How to charge my two engine separate batteries from the service bank in winter when the engines are stoped?
The service bank is charged by 3 MPPTs and is connected to the out of the a couple of argofets (see the scheme below).
Can I use a pair of CC-CC IN (service bank) OUT (engine battery)?
Thanks for your help
Use a Blue Smart IP22 Charger with 3 outputs and connect 1 output to starter 1 and an second output to starter 2.
Or a Blue Smart IP22 Charger with one output and connect them to one of the argofets input to charge all 3 batteries together 
Thanks for the answer. I had the same question.
Now, how can we monitor this in VRM and Cerbo?
Thanks in advance.
So like that it will charge from Service Bank?
I thought the IP22 charger was a 230V input?
Unfortunately, I misunderstood your question.
How high is the voltage on the service battery?
If it’s just a matter of trickle charging over the winter, then the solution could work.
Please use the translation function
Another solution that comes to mind would be to connect one of the MPPT devices to the Agrofets input for the winter months, perhaps with a smart battery sense.
However, these are all solutions that require a certain amount of expertise in planning and installation. On the other hand, they are also very inexpensive.
The service battery is 12V
12 V lead?
With what end-of-charge voltage?
It depends on the technical solution you choose.
In the article I linked to, I can measure the voltage of the starter battery via the input of the charge booster.
This seems like a good idea. More work to install than an AC to DC Charger, but more efficient.
At the moment I have AC CHangeover switch to my shore AC-DC Engine Battery Charger, so during winter I move the changeover switch to the On board Inverter that is powered by Service battery,
Then I log in to VRM every 3 weeks and turn on the inverter remotely then the AC/DC Engine charger comes on and I leave it to run for 8 hours to maintain the engine batteries.
Its not ideal, your proposal here seems easier and more hands off. Which diode do you suggest for this?
Many thanks,
Alex
I tried it with:
Si rectifier diode P600A P600 50 V 6 A € 0.19
PTC FUSE 16V, 3A € 0.56
alternatively
SCHOTTKY DIODE SB540-E3/54 DO201AD VIS € 0.32
Experiment a little with the diodes and their voltage drop at your own setting until you have the desired voltage
See complete post for details.
Is there a plug and play solution?
Even it is expensive.
Read my linked posting above , there are some alternatives discussed.
OK, 250 Euro per Unit
I think that’s a bit over the top.
You have my ideas; please figure out the rest yourself.
It is only because I am not sure to be able to play with diodes or other type of equipments (I am not expert).
So If something unidirectional (from service to engine) is available on the market easy to install and compatible with my instalation it can be my choice.
Perhaps this solution as well who is cheaper.
There is so many solutions and I do not know wich one is better for me.
Hi @Speedboard
The topic of standby chargers is discussed here time and time again.
It is important that you are confident in your planning and installation skills and that you ultimately take responsibility for your work.
Otherwise, please ask a local specialist to do it for you !
My solution is based not only on one or more diodes for decoupling and voltage reduction, but also on a self-resetting PTC fuse that limits the current. This circuit is from the Schaudt EBL 99 and is often discussed in forums where you can also find the circuit diagram.
I use also the programmable output of the solar charge controller, which only switches on when the service battery is fully charged (in my case, lithium and not lead) and only provides a trickle charge of around 13V. The parts only cost a few cents; the postage is the most expensive part.
Your personal challenge is to achieve exactly the voltage you want for a trickle charge and to design it in such a way that it works in all operating conditions.
In both of your designs, for example, is the question open what happens when you run the engines.
I would install a summer/winter switch for this purpose if necessary.
However, in order to make such statements with certainty, one would need to be on site and be able to take measurements.
Therefore, i kindly request that you consult a local specialist if you do not feel confident about doing the project yourself.
OK I folow your idea,
I ordered the diodes, PTC, relay with optocoupler, and veroboard.
I will put in serie the PTC and the diode between the Service Battery end one starter battery, and the same between service and the second battry.
Normaly on the two shunts I have on both starters batterys, I shoud see (when the voltage increase from the MPPTs) a charging curent to the starters batterys?
And during the period I use the engines I open that circuit with a relay.
Am I right?
If yes thats effectively a cheap solution.
Perfect, thank you.
