On my EBL99, their are just two electronic modules. The LAS1218 charger, which is connected to 240V. And the BW99 voltage monitor which is basically there to disconnect all the outputs (except for the boiler frost protection valve) by triggering two big 60A latching relays.
These are the things that make a click when you turn it on and off at the control panel.
The BW99 is powered purely from the 12V batteries. And is a part that can apparently get in a muddle sometimes, leaving you locked out, if it decides not to close the isolation relays again.
It pulls those relays out if it detects the batteries have dropped to 10.5 V. And won't turn them back on again until 11V has been reached again.
The LAS1218 is the only part that uses 240V. The starter
battery maintenance feed is nothing more than a power resistor to limit the current to it, not something any cleverer.
If that has actually failed (they used to be notorious for this), and you haven't realised, well it won't be supplying a trickle charge to the starter. You may still have a light on the indicator panel to say mains is present, but the charger may not actually be doing anything. So do check both your EBL, and your second charger.
At times, when your batteries are in a relatively low state of charge, each of them ought to be putting out nearly 18A. I.e. disconnect second charger, measure what EBL is putting out. If anything. Switch off, plug second charger in again, measure again, you should be seeing nearly twice the current. If not, something may not be right.
Otherwise the EBL99 is just a connection box,
fuse box, and a few other relays, mostly operated by the D+ input from the alternator. It has nothing inside to regulate the alternator input, that's just done by switching an external relay, fed by the D+ signal. The only protection is by 50A fuses. Basically an EBL99 can only supply a maximum of 50A on
battery. (plus maybe another 18A or 36A with the second charger when on mains, and whatever a
solar input into it might also be giving).
So tops, that might power a small
inverter if wired through a spare EBL output. But my 300W one is wired straight to the
battery terminals.
Now this is for my EBL99, I don't know what you have, but if you tell me the model number I could try to dig out the manual and see if there is any more sophistication inside yours. At least Schaudt do provide a pretty complete block diagram of what's inside, a bit muddled but you can figure it out from that. And it's all quite appropriate and cost effective I think for OEM installs, and they have maintained continuity of the block connections so, I could probably just pull out my old EBL99 and plug in the latest model if something failed badly. Or just keep it as a connection,
fuse and relay box,whilst putting in Say a Votronic Triple alongside to do the clever stuff. Which would be cheaper and better.
Enlarge your
battery bank, have a powerful alternator, well the thing, and the wiring, the external
battery cutoff relay as they call it, and the fuses are sized for 50A max in from the alternator. Or out from the batteries. And you might be close to or over that with say a big lithium bank that can potentially accept charge at a much higher rate than that, if the alternator can deliver it.
I would only ever plug my generator into the hookup point. Where it first goes through the 240V panel with RCD and MCB trips, for my safety and that of the van's systems. Please don't consider plugging it straight into an additional charger and bypassing all of that, and the van's hopefully correctly installed 240V circuits.
Every appliance on my van is chosen to be double insulated, so I don't fear the dreaded live-neutral reverse fault, even no earth, that I have seen on several occasions on foreign campsites. But before plugging in I first use a cheap little plug in tester to check, and if necessary use a live-neutral crossover adapter. If there is no earth then I won't connect.
Running a generator I don't need nor want an earth, but if on EHU I do, if only so that I know other vans are likely to be safe, since many of them won't have thought about these simple precautions, don't have double-insulated kit, might even try to hoik a bit of stuck toast out of an electric toaster with a metal fork (yes I have seen that done, well I turned the switch off first so I must be safe, ahem no, quite the opposite if you have LN reversed), use metal bodied kettles where the only thing between them and live power is the ceramic insulation inside the element, etc.
Visiting another, got a tingle when touching the door handle to get in. Gently asked if that was usual, oh yes, particularly in wet weather, but you get used to it it's only a tingle. Oh dear.
It is also helpful to have chargers and appliances that can tolerate a wide variety of voltages, preferably everything from nominally 110 to 240V. Actually I have seen 260V at one UK site, where I think the transformer on the wooden pole must have been wrongly tapped (apparently replaced recently when the previous one exploded and burst into flames) Sometimes I've needed both my 25m and my 50m hookup cables together to find a nice spot, plus whatever the drop might be in whatever rickety distribution system the site might have. Shared with others say turning heavy current appliances on and off. Up and down it goes.