Exploded battery.

[CorinneD]

Hi folks - hope you may be able to help us. We are fairly new to motorhoming and have only owned our motorhome for just over a year. It is a 2005 Compass Avantgarde 300. Once we "put it to bed" for the winter hubby plugged it into a mains supply at home and thought it would be ok for the winter as we tend to keep a very small tube radiator inside to stave off damp etc. He goes out to check every couple of days as we had a mouse problem last year. He went out to check it a couple of days ago and noticed the external battery compartment was open. On further inspection the lock had been blown off and the battery had exploded. Apart from the lock everything was ok but we are not sure how to proceed. Our questions are - 1. Should it not be left on EHU for a long time and could this have caused the problem? Also, could have been a fault with the van's system i.e not recognising the fact that the battery was charged and not cutting out? If that is the case how can we check the system to fault find? It was a low maintenance leisure battery. Many thanks
Corinne

 

[meanders]

More likely a build up of hydrogen in the cabinet, then something sparked. When you charge a battery it gives off hydrogen that rises. Always remove the cover and vent well before doing anything.

We had one that the dealer failed to vent before putting the meter on it and it blew up in his face.

Ours is on hook-up but on a timer for 4 hours a day.

 

[VXman]

More likely a build up of hydrogen in the cabinet, then something sparked. When you charge a battery it gives off hydrogen that rises. Always remove the cover and vent well before doing anything.

Shouldn't be a problem. If you are driving it will be charging constantly. Mine is connected to solar so is charging all the time. The charger should manage any charging and lead acid batteries like being charged all the time.

So, should be ok on EHU too. CorinneD needs to check the charger is working correctly. Should go to float once charged fully - around 13.2V. Maybe the battery was faulty?

 

[Raul]

In normal operation, the gassing is minimal, not enough to cause a blow up. Even without vents. The problem is the charger putting to much charge causing the battery to excessively gas, eventually leaving the battery dry.
So the charger needs to be switched off, it’s not compatible with that kind of battery for long periods. There are battery maintainers that can be left connected indefinite.

 

[Derbyshire wanderer]

A battery charger of that age would be relatively simple and would be overcharging the battery and boiling it over time.
Should not be left on permanent charge unless you us a proper charger designed for monitoring the battery indefinitely.

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[CorinneD]

How would we shut the charger off? It is inside the van under the seat where the wires come in etc?

 

[RogerIvy]

Most likely a bad or faulty charger. It happens. I’ve left good batteries on a decent charger for years.
One of the nice things about Lithium is they don’t have thermal runaway.

 

[PhilandMena]

Lots of assumptions being made here ! The battery needs to be replaced. Also the the on board charger should be checked out to ensure its OK for the type of battery fitted and supplying the correct charge, this can be easily confirmed with a cheap digital mutimeter.
Its possible the battery that has exploded had developed an internal fault or had never had its acid levels checked, assuming it was lead acid.
If the charger is working correctly and is a smart charger you can safetly leave it connected and switched on for very long periods.

 

[Phill D]

How would we shut the charger off? It is inside the van under the seat where the wires come in etc?

I assume it’s by plugged into the mains, put a timer on the plug to switch on a couple of hours a day.
Ps; after replacing the battery and checking things out .

 

[CorinneD]

We purchased a Battery Master and connected that as we thought it was supposed to charge the van battery and then feed into the leisure battery.

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[CorinneD]

Sorry for all the questions. Just been doing a bit of research and have seen things which state there should be a tube from the leisure battery to outside. Haven't seen one of these on a leisure battery so how would we achieve this?

 

[Raul]

Sorry for all the questions. Just been doing a bit of research and have seen things which state there should be a tube from the leisure battery to outside. Haven't seen one of these on a leisure battery so how would we achieve this?

Only if you have a battery that provides a tube take off, if it’s a sealed battery, and still gasses, it’s excessive charging at fault. Your charger more than likely boiled the battery until the plates run dry.

 

[Phill D]

We purchased a Battery Master and connected that as we thought it was supposed to charge the van battery and then feed into the leisure battery.

unless the battery master is connected differently the standard connections keep the cab battery charged from the liesure battery from the liesure battery when the cab battery drops to hab battery has a difference of i believe 0.5volts.
so the main charger charges the hab battery and the battery master trickle charges the cab battery from the hab battery. not the other way around.

 

[Spriddler]

Deleted - must pay more attention.

 

[Pausim]

We purchased a Battery Master and connected that as we thought it was supposed to charge the van battery and then feed into the leisure battery.

The Battery Master is designed to provide a trickle charge to the engine battery taking power from the leisure battery. It will not protect the leisure battery from overcharging and gassing. Many older motorhomes had a 12V power supply rather than a proper battery charger designed for long term battery maintenance. If you want to leave a lead acid battery on charge for long periods you need a proper multi stage charger that monitors the battery state and adjusts the output accordingly.

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[CorinneD]

unless the battery master is connected differently the standard connections keep the cab battery charged from the liesure battery from the liesure battery when the cab battery drops to hab battery has a difference of i believe 0.5volts.
so the main charger charges the hab battery and the battery master trickle charges the cab battery from the hab battery. not the other way around.

Sorry my mistake - it is they way you say.

 

[Kannon Fodda]

Too many older and even quite new motorhomes have too basic a charger system.

Ideally the charger will be smart and has phases for bulk, absorption and finally float. Those can be left on for a while.

The basic chargers simply output a constant voltage to the battery. The Sergent unit on my 2019 van output a continuous 13.8V at up to 12A. Any battery on the receiving end would have been continously overcharged even when it was full. Even a so called sealed lead acid would suffer.

With the basic charger you have to manually intervene to prevent overcharge and thus timer becomes important.

 

[Pausim]

Too many older and even quite new motorhomes have too basic a charger system.

Ideally the charger will be smart and has phases for bulk, absorption and finally float. Those can be left on for a while.

The basic chargers simply output a constant voltage to the battery. The Sergent unit on my 2019 van output a continuous 13.8V at up to 12A. Any battery on the receiving end would have been continously overcharged even when it was full. Even a so called sealed lead acid would suffer.

With the basic charger you have to manually intervene to prevent overcharge and thus timer becomes important.

These 13.8V fixed voltage units should be described as power supplies not as chargers.

 

[Richard n Ann]

The basic 'chargers' that output 13.8v aren't actually chargers but power supplies, they never fully charge the battery and they shorten the batteries life.

Also if the battery is faulty, even a smart charger will cause a problem. Our battery had a shorted cell in 2019, the solar regulator thought the battery was flat so put full power into it, the battery got hot, fortunately the solar regulator shut down because I fitted the optional temperature sensor.

I never leave a high power charger unattended now, I use an optimate maintainer at home which is low power and incapable of getting anything hot.

 

[Thornebt]

Too many older and even quite new motorhomes have too basic a charger system.

Ideally the charger will be smart and has phases for bulk, absorption and finally float. Those can be left on for a while.

The basic chargers simply output a constant voltage to the battery. The Sergent unit on my 2019 van output a continuous 13.8V at up to 12A. Any battery on the receiving end would have been continously overcharged even when it was full. Even a so called sealed lead acid would suffer.

With the basic charger you have to manually intervene to prevent overcharge and thus timer becomes important.

I've got a Sargent EC325 unit in my 2010 Autosleeper. The EC325 manual says it has an intelligent charger that accurately controls the charging current. But your Sargent unit outputs a constant 13.8v.

Hopefully my Sargent unit will not cook my battery even if left on EHU for a week or two.

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[PhilandMena]

I've got a Sargent EC325 unit in my 2010 Autosleeper. The EC325 manual says it has an intelligent charger that accurately controls the charging current. But your Sargent unit outputs a constant 13.8v.

Hopefully my Sargent unit will not cook my battery even if left on EHU for a week or two.

Or even a few months at a time. I've been doing this for years with my 2011 Autotrail. Too much misleading or wrong information being posted on this forum.

 

[Abacist]

With the variety of types of battery nowadays, chargers have to cope with differing charging voltages and regimes and it must happen that chargers are set to the incorrect charging profile for battery concerned as well as the possibility of sending the incorrect voltage if it goes into a fault condition.

 

[CorinneD]

Thanks everyone. Given us some helpful info.

 

[Lenny HB]

The basic 'chargers' that output 13.8v aren't actually chargers but power supplies, they never fully charge the battery and they shorten the batteries life.

With those chargers you are doing well if you get two years out of a battery if on EHU a lot or leave it on at home.

 

[TheBig1]

It used to be more common to see batteries spontaneously decommission themselves in the days before smart chargers. Believe me when I say thank God you were not near it when the battery blew. Please consider updating the charger in your van when fitting the new battery. Not a difficult job. Either remove the old one or take out it's fuse. Plug the new one into a socket and just 2 wires to feed to the battery. You will gain safety and the new battery will charge better and last longer with a multistage smart charger

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[autorouter]

Sorry for all the questions. Just been doing a bit of research and have seen things which state there should be a tube from the leisure battery to outside. Haven't seen one of these on a leisure battery so how would we achieve this?

Batteries can be either vented or sealed. The old traditional construction has six vents, one for each cell. The kind of lead alloy used to make the battery plates causes gassing during normal charging operation. Such batteries should be in a well ventilated battery compartment, and need to be topped up with distilled water every so often to replace the water lost by the action of the charger on the battery fluid. Also the gases are explosive, so precautions need to be taken to vent the gases and avoid sparks that could ignite the gases.

However your battery was not this older type, because you said it was the 'low maintenance' type. These batteries are sealed, and use a different kind of lead alloy for the battery plates which do not produce gas during the normal charging process. They have a built-in pressure release valve in case a faulty charger or an internal battery fault causes gassing. These batteries do not need to be enclosed in a special battery compartment like the vented batteries. Some of these batteries have a vent tube which is intended to duct any small amount of gas produced to the open air outside the vehicle. If a low maintenance battery explodes, it must be due to a serious fault in either the battery or the charger. I think you need to have the charger checked before you connect up a new battery, or the same thing might happen again very soon.

Most modern battery chargers are 'intelligent', in that they constantly monitor the battery voltage and amps, and know the state of charge of the battery at all times. They provide voltage and amps suitable for each stage of the charging process. When the battery is 100% charged, the charger will dial back the charging to a 'float' charge, which keeps the battery topped up but won't overcharge it.

However there are other battery chargers that simply push out a constant voltage regardless of the battery state. These are not intended for charging the battery indefinitely, but even so they shouldn't create enough of a problem to cause an explosion. These simple constant voltage chargers are becoming less common, but may still be fitted even to quite modern motorhomes.

If your charger is suspect, I think it's better to fit a new intelligent charger rather than buy a new charger of the simple constant voltage type. And from what I've seen, there's probably not much difference in the price anyway.

 

[AdrianChen]

I've seen a couple of battery explosions/bursts, both without any flame or burning and no signs of fire damage to the battery locker/boxes, so presumably just a build up of pressure within the battery case, perhaps faulty pressure release valves, or blocked vents and tired battery. One pair were 6d engine start batts and went as the engines were being started, had been left on a smart charger for some months, turned out the charger was fine and the battery was blamed apparently either distorted plates, or build up of sediment. The other a 4 year old 100AH leisure battery that was less volatile, but covered the locker in acid and muck, had been left 48hrs on a an early type "safe" charger which may not have worked, but I know the battery had been cycled regularly below 50% in its life.

A third lot of 4* 185AH AGM (VRLA) types I came across belonging to a friend, were being maintained by an expensive modern smart charger all 4 had melted and swollen so badly the battery box had to be cut up to remove the batteries after they had cooled down, it took 48hours for them to cool. It was on a whim he went to check the boat and noticed the smell, had the charger not been disconnected I suspect ignition might well have occurred in this case, and the damage would have been spectacular, and dangerous.

My reaction to that has been to be wary of how batteries are treated, and maintained over their life, especially as they get older even if they say no maintenance. So I now tend to replace mine when the capacity has dropped to the point I notice it, or I see any other sign of trouble which I did on one of my own AGM banks (6*185AH cases distorting on 4). Happily it seems to be a rare(ish) occurrence in truth.

I've so far only had one problem with Lifepo4, caused by a faulty cell which the BMS detected and shut the battery down. This was one of a pair left on the makers charging/maintenance system, the second unit was fine. The makers agent said there was some float charge leakage past the BMS that had overcharged the cell.