xavier-64 avatar image
xavier-64 asked

ORION DC DC Charger replaced by a MPPT Charger

Hello all !
Not really a question but more a result of my reshearch on how maintain a Small motorbike Lithium Battery (CA: 300A) in a correct state for starting a genset. and linked to that post :

The truck is powered in 24V as the van part... so 2 set of 24V batteries are available...

At the begining I was powering the Genset on with two DC/DC 24/12 70A Orion converter... It works !! but some power was still missing and the starter engine was not runing so good !!

So since today, here the setup for my genset management with the Cerbo GX....

The Dometic Genset have an Automatic mode status where it is possible to power it up and down with a simple NO relay. (i.e: Venux or Cerbo GX relay).

The point is, in this mode, with the space I have I was only able to place a 5Ah motorbike lithium battery. After 5 days in automatic mode, the battery is discharged... and not enough power is remaining to power on the Dometic TEC40D genset. one detail.

So the goal is to keep the battery in good health with a charger... but witch one ????

The defect of standard charger is 230V AC power is needed... unless I have it in the RV... I don't what to keep it all the time plugged on....

The Orion DC/DC charger ... interesting as it can act as a charger or generator (as well for the standard charger) but... no real communication is possible but with the BT..... and no DC DC charger really compliant with a 12V/5AH battery..

Then after some brainstorming... some figures drawing.... I look on my truck solar implementation and the MPPT charger give me an idea....

Why not using a MPPT charger for the purpose I need.... :

- input 24V output charger12V

- lithium compliant with all settings needed (voltage, current, temperature)

- BT and communication ( to connect it to a GX device....;-) ) or remote power off/or

So that's it ... since today, I use a 75/15 MPPT charger as a genset 12V 5ah batterie managment (with the help of a small BT battery sence) ... let see with coming days,weeks and months...

So here some screen shoot with the victron connect app, I do not yet integrated with the GX device as this is a test/experience. (so please no comment with the temporary/quick wiring :-( )

I also change the min temperature from 5 to 3 for testing purpose but also because the temp sence is not inside the batterie... so I suppose 1-2 °C of difference... I will tune it later...

the list of devices.... mppt01.jpg

just connected...


Batterie status


After some minutes...


the quick setup and wired up !!! (We can see one orion DC/DC 24/21 still in place as start assist)


So now some weeks of testing and the next step is to implement the same features but with a smart dongle + temp sensor + the MPPT + the ON/OFF remote cable... and there is also a tirth version that will imply more work on my side...

here the schematic / electrical figure principle and draft


So if some Victron experts could give some feedback or comment !


MPPT SmartSolarorion-tr smartshowcase
mppt00.jpg (27.5 KiB)
mppt02.jpg (21.0 KiB)
mppt05.jpg (27.3 KiB)
mppt01.jpg (78.5 KiB)
mppt03.jpg (119.8 KiB)
mppt04.jpg (89.4 KiB)
1675800543485.png (46.9 KiB)
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

3 Answers
kevgermany avatar image
kevgermany answered ·

Looks very interesting. Thanks. It will be very interesting to see your future stages.

Be careful trying to mix Victron's Bluetooth networking with Victron's other network options, it's intended as a standalone network.

1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

xavier-64 avatar image xavier-64 commented ·


Thank you for the comment @kevgermany !

In fact, this is testing phase. the BT use is in standalone or MPPT and Battery sense coupling by the fact of Lithium thecnology battery request the temperature sense.

Next step will be with a smart dongle + temp sense + MPPT + Remote ON/OFF RX MPPT cable as communication support avoiding BT use between components. And to see how I can handle that with the Cerbo GX ... (Temp sense and remote ON/OFF cable are not yet ordered)


A last step will be in the future (perhaps next winter study) integrating the Genset management and its battery with a Raspberry PI or BBB card....

The goal of this test is to "approve" the use of a MPPT charger as a DC/DC converter and charger (24V to 12V in my case) with, If I'm right , some additionals features and possibles settings , than an Orion DC/DC converteur charger that is not existing in that range for small lithium batteries charger.

So is like using it with a constant sunlight iradiation converted by connected solar panel, replaced by a other DC source (DC 24V in my case)

Thanks for you comments !


P.S. : this morning.. -4°C inside the genset box ... Lithium Battery 13.2V ... waiting temp to rise up...


0 Likes 0 ·
mppt06.jpg (26.5 KiB)
djsmiley avatar image
djsmiley answered ·

I only would recommend adding some current limiting. Now this is a 2A fuse, so if the MPPT wants to charger with >4A (approx) at the 12V side, the fuse will pop.

You can install a bigger fuse, but can't go over 15A since thats the PV current limit of the MPPT.

A small (5-6 ohm or so) resistor in series with the fuse would be fine, that will prevent the PV current to exceed approx 6A, so you're within the range. You do need a resonable big one mounted to the chassis, since in worst case it will dissipate some heat, but I think a 50W one will be fine.

1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

xavier-64 avatar image xavier-64 commented ·


thank you for the comment @DJSmiley

The max curent in charger settings is set to 2A


So today, after 1 day of automatic mode genset ON and 1 correct Genset start, the max current comming from the MPPT charger was 2A, and from the PV side 26Vx1.1A => 28W.

So I suppose I can keep the 2A fuse as it is and perhaps protect the output with a 5A fuse, As I try to remove/replace the 20A embedded fuse but too hard to remove....

So I've re-wired a bit the system to test it some weeks and then upgrade the system as the new material will be delivered.... (Ve.Bus smart Dongle + Temp sensor + Remote ON/OFF cable)


0 Likes 0 ·
mppt07.jpg (36.7 KiB)
kevgermany avatar image
kevgermany answered ·

Some behind the scenes checking says will probably work, but fuse well below the input current limit.

Definitely NOT supported.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.