autotrail 3rd battery, inverter wireing and extra solar pannals (1 Viewer)

[Scout]

My new to me autotrail Arapaho, bought privately, as 3 leisure batteries
No: 1 is connected by the autotrail harness with a 20amp fuse,

No: 2 also is connected by the autotrail harness with a 20amp fuse,

No:3 is connected to no:2 by some heavy looking cable and does not appear to be fused in its own right, it’s just connected to the terminals of No:2, so both 2 & 3 are protected by 1 20 amp fuse? This is making 2 & 3 into one big battery?.

The 2kw inverter is also connected to the terminals of no: 2 there does not seem to been a fuse or isolator switch for this. This to me does not seem correct?

Fitting extra solar panels to an autotrail

I already have the standard fit 85watt solar panel wired to the Sargent charger with built in controller. I’m thinking of add extra solar panels to keep up with the inverter usage and feed the leisure battery’s, probably 2X 150 watt, from what I understand this should have an independent controller with the output going to the leisure batteries, is this correct?

Comments please, please note whilst I have a basic ground with electric, at the moment I have chemo brain and I’m not 100% fit.

 

[ES Cumbrian]

Inverter should be fused between it and the battery you would need 150 amp maybe more depending on what you will be running from it.

 

[tonka]

Battery connections sound fine, the Autotrail come with a facility to use 2 harnesses for connection so a third would need to be made using the method you state. The wiring you now have will make no1,2 and 3 all into one big battery... Fusing of the inverter may need looking at....
Ref solar, you don't state what Sargent unit you have but at very best case (ec500) it will at max take 120w. So you will need to re-configure with a separate regulator and maybe a duel version to maintain power to both leisure and engine batteries..

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[andy63]

Hi Phil. .. the set up you describe doesn't sound ideal...
You may not be up to it at the moment but if you had the will a complete rewire of the batteries so that they are all paralleled at source would be the way I'd be inclined to go...
The autotrail wiring from battery to Sargent unit is fused at 20a and doesn't look up to much more on the ones I've seen...
The batteries are connected at the Sargent unit anyway so in effect are connected in parallel. .
On the solar side I'd be inclined to fit the panels as you suggest and wire them independently of the Sargent maybe even removing the one built in through the Sargent so it can't disrupt the charging of the panels you plan to fit....
@Jaws has had a fair bit to do with auto trail and Sargent wiring and hopefully will advise you...
Andy.
Ps.. agree your inverter wiring shold be fused and ideally have an isolated switch..

 

[Abacist]

The AutoTrail charger in the Sargent unit is not man enough to charge your battery bank with 3 batteries especially after using an inverter - check your AT handbook. You need to think about getting a bigger, more sophisticated charger that will replenish the batteries more quickly and completely otherwise your 3 batteries most likely will not recharge back up to capacity. Solar input will help but you currently have an inbuilt weakness because of this.

 

[Jaws]

I can only say what I did, which has eliminated the uneven and frankly weird way the Autotrail/Sargent set up works.
After speaking to Sargent to confirm what I had found, I joined both the feeds from the charger together at the battery end ( although both wires are connected at the charger end there was always a very very small difference in the delivered amperage )

I used cables equal to 6 x the thickness of the wires from the charger to the battery bank to join the batteries together.. I needed nothing thicker as I have absolutely no intention of using an inverter due to my hatred of all things inefficient
If using an inverter I would suggest using coupling cable 50% greater than the recommendations of the inverter manufacturer to be on the right side of the game

The charger can only deliver what it is able to. It will charge the three batteries but from flat to fully charged will take longer than with a two battery set up.
I have 300w of solar panel on the roof running through a pretty expensive Italian controller.. That assists the Sargent charger nicely

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[Reallyretired]

If you're using the inverter to capacity you will need a 300A fuse to allow for startup of appliances.
There could also beneficially be a fuse in the + line between the batteries though 150A should suffice as half the current should come from each battery, assuming they are wired in parallel.
I assume the inverter doesn't draw any current from the other, single, battery, otherwise the 20A fuse won't last long.

 

[andy63]

I assume the inverter doesn't draw any current from the other, single, battery, otherwise the 20A fuse won't last long.

Not directly. But if the wiring is as I am thinking it could as batteries 1 &2 will be connected together at the Sargent. .
So if the load on 2&3 from inverter is heavy and drops the voltage sufficiently then the 20 amp fuse on battery one would pop...
Andy

 

[funflair]

So it looks like no1 is missing out on the "inverter party" and will have a higher level of charge and higher voltage when the inverter is running so it will try to rectify this via the Autotrail charger cables and 20 amp fuses, not ideal in my view, will it blow the 20 amp fuse? dont know.

If the Autotrail/Sargent wires just pair up at the charger I would be tempted to make all three batteries one big block with heavy interconnects and tap the inverter across the opposite corners, then likewise with the charging cables.

Martin

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[funflair]

If you're using the inverter to capacity you will need a 300A fuse to allow for startup of appliances.
edited post
I assume the inverter doesn't draw any current from the other, single, battery, otherwise the 20A fuse won't last long.

The inverter will draw from battery 1 but but only indirectly via the battery charger cables and at a rate relative to the differential voltage between battery 1 and battery 2/3.

Martin

 

[Scout]

Thanks for all the replies I’ve taken the advice on board, as soon as my finger get some feeling back from the bloody chemo I will, make a start.

1st job will be to take off the batteries, you can see from the pics they look like different makes and sizes, once I determined how good they are and what size AH they are I will decided if I keep them, or ditch them and start with known good ones.

I will at that point decide whether I need 3 or just fit 2, I will join them plus to plus minus to minus with 25mm cables. I have a 3rd autotrail battery lead coming from a funster (thanks) so I’ll have a choice of using it or keeping it as a spare.

I’ll fit a large fuse to the inverter at the battery end and double pole isolation switch on the inside. I might relocate the inverter to the side panel to save room and put a wire cage around it to ensure air flow.

The output from the inverter needs sorting, it powers everything, it’s just been wired to the input of the van, and need relays to power only the two mains spurs from the EC500.

After I’ll think about adding more solar. Heres pics of the current (no pun intended) insallation

 

[Scout]

Update:

Last week as I didn’t have time to take off the batteries, so I tested them by charging them for 3 days, they were showing 13.7volts at the autotrail 480 control. I then unplugged the mains. I put on the inside lights and the panel showed a current draw of 4 amps, within 4 hour the battery alarm was going and the a panel shed 10.5 volts.

I took this to mean 1 or maybe all of the batteries was duff, As I’ve no knowledge of the age of the existing batteries and the fact that they all appear to be different makes I’ve decided to start fresh with two new batteries of up to 130ah, which I will order later this week.

I spoke to Sargent electrical a few times and they said if I fit extra solar, I will

A: need a separate controller feeding the leisure batteries

B: need to program the existing panel going into the Sargent ec500 to feed ONLY the hab battery? Has anybody done this? Is it correct?

They said this because if two feeds from two different solar controllers feed the same bank of batteries it can cause confusion to the controllers and end up being worse off not getting a full charge.

The other thing I could do is disconnect the existing panel from the Sargent ec500 and connect it into my new regulator using that to feed both banks of batteries,

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