Redneck Battery Recovery

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If any of you remember my redneck ELD bypass story then you'll probably know the general direction this is headed.

My grandma is preparing to sell her RV and had my dad and I look over it and we found that all 3 batteries were dead. The starting battery had discharged to 4 volts, and the house batteries were both at 6 volts. Our trickle charger was able to save both the house batteries but would not even acknowledge the existence of the starting battery.

Since I do car audio, I have dual 250-amp 3-phase hairpin alternators from Custom Electric plus dual batteries in the back so I got an idea.

I got my jumper cables and connected my starting battery to the RV's and let my car idle for about 15 minutes, took the jumpers off, and it was now resting at 10 volts although slowly discharging but not nearly as bad as it was before. I quickly grabbed the battery and ran it up into the garage and connected it to the trickle charger which now turned on and began to finish recovering the battery.

If it's stupid but it works... it's stupid... but it works.
 
Good reason to keep a dumb lump buzz box charger around.

Pics of your setup?
 
Originally Posted by eljefino
Good reason to keep a dumb lump buzz box charger around.

Pics of your setup?

The charger we had was a dumb lump buzz box from the 70s, and I have a newer Schumacher one as well.

Also what do you want to see? How I accomplished this or how my alternators and batteries are all together?
 
iI think there were some youtube vids about guys recovering old nickel and lead acid batteries from power tools by blasting with high amperage, just tapping it on the terminals. Something about desulfating the plates? Just the thiught scares me, but maybe some people with bigger stones than me can try.
 
That works (sometimes) on ni-cads. Ni-cads get strands between the layers that short out the battery, a blast at high amps burns them out and the battery will work again. I wouldn't try it on a lead acid battery on a bet.
 
Okay here is pictures of my setup.

Here is the alternator, Custom Electric 250-amp hairpin 3-phase
[Linked Image]


Here is my starting battery, I beat out the sides of my battery tray with a hammer and shoved in a Walmart-special 24F in place of the old 51R, with an improvised tie-down until I find something better.
[Linked Image]


The above are both old pictures, I've since attached a run of 1/0 gauge OFC wire from the alternator direct to the battery:
[Linked Image]


Here's in the back of the car, the batteries are behind the speaker box and not visible in the picture.
[Linked Image]


Last but not least, tonight's festivities:
[Linked Image]
 
Originally Posted by cwilliamsws6
If any of you remember my redneck ELD bypass story then you'll probably know the general direction this is headed.

My grandma is preparing to sell her RV and had my dad and I look over it and we found that all 3 batteries were dead. The starting battery had discharged to 4 volts, and the house batteries were both at 6 volts. Our trickle charger was able to save both the house batteries but would not even acknowledge the existence of the starting battery.

Since I do car audio, I have dual 250-amp 3-phase hairpin alternators from Custom Electric plus dual batteries in the back so I got an idea.

I got my jumper cables and connected my starting battery to the RV's and let my car idle for about 15 minutes, took the jumpers off, and it was now resting at 10 volts although slowly discharging but not nearly as bad as it was before. I quickly grabbed the battery and ran it up into the garage and connected it to the trickle charger which now turned on and began to finish recovering the battery.

If it's stupid but it works... it's stupid... but it works.


Almost all alternators are three phase. Not sure why you need a lot of power for car audio? Why so loud? I am old enough to be on Medicare and listened to my share of loud rock and roll music when I was young. Now I listen to a hissing static in my ears 24x7 thanks to tinnitus.
 
Instead of beating on the CR-V battery tray buy one for an Odyssey. About $25, fits the same space, and holds a 24F perfectly. The cables even reach.
I swapped out the 51 in our '14 CR-V when we towed it behind our motorhome for about 5 hours and it went flat. It died shortly thereafter.
 
Originally Posted by eljefino
Good reason to keep a dumb lump buzz box charger around.


Always!

I have a Black & Decker automotive "smart charger" that hates to see anything under 10 volts.

Using jumper cables or the "dumb" buzz box to "fool" it- - Once the voltage is high enough, it'll take over and charge like it should.
 
Originally Posted by redbone3
I wouldn't try it on a lead acid battery on a bet.


I've tried using my DC arc welder on low amps (40-50?) and OCV of ~35-40 to "blast" a lead acid battery back to life.

It will boil the acid - but it won't make a bad battery new again.
 
Originally Posted by redbone3
That works (sometimes) on ni-cads. Ni-cads get strands between the layers that short out the battery, a blast at high amps burns them out and the battery will work again. I wouldn't try it on a lead acid battery on a bet.



Yup that does work on nicads. Just a couple taps with a MiG or wire feed welder works .
 
this is why i keep the old dumb chargers.
but this has a benefit.
i get lots of batteries given up for core deposit that are still young but deep discharged to the point of being ignored by "smart" chargers.
and these often come in groups of 4 since my source is the core pile of a heavy truck dealer.
the jumpstart technique is just as good as a dumb charger.
dont even need run run the donor.
all that is needed is to get the battery above around 8v.
this seems to be the point where both of my newer chargers will "see" that a valid battery has been correctly connected.
 
Jump-starting a "dead" battery and then driving the car for a while is how 90% of car owners deal with this situation. There will be "experts" who critique this but to repeat what you said, "it works".
 
Originally Posted by hallstevenson
Jump-starting a "dead" battery and then driving the car for a while is how 90% of car owners deal with this situation. There will be "experts" who critique this but to repeat what you said, "it works".

I had a coworker whose husband drained his car's battery with the lights on. So I lent my jump starter although I didn't do the jump myself. I was told that he didn't drive it long and in the morning it wouldn't start again. So instead I asked if they had access to power where he parked (apparently it was an apartment carport with access to outlets) and then recommended using my 1.5A Schumacher charger overnight. I wasn't sure it was going to be a full charge, but it was sure as heck going to be better than just driving 3 miles. I then recommended taking it for a nice drive on the weekend if they couldn't leave it charged 24 hours.

Of course my 12A charger would have done a full charge in a few hours, but I happened to have that 1.5A one (which I can't find any more) in my trunk.

I've told the story about how I wanted to test drive a 2018 Subaru BRZ and pretty much every one they had on the lot had a dead battery. They brought out the jump starter and then I took it off the lot and stalled it a black away. It of course wouldn't start, so I turned on the hazard lights, which stopped after about 20 seconds. Then at the suggestion of a pedestrian I propped up the hood to show that there was a problem. But yeah - the people at the dealer thought it would be OK to jump start it and then drive away. The first time I ever had my WRX jump started I just drove off after about 5 minutes of idling, but I was familiar with the clutch on that car and wasn't worried too much about stalling. After 10 miles it should have been no problem restarting.
 
Originally Posted by kc8adu
this is why i keep the old dumb chargers.
but this has a benefit.
i get lots of batteries given up for core deposit that are still young but deep discharged to the point of being ignored by "smart" chargers.
and these often come in groups of 4 since my source is the core pile of a heavy truck dealer.
the jumpstart technique is just as good as a dumb charger.
dont even need run run the donor.
all that is needed is to get the battery above around 8v.
this seems to be the point where both of my newer chargers will "see" that a valid battery has been correctly connected.

The newer ones that are "microprocessor controlled" require a certain voltage be sampled before they'll start charging. I think it's probably programmed that way because of worries about charging a damaged battery. But of course a few minutes on a manual charger and it should put out the proper voltage.

Of course the olds ones aren't really all that advanced. I've got Schumacher manual 1A wall-wart. It has absolutely no smarts other than simply an analog circuit. I tested it once with a multimeter and it was around 16V open. I'm sure the voltage would have gone down when connected to a battery, but obviously it was designed to put out the correct voltage when connected to a real battery.
 
Remember, the vast majority of people don't have battery chargers.

In the case of the Subaru test drive, well, if you hadn't stalled it, it would have been fine
grin.gif
grin.gif
If you didn't buy it, I suspect the battery would have a hard time starting it the next time someone tried too.
 
A lead acid battery cannot be recharged from 80%, to 100% state of charge in less than 3.5 hours, although a high amperage charging source seeking a higher voltage can bring the battery to 80% charged fairly quickly.

Those 3.5 hours for 80% to 100% assume the charger is capable of enough amperage to bring the battery to, and hold the battery in the mid 14.5 volt range.

A 30% charged battery can easily start a modern fuel injected engine, especially an already warm one.

Very few voltage regulators, whether on a grid powered 'smart' charger or an Automotive voltage regulator which controls the alternator's amperage output, will allow mid 14 volts to be held for very long.

A lead acid battery ideally, fr maximum longevity an maximum capacity retention and cranking amps throughout its lifespan, always wants to be 100% charged, and kept cool.

A 1.5 amp maintainer, attached to a well depleted battery, has pretty much Zero chance of bringing the battery to full charge overnight.

A 12 amp charger has almost zero chance of fully charging a depleted lead acif battery 'in a few hours', as 3.5 hours from 80% to 100% is unassailable fact, and almost every 'smart' charge out there is not designed to fully charge a battery, they are designed to NOT overcharge it.

Reaching a true 100% state of charge can only truly be verified with a temperature compensated hydrometer on a flooded battery
Those who believe the green light on a charger indicates a full charge are delusional, misinformed/ignorant, or some combination of all three.
The green light indicates ONLY that the charger has decided it has held the battery at an absorption voltage ( Mid 14's) for long enough. A good temperature compensating hydrometer, like the OTC4619, will easily prove this time and again to anybody who doubts it, but ignorance is bliss, proveable time and again, which is a shame.

The time in which a battery needs to be held at absorption voltages, in order to reach full charge, varies with every battery, and changes as the battery ages. It changes with battery temperature, it changes with the state of charge at which the charger was initially hooked to the battery, it varies with the amount of initial amperage the charging source was initially able to supply. It changes with the length of time the battery was left at lesser states of charge, and the depth of those discharges.

An AGM battery can only be determined to be fully charge when it can only accept 0.5% of its capacity, measured at the 20 hour rate, so a group 31 AGm battery with 100 amp hours can only be determined to be fully charged, when it is held at 14.5 ish volts( at ~77f degrees) until amperage tapers to 0.5 amps or less.

No ammeter? guess what, you have NO IDEA how charger the battery is or not. Not able to hold the battery in the mid 14's?????, well one cannot determine full charge at lesser voltages.

Almost every battery, in every vehicle on the planet as you read this, are not 100% charged, but 99.9% of their owners will beleive the opposite.

The average state of charge, and the average temperature the battery is, determine the lifespan of the Lead acid battery.

The 'trickle charge it overnight' mentality in terms of battery recovery, as pretty much asinine in the extreme.

Lets assume the 1.5 amp charger is capable of seeking 14.5 volts( most are not).
Lets say the battery was depleted below 10.5v( which is considered 100% discharged)
Lets say the battery was 100% healthy when it was inadvertently depleted below 10.5v
Lets say the battery had, when new, 100 amp hours of capacity. This means it can , when new and fully charged, supply 5 amps for 20 hours before voltage falls below 10.5v)

A 1.5 amp charger ( seeking mid 14.5v) applied to such a battery for 12 hours would be able to return only a small fraction of the battery's capacity, 18 of the battery's 100AH capacity.

But this will likely be enough to allow the vehicle to start, and the vehicle owner will think the battery is indeed fully charged, when a hydrometer would laugh at this incredibly false assumption.

In the case of a 12v battery drained to sub 10.5v, most every modern 'smart' charger will not attempt to start charging the battery, and one can, like the OP, hook up another battery in parallel, for a couple dozen seconds, and many amps will flow into teh depleted battery, raising its voltage to the point a 'smart' charger will recognize it and start charging. To assume this 'recovers' the battery is unwise.

Batteries slowly drained to well below 10.5v have been damaged, capacity compromised. How much capacity they will be able to recover is dependent on just how long they have been left below 10.5v, and their condition before that level of depletion was allowed to occur, and of course the chargings sources amperage and the time in which it is allowed to hold higher batter charging voltages.

Such a battery is badly sulfated, the plates occluded with hardened sulfate. the best chance of recovery to dissolve that sulfate back into the electrolyte is NOT with a slow low amperage 'trickle' charger, but by a blast of higher amperage which will heat the plates, but not to over 100F, and 120F is the absolute limit.
Such a battery will likely require little amperage to have voltage be initially brought up into the mid 14's, but then, as the battery starts accepting this current and 'wakes up', the voltage will drop and the amperage it can accept will rise, assuming the charging source can provide higher amperage and is still seeking to bring the battery to and hold it at the mid 14 volt range.

This theoretical group31 battery( 13longx7widex9.5 inches tall is pretty much the largest automotive battery) should then be be allowed to accept 20 amps until voltage again rises to 14.5ish volts. How quickly 20 amps can get the battery to 14.5 amps is indicative of its remaining capacity and health.
Once the battery gets to the maximum voltage the charger allows, the amperage required to maintain that voltage decrreases, starts tapering in this constant voltage phase, also called absorption. If the amperage does not taper then the voltage keeps rising (constant current), and one should not allow a 77F battery to exceed 15 volts. Manual buzz boxes with high amperage available can easily push a battery past this. It is Effective but much more abusive than it need be, and dangerous, in terms of gassing hydrogen and oxygen and taking that sulfuric acid mist along with it.

Truly recovering a sulfated battery to its maximum remining capacity is not something any garage charge is capable of, no matter how much faith one has in its marketing.

After a sulfated battery is held at 14.5 volts until specific graity of the electrolyte stops rising, which can be anywhere from 8 to 24 hours, if the specific gravity is not in the 1.275 range, then ONLY higher voltages can possibly raise that specific gravity further. Such a charge is a Forced overcharge, called an Equalization, a term often misused. The battery can be brought to 16.2 volts, and will bubble vigorously and heat relatively rapidly, but the equipment which will allow this is few and far between. the battery must be monitored during an equalization and the charge stopped once the battery heats much beyond 100F as it will rise in temperature much quicker after this. Once allowed to cool, assuing the specific gravity readings are still below 1.275ish, the 16.2v can be initiated again. they hydrometer should be dipped into the lowest reading cell often and the charging stopped once the specific gravity no longer rises, accounting for the rising electrolyte temperature. Eye protection mandatory! No sparks or open flame nearby!

The Pulse desulfating chargers have been largely dismissed by the Marine experts who have performed many tests attempting to recover sulfated batteries. Any capacity recovery is the same as if the battery had been exposed to the same charging voltages for the same amount of time with a NON 'pulse charger'. Belive the marketing and in your purchase if you have to.

'Smart' charger by and large are not very smart. Any charging is of course better than No charging, but getting a battery to 95% charged, is only half as good as achieving 100% charged, in terms of maintaining battery capacity and performance.

Achieving 100% state of charge can be difficult if not impossible without a charging source which is capable of not only holding mid 14 volts for much longer than smart chargers allow, but also allowing Equalizing voltages upto 16.2 volts, a process which can be dangerous to the user and dangerous to the company who made such a product. As such most are emasculated and are not capable of truly fully charging a battery, but are intended to stop charging at a much safer 92 to 95% charged.

Getting the 95% charged battrey in the middle of its expected life to 100% charge, can require 4 more hours held at 14.5 volts.

I use an adjustble voltage power supply, modified with mroe ventilation heatsinking and better adjustment dial. i am oftern brougth batteries to 'recover', and watch voltmeters and ammeters and amp hour counters, and dip hydrometers often to see the results and gauge the health of the battery. So many of these batteries were placed on smart chargers before they were brough to me and their specific gravity was deep in the red and their smart charger would refuse to charge it for any longer. many of these batteries were unrecoverable, many accepted a lot of amp hours and returned to electrolyte levels in teh green and are still going a few years later.

I would recommend those with 'smart' chargers who want to get their batteries close as they can to 100% state of charge, apply a relatively load to the battery to drop the voltage to below 12.6( like headlights), then reattach the alligator clamps, plug in and restart the charger on the next lowest amperage setting, then remove the load. Lather rinse repeat. This might be effective, or it might not.

The truly 100% charged Lead acid battery, is a happy battery, and if regularly returned to 100% charged and living its life up in that range, will live a good long life, even in Southern Texas.

Living at lower states of charge is highly detrimental to Lead acid battery longevity and higher average temperatures of the battery exaserbate the capacity decline. The lower the average state of charge and the higher the average temperature the faster the battery deteriorates.

Do NOT assume your vehicle is trying to, or even capable of returning teh battery to 100% charged, even if one drives for 8 hours.
Anytime a jumpstart is required the battery should be brought to, the mid 14 volt range, and held there for several hours. it might take 12+ hours to bring the battery to the mid 14v range. that depends on teh amperage the chrging source is capable of delivering, and the voltage is is seeking to attain then hold.

Do not asusme a 'trickle' charge is seeking mid 14 volts. Do not assume a trickle charger even has enough amperage available to bring a battery to 14.5v.

A healthy battery when fully charged might require only 0.4 amps to be held at 14.5v, but a sulfated older battery with 1.5 amps applied constantly might never exceed 13.9v, no matter how long it is applied. I have one marine battery on its last legs where 5 amps cannot get it above 13.87v no matter how long it is applied. 1.5 amps cannot get it over 13.22.

The higher the voltage the more amperage is required to hold the battery there.
The less healthy battery will require more amperage to maintain the same voltage when near fully charged, compared to a more healthy one.
The less healthy depleted battery will rise in voltage faster with lesser amperage applied, than thehealthier battery.
The healthy depleted battery will accept more amperage and its voltage will rise slower, compared to one less healthy.
The vehicles voltage regulator controls how much amperage an alternator makes. This voltage varies greatly among different vehicles, and on the same vehicle depending on how long the engine has been running.

The battery accepts as much amperage as it wants at the voltage reaching its battery terminals.

How much amperage the battery 'wants' at a charging voltage, depends on its size and health and temperature and state of charge.
Every battery is different and will exhibit different behavior, as it ages.
"good enough' is Subjective. Opinion.

But a fact is the healthy lead acid battery canot be recharged from 80% to 100% in less than 3.5 hours, assuming a charging source is capable of holding mid 14 volt range, and the lead acid battery, ideally, always wants to be 100% charged, and kept cool.
 
Originally Posted by hallstevenson
Remember, the vast majority of people don't have battery chargers.

In the case of the Subaru test drive, well, if you hadn't stalled it, it would have been fine
grin.gif
grin.gif
If you didn't buy it, I suspect the battery would have a hard time starting it the next time someone tried too.

I saw a portable charger once at a dealer that was battery powered. I believe the idea was to just make sure that every car on the lot could start.
 
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