House battery drain

blkjak · Oct 31, 2012

very important "basic power thread" for all of us .... blkjak

wrcsixeight · Oct 31, 2012

I had written something up covering most of what I have already written in this thread but then I managed to find some work and have been busy with that. My former Stomping grounds in NJ just got smeared by  Superstorm Sandy and I have been more concerned with my friends situations there than anything else. I just did a quick reread of it, fixing a few things.  =====------------============ Vehicular Battery Charging. There are many misconceptions about Vehicles and their battery charging systems.  Most everybody overestimates the amount of energy stored in their batteries, as well as how much energy is returned into a battery from the alternator while driving. When a secondary battery is added to a vehicle the problems are compounded. First, while I have your attention, a little safety clause relating to lead acid car batteries.  Never wear jewelry when working near batteries. Always use eye protection.Always disconnect the negative cable firstBaking soda neutralizes battery acid.  Have some handy, and even better some already dissolved in water.Regular Flooded Batteries(those with  removable caps on top) offgas Hydrogen and Oxygen when being charged.  A recently charged battery has the potential for explosion if a spark is introduced.  Extra caution must be taken around these batteries.   Think Time and ventilation. Now a Few facts.The best way to keep a battery performing at its best is to not drain much energy from it, and return it to 100% as soon as possible.   The closer to 100% charged a battery lives its life, the longer its life will be.  This is especially true of engine starting batteries which are designed to provide a quick burst of energy to the starter motor.  Marine batteries give up a little cranking performance to be a little more resistant to deeper discharges.  Deep Cycle batteries are designed to release energy more slowly and not suffer as much damage when depleted further. A Batteries Cranking power is measured in Cold Cranking amps(CCA)A Batteries Capacity is measured in Amp hours(a/h) or reserve capacity. While in general a larger battery will have more capacity and cranking power, this is not always the case.  A large 62 pound Deep Cycle battery rated at 115 amp hours will have about 550 CCA, while 54 amp hour Optima battery at little over half that weight will yield over 900 CCA.  If you are looking at cranking power for a starting battery then the CCA rating is what is valid.If you are powering small loads for a longer period then the Amp hour figure is important.  Many true deep cycle batteries will not even list a CCA figure. Marine batteries are a cross between a Starting battery and a Deep cycle battery.  If the battery says deep cycle with marine and RV on it, it is not a true deep cycle battery, but a Dual purpose battery that excels neither in engine cranking or deep cycle duty.  Most batteries which say ‘Deep Cycle’ are not.  True Deep Cycle batteries cost about 30% more than an equal sized marine battery. Now let’s talk about the Alternator’s ability to recharge a battery.  A healthy but depleted battery can still start a car when it only has 20% of its charge available.  Many people assume that if it starts the vehicle it is fully charged.  Wrong wrong wrong.The alternator is capable of producing very high amperages when it is cold, and when it is spinning very quickly.  Each 25 amps produced by the alternator requires 1 horse power from the engine.  Alternator amperage is not free energy!    Alternators also produce a lot of heat.  When asked by a depleted battery to produce all the amperage it can, it will heat up faster than the engine spinning it.  The hotter the alternator gets, the less amperage it can produce, and ultimately the shorter it’s lifespan.If a battery ever gets so depleted that it needs to be jump Started, then in excess of 8 hours driving is required to bring the battery up to  and above 90%.  It is very difficult to actually squeeze in the last few amps into a battery whatever the charging source. High voltages 14.4+ and time are needed. While a cold vehicle alternator spinning at high rpm is capable of producing high amperages for a short while, these amperages fall to very low numbers far too quickly.  When a second battery is added to the charging circuit over longer thinner cabling, the performance suffers even more.  Even a Beefed up charging circuit is still voltage regulated.   The vehicle's voltage regulator, whether in the engine computer or the alternator itself, does not want to see more than ~14.5 volts, so the alternator only makes enough amperage to hold 14.5 volts.  Even on a depleted battery, this can be as low as 7 amps.The closer the battery gets to full, the less amps are required to hold the voltage, and thus it is revealed that fully charging a depleted battery from an alternator is almost an exercise in futility.Whenever a battery needs a jumpstart, the battery should be placed on a grid powered car 10 amp plus charger for a minimum of 12 hours.  This cannot be stressed enough.  Those that rely only on the alternator and continue short trip driving around town will be replacing the battery within a few months 9 times out of 10. Okay let’s talk about what happens when a secondary battery is added to the vehicles stock charging system and isolated from the engine battery with the engine off.  This secondary/ auxiliary/leisure/ house battery winds up getting depleted to some degree or another.  It usually is at a great distance from the engine battery, and even further from the charging source.  The Distance from the charging source via the wiring can be 25 feet or more, and that is only half the circuit.  This long length of wiring from the isolator/ solenoid is usually undersized, and when passing as much current as it can, it suffers from voltage drop.  The engine battery might read 14.5 volts, but the house battery might only be 13.5 volts.   It is almost impossible to fully charge a battery if it only gets 13.5 volts. Automobile engineers have bean counters and lawyers hovering over their shoulders.  It is safer to undercharge a battery than over charge a battery.  The automakers are not concerned about battery longevity so Voltage regulators, whether controller by the engine computer or the alternator itself, or an external regulator, by default, reduce voltages whenever it even suspects the battery is nearing full charge.  A voltage regulator in the average dual battery system only really sees the engine battery voltage so while the auxiliary battery might be screaming for high charging currents, the voltage regulator has little idea and drops the voltage back to 13.6, and then the auxiliary battery is seeing only 13.2 or even less.  It is winded, and is being fed through a kinked cocktail straw.The result is chronic undercharging of the house battery.  The result of chronic undercharging is premature failure, and poor performance until it fails.   While a grid powered battery charger can vary amps at a set voltage, a vehicle’s voltage regulator cannot.  The voltage regulator only allows the alternator to produce enough amperage to hold the maximum voltage setpoints.  Even  a discharged battery that could accept 25 amps from a grid charger, will only need ~ 7 alternator  amps to hold 14.5 volts.Upgrading the alternator will not significantly reduce battery recharging times in such situations, unless you are running 70 amps of driving lights or some other huge electrical load while driving.Some alternators have very poor performance at idle speeds and low rpms.  In this situation a better alternator can help.  Some alternators rated at higher amp numbers actually produce less amperage at lower rpms if the diameter is the same. All alternator ratings must be taken with a large grain of salt. Upgrading the alternator will only help charge batteries faster if they are Very depleted and only for the first half hour, or if the stock alternator has a pathetic idle speed output to begin with. There are some aftermarket voltage regulators available which can better recharge the batteries.  I have no experience with them and am suspicious of their claims.  I believe that they add unneeded complexity and might fight today’s computerized vehicles, setting off trouble codes or check engine lights.Some people wire an inverter and a grid powered battery charger to the engine battery to charge the house battery.  This works better in vehicles whose house battery is an extreme distance from the alternator. IE, those pulling trailers. .   Another couple not so fun facts.Batteries can self discharge ~15% a month at 75 degrees F.  AGM batteries 3 to 4%Whenever a battery is below 80% charged, the sulfates are building up on the battery plates.  The longer the battery sits below 80% and the longer the battery stays below 80%, the harder the sulfates become.  When the battery is recharged, one hopes that the sulfates are re absorbed by the battery electrolyte, but often only a percentage of them are.  At this point battery capacity has been lost, and in general, is never coming back.   Future degradation will accelerate, as the battery is cycled even deeper to a lower portion of its remaining capacity. Most Auxiliary batteries live their whole life in the 50 to 80% range, and most will last from 6 to 15 months being abused like this.  If one wants to maximize battery life, one should ensure the battery is returned to full charge at least weekly, and we now know that the alternator is pretty much incapable of doing this unless driving for 8+ hours.  Either solar or a grid powered battery charger and enough time is required to achieve 100% State of charge.  Even then, a battery has a limited number of cycles, but that number is dictated by not only battery construction, but more importantly how it is treated.  Shallower cycles and prompt, full recharges are the keys to maximum battery life and performance during that life. Lead acid batteries have no memory.  Never discharge them completely.  That applies only to Ni-Cad batteries Now, how do we figure out when a battery is fully charged?  There are a couple tools but some big asterisks next to some of them. A fully charged battery cannot accept much amperage.  Some older battery chargers have an ammeter, a needle which shows how many amps it is producing, but different voltages and different temperatures will vary the acceptance so this is not very accurate.  Generally the needle rises to its maximum when starting the charge cycle and tapers toward zero as it approaches full charge. Voltage is a great indicator, but **** VOLTAGE readings are only valid to determine State of charge on a battery that is RESTED.  Meaning it has not seen a charging or discharging source for several hours*******. Voltage readings are best taken at the Battery Terminals themselves with a Digital MultiMeter. It varies between battery, but generally:12.6+ volts = fully charged12.2 volts =50%10.5 volts = 100% discharged Right after driving or taking the battery off of a different charging source, the voltage will stay above 12.8 for a long time.  This is a surface charge and tricks people who monitor voltage into thinking the battery is at a much higher start of charge than it is.  The physical agitation of the battery while driving and charging helps the surface charge to last longer in my experience.Measuring voltage right after driving does not give an accurate diagnosis of state of charge of the battery.   12.8+ volts right after driving, 6 hours later, without load on the battery, could easily fall to below 12.0 volts.  It takes a long time for surface charge to burn off, even with a small load applied.  This is why you can jump start a car drive it a mile, shut it off and instantly restart it, then drive for an half hour, shut it off for 2 hours and then it will not start.There exist battery monitors which have a measuring device which counts amp hours into and out of the batteries and are accurate within say 10% or so.  These require that all the charging and discharging currents run through a Shunt, and wiring this can be complicated to the electrically challenged.The Best tool for battery diagnostics is A hydrometer, but these cannot be used on sealed flooded or AGM batteries.  A glass hydrometer is significantly more accurate than a plastic one.  The Glass float is very fragile.  Both must be rinsed completely and dried after use.  Specific gravity readings are the best way to determine state of charge.  Temperature compensated hydrometers are even better.  It is best to take readings on a new battery when it is fully charged and record them for each cell.  Later on one can use the hydrometer after a ‘full charge’ is applied and see if the readings are similar to when the battery was new. This often reveals that ‘Smart’ automatic chargers stop  charging well short of 100%.  The hydrometers readings are not affected by surface charge.  I often take readings while the batteries are still charging, and bubbling slightly.  9 times out of 10 the battery charger stops well before maximum Specific gravity readings are achieved. Using a hydrometer is a PITA, but invaluable if you care to know when, and how much effort is required to get a battery up to a true 100%. Sometimes one hears about desulfators/ battery desulfination.  There are some battery chargers that send charging pulses at various frequencies to break up the hardened sulfates and either dislodge them so they dissolve back into the electrolyte, or fall to the bottom of the battery and reveal fresh plate material.  I have used such a charger and seen slight short lived improvements.  Some others claim they are magical battery rejuvenators.  I don’t believe these stories of magical battery restoration.  We humans like to convince ourselves that our purchases were wise and beneficial.  Convincing others of this makes it easier to convince oneself, so it is widely done. Sometimes those who refer to desulfating a battery are actually referring to Equalizing a battery.  Equalizing a battery is an intentional overcharge to make sure each cell in the battery is as high as it can possibly go.  Voltages in the low 15’s to low 16’s are required for this intentional overcharge.  This heats up the battery, and the electrolyte is actively bubbling away.  The heating alone can dissolve some of the sulfates back into the electrolyte. Often one needs to use an older manual charger to get the voltages this high and hold them there.  Never allow the battery to exceed 120F!Do not attempt to equalize AGM or GEL batteries! Battery manufacturers all have different recommendations on how often to perform an equalization.  A hydrometer which reveals large differences from cell to cell is a better way.  Some manufacturers say to equalize weekly, or monthly if cycling the battery nightly. Equalization is hard on a battery, but so is sulfation.  You can see that battery charging can be taken to ridiculous levels of complexity if one chooses.  Even then the most knowledgeable  OCD persons will suffer premature battery failure at some point, and usually at the worst possible time. The battery should be unhooked from the vehicle for equalization voltages, they can damage electronics.  The cells should be checked for electrolyte levels beforehand.  Only use Distilled water in batteries.  Tap water/spring water/mineral/rain water is not acceptable unless in an absolute emergency.  The cells need to be filled to just below the little arms which hang about 1 inch below the opening of the cells. Allowing the water level to fall below the tops of the plates almost always kills the battery shortly afterward.  Lots of charging cycles back to 100% greatly increase water usage, and more so the older a battery gets.  Some batteries use a lot of water, others not so much.  Hot weather increases usage. A couple more points in this section.AGM ( Absorbed Glass Matt) batteries have the electrolyte absorbed in a fiberglass separator between the battery plates.  The will not leak even if the case is cracked.  They will not offgas unless overcharged and are a much better option for those with batteries in the living compartment, though technically, they should be vented to the exterior as well.AGM batteries are at least twice the price of a flooded battery.  Some maintenance free batteries look like AGM batteries, with the lack of caps to check electrolyte, but are still liquid electrolyte batteries.  If the Battery is not twice the price or more than the flooded battery of the same size, it is not an AGM.The other Benefits of AGM is that they have little self discharge and can be stored for longer periods before self discharging below 80%.  They have less internal resistance and can be recharged much faster at higher rates than a flooded battery could endure.  With this less resistance, AGM batteries designed as deep cycle batteries have such high CCA ratings that they are fit for car starting purposes too.  Depleted AGM  batteries in a vehicle with a burly charging circuit can ask for everything the alternator can produce, and more.  Such vehicle’s alternators can be overheated and live short lives.  Since most vehicle’s charging circuits are woefully inadequate to support such currents, this is rarely an issue. Many people call all batteries with no caps GEL batteries.  AGM batteries are NOT Gel batteries.  Gel batteries do not have glass separators to soak up the liquid electrolyte but the electrolyte itself is a gel material.GEL batteries have very specific charging requirements and are not suitable for vehicular use.  They excel in other applications where the charging current can be strictly controlled. In the next installment I will discuss methods to increase current which makes it to the house battery.

grammahugababy · Nov 1, 2012

What do you mean "how bad I want to go to the RTR"!!!!!!!!   You have to come to the RTR!!!!   We need you.  Mutt wants to see Tony and Homer and all his other friends.  Come on Mutt help me out now.  Tell her you NEED to come to RTR. Tony is bringing chicken strips and you know how much you love chicken strips.  

twokniveskatie said:
\ and how bad I want to go to the RTR.

Guest · Nov 1, 2012

What do you mean "how bad I want to go to the RTR"!!!!!!!!   You have to come to the RTR!!!!   We need you.  Mutt wants to see Tony and Homer and all his other friends.  Come on Mutt help me out now.  Tell her you NEED to come to RTR. Tony is bringing chicken strips and you know how much you love chicken strips.

x2 Bri

Nemo · Nov 2, 2012

X3!!

bk2valve said:
What do you mean "how bad I want to go to the RTR"!!!!!!!!   You have to come to the RTR!!!!   We need you.  Mutt wants to see Tony and Homer and all his other friends.  Come on Mutt help me out now.  Tell her you NEED to come to RTR. Tony is bringing chicken strips and you know how much you love chicken strips. 

Click to expand...

 x2 Bri

twokniveskatie · Nov 2, 2012

Hahaha! I was whining, didn't you recognize??? Lots been happening on that front. Will find out soon but think I may have found someone to take over my half of the farmhouse, and just store a few things in the spare room closet. The farm will always be a home base, but I will be more full-timing it from here on out. I am psyched, and just wish I could get over whatever I have so I can get busy with what needs done! Gonna be a whole lotta huggin going on

House battery drain

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House battery drain

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