Marvinstephen Posted June 9, 2016 Share Posted June 9, 2016 Hi from a newbie to this forum and to motorhomes. I read all forums and blogs with interest when choosing and buying my very first motorhome, but didn't expect to be participating so soon! More on that later. Firstly thanks to all of you involved in earlier threads on repairing electric steps. On the way home from a fantastic trip to Spain, the electric step on the habitation door on my Hymer B-Classic 575 (2004 plate) stopped working. Back home I read all the posts I could and eventually got the courage to remove the motor and investigate. Although not working when on the vehicle, once removed and the back plate taken off, it decided to respond to a 12V charge. I cleaned and re-greased it, re-fixed the back plate and re-attached and to my surprise it is now operating as before. Just one question.... when the step is operating, the 12V gauge (above the habitation door) swings into the red/negative sector (about 1/3rd), then almost to full 'draw' as the motor reaches it's end point, then returns to the centre point once the switch is released. FYI, the leisure batteries continue to maintain their charge (~14V) with the solar panel fitted. Now I don't remember this happening previously - is this normal (and I just didn't notice before), or is it indicative of a problem with the step motor and/or 12v system? NB: The 12v system tripped out a few times when the step was faulty. We could re-set it either by switching on and off at the panel above the door, or by repeatedly switching the Electroblock (99) on and off. All advice greatly appreciated. Link to comment Share on other sites More sharing options...
Robbo Posted June 9, 2016 Share Posted June 9, 2016 Wecome to the forum. I had a Hymer and as far as I remember there were two gauges, one for volts and one for amps. I think you are looking at the amps drawn when the step is being operated. I don't think you have anything to worry about as it's only over a short duration. I would be more worried if the voltage started dropping rapidly. Whenever you draw current the ammeter will show a negative discharge, whether this is the step, the water pump, the lights etc. Link to comment Share on other sites More sharing options...
aandncaravan Posted June 9, 2016 Share Posted June 9, 2016 When you operate the Step, it is normal for the Ammeter to record the current draw, as it will for all consumers. One third (10amps?) seems a bit high for a step motor though? When the step is fully extended or retracted, the Motor will stall but keep trying to retract/extend the step so draw a lot more current which will again be recorded. However 30 amps (assuming you have an IT992/IT994 or equivalent) seems exceptional? Is the Step Earth point absolutely perfect? A poor earth can result in a high current reading. It is important you release the switch as soon as the step reaches it's end stop as the current being drawn could place a strain on the wiring/Motor. Some vehicles have a Step controller that cuts the power to the step motor when the 'Stall' current threshold is reached to prevent damage, even if the switch is continued to be held in. I would guess that the reason the Schaudt Elektroblock EBL 99 'tripped out' was because the current draw was so high (and maybe the battery also past it's best?) causing a voltage drop that led the EBL 99 to believe the battery had dropped below the 10.5v cut off point, so shut down? If that is the reason for the shutdown, next time wait 30 seconds for the voltage to recover and turn the IT992 on/off switch back to on. Suggest you do not operate the EBL 99 front 'isolation' switch, as the EBL has a habit of not powering back on when the switch on the front of the EBL itself is used. If the battery is tired, a replacement quality battery, might make an improvement to the step operation? I would suggest that if the step can drop the voltage so low that the EBL shuts down, the batteries may be long overdue for recycling? The Solar Panel will mask the batteries true ability, as most of the time you will rarely see the actual battery voltage, just the voltage at the battery from the Solar Charger. For example, you might be seeing a 14v charge current on the display from the Solar Regulator, but the 'real' battery voltage might only be 11.6v? Try disconnecting Solar, and all other charging, turn off the IT992 above the door then wait 2 weeks before rechecking the habitation battery voltage. It shouldn't have dropped at all. Suggest that when you 'disconnect the Solar' you only isolate the Solar Panel from the Solar Regulator, not the regulator from the EBL 99/battery. Link to comment Share on other sites More sharing options...
Marvinstephen Posted June 10, 2016 Author Share Posted June 10, 2016 Guys, many thanks for your prompt and helpful feedback. In response: - The Amp meter of the IT992 shows a draw of ~ 2.5A when the step motor is running, with a spike of ~25A whilst the switch is depressed at the end of travel (for some reason seems to be more so when step at the bottom end of travel rather than raised?) - Again, I'm not sure if this was the case previously, but the more I think about it the more I'm sure I rarely saw any movement on the Amp meter even when numerous 12v items were in use - Step earth point - I'm not sure where this is. There is only live and neutral feed to the motor with no earth wiring visible, unless it is just earthed through it's attachment to the frame - the 12v was tripping out during the night, so the theory of low battery voltage could make sense - I would be worried if it was a leisure battery problem. The van has 2 leisure batteries, Exide Gel G80 (12v 340A (DIN) 80Ah (20h) 90 Ah (100h). They both look relatively new (not very technical!) and I've only had the van for 13 months. They're under the driver and passenger seats and so access is a little difficult. Should they have a date stamp somewhere? - Willing to try your suggestion to test batteries by isolating the solar panel but..... I'm going to sound dim on this one as I have no idea of how or where the solar panel is wired into the system. The only item I can find is next to the Electroblock is a 'Schaudt Solar-Laderegler LR 1214 (12V 14A)', with 4 feeds, ie, Solarzelle '+ 'and '-' and Batterie '+' and '-'. Is this where I should isolate the solar panel? Link to comment Share on other sites More sharing options...
Dr Dave Posted June 10, 2016 Share Posted June 10, 2016 Sorry just wondering in aandncaravan's post how a poor earth can increase the current? Link to comment Share on other sites More sharing options...
aandncaravan Posted June 12, 2016 Share Posted June 12, 2016 Dr Dave - 2016-06-10 9:54 PM Sorry just wondering in aandncaravan's post how a poor earth can increase the current? Dave, I guess you ask the question because you assume the connection will be a fixed resistance and Current drop should occur along with the Voltage drop from the 'poor connection'? When I was 22 I was the proud owner of a 1963 Humber Sceptre. It suffered from a little bit of tin worm that I had on my list of things to do at some time in the future, when the exhaust fell off. A weld had broken. In the day, 40 years ago, I saw an advert for a 'Welding Kit' that basically comprised a set of Jump Leads for a 12v battery, with a one end of the Positive lead being modified to accept a welding rod. I bought one with intention of tackling the exhaust and the Tin Worm, but soon found that it had been a Con. However, not being able to afford any other solution I was determined to make it work. I got another good 12v battery from a scrap yard and connected two to give me almost 25v and although the Weld looked appalling, it sort of worked. By the time I had finished welding the exhaust, the batteries were destroyed from the huge currents required to melt the thin exhaust steel. That taught me a lot about the limitations of batteries when passing sustained high current, but also helped me understand why some power supplies in the TV's I repaired as my Saturday job, were destroyed when the current they were passing should not have been able to create the damage I saw. I knew that when a poor connection occurred, the Voltage drop across that connection generated heat. However, because that also resulted a drop in current, the damage should not have been as great as I was seeing. The welding showed me that where a connection had a varying resistance, maybe where it actually became 'open circuit' at times, the Current that was drawn in 'jumping the Air gap' could be enormous and enough to melt steel. Since those days I have seen many poor connections, particularly those involving corrosion and dissimilar metals, that vary connectivity and resistance even as electricity is applied. Don't forget that at a Step Earth Point there are often two connections with quite different 'properties'. The first is the usual steel 'ring Tab terminal' that is crimped onto the Copper Wire which gives dissimilar metal corrosion between the steel 'Ring Tab' and the Copper wire. Plus the second connection point where the Steel ring tab bolts to an often Steel/Zinc body point that also corrodes. Many people just unbolt the Cable/wire Ring terminal, clean it and the Chassis point, then bolt it back together when it is the corrosion at the point where the Ring terminal connector crimps onto the Copper cable that is the prime issue. In 'the old days' these Tab rings were often Brass, so less corrosion seemed to take place between it and the cable. You can appreciate that many different factors with both Voltage and Current might come into play due to both the nature of the metals, the humidity and the corrosion bi-product material itself? We advise that where poor Earths are suspected you don't just clean the Chassis/connector, but cut the old terminal connector off the cable and fit a new one. If you cut the junction open you may find, as we do, a white and green mess of powdered corrosion. Some Electric Motors have also been seen to draw more current when the voltage drops across a poor connection. We often see higher than normal current drawn through the wiring to Step electric motors with poor Earths/Connections. It is usually the prime cause of burnt Step Controller failure, like the Arsilicii ES803. Clean and eradicate the poor connection point and the current draw returns to normal. So while the Physics book might say it shouldn't, there are other factors at play, and it does. Marvin, 2.5amps is not a bad current draw for a normal working step. The stall current seems high but you can work around that by releasing the switch as soon as the step is retracted/extended. There should be a fuse installed by the Solar fitter to allow you to isolate the Solar Panel from the regulator at the point where the cables enter the van at ceiling level? That should be there for some electrical safety but also to allow maintenance work? If there isn't one, suggest you get one put in? If the batteries are under the seat they are a nightmare to replace, so people rarely do. As they are also £300 worth of Gel's, I would be confident in betting One Penny that they are a lot older than you think? Link to comment Share on other sites More sharing options...
Dr Dave Posted June 13, 2016 Share Posted June 13, 2016 aandncaravan - 2016-06-12 8:56 PM Dr Dave - 2016-06-10 9:54 PM Sorry just wondering in aandncaravan's post how a poor earth can increase the current? Dave, I guess you ask the question because you assume the connection will be a fixed resistance and Current drop should occur along with the Voltage drop from the 'poor connection'? When I was 22 I was the proud owner of a 1963 Humber Sceptre. It suffered from a little bit of tin worm that I had on my list of things to do at some time in the future, when the exhaust fell off. A weld had broken. In the day, 40 years ago, I saw an advert for a 'Welding Kit' that basically comprised a set of Jump Leads for a 12v battery, with a one end of the Positive lead being modified to accept a welding rod. I bought one with intention of tackling the exhaust and the Tin Worm, but soon found that it had been a Con. However, not being able to afford any other solution I was determined to make it work. I got another good 12v battery from a scrap yard and connected two to give me almost 25v and although the Weld looked appalling, it sort of worked. By the time I had finished welding the exhaust, the batteries were destroyed from the huge currents required to melt the thin exhaust steel. That taught me a lot about the limitations of batteries when passing sustained high current, but also helped me understand why some power supplies in the TV's I repaired as my Saturday job, were destroyed when the current they were passing should not have been able to create the damage I saw. I knew that when a poor connection occurred, the Voltage drop across that connection generated heat. However, because that also resulted a drop in current, the damage should not have been as great as I was seeing. The welding showed me that where a connection had a varying resistance, maybe where it actually became 'open circuit' at times, the Current that was drawn in 'jumping the Air gap' could be enormous and enough to melt steel. Since those days I have seen many poor connections, particularly those involving corrosion and dissimilar metals, that vary connectivity and resistance even as electricity is applied. Don't forget that at a Step Earth Point there are often two connections with quite different 'properties'. The first is the usual steel 'ring Tab terminal' that is crimped onto the Copper Wire which gives dissimilar metal corrosion between the steel 'Ring Tab' and the Copper wire. Plus the second connection point where the Steel ring tab bolts to an often Steel/Zinc body point that also corrodes. Many people just unbolt the Cable/wire Ring terminal, clean it and the Chassis point, then bolt it back together when it is the corrosion at the point where the Ring terminal connector crimps onto the Copper cable that is the prime issue. In 'the old days' these Tab rings were often Brass, so less corrosion seemed to take place between it and the cable. You can appreciate that many different factors with both Voltage and Current might come into play due to both the nature of the metals, the humidity and the corrosion bi-product material itself? We advise that where poor Earths are suspected you don't just clean the Chassis/connector, but cut the old terminal connector off the cable and fit a new one. If you cut the junction open you may find, as we do, a white and green mess of powdered corrosion. Some Electric Motors have also been seen to draw more current when the voltage drops across a poor connection. We often see higher than normal current drawn through the wiring to Step electric motors with poor Earths/Connections. It is usually the prime cause of burnt Step Controller failure, like the Arsilicii ES803. Clean and eradicate the poor connection point and the current draw returns to normal. So while the Physics book might say it shouldn't, there are other factors at play, and it does. The reason I asked the question is that whilst accepting that you have lots of experience and your answer was not a typo, then how could this occur? If one accepts that the resistance of the circuit is fixed when the step is operating normally taking into account the resistance of the supply leads and the earth (return connection) and the batteries internal resistance then as the total combined resistance could not reduce [excluding minimal temperature variations] and would only increase as the corrosion (the poor earth connection) took effect in theory at lease reducing the current overall supply current. With respect to your observations however the galvanic effects of the dissimilar metals could produce a rudimentary cell using the poor earth connection and the step as its plates which depending on its polarity could either combine with the supply voltage to produce a higher current in the circuit or conversely oppose the supply causing a reduced current. Even if this galvanic action only produced a volt or two from this rudimentary cell in a 12 volt circuit this would increase the current drawn by some magnitude. At first sight it looks like this may be what occurs with dissimilar metals around the connection acting as the plates and corrosion with road salt acting as an electrolyte. I must admit that I had not considered this possibility but it is quite feasible. I have in the past been involved in electrical installations in hazardous and harsh environments so I am fully aware that sometimes what you expect is not what you encounter. Thanks for your observations it has certainly stimulated some thought. Link to comment Share on other sites More sharing options...
aandncaravan Posted June 13, 2016 Share Posted June 13, 2016 Hello Dave, It is actually more complicated than that because these connections are vibrating as they are being used. The minute the Motor starts to spin it will vibrate and shake the connections. As the Step itself moves, often with a more jerky motion, there may also be bigger, random 'shocks' applied to the Earth connection. So what is making poor contact in one instant, might then go from a perfect contact, to one with open contact, etc. Potentially causing rapid changes in voltage and current at the Motor which might jump between 0 and 12v in a micro second. You can image that this collapse and rise of the magnetic field in the Motor Coils might have a 'transformer' effect in the Motor windings? I honestly don't know if it does, just pointing out that many factors might come in to play that at first don't seem relevant. Someone with far more experience than I would probably give other variations to the usual 'rules'. As you have seen in the field, one 'poor connection' can behave completely differently to another. . Link to comment Share on other sites More sharing options...
Keithl Posted June 13, 2016 Share Posted June 13, 2016 Guys, are you not missing one obvious point here... Namely that the step motor is not 'earthed' at the step! The motor has two wires and the positive and negative connections to these two wires are reversed to extend or retract the step. The earth will be somewhere within the MH wiring on the 'other' side of the step relay. Keith. Link to comment Share on other sites More sharing options...
aandncaravan Posted June 13, 2016 Share Posted June 13, 2016 You are right about the 'Earth' connection being a negative rather than a chassis earth, but the same applies whether the poor connection is at the Motor itself or any other point. Link to comment Share on other sites More sharing options...
Marvinstephen Posted June 14, 2016 Author Share Posted June 14, 2016 You know the old saying...... if it ain't broke...... I had another look under the step and found a switch at the top end of travel of the step (it's a single step which rotates on a single horizontal hinge like a door).The switch is a Hella 71/17G, with a tab that looks as if it is pushed when the step reaches the top of it's range and breaks/opens a switch . It has one feed in from within the vehicle with the other terminal earthing to the chassis. When moving the rubber cover the earth lead broke and came away from the terminal block. So, a poor earth has been discovered. An easy repair...if the terminal block wasn't totally seized so the cable cannot be re-connected! I've removed the whole switch (holding bolts seized) and hope to replace the terminal block screw, or replace the terminal block if it's possible. If not, I may have to order a replacement switch from NL. But I still want to get to the bottom of why the Amp meter is showing such large variations, where previously I'm sure I saw very little draw even with several 12v items drawing current. As per your very helpful suggestions to test the batteries, I've traced the cable from the solar panel, but the cable comes straight through from the roof to the Schaudt Solar-Laderegler next to the Electroblock, without any form of fuse/connector. So my only option to isolate the solar panel is to disconnect at the Solar-Laderegler. Is this wise and what's the best way (which leads to disconnect)? Thanks again for all the advice Link to comment Share on other sites More sharing options...
Marvinstephen Posted June 19, 2016 Author Share Posted June 19, 2016 I have repaired the Hella switch and it's corroded earth connection, realising that it's the switch for the step warning buzzer and so unlikely to be the cause of the 12v system draw. Finally, the step and the warning buzzer switch are now working. I haven't been able to test the leisure batteries as I'm unable to disconnect the solar panel, so I guess it's basically a question of watching how the system stands up on the next trip and constantly monitoring to see what affects the system. Once again, thanks to all who contributed to this thread with helpful and knowledgeable advice which has been much appreciated! Link to comment Share on other sites More sharing options...
aandncaravan Posted June 19, 2016 Share Posted June 19, 2016 The LR1218 manual (along with other Solar regulators) has a couple of warnings about the unit being connected to a Solar panel if batteries are not online : "Disconnect ”Plus Solar module" connector on the solar charge regulator before changing or removing the battery". I have always believed the warnings were because if the Solar regulator is receiving decent power from the Solar panel and applying it to the Battery when the battery is taken out of circuit, the power going through the regulator suddenly has no where to go and burns out the unit. Hence we advocate a fuse is fitted in the wiring as it comes in through the roof, or at least before it goes into the regulator. I would suggest you remove the connector from the Solar Panel + at the Solar regulator then connect the terminal you removed to a Fuse holder like that in the photo, a standard Blade Fuse holder. Then run a short wire from the Fuse holder to the LR1218 Solar Panel + terminal to complete the circuit. Only after the wiring is done should you populate the fuse holder with a fuse (10A fuse for a 100watt panel?) You should find that Schaudt included a fuse holder and connectors for this purpose in the Solar regulator fitting kit? Obviously insulate any bare terminals. If you do this you can remove this fuse whenever you want to do battery maintenance, or even just to see the 'real' battery voltage and not the Voltage at the battery from the Solar Panel charge? We sometimes hear, "no matter how much charge I take out of my battery at night, the Solar regulator has got the battery back up to full charge by mid morning....". When in fact the battery could be down at 11v but if the voltage display is interrogated during the Solar day, you will most likely see the 13.8v being put into the battery, not the battery voltage itself. Pulling the fuse at any time (and waiting about 2 hours for the voltage to stabilise) will show the actual battery voltage. The fuse also provides some electrical safety. More Solar Installation Hints and Tips here : http://www.aandncaravanservices.co.uk/solar-power.php Link to comment Share on other sites More sharing options...
Marvinstephen Posted June 19, 2016 Author Share Posted June 19, 2016 A simple solution, will do. Thanks again Link to comment Share on other sites More sharing options...
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