Lithium Motorhome Batteries.

[Gromett]

I'd agree that diagonally wiring a bank in the way shown in your drawing is a massive improvement, but it doesn't completely balance the 4 batteries.

Probably a good choice for most motorhome installations though.

However, if you have a sufficiently large conductor linking the individual batteries together there is in practice zero difference between the two methods especially as most motorhomes have only 2 batteries at most.

As Wissel says, this does not balance the the batteries at all. To balance a battery you need to remove it from the circuit and individually charge them to max. If you don't do this then as soon as the lowest capacity one is full charged the charger will cut off leaving the largest capacity battery undercharged. This undercharge over time will cause cross charging and damage to the battery that was undercharged.

 

[Wissel]

Just had a look at the article you linked to @giles b - good article imo

I have 4 batteries in my current build and method 4 in that article is exactly how mine are wired (the drawing I posted a few posts back is from my current build).

 

[haganap]

Well I am going to be going for Lithium batteries, @DMS can do them and if theyare good enough and now the preferred options for Morello's then they are good enough for me.

 

[Wissel]

Out of interest, why the new account @giles b ?

Just noticed your last says deleted?

 

[mojo]

Hello Haganap
I used Road Pro for my Lithium installation 3 months ago.Posted info in Dec but not sure how to make a link to the post.Photo also of the finished job.
The charge from our 180 amp smart alternator shows 54 amps through the Stirling b2b .
Here on our Spanish campsite we get 5.5 amps per day in the pitch price.Just dont need it.Kettle,micro,etc all back in from solar.
We do try to use it on the fridge though as its there.Will run our heating on elec before we leave to use the allowance up.

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[funflair]

Is this it @mojo

https://www.motorhomefun.co.uk/forum/threads/lifep04-power.164619/

Martin

 

[mojo]

Thanks funflair
Was that easy to do ?

 

[funflair]

Thanks funflair
Was that easy to do ?

Used the "search" box and then read that it was in "full Time" section found it there and then just copy the address from the browser bar or whatever they call it at the top of the page then paste, easy when you know how

Martin

 

[mojo]

Noted ,thanks

 

[Gromett]

This is why I am going to LiFePO4 batteries in my new build next year..

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[mojo]

The more amps all the better.I have a 150 amp NDS ,considerably less than the 400 featured.But this is plenty for us.However I have experienced a drop below 11.4 v when at 40% remaining capacity.This was running a 1000w kettle .Based on 10% unusable this means two thirds of battery before auto switching off/on .A lower wattage product such as toaster,etc at 750 w still ok untill ? capacity % .Never tested just a day to day experience .Not a issue as solar or engine often keep it above the 60% mark.
So for me down to 10% from 40% will require lower wattage products but no problem on 12v stuff.

 

[sallylillian]

This is why I am going to LiFePO4 batteries in my new build next year..

Thats a very useful video as I am considering Lithium for the very benefits demonstrated. Do you think the results are peculiar to the Winston battery or it could be seen as a generic expectation?

 

[Wissel]

This is why I am going to LiFePO4 batteries in my new build next year..

So impressive isn't it. I watched his videos before buying.

For me the more impressive part is the charging rate these batteries are happy with. I could (safely) charge my batteries at 200a per hour, but won't be as I'd need a huge alternator that was rated to run flat out for long periods (huge money I expect).

Instead I'll be charging at 60a when driving (0.15c in my case) which doesn't sound a lot, until compared to how a lead acid battery charges the last 20%ish of it's capacity.

The more amps all the better.I have a 150 amp NDS ,considerably less than the 400 featured.But this is plenty for us.However I have experienced a drop below 11.4 v when at 40% remaining capacity.This was running a 1000w kettle .Based on 10% unusable this means two thirds of battery before auto switching off/on .A lower wattage product such as toaster,etc at 750 w still ok untill ? capacity % .Never tested just a day to day experience .Not a issue as solar or engine often keep it above the 60% mark.
So for me down to 10% from 40% will require lower wattage products but no problem on 12v stuff.

Can I ask how you saw the voltage drop to below 11.4v?

It's just that I'm fairly sure that a LiFePO4 shouldn't suffer from voltage drop? To give an example, in the video above the guy is running over 100A draw on a flattish battery and showing 11.69v.

Do you know the minimum voltage for your battery? I know on mine it's 2.8v per cell, so 11.2v, but I'm setting my BMS at 2.9v per cell so 11.6v to add more safety. This is because taking a LiFePO4 battery too low, just once, can kill it.

Actually I just did a quick search and read that when charging from 240v, "
When the battery is fully charged (the display shows 100%), it is recommended that you disconnect or turn off the charger". Does the BMS not do this automatically?

I'm sure it must do, just couldn't see it stated.

 

[mojo]

It has a BMS and a user panel that shows % of battery left.It shows 115 amp draw when kettle on.It shows 11.9v at a high % of battery and diminishes the volts as the % of battery drops.
On 240 it does not have a cut off but shows 100% and no charge.Told ok for a few days otherwise use the battery occasionally when on site for longer period.

 

[Wissel]

It has a BMS and a user panel that shows % of battery left.It shows 115 amp draw when kettle on.It shows 11.9v at a high % of battery and diminishes the volts as the % of battery drops.
On 240 it does not have a cut off but shows 100% and no charge.Told ok for a few days otherwise use the battery occasionally when on site for longer period.

So when full it shows 11.9v?

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[mojo]

Hi Wissel
Here are two pics .One shows solar charging .The other shows a draw from a 240v product and the volts.

 

[Wissel]

Thanks @mojo

I wasn't aware there was still voltage drop under load. I can't check this on my own setup yet, as until my charger arrives in around 2 weeks I won't attach the BMS and use the battery.

 

[Pausim]

The charging voltage looks low for LiFePO4. My Relion battery came with advice that it should be charged at 14.6v and anything less than 14.4v would not achieve a proper charge.

 

[mojo]

It shows about 14.2 from mains charge.
I know that on a good day the solar replaces over 40% while we are out for the day approx 60 amps .On.engine it shows +54 amps hr

 

[Wissel]

The charging voltage looks low for LiFePO4. My Relion battery came with advice that it should be charged at 14.6v and anything less than 14.4v would not achieve a proper charge.

This depends on the battery @Pausim

The charger I have ordered has 4 different LiFePO4 settings for different makes of battery. For Victron, for instance, it says to use the 14.2v setting. Whereas for your Relion it says to use the 14.6v setting.

Nothing is simple with this technology

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[mojo]

Here is the pic of my set up by Road Pro.Their website has some info.

 

[Gromett]

It's just that I'm fairly sure that a LiFePO4 shouldn't suffer from voltage drop?

I wasn't aware there was still voltage drop under load

When under heavy load there is an initial sag in voltage but this recovers over time (minutes not hours) even if the load is maintained.
The sag is not as extreme as for a Pb battery though.

Here is an example. Please note this is an extreme test. These are 8AH cells and he is pulling 75 - 100Amps from them. So the initial sag is as big as you will ever see.


As you can see a few seconds into the test the voltage fell to 10.69v then started recovering. At the 06:36 (video time) it starts recovering.

Check out how fast the bank recovers after the power is cut off... Blows Pb batteries away.

PS: I will say this again. These are 8AH cells putting out 75 Amps... The drop will be far less on 100AH cells or bigger when pulling 75 Amps. But it does demonstrate what this technology can do.

 

[Gromett]

Thats a very useful video as I am considering Lithium for the very benefits demonstrated. Do you think the results are peculiar to the Winston battery or it could be seen as a generic expectation?

Providing it is a good quality cell like CALB or Winston they are pretty much all the same chemistry/performance.

I am going for the Winston as they are the cheapest large format cells I can find. They have a good reputation.

 

[Gromett]

PS: I am a technology guy. It is what I work with and is my hobby.

However, for my van which I fulltime in. I avoid the latest toys. I want old, established, reliable over engineered stuff so that it can take abuse and last a long time. For instance when I was building it (yup a self build) I used heavy duty toggle switches for the lights, water pump etc etc. There is no control panel for switching stuff on or off or monitoring things.

So when I decide to go for a newer technology I have to be convinced it is not only better than what I currently use, it will last as long as the current tech and be as reliable as the current tech.

Took me a while to be converted to LiFePO4 batteries but I am now totally convinced it is the way forward especially now the prices are cost competitive with Pb batteries in TCO terms.

 

[sallylillian]

Providing it is a good quality cell like CALB or Winston they are pretty much all the same chemistry/performance.

I am going for the Winston as they are the cheapest large format cells I can find. They have a good reputation.

Thanks. What is your opinion of the Mastervolt Lithium package, apart from the obvious that it is expensive. Their implementation seems exemplary although I have in the past had no faith in their manufacturing (re-badged Xantrex Crap). But the likes of Concorde and Morelo have them as standard options and the Morelo Empire liner has them as standard full stop.

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[Gromett]

Thanks. What is your opinion of the Mastervolt Lithium package, apart from the obvious that it is expensive. Their implementation seems exemplary although I have in the past had no faith in their manufacturing (re-badged Xantrex Crap). But the likes of Concorde and Morelo have them as standard options and the Morelo Empire liner has them as standard full stop.

I have never heard of them sorry.

 

[mojo]

Two pics from this morning.Kettle (1000 watt) on and no kettle

 

[dpsuk999]

Your first picture shows a current draw of 109.8 amps but a 1000 watt kettle should only draw 83.33 amps give or take (1000w/12v) so not sure about the extra 26 amps?

 

[mojo]

Good morning dpsuk999
Indeed,it does show 80/90 but near the end of boiling time it increases.Also tv and lights are on.

 

[dpsuk999]

Ah I see, I didn’t realise the NDS battery was also powering your other 12v items I have a separate bank of Victron Gel batteries running my inverter and was in that ‘mind set’ when replying

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