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Dual Batteries

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When I ordered my vehicle I paid for the second battery. Can anyone help me with these questions
1. When I look at the electrical information on the screen and it gives me a battery charge percentage. Is this info only relating to the main battery?
2. If I attach a battery charger to the second battery will it only charge the second battery or will it also flow through to the main battery so both batteries will end up being fully charged
Many thanks
 

TheDocAUS

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1. The two batteries are not isolated from each other, but the % is the main battery. You install a cheap BLE battery monitor on each battery of you want individual information.

2. Not the best way to do it. It will charge the aux battery and some equalization will take place between the two batteries.

In my setup, I mated a CTEK250SE with the 120S. Then added a rooftop solar panel. That setup will charge both batteries. This thread shows the evidence. The graphs are from the BLE battery monitor mentioned in point 1.
 
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Thanks Michael I have now got a full primary battery and transferred my charger over to the primary.
Thanks again
 
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Hi Mi
Thanks Michael I have now got a full primary battery and transferred my charger over to the primary.
Thanks again
Hi Michael I have bought a monitor and put it into my second battery and can see that it is charging ok. Is there a way of telling what the State of Charge of this second battery as is shown on the Ineos screen for the main battery. I know the Ineos system won’t show me the State of Charge but does the monitor tell me this.
Also the state of charge goes up to a maximum of just over 80% for the main batteryafter a long drive. Will it never get up to 100% ?
Also if I check the state of charge after the car has sat overnight with nothing drawing power it drops by about 10%. Is this normal?
Last question. Do you know how the second battery decides to top up the main battery. My logic tells me that the main battery would always be drip fed from the second if it is depleted whether the engine is running or not.
Would appreciate your input and hope that you don’t mind my questions
Many thanks
Nigel
 
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Hi Mi

Hi Michael I have bought a monitor and put it into my second battery and can see that it is charging ok. Is there a way of telling what the State of Charge of this second battery as is shown on the Ineos screen for the main battery. I know the Ineos system won’t show me the State of Charge but does the monitor tell me this.
Also the state of charge goes up to a maximum of just over 80% for the main batteryafter a long drive. Will it never get up to 100% ?
Also if I check the state of charge after the car has sat overnight with nothing drawing power it drops by about 10%. Is this normal?
Last question. Do you know how the second battery decides to top up the main battery. My logic tells me that the main battery would always be drip fed from the second if it is depleted whether the engine is running or not.
Would appreciate your input and hope that you don’t mind my questions
Many thanks
Nigel
I have found the charge percentage for the second battery on the monitor and it is currently reading 100% which is good news. Thanks
 
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TheDocAUS

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Hi Mi

Hi Michael I have bought a monitor and put it into my second battery and can see that it is charging ok. Is there a way of telling what the State of Charge of this second battery as is shown on the Ineos screen for the main battery. I know the Ineos system won’t show me the State of Charge but does the monitor tell me this.
Also the state of charge goes up to a maximum of just over 80% for the main batteryafter a long drive. Will it never get up to 100% ?
Also if I check the state of charge after the car has sat overnight with nothing drawing power it drops by about 10%. Is this normal?
Last question. Do you know how the second battery decides to top up the main battery. My logic tells me that the main battery would always be drip fed from the second if it is depleted whether the engine is running or not.
Would appreciate your input and hope that you don’t mind my questions
Many thanks
Nigel
Nigel

The SOC does seem to differ between cars. Mine says 100% SOC when it is really around 95% per cent.

The BLE app, not the car, will show you the SOC (estimated based on battery voltage). The BLE holds data for 30 days and when the app connects it downloads the data. The data can be viewed in app, this is from my aux battery.

aux24apr2024-jpg.7854455


I use the SOC and the amps charging to work out the real SOC (of both batteries). Assuming no big draws are operating (like the thermo fans in helicopter mode) and the charging amps are around 5 amps, the SOC is really 98-100% regardless of what the Grenadier SOC says. As a battery(s) nears full charge it cannot take much current. Once they really hit 100%, the amps maybe only 1-2 amps. On a few long drives the draw has been zero amps. Using amps like this makes it easy to work out what is really happening- but I have done it for years, so it require a little practice.

Mine does not lose 10% overnight, unless the PWR is left on. Leave that on and and there is a big drain overnight. Turn it off, only a modest drain 1-2 %. So check PWR is not on. There are big draws if the PWR button in on (draw will vary depending on what accessories you have fitted). Mine car behaves the way you describe if the PWR is left on (see PWR switch on far left below).

1731574054488.png


The main and aux battery are not isolated from each other, so there is equalization taking place. The graphs here show this happening, the fridge draws on the aux battery overnight (the fridge circuit is wired onto the aux battery terminals) and you can see a power draw from the main battery as well (just smaller). The graphs also show my solar panel charging the aux and main battery.

Note: may car is fitted with a CTEK250SE mated to the 120S.
 
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Mr. Largo WINCH

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Bonjour,
Un lien un peu ancien sur mes recherches concernant la gestion de l'électricité sur le Trailmaster équipé de deux batteries.

La documentation du CTEK présente sur les véhicules équipés de deux batteries, précise que le fil rouge du CTEK doit être connecté au contact du véhicule. Un fil connecté au contact est disponible derrière la batterie auxiliaire. Il s'agit d'un petit fil jaune qui devait initialement servir à commander un relais pour l'alimentation d'un compresseur qui n'a jamais été posé.
Depuis que j'ai fait cette modification, la batterie principale se recharge à 100 % (affichée au tableau de bord) après seulement quelques dizaines de km.
Il faut savoir que le Greandier est équipé d'un alternateur dit "intelligent" (Smart Alternator) qui ne fonctionne pas comme les équipements présents sur les véhicules anciens. Pour le vérifier, il suffit de se positionner sur l'écran « Off Road » et de choisir l'onglet « Electricité ». On voit alors sur l'écran la tension de charge de la batterie principale. Moteur tournant au ralenti, la tension activée est de 14,2 V. En roulant normalement en accélérant, la tension monte légèrement à 14,3 V. Lorsque vous décélérez en lachant la pédale à l'approche d'un feu rouge ou d' un stop, la tension de charge affichée monte jusqu'à 14,9 V. Il s'agit en fait d'une forme de récupération d'énergie qui sert à charger la batterie principale et la batterie secondaire. Il existe un voyant sur le CTEK qui indique dans quel sens se fait la charge de la batterie principale vers la secondaire ou l'inverse. Le CTEK permet également à la batterie secondaire de venir en secours de la batterie principale lorsque la tension de celle-ci est faible pour le démarrage.
Depuis que j'ai fait cette modification, qui est conforme aux spécifications d'installation du CTEK, je n'ai jamais eu de problème de charge de la batterie principale.
 
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Heet33

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I am most familiar with dual batteries on an RV; house and chassis. Is any plug in the Ineos hot when car and power switch is off? Or do I need to wire my fridge directly to the second battery? You’d think one would be as this is one of the main reasons to have a 2nd battery. I haven’t found any good literature on the dual battery schematics etc. sorry if question has been asked before. Any help understanding or directing me to the right source is appreciated
 
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anand

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I am most familiar with dual batteries on an RV; house and chassis. Is any plug in the Ineos hot when car and power switch is off? Or do I need to wire my fridge directly to the second battery? You’d think one would be as this is one of the main reasons to have a 2nd battery. I haven’t found any good literature on the dual battery schematics etc. sorry if question has been asked before. Any help understanding or directing me to the right source is appreciated
There's plenty to read up on the system here on the forum... The short version:

Ineos' dual battery implementation is intended that everything is wired to the main (starter) battery and the aux battery exists to trickle charge (technically "pulse" charging) the main battery as it is depleted. If the starting battery is <9.5v (this is from memory, the CTEK manual has the details) for more than a few seconds (engine cranking) the CTEK Smartpass 120S will direct connect both batteries for 10 seconds in an attempt (or hope) that the aux battery has enough power to assist in starting the vehicle.

This is a very unique way of handling it, and unlike most (all?) other dual battery systems.

As far as constant 12v, you can flip the overhead PWR switch to on and then the cargo area 12v outlet will be constant power; with that being said, the wiring going to that 12v outlet isn't very large, so you will experience some voltage drop which may prematurely trigger the low voltage cut off on your fridge
 
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