Lead acid battery fettling

[jon hill 3Participant @jonhill3]

On taking out the campervan recently I noticed the leisure battery draw was faster than it could recharge on solar.  Bearing in mind the plentiful sun we’ve been having I checked the battery to find that it wasn’t storing suffient capacity.

Its a yuasa lead acid 100ah leisure battery.  Annoyingly the cells were capped with a lightly glued on cover which I removed to discover they were looking very thirsty for de-ionised water.

Providing I can get better performance after a charge should the dust cover be re glued on to minimise potential acid leakage? The battery is clamped to the floor in the back of the van so minimal tipping hazard.

[Julie AnnParticipant @julieann]

Given that the cell caps were glued in place the battery is almost certainly a sealed lead acid battery, of which the most common type is gel. They don’t have a liquid electrolyte, which is why it looked dry. Instead the electrolyte is a very viscous gel. Since there is no liquid electrolyte spills caused by the battery being tipped is not an issue. Gel cells should not be topped up with water.

If the battery wasn’t fudged before, adding water to the cells has most likely fudged it now.

Julie

[noel shelleyParticipant @noelshelley55608]

I beg to differ ! Many wet lead acid batteries are now sealed as in theory modern charging electronics do not drive the water off so no need to top up and since you can’t you have to buy a new battery if things dry out. Many modern systems only charge the battery to 80% and the alternator is controlled by the ECU this can lead to some interesting situations. The first thing to do is ascertain what type of battery you have, wet or gel.  IF it is a gel cell then there is little you can do. I have a gel cell that is over 20 years old and still works fine – and I don’t know how it has lasted – it’s not from the care I’ve given it.

You mention solar, has it been over charged, or left flat over winter. I would glue the top back on, but go easy on the glue. Good luck. Noel.

[Russell EberhardtParticipant @russelleberhardt48058]

The gel batteries need a diferent charging regime to the wet batteries.  I recently changed the domestic battery in my campervan from wet to gel type and was told when I bought the new battery that the charger had a switch that needed to be changed over for the correct charging.  I had to dismantle one of the seats to get at the charger and use an inspection mirror to find the switch.

Russell

[Dave WoottonParticipant @davewootton]

Only slightly off topic, but does anyone remember some little tablets called something like Batt Aid that you dropped into your aged car battery in order to restore it to life again? I worked as a Saturday boy in an old fashioned motorcycle shop and there was a card of them on display, never remember any being sold. just wondered if anyone remembers them and if they worked at all?

Dave

[noel shelleyParticipant @noelshelley55608]

Hi Dave , YES I remember them and you got the name right. I never used them, nor do I claim to be a chemist so others on here may well correct my thoughts. As a battery is left flat the plates sulphate up and the battery cannot then be recharged. Lead sulphate is not soluble in the dilute acid, BUT if you remove the acid, flush with water and then fill with a hot solution of EDTA, ( ethylene diamine tetra acetic acid )a common food additive and readily available chemical for a while this will dissolve the sulphate which is then removed, more flushing and then replace the removed acid. I tried it with a set of EV batteries some years ago with some success ! it is a messy process and some would say dangerous ! Noel.

[Dave Wootton]

On Dave Wootton Said:

Only slightly off topic, but does anyone remember some little tablets called something like Batt Aid that you dropped into your aged car battery in order to restore it to life again? I worked as a Saturday boy in an old fashioned motorcycle shop and there was a card of them on display, never remember any being sold. just wondered if anyone remembers them and if they worked at all?

Dave

Remember them well.  I always thought that they were simply an acid in solid form but I do remember the claims at the time made you think they were capable of bringing an old battery back from the dead!

[Dave Wootton]

On Dave Wootton Said:

Only slightly off topic, but does anyone remember some little tablets called something like Batt Aid […]

Google’s AI does 

Just put this into the search:

bat aid chemistry

MichaelG.

[jon hill 3Participant @jonhill3]

Hi all just to clarify as Noel pointed out it is a wet cell (says on the side filled with dilute h2so4) and a lot of battery manufactures seal the tops.  Although there are still breather holes.  I think this one has sat in a hot van for a few years hence loosing approx 1/2 ltr of electrolite in each cell.  Hopefully re-usable.

Ill dig out some pics

I have used things like batt aid in the past, other people have said they are the same as camden tablets and some folks use epson salts.  However Im not keen on changing the battery chemistry with such additives, if I can re-desolve the sulphates  all well and good.

.

[Robert Atkinson 2Participant @robertatkinson2]

If there was no liquid electrolyte visible it may be an absorbed glass mat AGM cell. These as classed a non-spillable. Only way to be sure is to look up the part number.
AGMs are pretty durable. My favorite is the Hawker SBS range. I have one that is still going strong at almost 30 years old. It’s first two years were hard work as itwas in Thrust SSC and for most of the time there was no onboard charging.
For recovery from deep discharge Hawker recommend connecting to a constant voltage source with a current capacity of at least half the Ah rating. The exact voltage depends on the model and temperature.
When faced with one that is so sulphated that it won’t draw any curent at normal voltage I’ve had about 10% sucess using a high voltage source limited to very low current. We are talking at least 50V current limited to about 0.1% of the Ah rating left for days. When the voltage comes down to about 2.3V per cell switch to normal contant voltage charging at high current.

Robert.

 

[Dave WoottonParticipant @davewootton]

Good heavens! they still make Bat Aid, and it seems it may even work. I worked in the shop in the early 70’s as a spotty 15 year old (Joe Francis Motors, New Eltham), astonishingly 53 years ago and the packing looked old then. I had always assumed they were like other things advertised in those less sophisticated times, such as X ray specs and arc welders that worked from a car battery, usually purchased more in hope than anger. Perhaps I should have sent for the X ray specs after all!

Dave

Even more off topic I remember a device called a Turbovisor which attached to the front of ones crash helmet to spin rain off ensuring clear vision, used to be advertised by Honda ace Jim Redman in the late 60’s. Always caused great hilarity when we regularly saw a chap using one when we were on our way to school. Sorry really gone off topic now!

[noel shelleyParticipant @noelshelley55608]

The spinning screen was in the marine world called a Kent Screen and driven by an electric motor. Noel.

[jon hill 3Participant @jonhill3]

Here a few pics, apologies for the quirky uploads, the closeups are supposed to show the electrolyte covering the lead plates after topup.  Its difficult getting the plates to show up.

[Dave HalfordParticipant @davehalford22513]

Jon, In a commercially made camper van the original battery would have been sealed, with a vent pipe leading outside to dump the charging gas safely. My Jeep has the same system as it sits under the front seats.

Tipping is the least of your worries.

[jon hill 3Participant @jonhill3]

Hi Dave my campervan is a custom converted panel van and its a bit Heath-Robinson to say the least! Sadly the previous owner didnt give me a wiring diagram for inverter/bms/solar charger.  Prior to powering up what can be described as a beer fridge it has only had light use to power led lighting.  I dont have a whale pump, tv or electric heater.  I did consider running a 500w angle grinder on the inverter but this might be too much of a current draw…..

[jon hill 3Participant @jonhill3]

Incidently re hydrogen gas from battery charging; surely its so volatile and in negligable amounts whilst charging it would escape before being a fire risk?

[bernard towersParticipant @bernardtowers37738]

you wouldnt say that if you see what happens when someone disconnects with the power on.

[noel shelleyParticipant @noelshelley55608]

It was only a small spark and a BIG battery – a 622, when the dust settled one end was missing ! I always blow over the terminals before disconnecting – it might help. Noel.

[Robert Atkinson 2Participant @robertatkinson2]

That is a flooded maintenance free battery. So no harm in topping up. I can’t find a charging spec but standard 13.8V to 14V should be OK. You could even try the Bat Aid tablets.

Robert.

[jon hill 3]

On jon hill 3 Said:

Incidently re hydrogen gas from battery charging; surely its so volatile and in negligable amounts whilst charging it would escape before being a fire risk?

Unfortunately no.  Yes, hydrogen quite quickly rises in free air duebto being of the lightest density and most actively diffusive gas.  However, it is derived from water in the electrolyte.  Water is hydrogen and oxygen so, when electrolysed, is broken into the perfect stoichiometric ratio of Hydrogen to Oxygen to reform into water if a spark is able to ignite it.  The extremely rapid recombination is the explosion within the battery.

some battery chargers, such as some of the CTEK range have a ‘reconditioning’ mode which can re-dissolve the sulphate on the plates and extend the life of the battery.  It is not a magic bullet, particularly if the battery is close to end of its limited life.

[jon hill 3Participant @jonhill3]

Thanks for the explanation, I re battery gas explosion. I think I will look into fitting a vent tube when I put the battery back or replace it.  Is there any safety issues which replacing the battery for a larger ampere hour? IE to the charge controller / BMS…. As far as I am aware the only charging to the leisure battery is via the glass solar panel on the roof.

[noel shelleyParticipant @noelshelley55608]

Venting when a battery is on charge is always a good idea, a few holes in the top of the box. A bigger battery, This may be fine depending on what the current draw is, recharging may be your limiting factor, ideally a battery should be kept fully charged. The charge voltage will remain the same, for the same type of battery, and as you are using solar your current will be what you get – depending on sunlight. It would depend on your needs as to whether it would be worth fitting a split charge system from the vehicles electrics to be able to recharge via the alternator, eg when using an inverter to power a grinder. There are numerous ways a battery can be recharged. Good luck. Noel.

[SillyOldDufferModerator @sillyoldduffer]

The chemistry and ways in which Lead Acid batteries decline is explained by Wikepedia.  One issue is that leaving them to discharge slowly forms insoluble Lead Sulphate, reducing the amount of charge the battery can hold, and how much current it can deliver.

Car batteries last because they’re operated well within their comfort zone.  A a short heavy current is drawn every time the car starts, followed by a fairly aggressive recharge as the car is driven along – takes about 20 minutes.  The cycle discourages sulphation.  Conversely,  leaving a car standing slowly kills the battery.

Leisure batteries have a different internal construction.  They are less vulnerable to sulphating, but still do it.

Batt Aid type chemicals, might remove enough insoluble sulphate to gee up the battery, but it’s a gamble.  The improvement is  temporary and the battery does not fully recover fully.  Worth a try, but keep expectations low!   Whether or not the trick works has never been proven.   If the battery is too far gone, the treatment won’t work at all.  Confusingly, any improvement is short lived – the battery seems better for a while, but charge is reduced, and it soon declines.  Unfortunately, people tend to report initial success, but not how long the fix lasted.  Murky!

Another might work dodge is to discharge the battery quickly enough to expand the plates inside by rapid heating, enough to dislodge the Sulphate, which falls to the bottom of the cell.  Not enough to dislodge the wanted filler or cause other damage. A suitable resistance is needed, something that will draw a 100A for a few seconds without catching fire!   I leave it to the reader to spot reasons why this one is best avoided.

Battery recovery is on the border between solid science and mumbo-jumbo hearsay.   For example, if the battery was over-charged, causing the water to electrolyse into Hydrogen and Oxygen, then it really is good to top up with distilled water, and to check the acid concentration with a Hygrometer.   In ye olden days, this was essential maintenance because vehicle voltage regulators were clunky inaccurate electromechanical devices that allowed a fair bit of overcharging before switching off.   Electronics have long since fixed that, so now it’s rarely necessary to add water and acid.  Difficult even to buy battery acid.    Conversely, if battery is on the way out, the door is open to folk remedies, with mixed results of dubious value.  The evidence isn’t encouraging,

If the battery life is usefully extended by several months, the treatment was worth it, otherwise the money would have been better put towards a new battery!   In my youth, my car wouldn’t start one cold morning, but I topped the battery up, applied the tablets and recharged it.   Got me through the winter, then I had to replace it.  At the time, I thought that was a win.  Now, I wouldn’t take the risk: I want my car to start reliably and am happy to pay for it.

Dave

[cogdobblerParticipant @cogdobbler]

Some Russian friends told me that back home on the farm they cut the top off the battery casing, pulled out the plates and scraped the sulphate off. Then welded the top back on the battery casing with their plastic irrigation pipe welder. Needs must!

 

[Stuart Smith 5Participant @stuartsmith5]

Jon

Looking at the dates on the side of the battery it looks like it was made early 2019. So it is over 6 years old. If you replace it with the same one ( around £100) it will have cost just over £15 a year. Doesn’t seem too bad to me.

My club has a battery electric loco with two of the exact same batteries. Though not traction batteries, they have lasted over 3 years of quite heavy discharge / recharge every week. They started to not last the full day of running even though they seemed to be fully charged.

We replaced them with the same ones a few weeks ago (just over £100 each at the time).

Stuart

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