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2 x Cranking Batteries?

jrmoo

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Feb 27, 2018
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australia
Hi All
I have a 2006 100 series 4.2 TD. It has two batteries which both seem to be used for crank as well as all electrical. Battery on drivers side seems to be connected straight to alternator and a couple other small accessories, while the other battery connected to all fuses and other electrical. The Positives between both batteries are linked with a heavy cable. My queries are
Does the vehicle require both to start? Can I make one an auxiliary battery?
With both Batteries connected, if one dies, what will prevent it from draining/damaging the other?

My Batteries are both Amaron Pro 775 CCA 95 AH. If I need to go a third battery for a fridge/etc what would people recommend. I would be looking at putting a redarc or DC-DC charger between 2nd and 3rd battery?

Thanks in advance
 
Hi Jrmoo and welcome.

Be great to see some pictures and share some background details about yourself.

Important info required.

1. What fridge
2. Duration of use,
3. Budget
4. Professional install or DIY

I’m in the process of doing the same having bought the 40L Engel fridge freezer and making custom draws build.

Firstly before you go about changing things it’s important to note how your going to use the setup you desire. Using both batteries your only going to be able to run the fridge whilst driving successfully and a little extra.

For me I only need a days charge or so for the fridge and then setting off again for now.
For this I’ve enquired with my electrian and going to go with the least expensive option.

I’m gonna add a 100amp enclosed battery (safe with no gases) to the rear build.

Best solution to wiring in this setup is to use all three battery’s to start the vehicle and charge whilst moving and then isolate the additional 100amp when the vehicle turns off automatically at the ignition. That way you can use like me if fitted plenty of 12v USB & cigarette lighter sockets at the rear for things.

This way your car doesnt die and the battery for the fridge is enough.

Addictional benefit you also have a spare battery if ever one battery dies to start the vehicle upfront.

Gonna get the transit cover addictionally as it’s hot here too that will save some amps. If you have one great otherwise consider this investment.

Hope this helps a little....let us know how you get on.
 
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Thanks Dervis
I'm considering a 60 litre Engel, and plan to do a few family trips ranging from 2 days to 6 weeks on the road. Would be driving most days, so would expect some daily charge for the third battery.
I like your point on having a third in the fact that it gives you an extra battery if one fails. Think this would be the best option. It already had draws with a compartment at the back of the draws where I could place the third battery. I have a 130AH AGM deep cycle battery I use in my boat which I may use as a third battery when travelling. I am happy to do all the wiring myself. I have a couple usb and cigarette outlets also which would be coming from the passenger side battery.
I'm not sure what solution to use to prevent a bad battery either #1 or#2 from draining the other. I could get voltage read out gauges for each and mount inside cab and then keep an eye on them, hoping to pick up on a bad battery before it catches me out.
When you mention transit cover I assume that's for the Engel?
Thanks again
Here are a couple picks of the new cruiser

IMG_3244.PNG IMG_3245.PNG IMG_3262.JPG
 
My advice is, anything electrical you wish to add to the vehicle, keep it separate to the vehicles main electrics. Standard vehicle electrics are extremely reliable until you chop into them so I would fit a third battery to supply all your ancillary items. It makes fault finding considerably easier and means a fault with the installed products (which is the most likely electrical fault) is unlikely to cause a problem with the vehicle. The only link should be via a quality controller such as intervolt to supply the third battery.
 
Exactly what Moggy said. :text-+1:

The only thing I would add is I didn't think any of the 100's came with 24v starters, so it sounds like someone has got in there and done some re-jigging although I have no idea why. However, there are a lot of people on here who know a lot more than me so i'm sure someone will correct me....
 
Hi All
I have a 2006 100 series 4.2 TD. It has two batteries which both seem to be used for crank as well as all electrical. Battery on drivers side seems to be connected straight to alternator and a couple other small accessories, while the other battery connected to all fuses and other electrical. The Positives between both batteries are linked with a heavy cable. My queries are
Does the vehicle require both to start? Can I make one an auxiliary battery?
With both Batteries connected, if one dies, what will prevent it from draining/damaging the other?

My Batteries are both Amaron Pro 775 CCA 95 AH. If I need to go a third battery for a fridge/etc what would people recommend. I would be looking at putting a redarc or DC-DC charger between 2nd and 3rd battery?

Thanks in advance
The two batteries act as one. It's just easier to place 2 smaller batteries than one huge 200 AH. With the fairly thick cable connecting the two, it doesn't really matter where you connect the loads, on left or right battery.

The car has no problem starting on only one battery, in your climate. You should probably find a battery with around 900 CCA instead though, to get the starter to run at full speed. (All batteries have an internal resistance, and with 2 batteries that resistance is halved. Bigger CCA means lower internal resistance). Also, you should disconnect the heating grid. That heater grid is a bigger load on the battery/alternator than the starter is. The heating grid is not required for easy starting. It's purpose is to give a bit lower emissions when cold. It stays on for 90 secs when cold, and draws a ton of amps.

Generally, it's always better with more AH than with less, but, for expedition/camping the best is if you can dedicate one battery to starting and running; and move everything else, including dome lighting, radio, fridge, etc to a second battery (set).

If you change to a single running battery, you have a bit of rewireing to do. I think there is a thread or two in here on the subject.
 
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Exactly what Moggy said. :text-+1:

The only thing I would add is I didn't think any of the 100's came with 24v starters, so it sounds like someone has got in there and done some re-jigging although I have no idea why. However, there are a lot of people on here who know a lot more than me so i'm sure someone will correct me....
they're connected in parallel, so 12v but double the amps, very common on big engined diesel 4x4s

more Ah is not necessarily better, especially on domestic type batteries. For batteries of the same physical dimensions more Ah means more but thinner plates, which makes them less durable and more prone to warping. Less Ah will give you a more durable, longer lived battery
 
Thanks People for your advice. Some great points that I will definitely take on board.
Yeah batteries are in parallel so only 12V. Realised I couldn't hook up individual volt gauges to each battery as they are connected and will read the same:tearsofjoy:. In think it would be best to just leave the 2 batteries set up as they were intended and go for the third.
I have an old voltage sensitive relay VSR which I will use between the 2nd and 3rd battery. I'm also looking at putting a low voltage disconnect between 3rd battery and fridge so as not to drain the battery too low, too many times, which could otherwise shorten battery life. I've also been told I should put in circuit breakers, close to batteries 2 and 3. what do you guys recon.
Thanks again
 
Does the fridge not have a built in cut off? Most do which can be set to high medium and low points. My Waeco and National Luna certainly do.
 
I haven’t purchased new fridge yet or done research on what features it has. Your probable right Chris, a new fridge may have this built in. I have an old 95ltr evakool fridgemate which would try to keep cycling regardless of charge left in battery.
Cheers
 
Hi Jason

I run a similar twin battery setup with the two cranking batteries permanently in parallel. With that I can easily run the old Engel fridge for 24-48 hours and have plenty in reserve for starting the vehicle. If I am camping in one spot for a few days I might need to monitor the battery voltage more closely. While the batteries are linked in parallel you can't get individual voltage readings, only the average of the two. I have isolating connectors on both the negative terminals so that I can easily disconnect either battery to let me check the voltage of each battery separately. If necessary, and with two healthy batteries, I could disconnect battery #1 when camped, keeping it at full charge for starting. When ready to move on, connect battery #1 and disconnect #2, then start the car, then reconnect #2 to let it charge. That's what most of the "battery management" systems do for you automatically. Sounds complicated but only adds a few minutes to the departure process.

In a few month's time I will have a slide-on camper fitted which has it's own battery for the fridge and accessories, and solar to regain some charge when camped up for more than a day or two. I like the two cranking batteries in parallel to give me more capacity to run the winch when needed.

In a previous vehicle I did have a situation where for a few months the auxiliary battery was supporting a failed main cranking battery. I only realised it after I removed the auxiliary battery to treat some rusty spots on the inner guard, and found the car wouldn't start! So you raise a good point, and yes it is good to check the batteries individually on a regular basis.
 
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...I have isolating connectors on both the negative terminals so that I can easily disconnect either battery to let me check the voltage of each battery separately. If necessary, and with two healthy batteries, I could disconnect battery #1 when camped, keeping it at full charge for starting. When ready to move on, connect battery #1 and disconnect #2, then start the car, then reconnect #2 to let it charge. That's what most of the "battery management" systems do for you automatically....
Excellent battery management system.
Most cranking batteries don't like deep discharge over time, as they loose some of their rated capacity each time. So, for using this system, we have to find batteries than can tolerate both deep cycle and have a high CCA for for starting.
For parallell batteries, it is important that they are of the same make, type and age, preferably a matched set, and always changed out (replaced) as a set.
 
So the 100 is different from the 80??
My 80 does the crank in 24v but the electrical system works in 12v!
There's a relay managing this during the start up.

I have an ARB 78Lt with two Yuasa 640 SHD (115Ah 1000Amps) and there's no problem at all to power the fridge for two days...

Screenshot_20180306-195854.jpg
 
Yes, the 100, and some 80s, are different from your 12/24 volt system.
 
hi Gents
from my experience - cigarette lighter sockets are the worst type of socket for 4x4's. Most are craply manufactured and the male socket wiggles lose with travelling. Better Brad Harrison type connections - if possible. rgds.
Brad_Harrison_Grey_50_AMP_1024x.JPG
 
hi Gents
from my experience - cigarette lighter sockets are the worst type of socket for 4x4's. Most are craply manufactured and the male socket wiggles lose with travelling. Better Brad Harrison type connections - if possible. rgds.View attachment 143966
:text-+1:
These are superb simple connectors from 20A up to many hundreds. Used on many DC applications from UPSs to Fork lift trucks.

Otherwise known as Anderson or Torberry connectors.
 
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