Complete Off-Grid 12v Dual Battery Masterclass PART 2: Battery Charging Secrets Revealed

g'day and welcome to part two of our complete  off-grid 12-volt dual battery master class now   in part one I went through the absolute basics of  a dual battery system I touched on your vehicle's   12-volt system and I explained that the easiest  way to get a dual battery into your vehicle is   by using a completely separate battery now the  problem with that is that you need to charge it   separately to so in part two I'm going to show  you how to integrate your second battery into   your vehicle's 12-volt system so it'll charge  while you drive now that's gonna involve running   some heavy duty cable from the starter battery  all the way back to your second battery so that   your alternator can charge both the next step  up is to permanently mount it and connect those   fused heavy-duty wires you've run from the  positive terminal of the starter battery to   the positive terminal of your second battery  and connect the negative to the negative the   next thing you want to add is an isolator  on the positive cable too unless you want   both batteries to be constantly connected if you  didn't use an isolator your two batteries would   charge and discharge at the same time so if you  stopped at camp and ran your fridge would draw   power from both batteries that means you'd  flatten your starter battery and deep-cycle   battery and not be able to start your vehicle  once they discharge too far the isolator would   separate your main vehicle 12-volt circuit from  your deep cycle battery accessory circuit just   like having a battery box on its own with the  isolator turned off your fridge and accessories   won't draw any power from your starter battery  and if you leave your headlights on it won't   flatten your deep cycle battery either the most  basic isolator is a physical switch and an easy   demonstration is to use a valve let's open it  up and see what happens let's assume the fridge   is already running in the back of the vehicle  as it's the morning of your trip the fridge is   draining the auxiliary battery but because we've  turned the isolator on the batteries are connected   the first thing you'll notice is they're wanting  to equalize their voltage now if we were to start   the vehicle the alternator starts charging and  both batteries are getting charged up the front   battery will be receiving around 14 volts from  your basic alternator and the auxiliary battery   in the back will be getting 14 volts less any  voltage drop across the wiring that could be a   problem if you're not getting enough voltage to  really properly charge your second battery the   other problem of course is if you pulled up  at camp and forgot to turn the isolator off   to disconnect the batteries your fridge and  accessories would again drain both batteries   but close the valve and they would separate  leaving your starter battery nice and charged the next step is to add a dual battery kit with  a smart battery isolator also known as a voltage   sensitive relay or VSR a smart battery isolator is  similar to a manual isolator but it automatically   connects and disconnects the batteries depending  on the voltage of seeing I'm going to use a 12   volt electric valve here to show exactly how  it works and to that I'm connecting the smart   battery isolator this particular smart battery  isolator connects the batteries once it sees   thirteen point three volts this means that so  long as your vehicle is on and the alternator   is charging your starter battery it will also be  charging your auxiliary battery plus it means that   when you turn off your vehicle the battery voltage  slowly drops and once this unit sees twelve point   eight volts or less it will disconnect and the two  batteries will be isolated essentially leaving you   with two distinct 12-volt systems again there  are some issues with Isolators though whether   it's a physical switch or a smart isolator first  they'll only charge at the same voltage that your   alternator is pumping out - any voltage drop  to reach your second battery that's not ideal   as I mentioned earlier plus it's made even  worse if you're running specific batteries   that need a higher charge voltage AGM batteries  for example need around fourteen point six volts   and second they're not really compatible with  modern vehicles that run smart alternators or   temperature compensating alternators temperature  compensating alternators adjust their output based   on the ambient temperature under the bonnet so  they don't overcharge your starter battery the   problem is if you're running a battery in  the back it's going to be a very different   temperature and will be able to accept a very  different charge rate smart alternators take it   one step further and can adjust voltage and  current completely essentially turning your   alternator on and off when the battery under  the bonnet is nearly fully charged the smart   alternator will reduce its output and when it  is fully charged the smart alternator will stop   charging completely if you're running a smart  battery isolator on a smart alternator it'll   disconnect the two batteries and stop charging  even while you're driving as soon as the voltage   drops below twelve point eight volts it won't  reconnect and start charging until the alternator   kicks back on and it sees higher than thirty  point three volts that means your fridge and   accessories in the back could be draining your  auxiliary battery while you're driving without   you knowing you could pull up to camp expecting  a full battery when it's already used some of   its capacity even with a dual battery system  that uses a basic or smart isolator and your   vehicle alternator is putting out a constant 14  volts if you're using different battery types or   have any voltage drop it's never going to  work or charge a hundred percent properly   if you need to charge your battery whenever  possible with solar or better yet use an actual   240 volt multistage charger with a setting for  specific batteries whether it's flooded or AGM the solution is a DC DC charger it combines an  isolator with a multi-stage battery charger not   just a constant alternator charge plus they're  able to charge different types of batteries with   different chemistries like AGM flooded or calcium  batteries and they're perfectly suited to a smart   alternator some models like this even have a  regulated solar input to they work by taking   the input voltage from the starter battery  and boosting it up to the required voltage   to perfectly charge your auxiliary battery so  what are you trying to charge an AGM battery   from an old alternator that's putting out 14  volts or a temperature compensating alternator   this drop right down to 13 volts the DC  DC charger will still be able to provide   the correct voltage that your second battery  requires there's a couple of other benefits to   DC DC charges directly monitor the auxiliary  battery voltage and state of charge and then   vary the voltage and current that it's charging  not just a constant charge like your basic or   smart isolator provides and good DC DC charges  also read the auxiliary batteries temperature   and adjust their charging to suit pushing too  many amps into a battery causes them to heat   up and as we know heat is the biggest killer of  batteries because their position closer to the   auxiliary battery where it's at the end of the  wire run even if there is some voltage drop in   the wiring a DC DC charger will still provide  the correct voltage to the second battery and   for the same reason they're perfectly suited to  a temperature compensating or smart alternator   not only will it boost the voltage up as required  but particular models have an ignition sense wire   that when connected to an ignition source tells  the DC DC charger to start charging that means   that even with the smart alternator turned off  and not charging the DC DC charger will continue   so long as your vehicle is on that in turn will  drain your starter battery over time and cause   the alternator to turn back on that means you're  still able to save fuel without over draining your   auxiliary battery the next awesome function of  some DC DC charges is the solar input but I'll   go into more detail on that in part 3 when you're  shopping for a DC DC charger do your research you   want to look for a model that's a little put out  the statement amps even when it's working hard   or heating up for example this 25 minute model  is able to put out 25 amps even when internal   temperatures are approaching a hundred degrees  Celsius of course it also features that battery   temperature sensor so it's been designed so that  the battery is the limiting factor because battery   shouldn't be charged over 50 degrees Celsius this  DC DC charge will taper off the charging if your   battery starts warming up too much again that's  an advantage over a more traditional dual battery   setup not to mention they're almost a necessity  if you're running batteries that require different   charging voltages and in many setups that's the  case whether it's due to the battery chemistry   needing a higher voltage than your alternator can  provide or whether the battery location means the   voltage drop will make charging inefficient  they're also particularly important if you've   got a smart or temperature compensating alternator  at the end of the day your dual battery system can   be built in a number of ways but a DC DC charger  combines a lot of the features you need into one   unit it'll always charge your battery more  precisely than a basic system and some give   you the option of plugging solar directly into  all-in-all do your research and decide which   setup is right for you whether it's a separate  battery in a battery box that you charge with   solar and top-up at home every time you use it  or a completely permanent multi-purpose DC DC   charger that means you never even need to think  about your auxiliary battery you just know it'll   charge your second battery properly every time  when you're driving all connecting your solar   panel directly keep an eye out for part 3 where  I explain how to set up your system so you never   have to turn off your fridge again plus remember  to subscribe and check out the rest of the channel   for more full driving camping 12-volt off-grid  power and cooking tips tricks and techniques you

Channel: 4WD Supacentre

Views: 281,067

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Keywords: air compressors, camping gear, exhausts, 4x4, 4wd, camping tents, off grid, free camping, freedom camping, bush power, camping 12v, deep cycle, dc charger, dc-dc charger, solar power, camping solar, camping solar panels, solar blanket, agm battery, dual battery, dual battery install, dcdc, battery charger, battery charging while driving, starter battery, battery isolator, camping battery setup, 12v battery setup, dcdc charger, dual battery kit, batteries for camping

Id: 9ehQ_TKZwTA

Length: 9min 51sec (591 seconds)

Published: Wed Dec 11 2019