Replace AGM battery with LiFePo in a motorhome

German community
1

Hello,

I’d like to replace the 95Ah AGM battery in my motorhome (the leisure battery) with a 200Ah LiFePO₄ battery. I know this topic has come up before, and I’ve already searched for information and contacted a Victron installation partner. Nevertheless, I still have some unanswered questions, and I’d like to draw on your experience.

What I have:

Schaudt EBL30, WA121545 booster (LiFePO₄-compatible, with isolating relay and D+ input; the negative connections are joined here), 2 x LAS 1218-S chargers (1 x connected to the EBL for the leisure battery, 1 x for the starter battery)

2 solar panels rated at 100Wp each, connected via a Victron MPPT 75/15 to the EBL’s solar controller input

Victron SmartShunt 500A/50mV (on the leisure battery)

Raspberry Pi with Venus OS

What’s important to me:

Doing the installation/conversion myself, saving weight, a little more energy independence

My idea:

Disconnect and remove the Schaudt charger (which isn’t LiFePO₄-compatible) from the EBL and the current leisure battery. Replace it with a Phoenix Smart IP43 and SmartBatteryProtect 12V/100A, and a Victron 200Ah NG LiFePO₄ battery.

My questions:

Should the new charger be connected to the EBL or to the LiFePO₄ battery?

Can I keep the Schaudt booster? (Reprogram it for LiFePO₄ and adjust the current and PowerReduct) — either way, what should I do with the negative connection between the leisure and starter batteries?

Should I leave the current solar controller connected to the EBL or connect it directly to the LiFePO₄ battery (and reprogram it)?

How can the starter battery benefit from solar power to a certain extent? At the moment, a maximum current of 5A flows from the EBL to the starter battery via the booster.

Why are most people trying to push me towards a MultiPlus? I don’t need 230V in the motorhome (except perhaps when connected to shore power).

So, ideas/suggestions are welcome. Have I forgotten anything?

Many thanks in advance,

Marco

5

Hello @Olli,

Since our setups are identical apart from a few nuances, here are my thoughts and a few facts about your plans.

I assume the AGM is installed under the passenger seat, right?
If so, I’d choose a battery designed to be installed in the seat box. The terminals are then on the back rather than on top, which makes cable management much easier.
As far as I know, you also need an external BMS for the Victron NG, but that’s just an aside.

Just because the EBL doesn’t have a switch position for LiFePO4 doesn’t mean it can’t charge a LiFePO4 battery. Set the switch to GEL and it’ll charge the battery at 14.4V, at a maximum of 18A for 16 hours (up to 288Ah). If the battery is full before then, the BMS will take care of it. A charging voltage of 14.4V is perfectly fine for LiFePO4.
You can/should switch the booster to LiFePO4, and the same goes for the MPPT.
In other words, from a hardware perspective, everything can stay as it is.

I’d leave it there. For one thing, the necessary cables are already installed and the appropriate fuse is in place. To be on the safe side, I set the MPPT to a maximum charging current of 14A, since a maximum of 15A is permitted through the EBL.

As things stand, it can’t.

Well, think about why sellers want to sell things… :laughing:

Same here, but we seem to be very much alone in that… :man_shrugging:

6

Hello Marco

I find your setup a little odd. What additional consumers do you have connected to the starter battery that it needs its own 18A charger? Charging the starter battery via the EBL and booster should be more than enough.

The same goes for the leisure battery. Do you really need 36A constantly? Apart from the fact that a 36A charging current isn’t exactly going to prolong the life of a 95Ah battery.

The LAS1218-S chargers are exclusively for AGM2 batteries, with a fixed end-of-charge voltage of 14.7V. The “S” here stands for starter battery. Since they can’t be reconfigured, unlike the EBL, you can’t continue using them for LiFePO. Of course, the one for the starter battery can still be used.

7

Hello Hannus,

Thank you very much for your reply. The Schaudt setup is the “standard equipment” in my Hymer.

The EBL has no separate/internal charger, so one LAS is connected to it and supplies only the habitation battery. The other LAS is only for the starter battery. Both naturally operate only when connected to shore power. The booster is only for the habitation battery and operates only when the engine/alternator is running.

It is clear that the LAS cannot handle LiFePO4, which is why I asked whether I should replace it with a new one from Victron for LiFePO4.

Best regards,
Marco

8

Yes, it does…
You can also connect another 18A charger to the EBL, giving you 36A for the leisure battery. Whether you need that is for each person to decide for themselves, or the manufacturer may already have made that decision for you… :wink:

9

Hello Sender,

Thanks for your message. In my Hymer, the electrical installation and the AGM battery are under the seat in the seating area.

But your suggestion to leave the setting on AGM also means that I can’t use the full capacity of the LiFePo. Also, according to the information I have, with AGM it charges for only 4 hours and then switches to maintenance mode.

If I leave the MPPT on AGM, it’s the same effect as above. If I switch to LiFePo, the charging curve won’t be suitable for the starter battery.

On the subject of charging the starter battery via solar, you write “as things stand, not at all”. At the moment, however, the EBL supplies solar power to the starter battery via the booster. Here, “a little” is enough as a maintenance charge too. If I disconnect the MPPT from the EBL, the starter battery wouldn’t get any maintenance charge at all.

Let me know if I’ve misunderstood anything.

Regards, Marco

10

That’s why I wrote:
GEL!!!

With AGM, the voltage would be too high, which would put significantly more strain on the battery in the long run than anything else.

More than enough has already been said on this forum about the tiresome subject of the starter battery…
Here, for example…

Even if the MPPT stays there, it won’t charge the starter battery!

11

The EBL30 has an internal charger that can be set to 14.4V (GEL), which also makes it suitable for LiFePO batteries. Unfortunately, the additional charger cannot be adjusted and should no longer be used for LiFePO batteries.

EBL30
EBL30741×355 74 KB

Back to your setup. The chargers and booster are designed for at least two leisure batteries. If you really only have one 95Ah battery installed, then you’ve been cheated.

Your solar regulator and booster are connected directly to the leisure battery. So your starter battery is also always charged via the booster’s bypass.

12

@Olli, please ALWAYS try to get your information from the source wherever possible.
On the internet — and unfortunately this forum is absolutely no exception — all sorts of wild claims are made…
You certainly haven’t been cheated, because nothing was sold to you that doesn’t exist, or doesn’t work, or anything like that… (a statement that is also very questionable from a legal perspective!!!)
The truth is that Hymer, together with Dethleffs, bought the former agricultural machinery factory in Neustadt in Sachsen in 2005 and has been carelessly churning out “budget” motorhomes there ever since under the name Capron, aka Sunlight, Carado, Glücksmobil,…
Now, the supposedly better Hymer brand does need to distinguish itself here and there, so a 36A charger instead of an 18A one might seem plausible to anyone with even a little less knowledge, right? But that isn’t even remotely fraud; it is there: 1x18A in the EBL + 1x LAS 1218-S extra…
A look at the booster’s manual shows that the leisure battery isn’t charged by the MPPT (7.4.4 Setting the “Bypass” switch)

Screenshot 2026-10-29 190831
Screenshot 2026-10-29 1908311117×498 110 KB

When 230V power is available (and only then), the starter battery is topped up with a maximum of 5A, but from the 18A charger integrated into the EBL, not from the MPPTs!!!
Knowing this, one can certainly question the usefulness of the LAS 1218-S charger for the starter battery (if it is actually installed). However, Hymer does sometimes have a rather “interesting” take on electrical engineering anyway: AGM and LiFePo4 batteries are sometimes mixed in the habitation area, and this is even sold to the customer as an advantage — you can find all of that here in the forum. By comparison, a separate 18A charger for the starter battery is almost trivial.

So, once again: be careful with any information you come across; when in doubt, simply take a measurement… :wink:

13

Just reading often isn’t enough; you also have to understand it.

The booster charges the starter battery from the leisure battery if its voltage is at least about 0.7 V higher. It doesn’t matter whether the leisure battery is being charged by the mains charger or the solar controller. The only important thing is that the charging voltage is high enough.

14

First and foremost, making claims isn’t enough; you also have to be able to back them up!!!
Where are the measurements, screenshots, etc. that prove your theories???
The Boosters manual and my own experience say otherwise, so let’s see your evidence! Do you even have the devices mentioned above in use, or any other experience with them?
The Boosters manual states unequivocally that the EBL bypasses the isolating relay via SDTBUS, but only when a 230V supply is present. So much for reading comprehension—incidentally, one of THE main problems Germans have in the PISA tests…

Quite apart from that, I find myself wondering once again how your posts are supposed to help the original poster, but that doesn’t seem to be what you’re aiming for anyway.
It’s really sad what this forum has become…

15

Mea culpa!

I mistakenly assumed that the bypass worked in a similar way to the auxiliary charging circuit on Votronic boosters. In fact, it only connects the booster’s input and output (with current limiting) for the voltage display and conditional charging of the starter battery on EBLs with SDTBUS. There are only two of those, by the way. All other Schaudt EBLs do not need the bypass functions.

Of course, you could also use the bypass to charge the starter battery without SDTBUS. However, since the current can flow in both directions in this case, it’s better to avoid that, so you don’t end up with a flat starter battery if something goes wrong.

So the bypass should always be disabled without SDTBUS. In that case, the starter battery obviously won’t be charged this way, as you rightly point out. It would be better to use a StandbyCharger instead.

16

No worries, it happens…