StuartO Posted June 7, 2016 Share Posted June 7, 2016 I renewed my leisure batteries (on age, they were still going) and experimented by replacing two Exide G80s with one, to save weight. I have had 130 watts of solar panels for several years and they had always been enough. We relatively rarely overnight without being connected to an EHU, mostly in transit when we are using an Aire in France. This year we have only done two or three nights off EHU and first impressions are that by dropping to one battery we have now got limited power and our TV's can stop working. Our TVs are 17" domestic types which nominally run on 12 volts, in that they came with 12v transformers, which I disposed of in order to connect them to the MH 12v system directly. They draw about 4 amps in use and almost 1 amp on standby. We only use one TV at once by the way, we're not that bad! Our TVs are voltage sensitive and the picture disappears when the leisure battery voltage drops to 12.6 volts, at which point we still have plenty of battery left for more essential requirements like lighting, so it's only the TVs that ever go off. Even in druzzy weather the solar panels get close to recharging the single 80AH leisure battery each day, so we get back to using TVs the following evening, even if I have to remember to switch off overnight rather than switch to standby. So do I need to revert to two leisure batteries and/or uprate the solar panel capacity, to cover my needs? I could of could sacrifice TV or discipline myself to switch off properly, but apart from that option, it begs an interesting question if I try to work out what I could do to upgrade my system. It becomes necessary to consider the weight as well as the cost of making changes. There are several options. The TVs are old and they receive digital only with the aid of additional boxes, so they could be replaced by more efficient modern ones. I could fit a second leisure battery again to increase 12v service capacity. I could add another solar panel, to improve charging capacity in poor weather. Or I could do nothing and settle for what I've got, which does all I really need. An extra Exide G80 would cost £150 and a chunk of weight. Adding an extra 100 watt solar panel (professionally) would cost £275 and a smaller chunk of weight. Replacing the TVs would probably cost £300 plus each and save a small amount of weight, but it would enhance our viewing experience because they will be more moderm TVs and less fiddly to tune etc. And doing nothing would cost nothing in money or weight. Decisions, decisions....... Link to comment Share on other sites More sharing options...
veletron Posted June 7, 2016 Share Posted June 7, 2016 Hi 12.6V off-load equates to about 80% state of charge on the batteries, if you are seeing 12.6V while the telle is on, drawing 4A, then the batteries are likely above 90% SOC. Best course of action given your usage scenario is to buy a new MH specific telle! The extra solar wont really help given evening viewing when input from solar panel will be low, combined with the relatively high voltage at which your existing telle stops working. Adding an extra battery would hold the voltage up above 12.6V for longer (and voltage drop due to load will be lower), but batteries are a consumable item, replacing that extra battery twice will see you having bought that new telle. I have a 17" avtex with built in DVD player, it pulls just over 2A, and will run on 11.5V no bother (I have a mains inverter and with a mains kettle attached, on-load voltage can drop to 11.5V. Treat yourself! Nigel Link to comment Share on other sites More sharing options...
aandncaravan Posted June 7, 2016 Share Posted June 7, 2016 You can buy a Voltage booster, WA1206 I think?, that takes in anything between 10.9v and 15v and puts out a fixed 14.2v to run the TV, but there will be some conversion loss. Your total draw could be 5amps? 12.6v is still quite a healthy battery, so agree with Veletron, that replacing the TV is the way to go. Not just because it will continue to work at a lower voltages down to 12.2v, but at half the current consumption the batteries will last twice as long, effectively 'doubling the battery bank' as that is most likely your biggest consumer?? You might find that just replacing the one TV used the most will do the trick? If you save enough power so that the second TV, when that gets used, starts off with a battery at a high voltage, means it takes longer to loose the voltage? For example if one TV is in the 'Lounge' and the second in the bedroom and only one used at a time. By the time you activate the 'bedroom' TV later in the evening the battery will still have enough power to give another 3 hours viewing than previously because of the much lower power draw of the 'Lounge' TV? What about replacing just one TV fitted with some kind of 'quick release' bracket so it is easily relocated to the second viewing area, rather than a second TV? Link to comment Share on other sites More sharing options...
colin Posted June 7, 2016 Share Posted June 7, 2016 Our 18.5" Avtex draws less than 2amp max and less than 0.5amp on standby, but it just takes leaning over to switch it of, so that's what we do. Have you included the digibox in calcs? as some of these are also power hungry, you could easily be drawing 8amp. Link to comment Share on other sites More sharing options...
aandncaravan Posted June 7, 2016 Share Posted June 7, 2016 Brilliant idea!! How about you get a powerful light plugged into the 12v supply and shine it at the Solar Panel on the roof so it charges up the batteries while you watch TV!!!! Link to comment Share on other sites More sharing options...
Charles Posted June 7, 2016 Share Posted June 7, 2016 1 amp on standby? That's 12w when it's not switched on! I'd be buying a new TV. (And 0.5a is also too much) Link to comment Share on other sites More sharing options...
StuartO Posted June 9, 2016 Author Share Posted June 9, 2016 Thank you for the replies. We seem to have a consensus, that my old TVs are too power hungry, especially if left on standby, so if anything needs changing, it's them. An extra leisure battery wouldn't help much and nor would an extra solar panel, so no point in spending money or adding weight by doing either or those. And my old TVs work, receiving both broadcast and satellite digital signals - and they have 17" screen and are built in, so replacing would require quite a bit of work. And they can be powered off when not in use rather than left on standby, so do they really need replacing, just to give me unlimited screen time when not on EHU? The lesson for me is that one should never jump to a conclusion that more solar power or more leisure battery capacity is needed, lest you sacrifice payload as well as spend unnecessary money achieving it, nor should you replace old accessories if they are still reliable and still do the job, unless you can afford it and want to treat yourself. Link to comment Share on other sites More sharing options...
lennyhb Posted June 9, 2016 Share Posted June 9, 2016 Another vote for changing the TV, our 19" Cello draws 1.5 amps and works down to below 11 v, when I had problems with the batteries the TV was still on when the Elektroblock tripped out at 10.5v. As said you could buy a voltage stabiliser for about £40 money probably better spent on a new TV. You may be under an illusion on how fast your battery is recharging from Solar bear in mind once it reaches 14.3v it needs to maintain that voltage for 8 hours for a full charge on a Gel battery. For you usage off grid you shouldn't really need the solar, if starting from scratch my recommendation for your usage would be two batteries and no solar. If you are using your van in the UK there is no substitute for a big battery bank as solar output is too unreliable, if using most of the time in southern Europe much better gains to be had from solar. Link to comment Share on other sites More sharing options...
Brambles Posted June 9, 2016 Share Posted June 9, 2016 As you rarely overnight without hookup it hardly seems worth the expense of an extra battery. I would go the route of a new TV, or indeed 1st try running a heavier cable for the 12 volt supply to the TV's from the batteries. This may well solve your issue albeit a little tricky to actually do. Link to comment Share on other sites More sharing options...
StuartO Posted June 9, 2016 Author Share Posted June 9, 2016 Brambles - 2016-06-09 2:39 PMAs you rarely overnight without hookup it hardly seems worth the expense of an extra battery. I would go the route of a new TV, or indeed 1st try running a heavier cable for the 12 volt supply to the TV's from the batteries. This may well solve your issue albeit a little tricky to actually do. Good point about the cable diameter because I simply spliced into the nearest lighting circuit, which was not ideal. But Hymers are built with decent cabling and I seem to have got away with it for 10 years! Link to comment Share on other sites More sharing options...
StuartO Posted June 9, 2016 Author Share Posted June 9, 2016 lennyhb - 2016-06-09 11:24 AM ....You may be under an illusion on how fast your battery is recharging from Solar bear in mind once it reaches 14.3v it needs to maintain that voltage for 8 hours for a full charge on a Gel battery.For you usage off grid you shouldn't really need the solar, if starting from scratch my recommendation for your usage would be two batteries and no solar.If you are using your van in the UK there is no substitute for a big battery bank as solar output is too unreliable, if using most of the time in southern Europe much better gains to be had from solar. My Schaudt Elektroblock measure the flow of electricty in and out, so I think the battery levels I get from that are pretty reliable aren't they? Anyway my 130 watt panels seemed to deliver a full recharge of both batteries when I had two, so no plans to upgrade. For my pattern of use I think one leisure battery is enough. Link to comment Share on other sites More sharing options...
lennyhb Posted June 9, 2016 Share Posted June 9, 2016 What I was trying to point out is that most people take it the batteries are fully charged when the voltage reaches 14.3, for a wet cell that is not far off as it just needs to be at that voltage for ½ to 1 hour to be completely charged but a Gel needs to be at that voltage for around eight hours. I have 200 watts of solar and I know if I run my batteries down 60-70% it will take several days of clear skies and bright sunshine to recharge in middle of June when solar output is at it's highest. If you want quick charging you need to fit wet cells but that is balanced out by Gel's being able to stand a higher discharge. Link to comment Share on other sites More sharing options...
Barryd999 Posted June 9, 2016 Share Posted June 9, 2016 Yes change the Telly. 4amps is a lot for a TV. I got a 16" Akura TV a while back and it only draws 1.2 amps. I dont think there is anything on the market that size that draws less not even the expensive Avtex. Mine cost £90. I never let my battery drop below 12.1 amps but this time of year with just a single 100w panel and mppt controller its showing full charged by mid morning anyway. Link to comment Share on other sites More sharing options...
veletron Posted June 9, 2016 Share Posted June 9, 2016 The only way to have an accurate idea of how well a solar panel recharges the batteroes is by way of an AH counter that measures AH in and out. Some motprhome control panela feature this as standard, but most dont eapecially budget ones. The Nasa BM1 is a good bit of kit to fill the gap, it measures AH discharge/charge, time to charged/discharged based in programmed capacity of battery bank and attempts to give an idea of the SOC even when under load/charge via an algorithum. The latter being its least accurate feature! Charging efficiency of lead acid is lower than 1:1 so, if you remove 10AH by watching telle and then get 10AH from solar, SoC is not back where it used to be. You would need to put roughly 110% back in. They fit neatly into the void above the passenger/driver front seatbelt. In use, I reset it to zero on my breaks before I set off, and then I have a good idea re capacity while away. Good call on the cable run, i'm betting there is much less than 12.6V actually at the telle under load when the telle stops running properly. If this is the case then a new telle that draws less current may only be a partial fix. As for the voltage, running a Gel down to 12.1V (off load) likely OK, but both open and sealed lead acid should not be taken below about 12.3v (eg 50% capacity) (off load) if you want a long service life from it. If you frequently go below this then the number of times it can be cycled while retaining good capacity decreases and you end up buying a new one sooner. Adding a second battery Reduces the chance of your draining the bank, it not only doubles the capacity, but could more than double the service life all depends on your usage. Nigel Link to comment Share on other sites More sharing options...
aandncaravan Posted June 10, 2016 Share Posted June 10, 2016 veletron - 2016-06-09 8:27 PM As for the voltage, running a Gel down to 12.1V (off load) likely OK, but both open and sealed lead acid should not be taken below about 12.3v (eg 50% capacity) (off load) if you want a long service life from it. If you frequently go below this then the number of times it can be cycled while retaining good capacity decreases and you end up buying a new one sooner. Adding a second battery Reduces the chance of your draining the bank, it not only doubles the capacity, but could more than double the service life all depends on your usage. Nigel Nigel, I agree with your cautionary words on discharging a battery, but even so, I think you might be giving more credit to a Gel battery than it deserves? Even a specialist Long Life Gel will have it's life significantly shortened if you take it below 30% discharge, let alone 50%. A Victron Energy Ultra Deep Cycle battery will last for 1,500 cycles if you discharge to 80% discharge, or just 20% charge left in the battery. However, if you discharge it to only 30% (70% charge left in the battery) you get a whooping 4,500 discharge cycles. See section 9 in the Victron Energy document towards the end of the FAQ section here : http://www.aandncaravanservices.co.uk/agm-batteries.php The depth of discharge, even on a specialist Deep discharge battery, can have a dramatic effect on battery Life. The ideal for long battery life, seems to me, to not let any battery drop below 12.4v, regardless of technology Gel or Wet. Doing so may shorten it's life far more than people think. Rather than shorten the Life of an Ultra Deep Cycle battery by deep discharge, as you point out, it may be a more cost effective strategy to have two conventional batteries and 'shallow' discharge them. Taking 60Ah out of a Exide G80 80Ah Gel will hammer the battery far more than taking 30Ah each (or just a 30% discharge) out of two Varta LFD90's, . The cost of an G80 versus 2 x LFD90's is pretty much on a par, but the difference in life when the same Ah are drawn would be staggering. Recharge time for the LFD 90's would also be shorter, as you note above. Operating a Battery bank in this way will also place little strain on the Alternator and mains charger. Bringing a battery back up from a Deep Discharge will tax any charging system, probably with a resultant loss in efficiency? Link to comment Share on other sites More sharing options...
StuartO Posted June 10, 2016 Author Share Posted June 10, 2016 It's perhaps important to remember that a leisure battery is carried in order to make use of its discharge capacity, so avoiding discharges just to prolong the battery's life wouldn't necessarily make sense. You might as well carry some lead ballast around. My original pair of Exide G80s lasted over ten years, probably because I spent most of my camping days on an EHU not drawing on them. That's why it makes sense for me to replace them with a single leisure battery. I bought another Exide G80 because there was an exceptionally good deal available and might otherwise have followed AandA's recommendations to try something different. Link to comment Share on other sites More sharing options...
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