Master
SubscriberOK this makes sense, seems to me that the 2nd battery is only in the circuit when the engine isn't running . I am no auto electrician , but to my simple mind this would be the design. Also of note is some cars have a very small battery and some have the larger, so unless a different electrical system is used , which it may , hooking a small secondary battery into the starting circuit would make no sense.Originally Posted by drivesafe
So if I need a DC to DC charger, which seems likely , the problem will be isolating the OME input , charge, circuit I would assume.
I know you can now but Lithium starter batteries, which since I want to tow a Van may be a good weight saving measure , I am wondering how if these batteries are fitted they are charged?
Really appreciate the input , it has taken me ages to get around to this , it might be I just have to fit a 3rd battery on the LHS with a DC to DC charger and just run my accessories from this.
Master
SubscriberBuild a DIY Lithium LiFePo4 Headway 12v Battery replacement - YouTube
DCS LiFePo4 Lithium Under Bonnet Setup with Alternator Charging - 12 Month Review - YouTube
My thoughts are why not put two batteries in, replace the standard battery and if space allows put the other where the current 2nd battery is?
I think space will work out by laying the second battery on it's side. My current batteries are 5.5 years old so replacement will be coming up , Nig plus is I'll be 20 kg less in weight.
Master
Not sure if it makes a difference, but the RRS batteries are specified as AGM.
OldBushie
Hi again Bails, that second video is about lithium batteries installed in a Toyota.
Toyotas have a simple Variable Voltage alternator operation, and this is totally different to you Land Rover SMART alternator operation.
While that company shows a D4 set up with a lithium cranking battery, there are no reports on how it actually performs with the LR SMART alternator.
I suspect the D4 BMS will continually see what it thinks is a fully charged cranking battery and will not start to charge the lithium battery until the lithium battery is near flat.
As stated, just my suspicion as there is no feed back on this type of setup in any modern Land Rover.
Master
SubscriberOK so If I put Lipo4 batteries in both positions, so now have like for like, do you see an issue?
DCS are claiming that their batteries are drop in and have built in BMS ? My thoughts are since my batteries are old replace both and I can have 200 amp hrs of lithium on board.
OldBushie
Hi again Bails, contrary to the claims that company makes, you have a vehicle with a SMART alternator, as such, the voltage varies between 12.2v and 14.7v, depending on the state of charge of your batteries.
Because lithium batteries run at a constant 13.2v, until they are nearly flat, your D4's BMS will see the battery voltage is high and will not try to charge the lithiums.
In a worst case scenario you are likely to drive from one camping spot to another, leaving one location with low lithium batteries and arriving at the next location with flat batteries, regardless of how long you drive.
The advertising is all good and well, but short of replacing your alternator with a special one, and then fitting the lithiums, just dropping lithiums into your existing setup is likely to be a Russian Roulette type of operation.
As stated above, no one has posted up how vehicles with SMART alternators ( like yours ) work with lithium batteries.
OldBushie
Hi again Bails, can I make a suggestion, that should help you determine whether you will actually be able to fit a lithium battery and be able to charge it properly.
Just a suggestion, but before you do anything about battery upgrading, buy two BM2 Bluetooth Battery Monitors and fit one to each battery and driver as you normally would for about a month.
Then post up what you find and you should then know if it is a viable proposition to go to Lithium batteries.
Master
SubscriberThanks I really appreciate the help. I think I have a wiring diagram , and if the 2nd battery isn't in the circuit when the car is running this is what I may do.
Put in a Dc to DC as you have suggested. Put in device to stop discharge at 80%, what ever these are called .
If this makes sense and can happen I think it will be my best option, battery to run fridge and accessories but enough left to power car accessories when engine is off.
OldBushie
Hi Bails and as I posted, I think you need to learn what your vehicles charging system does, before you spend any money on something that may cause problems.
A DC/DC will mean the batteries are separated, this may not be the correct way to go as your alternator can recharge your batteries at close to 100 amps per battery and the best you can achieve is 50 amps for one battery.
You could just try taking the earth/negative ( - ) lead off your second battery and see what occurs.
Master
SubscriberNow have the full workshop manual on the electrical system. Just need to "decode". do now understand how it works not sure I will be able to do the mods I wanted though. If you want a copy of the link let me know.
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