge, reducing the amperage as the voltage increases."
I consider this a careless statement. A constant voltage charger does not reduce the charge or amperage. It's the battery resistance that reduces the charge or amperage.
Please explain how the amperage in Stage 1 can be HELD (to max) without "current regulation" and how this is just about semantics.Every switching converter I'm aware of has current regulation. Some describe the charging cycle and algorithm from a voltage perspective and some from a current perspective. Some like WFCO don't explain the algorithm very well at all. But they all have current and voltage regulation, start out in constant current mode with a heavily discharged battery, then switch to constant voltage as the battery resistance decreases and allows the voltage to rise to its regulated limit.
There are 2 other issues that I consider separate. (1) PD converters don't supply their maximum current at the boost voltage. You could look at this negatively and say they're fudging the specs in an attempt to make the product look better than it is. Or you could look at it positively and say they're using the maximum power capability of the converter when they're able to, instead of setting an arbitrary current limit. It think both of these things are true at the same time, but they both also make comparisons with other converters difficult. I'd rather have the honest rating with the arbitrary current limit, which it sounds like Xantrex does.
And (2) the point Sam is making about the converter not knowing how much of its energy is going to the battery vs. other loads is totally separate, and compromises charging claims of all the converters pretty much equally.
RE: WFCO 8955 Charge Test & Question
"When Truecharge first enters a charge cycle, the bulk mode provides a constant current of 20 A (ie. Truecharge 20) to bring the battery back up to 80% capacity in the shortest period of time. Truecharge moves from Bulk to Absorption mode when the charger output/battery voltage reaches Absorption or gassing voltage (typically 14.4 V dependent on battery type switch setting, and temperature)."
This is all semantics! It's a constant voltage output of 14.4, current limited to 20 amps. Or you can say it's a constant current output of 20 amps, voltage limited to 14.4 . Same darn thing. All of the mainstream converters work the same way. Now if the Truecharge really switches to Absorption mode when the voltage reaches a threshold, it's a lot smarter than PD's stupid timers that are embellished by the documentation to sound really smart. And the Truecharge has an advantage with battery temp sensing. But the constant current statement is just saying what everybody else does in different words. Nothing deceptive here, just looking at it from a different perspective.
RE: Calculating "Battery Short Circuit Current Rating"
I'm hooking up a Xantrex inverter and the instructions call for a fuse/circuit breaker "that will handle the short circuit current rating of the battery".
That is an absolutely absurd statement in the instructions! What model inverter is this? I'd like to download the manual and read it for myself. I've found the Xantrex documentation to be pretty good overall but there are exceptions. There are other mistakes in some of the inverter manuals, and the installation instructions for my battery monitor defy understanding. I don't have a clue what the max current the battery can provide is, but I've seen a car battery melt a fairly substantial screwdriver.
RE: WFCO 8955 Charge Test & Question
The current rating for PD converters is at the normal charge voltage of 13.6. They will not supply the rated current at the boost voltage, with a 120 volt input. My PD9160A was able to supply a steady 50 amps at 14.4 volts. So if you're comparing to a converter that supplies it's advertised current at the boost voltage, you could just consider the PD9160 to be a 9150 for apples-to-apples comparisons. Since the PD9145 is a different generation design it's probably not safe to assume it would necessarily have the same characteristics.
