CTEK MXS25

Yes, sorry. To the Camper Trailer.

My Ctek charger was used in this manner, just by connecting to the cable that usually connects to the vehicle to allow charging whilst on the move.
This was an effective multi-mode maintenance charging regime I used.

Using this method, the bigger charger you purchase is not restricted to on-board camper trailer use and can also be used to provide a smart charging routine for your vehicle batteries from time to time.

My camper also has an on-board 240 volt charger but I was not overly confident in it until I had time to test it. I now tend to use this charger when in the garage at home.

I added a Ctek D250s Dual dc-dc charger to provide a better multi-stage charging system while on the move and also provide the connection of a solar panel when stationary.

I now find I have a sound charging system when travelling and while at rest and rarely need to use the on-board AC charger at all. (I also don't tend to stay at caravan parks with 240v power)

What size is the existing cable?

Are you having trouble charging the batteries with the existing setup?

What is the tow vehicle, and the current in car arrangement?

I had a single battery 120ah which worked ok and all charged ok i guess on van park power. Battery lasted a few days with out recharge in a bush camp running 2 fridges Waeco 80 & 50ltr but with more bush stops and longer planned this trip am adding another 120ah (getting 2 new Thumper Redbacks the same) and thouhgt I would want to recharge more efficiently and quicker with a larger charger and have it double as a portable charger also for other car batteries etc.

I do have 1kw genset and solar too

I'm a little confused, if the battery is charging ok now off the car I don't see the advantage of using a DCDC charger.

I don't know what the present charging current and voltage is but installing a 25A charger may limit the charging current while your at the same time going to be installing more battery capacity. It going to take around 6 hours drive time to bring the batteries back up (120AH) if discharged to 50% SOC.

Generally if the tow vehicle has an adequate charge voltage and adequate cabling has been installed charging straight off the alternator will you charge your batteries faster up to around the 80% SOC than a charger would. If your going to be deeply discharging your batteries or have lots of battery capacity I would stick with the present arrangement and see how it goes.

If your going to spend a fair amount of time at sites where power is available I would be spending the money on a bigger mains charger, if on the other hand more at no powered areas for long periods then more solar as gen sets aren't popular with other campers.

Cheers
Leigh

Sorry Leigh, present charging from car on tow is via Anderson plug to one 120ah battery and works ok. I am adding another battery to allow longer in non powered sites. I don't intend to get a DC/DC charger.

I have a small 3.6ah Ctek which provides a maintenance / trickle charge in to batteries when hooked into mains power. I was concerned this may be insufficient to recharge 2x120ah batts with amperage drain high and recharge low, I am unsure if I have that assumption right and need to validate that.

On the assumption I am right I concluded a larger charging unit, the Ctek MXS25 will refill the batteries more efficiently and quickly from a mains source and when a genset is hooked up.

Is my thinking flawed ?

Ok now see where your going:) The 25A Ctek will certainly charge your batteries quicker than the 3.5A unit.

When used with a gen set would be much more efficient than the 12V charge the gen set can supply.

Thanks for confirming my laymens logic isn't too far out... I wish you were here in Bundaberg I would see you to help me with some of the install aspects of various projects I have on the to do list.... I concede I get rather lost with electrical stuff.... volts, amps, current, ohms, resistance etc etc... so need to reach out to experts...

The wiring presently from the battery looks to be about 125ah gauge and is with batteries at the front are only a few meters from the fusebox.... should I run a 15, 20 or 25amp fuse on this circuit you think?



Again thanks

Hi what wiring are you referring to, if it is the wiring to the new battery/s from the existing battery I would use 10mm2 - 13mm2.

I would protect this with a 100A fuse.

The charger I assume will replace the unit that is already there, if the cabling on the charger will reach to the fuse box I run the cabling to the existing fuse and replace with a 30A fuse, the cabling on the charger being a 25A unit should be able to handle the current from the 30A fuse should a short occur.

I'm assuming the cabling between the battery and the fuse box would be around 10MM2, do they have a fuse between the battery and the fuse box, if not then there should be one rated appropriately for the cable.

Sorry, should have said if second battery is remote from the first battery it should be protected with 50A - 100A fuse or circuit breakers mounted as close as possible to each battery.

If the batteries are side by side then just jumper across.

I intended leaving existing wiring to the batteries which is around 10 / 13mm and is 100ah rated, me linking batteries in parallel with positive to one battery, ground to the other and linking positive to positive and negative to negative of each battery with 'jumpers'.... I understand this allows even / equal charge / discharge rather than all going in and out of the primary and distorting the condition of both over time... I am unsure I need another separate fuse do I as I assume there's one in the fuse box or somewhere between the battery and fuse box.... will check this... but I know the main harness including lights, water pump, 12v power sockets are on a 25ah fuse

There will be no anticipated increase in current current flow as a result of the change, its still the same fridges, lights, water heater, water pump and power drawn from small appliances... the additional battery is only intended to provide more amp storage for longer durations without recharge... suffice to say I intend including a small 600w inverter and this will be wired onto another circuit with a 15ah fuse.

The new 25ah charger I intended to wire into the same old circuit place of the 3.6ah one, but replace the wiring in to match the wiring presently being used on the charger (circa 6mm), and yes on the strength of your advice, upgrade the fuse to 30ah if you thinks that's whats needed.

Thanks for your guidance

Um that 600 watt inverter will require at least a 50 amp fuse....that is FIFTY amps.

Inverters are very very hungry things and not a good idea to run them with out the camper connected to the car and the engine running.

AND they need heavy cable.

Ask ya'self do you realy need an inverter

cheers

Thanks Bantam, you have just saved me another job.... Inverter in camper is off the list.... I will install one in the back of the car only....

If we need 240 in unpowered sites (laptops) we can always hook up the genset to the power in socket and plug in inside that way I guess...



Thanks heaps

My recomendation is..don't install it at all.

If you must carry one bolt it down in the lid of one of those heavy plastic equipment cases ( the knock off of the pelican cases)

and plug it in when you need it...you already have an anderson on the back of the vehicle.

You should never run a 240v inverter in a moving vehicle and if you mount it, it becomes an "electrical installation".

as far as charging lap tops...you can buy DC to DC power supplies for laptops that are far more efficient than using an inverter and doing two power conversions.

Same with charging cameras and phones.
Most of these charge from a USB connection and either 12 volt charging leads or 12 volt supplied USB power outlets can do the job nice.

cheers

Great idea and thanks very much.... hadn't thought of that...

I had visions of using it for 240 applications in the car while travelling (laptops / use / charging etc) but as you say may explore the DC options you refer to... the USB solutions for other stuff I understand and agree with.

As you say I can plug into car at camp if needed and I do also have the genset plug in option to provide the trailer some 240 if needed



Again thanks