Upgrade to LiFePO4 Lithium Batteries

59Loz

59Loz

Joined
Feb 15, 2022
Posts
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Location
Crewe, UK
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86,898
MH
Autotrail Expedition
Exp
Since 2008
Funsters,

I am considering upgrading my leisure battery to two 100Ah LiFePO4 Lithium Batteries. My rig is a 2024 Autotrail Expedition 68. My power unit is a Sargent EC362.
Will my current charging system support lithium batteries? I suspect not. If I have to make modifications what do I need to do and how do I make these without invalidating my warranty?
Another question (if I may) does a battery to battery charger work both ways? Will the leisure battery top up the vehicle battery?
I cannot source a wiring diagram which would give me some idea of what is required.
Any help would be appreciated. I am not a complete novice, my trade involves electrical engineering. However, modern motorhome electrics is not my field of expertise.
 
There’s a new lithium battery for sale in the classifieds
 
We replaced a 100ah battery with a 230ah lithium. Fitted in the same space as the original battery, but obviously more power and less weight. Why two batteries?
 
In a nutshell:
1. You will need to disable your split charge system and install a DC-DC (B2B) charger.
2. Your mains charger could be set to gel or AGM which would be OK (but it means you rely only on the BMS to protect the cells and it becomes the first, last and only line of defense)
3. Your solar controller is probably OK, but many people that upgrade to lithium prefer to change the controller at the same time so they can see exactly how it is doing (using the app with Bluetooth). A Victron MPPT is relatively inexpensive in the scheme of things. Of course, it depends on whether you have solar and what controller you already have.

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Price mainly and they will fit into existing space. You raise a good point I will look further afield before purchasing. My main issue is what I need to do to support a lithium battery.
 
RogerIvy said:
In a nutshell:
1. You will need to disable your split charge system and install a DC-DC (B2B) charger.
2. Your mains charger could be set to gel or AGM which would be OK (but it means you rely only on the BMS to protect the cells and it becomes the first, last and only line of defense)
3. Your solar controller is probably OK, but many people that upgrade to lithium prefer to change the controller at the same time so they can see exactly how it is doing (using the app with Bluetooth). A Victron MPPT is relatively inexpensive in the scheme of things. Of course, it depends on whether you have solar and what controller you already have.
Click to expand...
I do have solar but I believe my solar controller is integrated into my Sargent EC362 power unit.
 
To ensure long life of the batteries you will need to install a solar controller which has a lithium charging cycle unless you know your current system can be adjusted. This is because a system designed for lead acid might charge at up to 14.8 volts but typically lithium batteries should not be charged above 14.4 volts*. The same applies to the B2B, make sure it has a lithium cycle.

A B2B is for charging the leisure batteries from the alternator. To top up the vehicle battery I would fit a Battery Master from Vanbitz. This won't interfere with the B2B operating as it only let's a small charge flow into the cab battery. As mentioned above you will need to disconnect the split charge system which will involve doing something to the Sargent unit I think. It might be as easy as removing a fuse or disconnecting a wire but I have no experience of them.

However, have you spoken to Autotrail? If they offer lithium batteries as an option they should be able to advise on what needs to be done and this might help on keeping the warranty which I think otherwise will be voided at least on the electrical system if you make such major changes.

* Or whatever the battery manufacturer recommends
 
LithiumConvert said:
Most do not. But Sterling Power offer one which can be switched to work either way.
Click to expand...
Votronic B2B's charge the starter battery when the engine is off and the lesiure battery is being charged from elsewhere (mains or solar).

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59Loz said:
I do have solar but I believe my solar controller is integrated into my Sargent EC362 power unit.
Click to expand...
They fit a cheap controller inside the back of the distribution unit best to forget about that and fit a decent MPPT controller like a Victron.
Also as you are going to the expense of Lithium it is best to fit more solar to take advantage of the Lithium.
As it's a 2024 van if it has a smart alternator it should have a B2B if not you will need to fit one.

RogerIvy posted earlier in the thread talk to him and get some good advice also his company OffGrid Power Solutions can supply all the parts you need at very competitive prices and do the work if required.
 
There appears to be some confusion about some terms used in this post.

A B2B charges the leisure battery whilst the Engine is running ..of course the Engine (Starter) battery will independently be charged too from the Alternator.

Battery master puts a small charge into the Engine battery whilst connected to an alternative source,for example whilst off grid and using Solar.....I'm aware that some solar set-ups will charge both...

A Lithium battery is the best upgrade we have done....
 
jumar said:
There appears to be some confusion about some terms used in this post.

A B2B charges .....
Click to expand...
A B2B charges any one battery from any other.

You will most often find one connected to charge a leisure battery from the alternator but as mentioned above, they chan be used in other configurations.
 
Lenny HB said:
RogerIvy posted earlier in the thread talk to him and get some good advice also his company OffGrid Power Solutions can supply all the parts you need at very competitive prices and do the work if required.
Click to expand...
Plus 1 for Offgrid, they’ve supplied all of my kit (Victron and Fogstar) at brilliant prices in changing over my 23 Knaus from AGM to lithium. I’ve done it all myself over a few months. I’ve had brilliant advice throughout the process overcoming any issues with practical suggestions. I’m really pleased.

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Thanks, folks for all the advice and help. I am nearly there now. I know what I need and how to put it all together. I have had some information from Autotrail but not quite what I want. I am awaiting a further response in particular how to disconnect things and connect my system in an unintrusive way that will not invalidate the warranty. I have also looked at an integrated unit from Clayton Power. These units have everything built into one unit and can be very easily connected. One major advantage it can be easily removed and installed elsewhere. Anyone got any views on this?
 
59Loz said:
. I have also looked at an integrated unit from Clayton Power. These units have everything built into one unit and can be very easily connected. One major advantage it can be easily removed and installed elsewhere. Anyone got any views on this?
Click to expand...
That seems like putting all your eggs in one basket. If it breaks down you are stuffed. With separate chargers for B2B, solar and mains if one breaks down you still have another to get by. We have 4 solar panels but run them with 2 separate MPPT chargers for that reason too.
 
59Loz said:
Thanks, folks for all the advice and help. I am nearly there now. I know what I need and how to put it all together. I have had some information from Autotrail but not quite what I want. I am awaiting a further response in particular how to disconnect things and connect my system in an unintrusive way that will not invalidate the warranty. I have also looked at an integrated unit from Clayton Power. These units have everything built into one unit and can be very easily connected. One major advantage it can be easily removed and installed elsewhere. Anyone got any views on this?
Click to expand...
Personally I would have separate units as if you have an all in one and it goes down you lose everything.
I have Victron MPPT, Victron shunt, Sterling B2B, 2,000w inverter and 230AH LifePo4.
I have wired the inverter directly to its own sockets not integrated it through/into the hab wiring.
Likewise the MPPT and B2B are wired directly to the battery not through the hab wiring.
The MPPT, shunt and battery apps tell me what's going on, and far more accurately than my vans very basic habitation display.

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So many manufacturers it gets confusing. I just stuck to one. I have a 50A RENOGY MPPT controller. It can accept 650W of Solar and works with Smart Alternators and communicates via an RJ45 to the Bluetooth module, Inverter, both Lithium batteries and the displays. I can see what’s going on from the wall controller or my phone app.
The controller uses Solar to charge the leisure batteries and once full will send charge to the start batteries too. It gets and ignition signal to know the engine is on and will pull power as needed all automatically. Just using the one supplier for all equipment really helps for letting it work well.

My only problem is I currently have a dead solar panel. Working on that….
 
I have an Autotrail V line classic with a Sargent system (EC500) . Sargent technical dept were very helpful and talked me through how to bypass all of their charging systems and provided a wiring diagram showing how to fit an isolation relay that disconnects the split charger when the engine is running allowing a standalone b2b to charge directly to the leisure battery. The Sargent/Autotrail wiring is limited to 10A I think which is why they recommended wiring replacement chargers directly to the battery. Eg my victron b2b charges at 30A and requires cable suitable to be fused at 60A. Sargent specifically advised that any additional solar panel could not be run through their controller and must be wired directly to the leisure battery via a separate solar controller if that were the only upgrade.

So, you basically wire chargers ( solar, b2b and mains) directly to the leisure battery and disconnect the built in chargers. Set the charging profiles to lithium and as stated above, fitting a Vanbitz battery master between the leisure battery and the vehicle battery ( connected to the b2b charger terminals) takes care of trickle charging the vehicle battery from excess charge in the leisure battery when on mains or solar.

I replaced Sargent chargers with Victron smart gear and added a victron battery shunt and remote display so I could see the charging status of my batteries from the display or via bluetooth on my phone.

My gear:
Solar: As I only have a 100w solar panel I opted for a victron smart solar mppt 75/10

B2B: Victron Orien tr smart 12|12|30

Mains/EHU: Victron Blue Smart IP22 Charger, 1 output.

Monitoring: Victron shunt bmv712 plus bluetooth dongle. (They now do a 712 smart with built in bluetooth)

Its definitely worth giving Sargent a call.

Hope this helps.
 
Ditto. Was there a couple of weeks ago and they did a splendid job.
 
59Loz said:
Thanks, folks for all the advice and help. I am nearly there now. I know what I need and how to put it all together. I have had some information from Autotrail but not quite what I want. I am awaiting a further response in particular how to disconnect things and connect my system in an unintrusive way that will not invalidate the warranty. I have also looked at an integrated unit from Clayton Power. These units have everything built into one unit and can be very easily connected. One major advantage it can be easily removed and installed elsewhere. Anyone got any views on this?
Click to expand...
Just a thought on my motorhome the Sargent Electrics will only support 150 watts of Solar panels, is useless almost.

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59Loz said:
I have also looked at an integrated unit from Clayton Power. These units have everything built into one unit and can be very easily connected. One major advantage it can be easily removed and installed elsewhere. Anyone got any views on this?
Click to expand...
We wired one in recently for someone (so it feeds their normal 230v sockets).
My take on it is that for a reasonable capacity and power you pay more than you do for separate components (as I recall it cost about £3400).
 
Stewen said:
I have an Autotrail V line classic with a Sargent system (EC500) . Sargent technical dept were very helpful and talked me through how to bypass all of their charging systems and provided a wiring diagram showing how to fit an isolation relay that disconnects the split charger when the engine is running allowing a standalone b2b to charge directly to the leisure battery. The Sargent/Autotrail wiring is limited to 10A I think which is why they recommended wiring replacement chargers directly to the battery. Eg my victron b2b charges at 30A and requires cable suitable to be fused at 60A. Sargent specifically advised that any additional solar panel could not be run through their controller and must be wired directly to the leisure battery via a separate solar controller if that were the only upgrade.

So, you basically wire chargers ( solar, b2b and mains) directly to the leisure battery and disconnect the built in chargers. Set the charging profiles to lithium and as stated above, fitting a Vanbitz battery master between the leisure battery and the vehicle battery ( connected to the b2b charger terminals) takes care of trickle charging the vehicle battery from excess charge in the leisure battery when on mains or solar.

I replaced Sargent chargers with Victron smart gear and added a victron battery shunt and remote display so I could see the charging status of my batteries from the display or via bluetooth on my phone.

My gear:
Solar: As I only have a 100w solar panel I opted for a victron smart solar mppt 75/10

B2B: Victron Orien tr smart 12|12|30

Mains/EHU: Victron Blue Smart IP22 Charger, 1 output.

Monitoring: Victron shunt bmv712 plus bluetooth dongle. (They now do a 712 smart with built in bluetooth)

Its definitely worth giving Sargent a call.

Hope this helps.
Click to expand...
Great help. Thanks.
 
Cavs said:
Could you elaborate a bit, please? Is there anything dangerous or unlikey to work well? Thanks.
Click to expand...
My mistake I didn't realise it was a video I thought it was just a drawing. What set me off was the DC circuit breakers all over the place in that picture. They are notoriously unreliable.

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