Imurphy
Explorer
Joined 10 years ago
User Profile
User Widgets
All Activity
Re: high rate charging on generator
MEXICOWANDERER wrote: The "forever and a day" now needs elaboration. A C20 rate is plenty to meet OEM specs about minimum initial charge protocol. With fuel costing what is does I whack AGM with a C10 as long as cell temps do not increase at a rate of 1c hr or more. At 1c I back off. One thing everyone has to remind themselves of now and again. Is that rates and capacities are designed for the basic hands off user. If someone has the ability and/or attention span to actually pay attention, you can get away with a lot more than they will ever put on paper. The "forever" means gaining that last 5%. The bitter .5% goal is frustrating to the point of causing neurosis with generator recharging. The less frequent the batteries recharge min C20, the more infrequent full recharge is achieved to half percent of total capacity the more frequent Conditioning must br performed and if the option means burning diesel and knowing lots of expensive parts are rubbing in the process, personally I'd rather endure a root canal. Six hours. 6-lousy hours connected to public power is magic after an AGM sees a recycle. Six lousy rotten hours that a dedicated off-grid bank will never see. This is exactly and precisely where and when a modest solar array can become it's weight in gold. An array engineered to provide a winter solstice quantity of amp hours equal to this missing quotient amp hours caused by a battery that refuses to accept economical charging energy from burning petroleum. A 7 Kw genset loafing at 200-watts is tough to endure especially when a person is mesmerized by an exhaust plume. Either size the solar array to have 110% amp hour capacity of worst case winter solstice production or size the array to provide the last five percent or whatever factor is missing from generator charging. Hitting an accumulator hard is less damaging than slow starvation (within limits). The batteries must recharge or they are going to suffer. It is up to the owner as to how they wish to configure this task. Anyone can agree trying to 100%SOC off diesel is pointless. You "could" do it, but it would require multiple stages of AC power supply to be anywhere near efficient. Even running a Honda 2000 pushing a 20 amp automotive charger is a waste of fuel. This is where Solar can really shine. If you are able to bulk off a generator and let the solar do the rest you will be a winner almost every day. My philosophy on battery management is simple. The lowest cost per a given amount of kWh rendered. Sounds easy but it's a worthy challenge. An outage is not an outage. A Telecomm battery cannot fail without dire consequences. Fail means deliver performance not necessarily self-destruct or die of old age. An off grid bank can be rigged to provide a work around. This skews the design philosophy to the point where one cannot compare to the other. Telecomm failures cause heads to roll. So over compensation must over rule initial and operational cost. Unforgiving. Private banks are under intense scrutiny economics wise from inception. A heartbreaking majority are under intense pressure far beyond their capability (and reality). Little if any genuine attempts to match loads with realistic scenarios for recharging. An array is coupled to a bank then to a load. By error and trial shortcomings are discovered then "fixes" are cobbled according to budget and whim. Get your dander down people! I'm talking about the market in general and not the members of this forum. We need an example so allow me to play the Rhesus monkey. I needed a battery to perform a specific duty. It had to be AGM due to it powering a BiPap and emergency lighting in hotel rooms on the road yaddah. Power outages down here are a curse. Narrows the choices. A fast recharging durable 100 amp hour battery. Lifeline met the criteria. But experience taught me recharging via public power had to be fast. So I opted for an 80-amp charger. The load, the storage and the replenishment all met specs in all respects. My bank at home is a 3300 amp hour 12-cell flooded system. But an aggregate total of 400 +385+120+100 amperes charging via a 12.5 Kw genset allows me total latitude in powered recharging. Solar is not an option. Run and maintenance costs is the weak link. But the magic is I have full access to 60 amp 254 vac for enough hours to vastly simplify my life. That is the key. Does a system have access to public power and for how many hours a week? Total off-grid is challenging. Total off grid in conjuntion with trying to utlilize insufficient solar voltaic kWh is simply not resolvable unless adequate alternative charging is made available. A GRAND WELCOME TO THE FORUM from Mex is in order. And enveloped plates are not far off for telecomm batteries. You have a job worthy of calling challenging. The issues here are capacity, money, performance, money, maintenance, money, metering, money, lifespan, money, and last but not least, money. I play a hard role that is for sure. During the day I have to see things in black and white teletype'd name plate ratings. While at home, we get to do just about what ever we want. But there are a few things I do bring over from the telco world. Voltage loss restrictions on wiring and other wiring standards(efficiency and safety). As well as understanding the difference between a name plate rating and what a product will actually do. But when ever possible I try and engineer mixed grid and off grid systems as robust as I can based on budget. And many times using those very telco standards gets you there. One thing that is always in the back of my head when it comes to capacity and ratings. Under promise, over deliver. I never want to put out a system that does not meet its design spec, or barely meets the spec. I want a system built tough enough and based on numbers conservative enough that meeting the standards is the minimum performance. And that in 3-5-7-10 years that system is still meeting the standards. It is especially hard for off grid up here in AK. In the summer we have nearing endless hours of sun. And can see 18 hrs of "noon quality" light in a single day. This makes systems easy. But on the flip of that coin is the winter, when we may only get 45 minutes of noon quality sun a day. And sometimes not even that. I have designed and installed off grid systems for several customers living in full 2500 sqft homes with all the joys of a normal home. Having a system that leaves them dead in the water is not an option. Could it have been done cheaper, hell yes. But it would not have been "right". My personal systems are much less "complete" as I have no one to let down, no one to get cold in the night. Just me to be mad at myself. but I like to tinker, so having several systems that work but require constant toying with keeps me sane. I will help anyone put together a system. But you have two options. 1. cheap. but I will tell you upfront and in no uncertain terms that what you will get will require maintenance. and may not perform to spec for more than a year or two. 2. Will fulfill all of your needs plus reasonable performance and life margins. When given the two options, most people come around to the economics of a system that is overbuilt. After all these days no one seems to remember the term "duty cycle".500Views0likes0CommentsRe: high rate charging on generator
pianotuna wrote: Hi Imurphy, Welcome to RVnet! By hit it hard, do you mean discharge rate? Or charging rate? What would you suggest for the 139 amp-hour 12 volt battery for a maximum (safe) discharge rate? Imurphy wrote: Where in telcom we generally hit it hard, and there for don't get as many cycles out of them. Discharge. Everything in telcom is designed around a min 8 hour cycle life(load supporting). BUT, it is all to common for equipment growth to over run plant growth. Many systems have gone from 8hr min battery plants to battery plants to provide "carry through service". Basically last just long enough for the generators to come online. I know of many places that have 16,000+/- AH's of battery. But if the generator does not come online within 15 minutes things are going down. Usually due to space for batteries they start to shift focus not to battery backup but minimizing power loss all together. So they just buy a generator or two. And as long as that generator will run for more then 8 hrs with its fuel supply it makes the FCC happy. NEW E911 requirements have jumped this rating for many facilities to 24hrs as of Oct 15th of this year. That has caused a bit of a scramble for abilities pulling 302,000+/- watts, as there just is not anywhere left to put batteries. And the cost of huge Lithium plants is still largely out of reach for backup purposes.501Views0likes0CommentsRe: high rate charging on generator
MEXICOWANDERER wrote: Telecomm companies establish parameters for maintenance based on OEM guidelines. OEM is aware that their client wishes the very highest degree of performance reliability. So a operating lifetime max hours is agreed upon. Max hours of guaranteed reliability. Zero non performers. The batteries have a specified level of max discharge at which Telecomm shuts down transmission and the batteries go dormant. The percentage of charge remaining is unknown to me. We allow many plants to go as dead as they want. And rely on equipment's power supplies to shut down or brown out. Thou some sites we do terminate service for the sake of the batteries. Technicians operate by holy writ in the form of rote. They follow maintenance, troubleshooting and testing exactly and precisely according to company doctrine. It is all well documented then entered into a computer database for reference, study and analysis. Job one is the repeater must not fail. The largest piece of this information is trending. With out an accurate history of how the battery lives, one may declare it deceased early. Or worse off, wait to long to bury it. Transcribing telecomm writ to a usable form for RVers can be deceptive. What worked excellently for telecomm may not be in the best interest of somone whose use of the used batteries may be totally different. Telecomm is after 100.0% reliabilty at the expense of trade-offs. Are you aware of the tradeoffs?Most telcom plants trade cycle's for depth or discharge. As with any battery the less you use it, the longer you can use it. Where in telcom we generally hit it hard, and there for dont get as many cycles out of them. Understand this point. After an outage, telecomm batteries have forever and a day to recharge. Do you? Charge amperage ceilings are based on acheiving ultra maximum longevity. This is a moot point if telecomm batteries spend a majority of their golden years connected to shore power with incidental short interruptions for boondocking. In that scenario following Telecomm rote is the wisest choice as it most closely mimics what the batteries were designed for.Every battery mfg. has recommendations on how to use their battery. No one says you have to. But pumping to much current into a plant is a sure way to ruin it. And Telcom has restrictions on recharge. We do NOT have forever and a day to recover a plant. We have FCC regulations that state our systems have to maintain between 8 and 24hrs of backup at any given time. We recharge our plants as fast as we can. Its not uncommon to have an outage just hours after a previous one. This is the worse case. We also have to have the equipment to properly supply power to the load, and be able to charge the batteries ASAP. Even a back up generator or a fire alarm panel has regulations on max recharge time. When things shift to off-grid rote gets chucked out the window. Calculated charge maximum absorbsion voltage is not the same animal. Neither is maximum absorbsion voltage. Only float voltage remains thec same.Many battery MFG. understand the different use of their batteries. In the case of these UPS12-490's they call for a float of 13.65 ± 0.15 VDC average per 12V unit. While recognizing they may be used in a cycle service thus also state 14.40 to 14.80 VDC average per 12V unit for such use. Upping the voltage while still maintaining the recommended amperage increases the wattage of absorbed power. If you stick like glue to telecomm rote prepare to rum your generator a lot longer. You are mimicking unlimited time value recharging via your generator. Your fuel and your time. When I generator recharge 3300 amp hours of 24 volt battery it is absolutely different from charging using CFE shore power. One is 500+ amperes. The other is 120 amperes (the 4024 Trace). Coursing 120'amperes through a 1650 amp hour battery / 2 banks is a gentle recharge. Life with public power available is absolutely unlike recharging via a generator. The issue is time. The issue is money. Lots and lots of money. To do an in-frame on the Kubota is around five thousand dollars. Add that to $3.35 fuel, filyets, lube oil and labor and it makes shore power recharging calculations totally, completely and absolutely irrelevant. To the point of becoming absurd. Cost of kWh hr transcribed to usable battery kWh includes the ACTUAL cost of fuel plus generator wear and tear. I an not a telecomm company and nothing I manage even remotely can serve as a model for both economics nor management. Trust me not much we do is a model of economics either. In many cases with remote prime power sites. We would rather buy a new generator ever 2-3 years and burn thousands of gallons of fuel. Than have to purchase a new battery plant every fuel years. Its it alot cheaper to fuel and replace a generator than replace a battery plant. One of the things I love about Telco batteries is they are always available. They take a 48v string and toss it out. We get to run to the pile and pick out the best of whats left to make out 12 or 24v systems. I know I have a huge pile of batteries at home that were tossed aside. I currently have 8 180ah AGM batteries I am "reviving" from the telco world. they were taken out of service and left on a pallet for 2 years with out a charge. I have been able to bring them back to life quite well. And they currently follow their historical trending withing 80% of rated capacity. These cells were deemed to have a 7yr life span. They spent 9 years in service. 2 on a pallet and are about to be connected to an outback GS series radian, where I expect another hand full of years out of them in UPS mode. The biggest problem with most telco batteries is the amount of calcium they have. during discharge the plates swell. Over time this causes plates to short and the battery than no longer works. I would not hesitate to use old telco batteries. But I certainly would not buy them new for this use. For the money there are batteries that will serve the offgrid world better. But for cheap/free batteries, why not finish them off.500Views0likes0Comments
