Bitten the bullet and about to disappear down the lithium rabbit hole!😱

[Tarn2]

After much discussion with the boss, I’ve sunken into the scary depths of changing from lead acid to LiFePO4.
Current set up for the last five years has been 2 x 135ah LA, plus 2 x 100w Photonics Universe solar panels, plus Ablemail 30amp b2b. I’ve also had a c-tek 5a smart charger feeding in when on ehu. As well as the usual lights, I’ve got an 80 litre Dometic compressor fridge, Maxxfan and Truma 4e fitted. The boss uses a cpap and I’m instructed that a small ‘cool box’ is also essential for the raw dog food (unless I wish to fill up the Dometic with it!).
With the crazy prices of campsites we are using more off grid locations (did a ten day Scottish tour last month, with only 1 night on ehu), but the existing set up started to struggle, with the cpap failing a couple of nights.
Following a discount offer on them, I’ve jumped in for 2 x 100ah eco- worthy LiFePO4 batteries and discovering the seemingly endless add ons also deemed necessary - Ablemail suggesting a second b2b in parallel to boost charge to 60amp and a device to plug in (Abb-007) to facilitate change to lithium and Photonic Universe being incredibly helpful with advice to switch controller parameters to lithium. Also looking at a 230v 5a lithium charger from Eco- worthy to replace the C-tek.
Wish me luck guys, don’t really relish the prospect of doing the upgrade as suspect there’s going to be some replacing of cabling to cope with it and the thought of crawling underneath to run new cables in my seventies is not the least bit appealing!
Any advice, tips, warnings (or offers of help!) very gratefully received.

 

[ivorantony]

Only a observation but thought a 5 amp lithium charger is a bit pointless, surely 20 amps would be more appropriate,

 

[hja]

Why not get a quote for a reputable installer to do it?

 

[Tarn2]

Why not get a quote for a reputable installer to do it?

Would be up for considering that if anyone has recommendations and if any are happy to fit the batteries I’ve bought to the existing system?

 

[the1andonly]

Do you realy need a mains charger? Would existing be ok for part charges. 30A b2b enough to be getting on with and if experiance says yes then add.

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[Tombola]

Id try with the 30amp b2b for now, mine been fine with plenty lithium and the solar
' the 5 amp charger a bit small, go for 30 Id say

 

[autorouter]

One of the few negatives of lithium is they should not be charged when the temperature is below about zero degrees C. If the B2B is very near the batteries then the B2B temperature will not be far off the battery temperature, so it can use that as the basis to cut off charging. However if it's not very near, or even in a different section of the motorhome, then it's a good idea to fit a temperature sensor on the battery, connected back to the B2B.

If you are adding a second B2B then I presume you will be running an extra pair of power wires to the starter and leisure batteries. It would be easy to run the temperature sensor wires at the same time, but it would be a pain to have to add them after all the power wires have been installed.

From the description of the Ablemail B2B, I gather you have to add an 'interface card' to enable temperature sensing. I have no idea how easy that is, could be a quick diy job, or a 'return to factory' job, I don't know. Maybe only one is required for two B2Bs, and you could get the interface card in just the new B2B.

The interface card also has the facility for voltage sensing. This allows the B2B to know the exact battery voltage, without any error due to voltage drop along the power wires. It's a nice-to-have rather than an essential, but you'll have the interface card already installed and will be running extra wires for the temperature sensor anyway. So a couple of thin wires to the battery terminals for the voltage sensing is easy to do at the same time.

I know this sounds complicated, but I thought I'd say this to avoid the 'If only someone had told me' moment in the future

 

[headlight]

Would be up for considering that if anyone has recommendations and if any are happy to fit the batteries I’ve bought to the existing system?

Have a word with Vanbitz (members on here AshVanbitz) and Offgrid Power Solutions, Roger and Nigel Ivy who are also members on here.
Both very well respected installers.

 

[Tarn2]

Do you realy need a mains charger? Would existing be ok for part charges. 30A b2b enough to be getting on with and if experiance says yes then add.

Id try with the 30amp b2b for now, mine been fine with plenty lithium and the solar
' the 5 amp charger a bit small, go for 30 Id say

I did think that maybe try with just the one 30amp b2b to see how things go? The only concern is one expressed by Ablemail who say that “30a will take a long time to charge an empty battery pack and will get very hot, so if you persistently empty the battery pack, you may want to buy another 30a b2b and run it in parallel”. I’m sure they are offering good advice, but I did wonder how much the possible sale of
another b2b influenced that advice?

 

[Tarn2]

Do you realy need a mains charger? Would existing be ok for part charges. 30A b2b enough to be getting on with and if experiance says yes then add.

Not really sure but would tend to agree with you and see how it goes without one?

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[Tarn2]

Have a word with Vanbitz (members on here AshVanbitz) and Offgrid Power Solutions, Roger and Nigel Ivy who are also members on here.
Both very well respected installers.

Thank you for the suggestions, much appreciated

 

[Tarn2]

One of the few negatives of lithium is they should not be charged when the temperature is below about zero degrees C. If the B2B is very near the batteries then the B2B temperature will not be far off the battery temperature, so it can use that as the basis to cut off charging. However if it's not very near, or even in a different section of the motorhome, then it's a good idea to fit a temperature sensor on the battery, connected back to the B2B.

If you are adding a second B2B then I presume you will be running an extra pair of power wires to the starter and leisure batteries. It would be easy to run the temperature sensor wires at the same time, but it would be a pain to have to add them after all the power wires have been installed.

From the description of the Ablemail B2B, I gather you have to add an 'interface card' to enable temperature sensing. I have no idea how easy that is, could be a quick diy job, or a 'return to factory' job, I don't know. Maybe only one is required for two B2Bs, and you could get the interface card in just the new B2B.

The interface card also has the facility for voltage sensing. This allows the B2B to know the exact battery voltage, without any error due to voltage drop along the power wires. It's a nice-to-have rather than an essential, but you'll have the interface card already installed and will be running extra wires for the temperature sensor anyway. So a couple of thin wires to the battery terminals for the voltage sensing is easy to do at the same time.

I know this sounds complicated, but I thought I'd say this to avoid the 'If only someone had told me' moment in the future

Thank you for the advice. Totally agreed with you about getting all the wiring in now as that’s going to be a big enough pain (literally!), so definitely don’t want to repeat the process further down the line!
I’ve ordered the interface card, which appears to be a ‘plug in’ job and an app to make the changes, so hope it’s that easy? (never is though is it?).
The existing b2b is near the vehicle battery and away from the leisure battery location, so will see what temperature sensing options there are on the interface card.
Thanks again, much appreciated

 

[hja]

Thank you for the suggestions, much appreciated

We used Oaktree in Nottingham, but with their Ecotree batteries.

 

[headlight]

I did think that maybe try with just the one 30amp b2b to see how things go? The only concern is one expressed by Ablemail who say that “30a will take a long time to charge an empty battery pack and will get very hot, so if you persistently empty the battery pack, you may want to buy another 30a b2b and run it in parallel”. I’m sure they are offering good advice, but I did wonder how much the possible sale of
another b2b influenced that advice?

You had a usable 135AH from your 2 x 135AH lead acids.
Your 2 x 100AH LifePo4 batteries will give you a usable AH of around 160AH if you only want to take them down to 20% SOC, are you likely to "empty" them ?
Last Xmas I changed from 2 x 100AH lead acids to a single 230AH LifePo4.
Twice the usable power, 36kgs lighter and able to discharge at 200 amps continuous as opposed to the 40 amp continuous discharge my 2 lead acids were rated for.
A game changer as far as I am concerned.

BTW I also have 2 x 100 watt solar panels and a 60 amp B2B.

 

[Lenny HB]

I can't add much to what has already been said apart from I would add more solar.

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[the1andonly]

I can't add much to what has already been said apart from I would add more solar.

If any real money is to be spent i would also go more solar. I am what may be concidered over solared with 550w and only 100Ah lithium. Works for me but i dont have critical stuff like cpap and batteries now are less than half price i paid

 

[Tarn2]

You had a usable 135AH from your 2 x 135AH lead acids.
Your 2 x 100AH LifePo4 batteries will give you a usable AH of around 160AH if you only want to take them down to 20% SOC, are you likely to "empty" them ?
Last Xmas I changed from 2 x 100AH lead acids to a single 230AH LifePo4.
Twice the usable power, 36kgs lighter and able to discharge at 200 amps continuous as opposed to the 40 amp continuous discharge my 2 lead acids were rated for.
A game changer as far as I am concerned.

BTW I also have 2 x 100 watt solar panels and a 60 amp B2B.

Good point about the discharge rate, hadn’t thought of that one.
I’m hoping we won’t go anywhere near the “empty” mark with an extra 20% and faster recharge than the existing set up.
The saving on weight is always a bonus - means I can put another couple of bottles of my home brewed wines in! Although getting some good advice from others about adding additional solar, so may have to save some weight for that?
Noted you have a 60amp charger so you’ve obviously gained an advantage there.
Thanks for your input

 

[Tarn2]

I can't add much to what has already been said apart from I would add more solar.

Thanks Lenny, good suggestion, I’ll do some measurements to see what space I’ve got up there (or investigate replacing one of the 100w with a bigger one?). Bonus that I can get on the roof easier than crawling underneath!