An unusual 12V (starter) battery question

ProDave said:
I think it says Gordon Equipments Ltd but it is hard to make out even in the flesh so so speak. No sign of a model or type number.
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Gordon equipements ltd were a manufacturer of automotive electrical accessories.
In 2018 they changed their name to Durite Ltd, who are still trading.

If you can't find any other identification on the red box (possibly under the red cardboard) Iit might be worth contacting them.

Have you managed to trace the red box wires, it may provide a clue.
 
Yes I found the Durite website but that is all about dash cams and surveilance, not basic stuff like this.

The connections are V-, V+ in Output 1 +ve and Output 2 +ve. Output 2 is not connected. I strongly suspect there is just a pair of diodes inside there, I will try and make some measurements to confirm that.
 
Personally I'm struggling to comprehend exactly what's going on in your system.
Please take an hour with your multimeter and check that everything is connected as you believe and then draw a circuit diagram. It'll help I promise 👍
 
ProDave said:
Can't find my mystery red box, but found this, that looks identical apart from the badge to me Car Go relay https://www.durite.co.uk/amfile/file/download/file/3658/product/3707/
Confirming that is the split charging device.
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That's what I said earlier the CarGo is a relay.

r4dent said:
HC Cargo 161059
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ProDave said:
Can't find my mystery red box, . So the other red thing I photograph is the remaining mystery.
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Trace the wires.

Contact the manufacturer.
 
And reading the Victron manual, the primary function is to charge the habitation battery, but if there is surplus solar power it will also charge the "vehicle battery" which in this case it the aux battery under the bonnet, not the starting battery.

So all I want is to charge the starter battery as well so it is sounding like that maintenance charger discussed elsewhere will do what I want. Anyone else agree?
 
Is there any reason why you want to have 3 battery sources, habitation, aux and starter,? Why not parallel the aux to the hab and run everything of of your now increased capacity hab battery?
You'd then have a standard layout and could charge everything in a standard way and fit a new battery maintainer between the 2 batteries to keep the starter battery maintained during layup.
 
ProDave said:
Here is the mystery red box https://www.durite.co.uk/085206-electronic-charge-split.html (now discontinued)

So it too is a split charging device.

So begs the question, why do I have this, and a separate split charging relay? Some more investigation needed.
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Could be any number of reasons, maybe one on the diodes in the dual unit failed so they fitted another VCR? Ultimately the dual unit is only charging 1 battery at the moment because one of it's outputs isn't being used.
 
merl said:
Could be any number of reasons, maybe one on the diodes in the dual unit failed so they fitted another VCR? Ultimately the dual unit is only charging 1 battery at the moment because one of it's outputs isn't being used.
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I definitely need to start following wires, though that won't be easy.

The Red Gordon unit has terminals for ground, in and 2 battery outputs but only battery 1 is connected. I have yet to see the wiring of the other one.
 
ProDave said:
I definitely need to start following wires, though that won't be easy.

The Red Gordon unit has terminals for ground, in and 2 battery outputs but only battery 1 is connected. I have yet to see the wiring of the other one.
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We are now at step 4 of the Scientific Method?
1 Question - Your original post
2 Research - All the posts so far
3 Hypothesis,
Logic The red box was the original split charge relay with a wire from "battery 2 output" to the second cab battery
It failed and someone installed the CarGo as a replacement.
To save time they left the red box in place and just removed the output wire
The red box is in circuit and connected to cab battery 1 (+ve & -ve)

Proposition: Red box has a resistance and is drawing current, causing problems with cab battery 1

4 Experiment
Disconnect at battery end the wire connecting Cab battery 1 +ve to red box "battery 1"

I look forward to steps 5-7 of the Scientific Method (Data Analysis, Conclusion, and Communication)
 
When i find a load of faults or some dipstick has been tampering then i rip all out and start from square one, this sometimes is the best and fastest option.
 
So continuing the diagnosis / following of wires / working it out.

The red Gordon / Durite split charging device.

The only connections made are ground, +v in and V out 1

Vin connects to starter battery + V out 1 connects to truck aux battery +

My hypothesis.

The installer (whoever that was) did not want to mess with the original alternator wiring for fear of upsetting a modern vehicle that will throw a hissy fit at any anomaly, and left it as it was, charging the starter battery. He then used half of the function of the Gordon unit to charge the aux battery from the starter battery when the engine is running.

In spite of the blurb telling us this is some complex electronics, externally it tests as a pair of diodes (using the diode test function on the Fluke multimeter) but with a very low forward volt drop.

So engine starts, alternator charges starter battery, battery voltage rises, as soon as it exceeds aux battery voltage the diode conducts and sends some charge to the aux battery.

The aux battery in turn is connected to the Victron charger in the habitation unit and that too takes some of the power from the alternator to charge the habitation battery.

So perhaps not ideal, it appears to do as intended and all 3 batteries get charged from the alternator.

At rest, the solar panels via the Victron charger keep the habitation battery and truck aux battery charged. But the split charge diode (as I will now call the red box) prevents any back flow and the starter battery gets gradually drained by the always on 12V loads and discharges slowly.

The Car Go unit only has 2 thin wires connected. They disappear behind the starter battery and I have not followed them yet. Whatever it is doing, it does not involve high power loads. So it's function is presently still unknown. I will seek out the manual for that to work out what these 2 thin wires might be doing. At the moment I have not even figured out how to get the cover off to access any terminals on it. I will try that later, but the pesky rain started again and getting soaked while trying to work it out is not part of the plan.
 
And the mystery of the Car Go relay.

It is switching a low power (fused at the starter battery) output that goes to the demountable camper unit. This is on the third pin of the 3 pin commando plug used for the battery connection. It connects to the Victron charger D+ input.

The Victron diagram shows this as connecting directly to the alternator. Again I think the original installer did not want to mess with the original vehicle wiring so used this Car Go relay to simulate that signal so the Victron knows the alternator is running and switches it to charge from the alternator (rather than maintaining the battery from the solar panels.)

I must draw all this out as a circuit diagram before I forget it.
 
Sorry I had misread one of the your earlier posts and now dismiss my hypothesis.

But, based on this new research I have another.

The red box was installed as a split relay to charge the cab second battery. A job it is still wired to do.

The Blue box was installed as a split relay to charge the hab battery.
It was disconnected for a reason unknown, but maybe because a different means of charging the hab battery was installed.

This explains the wiring but not your cab battery problem.
 
r4dent said:
The Blue box was installed as a split relay to charge the hab battery.
It was disconnected for a reason unknown, but maybe because a different means of charging the hab battery was installed.

This explains the wiring but not your cab battery problem.
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That could be, but the present cables connected are way too small to carry any charging current.

A digression, that may explain what appears to be a haphazard install. This is a 2016 truck. It was fitted with a demountable camper unit when new, I don't know any details. 18 months before we bought it, the original demountable camper was replaced with a new, larger one (that's when we think the air assist rear suspension was fitted). My speculation is perhaps the original one did not have solar panels and the Victron charger, and the red split charge diode thing used both of it's outputs to charge the truck aux battery and hab battery. That all got changed around a bit with the new camper unit having the solar and the Victron charger.

This thread has meandered a bit while trying to understand what is there. So back to the original problem:

When it is parked for any length, between trips, the solar and Victron maintain the hab battery and cab aux battery, but nothing maintains the starter battery and like most modern vehicles there is constant draw from that for alarm etc so it starts to go flat after a few weeks.

What I need to solve this is something to keep the starter battery maintained during layup. To me the simplest is one of these simple DIY maintenance chargers to trickle charge the starter battery from the cab aux battery. Very simple to make and fit under the bonnet. Something like being discussed here. https://wildcamping.co.uk/threads/high-performance-diy-battery-maintainer.100567/

One last comment, I think the previous owner knew about the problem. His "solution" He has connected the aux cab battery to a 50A Anderson plug under the bonnet and made a set of jump leads to plug into that. I think he was intending (or did) use it to jump start the truck from the aux battery if the starter battery had gone flat. I would rather prevent it going flat in the first place.
 
Seems to me like a bit of a hotch potch and it's time for a re-wire along the lines of a standard system Dave? As I said in post 29, I can't see any benefit from having this ere aux battery thing going on and assuming it's working, the Cargo VSR would do a decent job of charging the leisure batteries and could be used again, you just need to do a bit of rewiring.
As for your experience with the starting power of a semi charged battery then consider that when starting an engine there's a current draw of a few hundred amps but only for a very short period of time, maybe less than a second, this amount of drain represents a very small portion of a battery's capacity so as long as the connections are good and the starter motor is in good shape I can't see any reason why a partially charged battery won't give the engine a decent crank for long enough to start it.
 
Have you thought of using one of those small solar panels designed just to keep starter batteries topped up?

Simple to fit and around £30.
 
I have a spare 12W panel (previously used on a boat) that I thought about fitting for that purpose, but the only practical place to mount it would be on the camper so another connector to plug and unplug and some fairly tortuous wiring. What's wrong with the maintenance charger to keep the starter battery maintained from the aux battery that is already being maintained by the solar?

I am thinking of making it as a "portable" unit, only fitted when laid up and removed when in actual camping use.
 
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