spospe Posted February 16, 2010 Share Posted February 16, 2010 Tracker - 2010-02-16 5:55 PM The engine driven alternator will fully charge the leisure batteries if you do enough miles depending on the state of charge when you start. However, as the engine battery rightfully takes priority it is only when it is getting towards fully charged that the full 10 amps will be pushed into the leisure batteries. It would be more going in if the cabling were heavier but those awfully helpful people at the factory are petrified that it might charge fully too quickly and emit explosive hydrogen into the van interior so they limit it to 10 amps which to be fair is generally adequate if not ideal. Rich At the risk of seeming pedantic, can I say again that the engine driven alternator will not fully charge either the vehicle starter battery or the leisure battery, no matter how many miles you drive. This is simply because that in order to FULLY charge a lead-acid, or gel type battery requires higher voltages than the alternator supplies. There are two reasons for this: a) The maximum voltage for a lead-acid battery equalisation charge is 14.7 volts and this is too high for long-term reliability of such automotive items as light bulbs (they are normally rated at up to about 13.6 volts). b) Such sustained voltages would quite quickly 'boil' the battery. The battery maintenance-charging regime, which includes an equalisation charge, can only realistically be carried out by an 'intelligent' charger of the Ctec variety. You state, quite rightly that the engine battery takes priority over the leisure battery. However the reason that this is so, is purely and only due to the resistance of the connecting leads. If you made the alternator to leisure battery leads of lower resistance than the alternator to engine battery leads, then the situation would be reversed. The split of charging current is simply in proportion of the resistance of the charging circuit of each battery. A normal 12 volt lead-acid battery has an internal resistance of about .03 ohm (which means that the theoretical maximum current of a full short-circuit is about 400 amps). As can be seen, if the leads from the engine battery were to be, say .2 ohm and from the leisure battery .3 ohm (same diameter cable, just longer) the charge current would split in the ratio of 2 : 3 (assuming same internal resistance). Peak charge current is governed by, firstly the battery voltage, a flat battery of say 11 volts will take a large current (way more than 10 amps) and secondly the resistance of the leads. It is the battery voltage, which is the important factor here, the lead resistance is only an issue when charging two (or more) batteries in parallel as described above. I'm going to watch the Olympics now, so good night to you all .............. Link to comment Share on other sites More sharing options...
Brambles Posted February 16, 2010 Share Posted February 16, 2010 Automotive 12 volt lamp bulbs are rated at typically 14.2 volts. Link to comment Share on other sites More sharing options...
Guest Tracker Posted February 17, 2010 Share Posted February 17, 2010 All good stuff fellas and I have no problem with being corrected - thanks. Link to comment Share on other sites More sharing options...
Brambles Posted February 17, 2010 Share Posted February 17, 2010 Brambles - 2010-02-16 11:17 PM Automotive 12 volt lamp bulbs are rated at typically 14.2 volts. Spospe, I think I might have this wrong, well not wrong but misleading and I have conflicting information in my test documents. The test specifications for ECE R37 approved headlamp bulbs is 13.2 volts, and for indicator lamps is 13.5 volts. I assume they have reduced the volts bacause of volt drop in the supply cables. 24 volt lamps - test voltage is 28 volts for all lamps. For instrument lamps it is 14.2 volts, I know this because thats was part of my job to know and I have checked one catalog I have and indeed it is 14.2v. So that seems to have led me into thinking all lamps are the same. For indicator and headlamp bulb filaments it does not give the nominal operating voltage but only the test voltage being as per ECE R37. (rotton people, why could they not state it in volts!) Incidently for the old style non halogen head lamps bulbs it says nominal voltage 13.8v which is what you said. I have checked my test specifications for one vehicle manufacture and it says operation 10.5 to 16 volts with one hour test at 18 volts. For lamp illuminosty (is there such a word? - must be the french chap who did the translation) and pattern tests the vehicle supply will be set to 14.4 volts and carried out as per ECE Rxx (lists all the lamp approval numbers). (The test voltage will be the one where the power is specified. e.g. A 21 watt bulb will be 21 watts at 13.5 volts. It is a requiement to mark the lamps 12 volts.) So it seems all very confusing but the importamt part of interest is the lamp bulb filaments are rated at a higher voltage than 12 volts. Apologies. Link to comment Share on other sites More sharing options...
spospe Posted February 17, 2010 Share Posted February 17, 2010 Brambles Thank you for the update, things are even more complex than I rememberd! It is good to keep up to date, when I was a lad a car bulb was a car bulb and all were equal; but not any more it seems :-) Link to comment Share on other sites More sharing options...
jhorsf Posted February 18, 2010 Share Posted February 18, 2010 and before you ask Rich no no one wants to buy 2 (part worn batteries) :D :D :D Link to comment Share on other sites More sharing options...
Guest Tracker Posted February 18, 2010 Share Posted February 18, 2010 jhorsf - 2010-02-18 12:35 AM and before you ask Rich no no one wants to buy 2 (part worn batteries) :D :D :D Can't think why not? There's tears of life left in them yet - as door stops! One of the easiest ways of seeing if your alternator is charging is to switch the interior light on before starting and if it gets brighter when the engine fires up that is because the alternator is charging and that I presume is why bulbs have a rating higher than 12v and why they seem to last so much longer these days! Link to comment Share on other sites More sharing options...
Brambles Posted February 19, 2010 Share Posted February 19, 2010 Tracker, Thought you would be posted back by now saying batteries have arrived. Remember to plug of the unused vent with a plug (either already in or use spare moulded in +ve plastic cover). Link to comment Share on other sites More sharing options...
Guest Tracker Posted February 19, 2010 Share Posted February 19, 2010 Ah - yes - well Jon - it seems the factors supplier is having difficulties as now he tells me that they sent the wrong ones so he sent them back. I don't know what they sent but at the moment I'm waiting for a phone call! Good job we ain't going away this weekend! You have to remember that this is Pembrokeshire famous for it's 'Pembrokeshire promise', which is like the Cornish 'drekkly', which in turn is a slower version of 'manyanna'! If I insert the isolator switch in the negative lead it will be easier and as there is not a grounded earth for the leisure batteries I can't see that it will not be as effective as the more usual positive cable - or is it? Still trying to decide whether to insert the battery isolator switch so that it cuts off the solar panel too because when the panel is charging the battery drain is so low that it will not matter - or whether to have a separate switch? Link to comment Share on other sites More sharing options...
Brambles Posted February 19, 2010 Share Posted February 19, 2010 You are better with the switch in the ground connection for battery. Usually it is easier as only one cable not multiple cables. 2. If you switch it off and the GND is isolated then +ve post cannot create a short to ground e.g. spanner to remove terninal ( hence why -ve terminal always removed 1st) . Need to check the specs for Solar regulator it is safe to operate with battery disconnected. Or Solar Panel is safe with it disconnected from solar regulator. Should be. Technically suppose you do not need to isolate the solar sytsem separetely but might prove useful in testing the system as a whole and how it behaves under different conditions. e.g. testing charging on just the power supply or Ctek. Link to comment Share on other sites More sharing options...
Guest Tracker Posted February 19, 2010 Share Posted February 19, 2010 Brambles - 2010-02-19 1:22 PM Need to check the specs for Solar regulator it is safe to operate with battery disconnected. Or Solar Panel is safe with it disconnected from solar regulator. Should be. Technically suppose you do not need to isolate the solar sytsem separetely but might prove useful in testing the system as a whole and how it behaves under different conditions. e.g. testing charging on just the power supply or Ctek. Ah! - but I thought we were disconnecting the solar panel to stop it cycling the charge every day and potentially reducing battery life whilst trying to do the very thing it was fitted for which is to prolong battery life? It has been sat there for two weeks now with the solar panel connected to the regulator but disconnected from any load such as the battery and has not yet come to any harm - I don't know about long term potential damage but isn't the solar generator like any other power source in that if there is no load called for it just sits there waiting to be called upon to supply? Link to comment Share on other sites More sharing options...
Brambles Posted February 19, 2010 Share Posted February 19, 2010 Yep, it should just sit there and not do anything. It does not matter if you isolate the solar panel separetely or not, but I would want to so I know when laid (layed - which spelling is it?) up nothing is being powered etc. I would also have a cover to put over solar panel so it ois protected from the sun when not in use and the sun's aging effects on the panel and to keep it clean. Having the cover also means you do not really need the separate switch. Cannot remember how fast a solar panel degrades with use - probablly not a lot, but I know they do reduce output as they get older, so way age it when you do not need to. All depends if you have easy access to panel or not. Link to comment Share on other sites More sharing options...
spospe Posted February 19, 2010 Share Posted February 19, 2010 My solar panel is made by Kyocera and guaranteed to give at least 80% of its rated output after 20 years continuous use. So unless you are planning on keeping your motorhome a very long time, I would not be too concerned about ageing of the panel (not so sure about the ageing of the user though :-) ) Link to comment Share on other sites More sharing options...
Brambles Posted February 19, 2010 Share Posted February 19, 2010 Ah well! not worth worrying about then. I really had no idea, just new they did reduce. With our amount of sunshine probably take 40 years then. Am still looking into this leaving connected and holding battery at 14.4 volts and whether it is good or bad for the battery. I would like to know what actually happens with your new batteries when you get them Tracker, it might be this does not actually happen. Will be interesting to see results of testing after fully charged and left on the panel. They may only be pulsing with a very narrow 14.4 volt pulse but battery overall voltage is a lot lower, and if below 13.8 volts then no problem leaving on. Link to comment Share on other sites More sharing options...
Guest Tracker Posted February 19, 2010 Share Posted February 19, 2010 My solar panel too is Kyocera and if I use the van for another 19 years I will be well pleased! Link to comment Share on other sites More sharing options...
jhorsf Posted February 19, 2010 Share Posted February 19, 2010 tracker http://cgi.ebay.co.uk/Numax-Marine-110ah-leisure-battery-x3_W0QQitemZ220559009809QQcmdZViewItemQQptZUK_CarsParts_Vehicles_BoatEquipment_Accessories_SM?hash=item335a576811 Link to comment Share on other sites More sharing options...
Brambles Posted February 19, 2010 Share Posted February 19, 2010 LOL, wonder where Tracker got the third green battery from --some farmer's sheep are no doubt straying out of their electric fence compound. Link to comment Share on other sites More sharing options...
Guest Tracker Posted February 20, 2010 Share Posted February 20, 2010 The lull while we resolve what batteries are available and what are not has got me into thinking mode again - always a dangerous thing 'cos when thinking starts doubts creep in! I know what Jon said about the Varta E33 957052000 90ah being a better battery in his view than the A24 811053057 105ah or the A28 813010000 110ah and as I could accomodate the extra height of the larger batteries it makes me wonder? I hear what you say Jon about better off load storage and a higher potential for usable capacity of discharge of the E33 BUT I am having some difficulty getting my head around how having a 40ah or 30ah deficit in overall capacity can be a good thing as that extra capacity is equal to a cold winter's night's worth of heating! Link to comment Share on other sites More sharing options...
Brambles Posted February 20, 2010 Share Posted February 20, 2010 Hi Tracker, go to page2 of posts about 3/4 way down it is explained. Link to comment Share on other sites More sharing options...
Brambles Posted February 20, 2010 Share Posted February 20, 2010 It is a very difficult one Tracker. If you were comparing the 90 Ah with other 110Ah offerings like Elecsol, Numax, etc there is no contest. Comparing the two Vartas is much harder. All depends on the rate of discharge, how deep and bear in mind the 110 will age quicker so the difference in capacity gap closes. Also as the 110 uses more water if the level falls it will have an effect of reduced capacity. Also as you may be slow to replace charge if using solar to recharge, remember you are in effect leaving discharged for 3 or so days at a time and not recharging the next day then the 90Ah will deteriorate slower. The specs for cycles is based on discharging and the recharging immediately not recharging a few days later so these 300, 400 or whatever cycles will never be achieved in practice. However bear in mind most times you will be no where near down at 50 or 60% discharge so actual camping night cycles is massively higher. Link to comment Share on other sites More sharing options...
Guest Tracker Posted February 20, 2010 Share Posted February 20, 2010 Thanks Jon - I should have said that it was reading that bit again as well as the Varta blurb that confused me. The Varta blurb states in one part that all their batteries can safely be discharged to 60% but at another place it says that they can withstand discharge to 80% without damage and it does not seem to differentiate beteen the calcium/calcium and the calcium/antimony for this? Given that on a long cold weekend I might need all the power I can get it suddenly struck me that an available 80% of 220ah is 32ah more than 80% of 180ah and that is almost one more full day's worth of 12v power? That scenario would be very rare and if it did shorten the battery life maybe that is a price worth paying for being warm and snug! So then I wondered about the calcium/calcium A24 105ah as being a good compromise - but I can't find anyone on t'web who sells it - so I guess it's back to whether 2 x 90ah is worth paying £25 more for than 2 x 110ah and it is still a question that bothers me. I apologise for monopolising your knowledge but, having discarded Numax, Lucas et al, I do so want to be sure that what I am about to do is the best option? Link to comment Share on other sites More sharing options...
Brambles Posted February 20, 2010 Share Posted February 20, 2010 Hi Tracker. Are you committed to the 90 Ah you have ordered? Link to comment Share on other sites More sharing options...
Brambles Posted February 20, 2010 Share Posted February 20, 2010 There is another factor to consider which I have not really taken into account yet or mentioned and this is charging a deeply discharged battery on the alternator. This allows it to charge at far too high a rate from being deeply discharged. This could well be a factor in your premature failure of batteries and many other people as well. Calcium Calcium batteries can charge at a very high rate, and the damage to the battery from these high charge curremts is less than with a Calcium Atimony battery. However in the Varta 110Ah Hybrid Battery the galss mat goes some way to reduce the effects. If you take any battery down to 80% Depth of discharge you are really asking for trouble as you have to recharge properly from this depth of discharge ...and an Alternator cannot do this. Not an easy one to work out in which would be better, the 90 or the 110. If you feel better with the 110Ah then go for it, The Tayna price is certainy very good for this battery, as in rest of Europe they appear to be more expensive that the 90 Ah not cheaper. The alternator charging a deeply dscharged battery certainly will not do it any good and the effects on the Calcium Calcium construction compared to the Calcium Antimony with glass mat I do not know. You woull think if you have a higher Ah to begin with and so after x nights it is discharged to a lower perentage DOD it would have to be better when chargeing on the alternator.... so would the 110 be better in this respect!!!! Swings and roundabouts considering, and I have mentioned this before, most batteries are murdered prematurely anyway and you have to weigh up the costs. Talking of Alternator charging, the worst thing to do is after deep discharge is to start the engine and drive off fast down the road. Much better to keep the engine revs very low and give the battery a chance to charge slowly at 1st, also better for a cold engine anyway not to race it immediately. I wonder if this is why your last batteries failed, because the dod was so great then when charging off the alternator they just could not cope with the high charge currents. Your confused Tracker, well it is confusing. If you need 220 Ah then you need the larger capacity, but you have to ask if you really need it. If you had 280 Ah would you just end up pushing 5 ot 6 nights in one spot instead and be back to the same issues? And if you take into account when you move after 3 days you may only be travelling enough to replenish half the charge before overnighting again.....work that one out!!!!! edit - some of the spelling. Link to comment Share on other sites More sharing options...
Guest Tracker Posted February 21, 2010 Share Posted February 21, 2010 Goodness me the more I learn the more I realise just how much I don't know! I never pull away on a cold engine as even in summer I like it to have it on tickover for about a minute or so to get the oil moving freely and then keep the revs down until the temp gauge starts to move up the scale. Similarly I try never to have my foot on the accelerator when the engine first fires as most engine wear occurs in that first few seconds of running so the slower the better. That's why seldom used low mileage cars are not always a better buy than high mileage well used ones - but I digress! I was totally unaware that the rapid charging of an alternator could damage a battery in a low state of charge and in that case it is no small wonder that my two failing batteries have given up with that sort of hammering after every night's use taking most of their available charge! On the other hand does the alternator charge that highly anyway as it does seem to be limited to about 10 amps maximum by the system - which is why I have assumed that it takes so long to recharge the leisure batteries when on the road? To be fair we don't usually stay put for than three nights on a cold winter's jaunt so at that rate about 90ah would be used which should be well within safe discharge capacity - it's just nice to have as much reserve power as possible. I must admit I can see the sense of buying the cheapest possible batteries and being prepared to dump and replace every two years - or less - as soon as they start to fail - in which case there is a strong argument for a pair of Lucas or Numax 110ah at £146 or £165 the pair! Link to comment Share on other sites More sharing options...
Brambles Posted February 21, 2010 Share Posted February 21, 2010 where are you getting Lucas at that price - do you mean platinum? Anyway - Its up to you what you go for but I recommend either of the Vartas. Link to comment Share on other sites More sharing options...
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