Charging caravan batteries

Onematch
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Charging caravan batteries

Post by Onematch » 14 Jun 2019 19:07

so I have a Bushlapa Rooimier withe two batteries and am wanting advice on powering the caravan batteries - would a straight connection from the main battery to a BH connection at the towbar be ok or should I install a DC to DC charger?

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Craig Lord
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Re: Charging caravan batteries

Post by Craig Lord » 14 Jun 2019 20:27

It depends on your alternator. If you have a "smart" alternator which can regulate the charge supplied to the battery depending on the load and state of charge then your auxiliary batteries may not always get the required amount of current needed to charge properly. Older alternators like the one in my vehicle supply constant 14.4 V if I remember correctly and this is enough to charge an auxiliary battery depending on its type...

Also, if you are wanting to charge deep cycle batteries then they often need 14V or more to charge efficiently to 100%. Most of the newer "smart" alternators do not supply constant 14V or more consistently so the deep cycle batteries will never reach 100% charge. In my opinion it's best to get a DC to DC charger which will match the charge profile of your 2 auxiliary batteries. Also make sure the cable that you run to the rear is sufficient to safely carry the demanded current and is fused properly. I'm sure the guys who are more clued up on vehicle electrickery will be of more help and maybe let me know if I'm also on the right track!
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Re: Charging caravan batteries

Post by Peter Connan » 15 Jun 2019 05:40

I disagree slightly.

Your alternator needs to charge (at least) 3 batteries. In a normal electrical system, the voltage is the same throughout the system. Even the smartest alternator can't give some batteries more voltage than others.

Now the problem is that different types of batteries require different voltages to charge optimally. And the one that needs the leasr is the vehicle's crank battery. What makes it worse is that feeding the crank battery the type of voltage that will fully charge any of the batteries usually recommended for fridge applications will destroy it pretty quickly.

So if you run crank batteries throughout, a lead from the alternator is OK (assuming you have massively thick cables). But if you want to use any other type of battery in the van, just get a proper DC/DC charger.

I would actually go a step further and recommend an integrated solution like the HCdP power panel.
That gives you DC/DC, a 220V maintenace charger, an MPPT solar panel controller, a variety of outputs and everything neatly installed with the necessary fuses and trip switches.

I promise that it is also cheaper than buying all the bits you need to put a complete system together.
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Re: Charging caravan batteries

Post by Craig Lord » 15 Jun 2019 08:14

Peter Connan wrote:
15 Jun 2019 05:40
I disagree slightly.

Your alternator needs to charge (at least) 3 batteries. In a normal electrical system, the voltage is the same throughout the system. Even the smartest alternator can't give some batteries more voltage than others.
Ok thanks Peter that makes sense! I was trying to say something similar but you did much better job. If you decide to run a line direct from the main battery you may at least want to install an isolator system that will disconnect the main and auxiliary batteries when the ignition is off to make sure that your main wont also be drained along with your auxiliary batteries but as always I bow to the experts :mytwocents:

Peter that power panel you speak of sounds interesting, I'm going to check it out
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Tinus lotz
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Re: Charging caravan batteries

Post by Tinus lotz » 15 Jun 2019 09:04

Rob you have 2 tow cars a 4.8 grx with normal alternator and a disco with a smart alternator ....
I would suggest a new c tec with a con wire to keep charge voltage above 14.7 ....
What batteries have you got in your trailer ?.
The smart pass allow more current flow for a faster charge to the back because 2 110a take a long time to charge at 20a
All smart batteries can only take 20% of full capacity per hour in ideal charge conditions...eg 14.7v
The smart pass allows 50a to flow to the back so you can charge 2 batteries full in 5 hours .
With the c tec you will have mppt solar ready also
Please put pics of your batteries so we can see what you have .
The crank battery gets charged within 30min and them depending on your dc load the voltage falls to stop it from overcharging the crank one my 4.8 gets to 13.6 or so very quick .
With your trailer all the way at the back wanting 40a you would be lucky to see 12v there

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Re: Charging caravan batteries

Post by Onematch » 16 Jun 2019 22:46

OK thank you all for the input!!

I have done another short road trip in the Patrol this weekend -EL to Somerset East - sorted the seat out and much happier, and comfortable - the more I drive this machine the more impressed I am.
We did a short trip on the gravel road from Alexandria (the Woody Cape road) to Cannon Rocks, this eve, on the way to Kenton - very impressed, as I have always used the Disco 3 with its air suspension which has been amazing - but daardie Patrol is 'n meneer!! Lights need to be upgraded through.

So Jan and I and my daughter are camping in the KNP in July for 10 days so will post pics of the battery set up and I will need the input please to power the Bushlapa Rooimier.

Just an aside - this has to be the nicest forum - just solve problems -

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Re: Charging caravan batteries

Post by Onematch » 18 Jun 2019 19:05

OK I chatted to Tinus and this is my Bushlapa set up.

I have two AGM 105 batteries in the Rooimier and all the electronics were redone using Victron hardware - pics attached I hope!

My Disco has two 30amp HCDP chargers - one charging to the Rooimier via a BH plug - the other for the battery box (I have a NL in the car) for the small 32 lit Engel.
Plus a direct BH plug to run the portable compressor directly connected to the charging battery with a fuse.

Sooo The Patrol is now the chosen retirement /photography vehicle (its been a very difficult choice!) so I need advice - do I remove the two HCDP 30amp chargers from the Disco and fit them to the Patrol - I don't have a monitor in the car to check charging, but the battery box has an indicator on the side (by the way I have not bought a battery for the box yet!).

The Rooimier has a 120 solar panel fixed to the roof and I have bought a semi flexible 100w China job to plug into the BH I had fitted at the back of the van with a 6m lead to put in the sun.

I need a couple of Hella connections in the car and a BH or two as we plan to do some fairly long solo (Rob and Jan) trips into Southern AfrIca taking mainly landscapes and a bit of wildlife.

My auto electrician is pretty sharp, but any/ all advice will help as I want it right the first time.

My Disco drawer system will fit it looks like (a Front Runner), and I need to almost design a reverse single draw system for the photo gear - I don't mind removing the second row of seats or remove one half of them.
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Onematch
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Re: Charging caravan batteries

Post by Onematch » 18 Jun 2019 19:14

Sorry more images!

The BH on the pic connects the 100w solar panel to the system.
The pic of the battery is from the top as they are a mission to remove!
The BH is the charging from the 30amp HCDP from the Disco.
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Tinus lotz
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Re: Charging caravan batteries

Post by Tinus lotz » 18 Jun 2019 19:40

Rob imho there is no dc charger in there other than the solar one ....def aggregated glas mat batteries so you would want to change above 14.7 at least
I would put the charging senter in the caravan and then just connect the bh to the car to much volt drop from the front .
What voltage is the hcdp putting out ?
The ctec is great with this ...but lets see what you measure
T

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Re: Charging caravan batteries

Post by Onematch » 18 Jun 2019 19:45

Supposedly 30 amps Tinus - but have not measured.

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