XRN Posted July 20, 2015 Share Posted July 20, 2015 At 05:30 on saturday morning the Carbon Monoxide alarm in the Hymer went off causing all sorts of panic to us sleeping inside. There didn't seem to be any obvious reason as all the gas appliances were switched off. The only thing I noticed at the time was that the leisure batteries were below 12.5 volts and they appeared to be charging from the EHU. Of concern was the charging rate was at 15 Amps on the analog battery charge indicator which to me seems massive. We have a solar panel which tends to keep the batteries topped up normally so I am at a loss why the battery would need a charge at this rate. Van is a Hymer 680, 2001 year and the Charge indicator situated above the Hab door is a red/ green needle type with values from -ve 25Amps (Red) to +ve 25Amps (Green). Normally the needle is just off the zero towards +ve and I have never noticed it going as high as when the alarm went off. Does this suggest I have a duff charger when on EHU? Googling has suggested that CO alarms will activate when they detect Hydrogen which would be given off batteries when charging. Any ideas what I should check first? Link to comment Share on other sites More sharing options...
Guest Joe90 Posted July 20, 2015 Share Posted July 20, 2015 I'm no expert on batteries or charging systems, but I'd check that you battery isn't knackered, perhaps the charger was going full pelt in an attempt to charge it, and over gassing as a result setting off your alarm. Link to comment Share on other sites More sharing options...
XRN Posted July 20, 2015 Author Share Posted July 20, 2015 That was my first thought too, it did however appear to be charging at a reduced rate later in the day till the battery charge was normal then the needle was in its usual position of just above zero. I will do as you suggest and give the batteries a visual check then get them tested. I am not sure where the charger is or what it looks like so a check of that might be beyond my technical knowledge!! :-S Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 20, 2015 Share Posted July 20, 2015 You haven't said what size or type of habitation battery (Flooded, AGM, gel etc) is fitted, or how old it is. If flooded, is the electrolyte level correct? If correct, have you disconnected all charging sources, switched off or disconnected all 12V consumers, allowed the battery to stand for 4 or so hours, and then checked its voltage at the battery terminals? You should be seeing about 12.8V if it is fully charged. If less, I'd be suspicious of the battery. Your next move would be to turn on lights to a known wattage (about 60W {5A} would be ideal, so 3 x 20W spotlights) and take further readings each hour for 4 hours. At the end of 4 hours you should have taken 20Ah from the battery. If the battery is an 80Ah battery that would equate to about 25% of its capacity, leaving it 75% charged and a voltage of 12.55. If the voltage gets to that level significantly more quickly (assuming it is an 80Ah battery) it is in trouble. Link to comment Share on other sites More sharing options...
XRN Posted July 20, 2015 Author Share Posted July 20, 2015 Thanks Brian, a useful diagnosis procedure, and most appreciated. Having only had the Hymer a couple of months I am not sure how old or what size/type the leisure batteries are so until I can get to them (in a box under the seats with a screwed down board on top) I can't update any further with that. As far as trying to identify the fault so far, that is nil. We only got back last night and just put the van in storage and its back to work today so tomorrow evening will be the first opportunity I have to look further. If I disconnect the batteries will the solar panel/controller be ok? Link to comment Share on other sites More sharing options...
Guest Joe90 Posted July 20, 2015 Share Posted July 20, 2015 XRN - 2015-07-20 2:22 PM Thanks Brian, a useful diagnosis procedure, and most appreciated. Having only had the Hymer a couple of months I am not sure how old or what size/type the leisure batteries are so until I can get to them (in a box under the seats with a screwed down board on top) I can't update any further with that. As far as trying to identify the fault so far, that is nil. We only got back last night and just put the van in storage and its back to work today so tomorrow evening will be the first opportunity I have to look further. If I disconnect the batteries will the solar panel/controller be ok? There should ( ideally ) be an isolation switch or fuse coming from the solar panel before it connects to your controller, if not carefully ( avoiding any short circuiting ) disconnect one of the wires coming from the panel to the controller, keep it isolated, then disconnect your batteries, the solar panel itself will not be harmed even though it is still exposed to sunshine. On completion of your investigations, first reconnect the batteries, before reconnecting the solar panel wire you have disconnected to your controller. Worth noting that some leisure batteries will only give around 150 charge discharge cycles, and you can get one go duff even before that. :-( Link to comment Share on other sites More sharing options...
XRN Posted July 22, 2015 Author Share Posted July 22, 2015 I have only been able to give the batteries a visual check so far. They are deep in a box which prevents any side stickers being visible to determine what type and size they are but a sticker on the box states that only Gel type batteries should be fitted so I am assuming that gel type are the ones installed. Only visible mark is that they are Bosch. There are 6 white caps on the top of each battery which I couldn't unscrew, does this suggest they are lead acid type or gel? I measured the voltage whilst they were standing and reads 13.7V with no consumers running, however the solar panel was still charging so probably not much use for diagnosing the problem. I used a gas detector from work and found that when the probe was put to the bottom of the box it picked up a low level of gas which was probably hydrogen from the batteries. I would have thought there should be a vent for the battery box to outside the hab area to prevent the build up of this gas but I couldnt find one. There are a load of wires on top of the batteries which I have no idea what they feed so disconnecting the batteries to do further checks is a bit daunting in light of other posters electrical problems after changing batteries. Link to comment Share on other sites More sharing options...
Guest Joe90 Posted July 22, 2015 Share Posted July 22, 2015 You've been very thorough, but I wonder if the CO2 alarm could be the culprit, they only have a certain life span, might be worth looking to see if there is a date on it indicating that, or it's manufacture date and or replacement recommendations, or even the batteries on the blink could possibly be another factor. Link to comment Share on other sites More sharing options...
starvin marvin Posted July 22, 2015 Share Posted July 22, 2015 XRN - 2015-07-22 9:12 AM I have only been able to give the batteries a visual check so far. They are deep in a box which prevents any side stickers being visible to determine what type and size they are but a sticker on the box states that only Gel type batteries should be fitted so I am assuming that gel type are the ones installed. Only visible mark is that they are Bosch. There are 6 white caps on the top of each battery which I couldn't unscrew, does this suggest they are lead acid type or gel? I measured the voltage whilst they were standing and reads 13.7V with no consumers running, however the solar panel was still charging so probably not much use for diagnosing the problem. I used a gas detector from work and found that when the probe was put to the bottom of the box it picked up a low level of gas which was probably hydrogen from the batteries. I would have thought there should be a vent for the battery box to outside the hab area to prevent the build up of this gas but I couldnt find one. There are a load of wires on top of the batteries which I have no idea what they feed so disconnecting the batteries to do further checks is a bit daunting in light of other posters electrical problems after changing batteries.[/quote For goodness sake take the van to somewhere/someone who knows what they are doing/looking at.] Link to comment Share on other sites More sharing options...
XRN Posted July 22, 2015 Author Share Posted July 22, 2015 I did suspect the CO monitor but it was brand new in June this year. I have taken it out and put it in the house to see if it goes off spuriously but so far not. Taking the van to "someone who knows what he is looking at" is easier said than done as most autoelectricians are reticent to get involved in motorhome habitation electrics and those that do are booked up till after the summer so that ends my holiday plans unless I can resolve it :'( Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 22, 2015 Share Posted July 22, 2015 XRN - 2015-07-22 9:12 AM I have only been able to give the batteries a visual check so far. They are deep in a box which prevents any side stickers being visible to determine what type and size they are but a sticker on the box states that only Gel type batteries should be fitted so I am assuming that gel type are the ones installed. Only visible mark is that they are Bosch. There are 6 white caps on the top of each battery which I couldn't unscrew, does this suggest they are lead acid type or gel? I measured the voltage whilst they were standing and reads 13.7V with no consumers running, however the solar panel was still charging so probably not much use for diagnosing the problem. I used a gas detector from work and found that when the probe was put to the bottom of the box it picked up a low level of gas which was probably hydrogen from the batteries. I would have thought there should be a vent for the battery box to outside the hab area to prevent the build up of this gas but I couldnt find one. There are a load of wires on top of the batteries which I have no idea what they feed so disconnecting the batteries to do further checks is a bit daunting in light of other posters electrical problems after changing batteries. The originals would have been gel type. How old is the van? Is it possible they have been changed? If original, and the van is more than 5 years old, they may be near the end of their lives, especially if they have been abused in the past. If they have been replaced with flooded batteries and are not vented, I'd say you should disconnect all means of charging for the time being, and leave the box open. Hydrogen is lighter than air, so will not be in the bottom of the box. Installing un-vented flooded batteries in a sealed box would be dangerous, with the risk of the hydrogen igniting and possibly causing an explosion. Very nasty! You really need to get the van to a motorhome dealership with a competent electrician and a decent workshop, preferably one familiar with Hymer electrics, for them to work out what is happening. Looks as though Lowdham in Huddersfield or Airstream in Tebay (Cumbria) would be your nearest. There should be a main fuse by the positive terminal of the battery. Once the chargers are both isolated, pull that fuse. That should leave the van safe to drive. However, speak to the workshop foreman beforehand, and take his advice on the best approach. Link to comment Share on other sites More sharing options...
Guest Joe90 Posted July 22, 2015 Share Posted July 22, 2015 He said at the top of the thread the van is 14 years old. :-S Must pay more attention, as my old teacher used to say. :D Link to comment Share on other sites More sharing options...
XRN Posted July 24, 2015 Author Share Posted July 24, 2015 Followed the advice and I think I have found the problem. Firstly, the batteries fitted are lead acid flooded type despite the sticker saying only fit Gel type, (probably because there is no ventilation). Removal of all the cell caps revealed one battery with no acid visible above the plates and the plates have started to blow so essentially its knacked. The other battery was low on acid but all plates were covered and is holding a charge. From a bit of info I found on another site (caravanchronicles.com) it also appears that they have not been wired in parallel in the best way which means that one battery is always lagging behind the other when both charging and discharging so one battery is doing all the work. 2 new batteries are needed I think, any advice on make and size and suppliers as we mostly use EHU when away? Is going back to one battery a good idea? Link to comment Share on other sites More sharing options...
kevina Posted July 24, 2015 Share Posted July 24, 2015 Well I would suggest putting one gel battery in for your type of use. Check the charger is set to gel batteries rather than flooded lead acid as it may have been changed from the factory preset. (small switch probably inside the casing). Kev Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 25, 2015 Share Posted July 25, 2015 XRN - 2015-07-24 9:26 PM.................... 2 new batteries are needed I think, any advice on make and size and suppliers as we mostly use EHU when away? Is going back to one battery a good idea? I question the need for two batteries if you mostly use EHU. But, that would depend on what you do when not on EHU, and for how long. One good quality (e.g Exide or Sonnenschein) gel battery of around 85Ah should get you through two - three days off EHU, but it won't thank you for discharging it too heavily. The often stated limit is about 80%, beyond which you would begin to affect its life in terms of the number of charge-recharge cycles it will sustain. Repeated discharging below 80% (depth of discharge, often abbreviated to DoD) is stated to reduce the number of cycles to below 900. This information is relevant to quality gel batteries only. This in turn depends on having a relatively gentle rate of discharge, so, for example, running a microwave through an inverter (or a 12V microwave!) or similar use will punish it more than merely having water and space heater, and lights, running. It also depends on how sophisticated a charger is fitted. As your van is now about 14 years old (thank you Joe, missed that) it seems likely not to be up to the standard of the more recent "smart" chargers, so it may be a bit "rougher" with the battery. But, if you are only off EHU for the odd night, and don't make high use of the 12V system under those circumstances, I'd question the need for a gel battery. They are considerably more costly for equivalent quality and capacity. However, if you change the battery type you must first check that the charger is switchable for other types. If you'd prefer a cheaper zero maintenance battery that doesn't require venting, I think AGM may be worth considering, and it would charge as a flooded battery. But, if you are prepared to install a venting tube and make occasional checks on the electrolyte level, the best value for money for capacity and quality would probably be obtained by installing a vented flooded lead-acid leisure battery. In the case of the latter, it may be wise to increase the capacity since the discharge limit of flooded batteries is about 60% in lieu of the 80% for gel (so making a 110Ah flooded battery roughly equivalent to an 80Ah gel). Whether you can do this will depend in part upon the space in your battery box. Just be aware that not all batteries of equivalent capacity are of the same physical sizes. Be very cautions about claimed capacities, as they are prone to over-statement. I'd suggest you have a look at Tayna's website, which is a fund of useful information, and also gives a lot of useful technical detail including physical dimensions. However, it seems they may not sell the Banner AGM batteries (fitted to my 2013 Hymer), which seems odd - but a phone call will probably reveal why. A rule of thumb in comparing is to look at the weights. For the same capacity in Ah and type the heavier battery should have the thickest lead plates and the greatest service life. If your use of the battery is really only occasional and very short term (just a few hours) the battery is spending most of its time ballasting the transformer/charger unit and the choice of type is not that critical, although a normal starter battery may not prove the best choice if you find you do have to fall back on it as your main source of 12V power - for example in the event of an extended mains power outage. But, if you are confident this would be the main risk, a so called marine or dual use battery may be adequate, and should be the cheapest option of all. It is likely to be a flooded battery and if so must be vented. Unless you want to go to "battery school" (our resident teacher is brambles, but he seems to be away at present, and I couldn't begin to supply the detailed technical knowledge in this field that he possesses), I think your best bet would be to stick to Exide or Sonnenschien for gel, or to Banner for AGM or flooded batteries. I believe Tayna are quite competitive for price, and they deliver all over UK so, coupled with their technical knowledge, they are a reasonable one stop shop if in a hurry. Otherwise, to get the best available forum advice, try a PM to brambles and see if he responds, or wait a few days longer to see if he picks up on this string. Link to comment Share on other sites More sharing options...
candapack Posted July 25, 2015 Share Posted July 25, 2015 Why do we talk about alarms going off? Surely they're off most of the time, and then go on as necessary (or unnecessary in case of OP). Sorry, off topic. *-) Link to comment Share on other sites More sharing options...
lennyhb Posted July 25, 2015 Share Posted July 25, 2015 XRN - 2015-07-24 9:26 PM Followed the advice and I think I have found the problem. Firstly, the batteries fitted are lead acid flooded type despite the sticker saying only fit Gel type, (probably because there is no ventilation). Removal of all the cell caps revealed one battery with no acid visible above the plates and the plates have started to blow so essentially its knacked. The other battery was low on acid but all plates were covered and is holding a charge. From a bit of info I found on another site (caravanchronicles.com) it also appears that they have not been wired in parallel in the best way which means that one battery is always lagging behind the other when both charging and discharging so one battery is doing all the work. 2 new batteries are needed I think, any advice on make and size and suppliers as we mostly use EHU when away? Is going back to one battery a good idea? Yep you have found the problem, Bosch don't make Gel batteries. If you look at the front of the Elektroblock there is a switch that changes the charge set up from Gel to Wet, if it's been left on Gel it will cook a wet cell. As Brian says if you mainly use EHU no point in having 2 batteries, if you fit a wet battery do make sure the Elektroblock is set correctly & the battery is ventilated, Gel's aren't much dearer than good quality wet cells these days you can get one from Tayna batteries for less than £150. Link to comment Share on other sites More sharing options...
XRN Posted July 25, 2015 Author Share Posted July 25, 2015 Thanks for all the helpful information guys, further investigations revealed the electroblok is in the gel setting which has probably compounded all the other issues I found!! It also looks like a previous owner has drilled a few vent holes in the side of the fibreglass battery box to outside so fitting a vent from a new battery wont be a problem. I will get one ordered tonight. Link to comment Share on other sites More sharing options...
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