I need to ask a basic question about charging the batteries in our stock standard 2015 Expanda caravan. Does the stock standard Expanda come with a DC to DC charger which I gather is what should Be used when charging from a car? Recently we upgraded our tow vehicle to a new Patrol which i got the dealer to organise the trailer plug. I was though a little puzzled when the sparky was asking the dealer whether we had a DC to DC charger in the caravan. I assumed we had but on our current trip found that the caravan batteries did not seem to be charging properly from the car. Not sure if that was because the plug was not plugged in properly, something to do with the “smart alternator” in the Patrol or what.
20' Series Car charging Expanda Caravan
- Thread starter Wombat6
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Hi @Wombat6 , a DC to DC charger is a specialized piece of equipment which is able to "upgrade" the voltage from your tug (alternator) to a higher voltage to make sure you get enough voltage to charge your van battery. An excellent piece of kit, but it comes at a price and is not part of any standard Expanda van. As you are obviously aware, in the latest vehicles, the "smart" alternators reduce output voltage (when they "sense" the tug battery has enough starting power) to a much lower voltage to save fuel and do not take into account any other storage battery such as dual battery systems and van batteries. That is why your van battery will NEVER be fully charged by your vehicle alternator. Some alternators can be "tricked" into recognizing extra batteries with electronic devices.
Your Setec ST-III manages mains charging when connected to 240 volt power AND also has provision to charge your van battery when travelling and connected to tug. However, there are limitations: Max charge current is limited to 10 amps, max charge voltage is limited to tug alternator voltage MINUS a 0.7 volt drop caused by a power diode (electronic device which allows current to flow only one way INTO battery) and that does not take into account any voltage losses in wiring between tug and van!! So just because you are driving for long periods between stops does not mean your van battery/ies will be fully charged when you arrive at your next camping spot!! Alternatives are solar panel power when you arrive or generator. That leaves you with only these choices: sufficient battery storage to last the times between usages or DC to DC charging when driving (and when stationary if you run the tug engine). Hope this clarifies things for you to make the appropriate choice/s.
What sort of camping are you doing @Wombat6 , caravan park, free camping off grid or a bit of both ??????
If just van park then don't worry about it ad 240 will do the job, if free camp off grid then it will depend on your set up as to if charging from vehicle is worth it.
On a majority of expanders the 12 v supply to van from 12 pin will go to the setek as well as supply the fridge, they are isolated though so fridge can't suck the van battery dry.
If just van park then don't worry about it ad 240 will do the job, if free camp off grid then it will depend on your set up as to if charging from vehicle is worth it.
On a majority of expanders the 12 v supply to van from 12 pin will go to the setek as well as supply the fridge, they are isolated though so fridge can't suck the van battery dry.
Boots in Action - thank you very much for your in depth reply, it explains a lot. So our 2014 Jeep for what ever reason must have delivered sufficient voltage to charge the batteries. However, our new Patrol with its smart alternator doesn’t. This explains the
Boots in Action - thank you very much for your in depth reply, it explains a lot. So our 2014 Jeep for what ever reason must have delivered sufficient voltage to charge the batteries. However, our new Patrol with its smart alternator doesn’t. This explains the concerns the sparky Nissan used had about whether we had a DC to DC charger (or words to that effect which I received second hand). So, if I move on from why an “off road” caravan doesn’t come standard with such, what are our choices. Do I get the sparky to install such into the Patrol or would it be better to get it put into the caravan because we do free camp and the car has always been our stand by generator if the caravan batteries go flat?
@Wombat6 you say your van is a “off road” model but is your van the outback model. If so the batteries will charge via the solar panel when driving or parked up at camp. No connection to the 12 pin plug on the drawbar and as such no connection to the car. The 12V connection installed by the auto sparky will power your fridge in transit and possibly also the ESC if fitted. When you go back for your next service request the dealer turn off the smart charge or enable the option for Aux battery charging. It will be one of those terms.
Correct @MDS69 , if the Nissan dealer will do that or if alternator is able to be modified without voiding the vehicle warranty - an excuse they may come up with!! @Wombat6 you will have to weigh up your options and power usages to decide which way to go. @Drover has put forward his suggestion and that works for him, but he is vigilant on his power use and never (if rarely) has to depend on alternative charging as he does not have a DC to DC charger to bring his batteries up to speed. He relies on solar power and his 2 battery storage and seems to have no problems. It is not a case that there is NO CHARGE going from your tug to your van. You will have power (AMPS) to your fridge and there is still power (AMPS) to charge batteries, but insufficient VOLTAGE to bring batteries to full capacity. You need a minimum of 14.0 to 14.7 volts (at the van battery terminals) to charge batteries to full capacity. If you have always depended on your tug to charge your van batteries, then your power usage must be higher than what your limited solar can put in. If that is the case, and you want to continue using the tug to charge flat/low van batteries, then a DC to DC charger is the the only option for you if free camping a lot.
Static running of your vehicle fir a few hours to charge batteries is not a great idea.
Ok, so I think I understand now. By default my “Outback” Expanda only comes with mains power charging for the batteries as well as charging from the single solar panel I ordered with it. My previous tow vehicle must have been pre smart alternators so could charge the battery although the caravan really should have had a DC to DC charger which the dealer made no mention of. However, as my new tow vehicle does have a smart alternator I will need to get a DC to DC charger. I like the reviews of the Cteck D250SA and gather as I have tow gel batteries should also get the Smartpass.
I have two remaining questions. Firstly, the Expanda Caravan plug only uses two of the large pins - 9 & 10 which I know feed the fridge. Would these also charge the batteries? Secondly, to work with a smart alternator the Cteck D250 needs a feed from the ignition. As this doesn’t seem to be part of the standard 12 pin wiring, I assume I will need to get a sparky to provide an additional wire to the trailer plug and I will them need to go to the trouble of passing this up the drawbar and into the caravan and then to the charger?
I have two remaining questions. Firstly, the Expanda Caravan plug only uses two of the large pins - 9 & 10 which I know feed the fridge. Would these also charge the batteries? Secondly, to work with a smart alternator the Cteck D250 needs a feed from the ignition. As this doesn’t seem to be part of the standard 12 pin wiring, I assume I will need to get a sparky to provide an additional wire to the trailer plug and I will them need to go to the trouble of passing this up the drawbar and into the caravan and then to the charger?
The standard wiring isn't even adequate for the fridge IMO. Many people complain of warm fridges on 12V and I have seen the pins heat up enough in the 12 pin socket to melt the plastic.
I would run large diameter cable (6 bs? with a suitable isolation device) from the tug battery to an anderson plug. Then another anderson plug with the same large diameter cable at the front of the van going to the fridge and the DC to DC charger. You can isolate the fridge with a fridge switch or a solenoid switched from the current 12v input from the tug.
This will ensure your fridge works on 12V and you have enough current for the DC to DC charger to work effectively.
I would run large diameter cable (6 bs? with a suitable isolation device) from the tug battery to an anderson plug. Then another anderson plug with the same large diameter cable at the front of the van going to the fridge and the DC to DC charger. You can isolate the fridge with a fridge switch or a solenoid switched from the current 12v input from the tug.
This will ensure your fridge works on 12V and you have enough current for the DC to DC charger to work effectively.
You are getting very close to the position now @Wombat6 . Yes, there are separate heavy wires from tug to connector to van fridge which need to be able to carry at least 15 to 16 amps plus continuously, hence the problem with burnt out pins (if loose connectors) and not using an Anderson plug. There is another lighter wire that is in the van harness from van connector which gets its power from being connected to the POS heavy wire for fridge. This lighter wire only has to carry 10 or so amps to go to the Setec to charge the van battery and uses pin 10 as the same earth return to tug as fridge. To get max voltage/current to van battery, I have a separate heavy wire from tug to van connector, and I use pin # 8 on my 12 pin connector which not only enables a heavier wire at the pin connector, but is rated to 35A, far greater than what the battery will ever receive or accept.
The cabling to the DC to DC charger only has to be sufficient to carry the current to fridge and battery, as voltage loss is not the problem then as the DC to DC charger will boost any voltage from tug to whatever setting you have on the Ctek D250..