Oxford Posted July 10, 2016 Share Posted July 10, 2016 I would like to install a second gel leisure battery and connect an inverter to it to run small appliances. (I already have a leisure battery to run the lights, water pump etc.) However, I do not want to hardwire it into the the existing electrical system, for a number of reasons. I intend to 1. clamp the battery in an ventilated underseat locker 2. attach an inverter and charger that are accessible outside the locker. Then I will 1. charge the battery off the mains when I am at home and at campsites 2. if necessary charge it off the 12 volt cigarette lighter (via a second inverter) if necessary. 3. use the power by just turnign on the inverter and plugging in. QUESTIONS A. Will this work? B. Can you recommend a good quality battery (about 100 Ah seems appropriate) and charger? C. Can you recommend a good quality inverter (about 1000W). (I assume that if the inverter is turned off then even if it is connected to the battery it will not draw power from it.) Thanks Roy Link to comment Share on other sites More sharing options...
hagrid Posted July 10, 2016 Share Posted July 10, 2016 short answer is no, your inverter will kill the second battery in no time. Link to comment Share on other sites More sharing options...
Billggski Posted July 10, 2016 Share Posted July 10, 2016 You would be best to consider using it to run 12v appliances. (12v to 240v inverter to 240v to 12v inverter just sounds a bit daft, 12v to 12v would be preferable) Link to comment Share on other sites More sharing options...
aandncaravan Posted July 10, 2016 Share Posted July 10, 2016 Hagrid is right about the Inverter giving the battery a hard time, especially a Gel which doesn't like continuous high power draw and takes twice as long to charge up. If you go on the Exide battery calculator website and enter the details of the load you wish to place on a set of 12v Batteries, it will calculate the battery bank size for optimum battery life. It calculated for me (similar calculation from Victron energy) that a 3,000 watt Inverter requires 15 x 100Ah batteries or 1,500Ah if the battery life is to be preserved. If a 2 year battery life is acceptable, then it suggests a 500Ah battery bank. Note that the batteries it proposes for the 500Ah bank are extra heavy duty Industrial ones. Suggesting you might need a few more common or garden Motorhome versions? Link to comment Share on other sites More sharing options...
AndyLou Posted July 13, 2016 Share Posted July 13, 2016 Hi I am no expert but most of what you say makes sense. A. Will this work? Yes as long as you don't draw too much current from the battery. I am not sure about your inverter to charger solution it sounds a step too far. B. Can you recommend a good quality battery (about 100 Ah seems appropriate) and charger? People are always talking about the Exide batteries being very good (not the gel one though) there was a thread on here about a test some company had done. A CTEK charger is often mentioned as the best too. I would have thought that if have the van plugged in at home then you could plug the charger in to the power sockets in the van. C. Can you recommend a good quality inverter (about 1000W). (I assume that if the inverter is turned off then even if it is connected to the battery it will not draw power from it.) As I understand it the inverter will draw power even if it is switched off the only way to make this work would be to disconnect it from the battery. I suppose a switch on the battery leads would work. Hope this helps or at least sparks more discussion. Andy Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 14, 2016 Share Posted July 14, 2016 Roy I intend to 1. clamp the battery in an ventilated underseat locker 2. attach an inverter and charger that are accessible outside the locker. This arrangement is uncontroversial and (technically) it wouldn’t really matter whether the battry type was gel, AGM or ordinary ‘wet acid’. If you choose a gel battery, the charger should have the appropriate ‘gel’ charging regimen. Then I will 1. charge the battery off the mains when I am at home and at campsites 2. if necessary charge it off the 12 volt cigarette lighter (via a second inverter) if necessary. 3. use the power by just turning on the inverter and plugging in. No problem with 1 and 3, but (as Billggski has said) although your idea to charge via the 12v cigarette-lighter socket and another 12v-230v inverter might be practicable in principle, it would definitely be inefficient. Best forgotten I think... Historically the gel battery most commonly fitted as original equipment to motorhomes was an Exide 80Ah and these generally performed and lasted very well. It has been said on motorhome forums that Exide gel batteries are rebadged Sonnenschein products. There is certainly an Exide/Sonnenschein business link, but the Sonnenschein batteries are usually marketed less expensively. Examples here https://www.tayna.co.uk/Sonnenschein-Gel-Leisure-Batteries-S420-1.html I can’t advise on which 1000W inverter would be ‘best’ to buy – it depends on what you want to power and how much you are prepared to pay. These links may be helpful https://caravanchronicles.com/guides/understanding-inverters/ https://caravanchronicles.com/guides/understanding-inverters-pt-2-buying-guide/ (As far as I’m aware, if an inverter is switched off it will not drain current from the battery it is connected to. If an inverter is switched on, but not powering anything, it should be expected that this will place a (smallish) load on the battery, but that scenario is not the same as the inverter being switched off.) Link to comment Share on other sites More sharing options...
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