Fitting Lithium

If you can make the room and can justify the cost then go for the 200 battery. I would of went for it but I had no room. With a 200 ah lithium battery you are getting 170 useable ah not like a normal leisure battery were you only get 100 useable ah.
I have all my new Renogy stuff installed now and tried it out over the Christmas and I am very happy with the results.

I am planning to replace two 5 year old Banner Bull 100Ah lead acids with a 200Ah LifePo4. To be honest, only for I'm trying to increase payload I would probably stay with lead acids from Halfords. But dropping 26kg is a lot and is badly needed, even though it comes at a premium cost.

I have an existing 100W solar with MPPT controller which has Lithium settings giving 6A in good sunshine - so all good there.

Existing 16A battery charger does Lead acid, Gel and AGM. I don't want the additional cost of replacing it so plan to use it on Gel setting for the lithium. I understand it will not charge the lithium fully but reckon the solar will do this. We use about 20-25 Ah per day in Summer, maybe 35Ah in Winter, so we should be well good for 5 days off grid in the summer and 4 days in Winter.

Also will have the direct charging from the alternator (not smart) when on the move, as per current set-up.

The existing charger also charges the Fiat battery via the split charge relay - I understand it will not charge fully on gel setting but will not be damaged either.

Anyone see any problems with the proposal, before I hit the buy button ?

I did consider going for one 100Ah lithium but as I see it, if I discharge down to say 15Ah ( don't want to go to hard zero as there is no emergency power as you have in lead acid below 50% DoD) and as I may not always start with a full battery due to charging on gel setting and relatively slow charging from the alternator while on the move, I reckon I may only start with a battery 90% full.

This would give only 75 Ah useable power which is a little bit tight for us, especially in winter weather when we wouldn't even have 75Ah.
I would love to buy a 120Ah lithium with integral bluetooth, but these do not seem to be a common size.

I think Kepworth do a 120ah with Bluetooth

With the exception of the split charge relay this is the set up I have being using to good effect , I have retained the EBL to manage the mains and alternator charging my solar controller is connected directly to the battery , as for your concern about 100ah not being enough it is worth noting that the lithium will run right down to 10v @aprox 95ah that's a lot of power and will charge very quickly if you are caught short running the engine a sort time or a quick run around the block will give you plenty of power to see you trough the night we seldom go on EHU these days. Of corse more is better but would you need it ? Lithium is completely different chemistry to lead acid and doesn't need the consent checking you get use to with LA . I do check the state of charge form time to time but there is no need, a couple of hours driving will give most people all the power they need .... just fit it and forget !

The alternator has a built in regulator,which controls it's output, and if you haven't burnt it out with the existing system, the Lithium won't , it will only charge it,to the same level as a lead acid.
Just finished fitting a pair of these yesterday, https://eu.renogy.com/12v-100a…e-battery/. into the second van in our family, they did a good deal when two were bought together,throwing in the Bluetooth monitoring system, also fitted was a new Victron Charger, we had already fitted with a 310 watt solar system.
Everything fitted into the old space with the addition of a piano hinge, some wiring, a couple of buss-bars and a shunt to do the monitoring, 10.30 last night, both were showing full charge.
Why you might ask?. The old original OEM charger, went off it's meds and fried two newish 95 ah banner bulls. while on EHU at the house. As they spent a lot of time off grid, it was an ideal time to go for the Lithium upgrade.

This is valuable insight and recommendation and for me, a hornets nest has been opened.
Having done some more research, it seems the general consensus from other motorhome forums is that a B2B is essential to deal with the concerns outlined by Baguette above. SOK have also just said I need a B2B. A Votronic 30A B2B with low temperature charging cut off is approx €200. On its own, this is a manageable additional cost.

However, in doing the above fact finding, I discovered my CBE - 516 3 charger has a desulphation phase which outputs 15.2V to the battery as the first charging phase. This is likely going to trigger the 14.6V max voltage cut off on the SOK BMS.
So, its looking like I will need to replace my mains charger also. If I go with a CBE 522-LT 22A (LifePo4) charger, it should be pretty much plug and play. This will cost approx €280. Right now I'm not sure if this will also provide 2A charging to the starter battery as my existing one does. If it does, it will be using a lithium charging profile, which may not be suitable for the starter lead acid.

So, I may additionally have to install a Van Bitz battery master to independently keep the starter battery charged from the leisure battery when motorhome is parked up. Approx cost €90.

So I could be looking at a total additional cost of €570, on top of the battery cost. On the positive side, with all of the optimised lithium charging kit described above, I reckon we could manage with one 100Ah lifePo4 which is €400 delivered from SOK

So basically I could be looking at €1000 to get a lithium battery with same capacity and longer life (compared to existing) and weight saving of 36kg.

Alternatively, I could get two 100Ah Halfords HLB 700 lead acids for €260 (when AXA 10% discount included) which are simply drop in and put the remaining € 740 towards increasing payload by fitting semi rear and possibly heavier springs on Front, with the aim to go from 3700kg MAM to 3850 kg or 150kg payload increase

Hmmmmm !!

Which Renogy unit did you fit ?

Just to update regarding my decision.

In the end I decided to stay with Halfords HLB-700 lead acid batteries to replace the knackered original 100Ah Banner Bulls. I was not happy to proceed with the LifePo4 as it involved considerable modifications to the existing CBE 12V distribution system & wiring.
So, in addition to the cost of all the add-ons, making wiring changes would have been quite difficult as all the existing 230/12V charger, 230/12V control & distribution system, and solar MPPT are installed in an extremely confined space within the double floor of the Rapido, accessible via a small external locker door.

In industry, I would always have specified that new electrical panels would have 25% free space to cater for future panel mods. Alas, Rapido seem to have completed the electrical installation and then installed the external wall to the motorhome after, thereby making further alterations quite a challenge.

Again, thanks to all who contributed information and suggestions along the way.

I have resisted the lithium route, I happy with the normal batteries, 200w solar panel, mmpt, 2x 110, does what it says on the tin. Maybe some day