317 Sprinter 2021 Aux Battery

[Paulyc]

Wanting to fit a Aux battery to power my night heater and a few charging sockets for phone/ipad etc
I have currently a 906 sprinter using a SRB630 Split charge relay, ive been told this will not work and i
need a different relay.

I have read quite a few articles some saying VSR relay and some saying DC to DC
Head is blown now.

I have 2 mates who both have 907 Sprinters
both vans 2018 316
1 uses SRB 630 no problems.
2 uses VSR relay as SRB630 didnt work.

I also read on the internet a 2021 907 317 had a VSR relay fitted and it cooked his alternator.

So now confused which way to go with this, any help would be grateful.

Thanks

 

[alexanderfoti]

So, the problem with those types of relays, is that the batteries will immediately equalize on ignition on.

You will also draw on both batteries for the starter etc, unless you switch the relay with a pin from the engine ecu that is only live when the engine is actually running (might not be present?)

SPLIT CHARGE RELAY 12V 140A 140 AMP VOLTAGE SENSITIVE CAMPERS CAMPERVAN VSR | eBay

Note: The benefit of this type of relay is that it does not require a connection to the alternator or any modifications to the existing vehicle electrical system. Maintains battery isolation when not charging, so starter cannot be drained by leisure use and vice-versa.

www.ebay.co.uk

This type would be better, as it will only start charging the second battery when the engine is running, but you will have the same equalization issue, and the battery will not charge that quickly.

A DC-DC charger is the best, as they will pull a lot of power from the alternator and battery to charge your leisure battery as quickly as possible, and will also apply intelligent charging algorithms which the alternator will not do.

DC-DC Battery To Battery Chargers | 12 Volt Planet

DC to DC chargers, also known as battery to battery chargers. For charging leisure batteries in Euro 5 and 6 vehicles with smart alternators

www.12voltplanet.co.uk

Like those above, however, they are the most expensive.

Ultimately, all 3 will work, but have different feature sets at different price points depending on what you need.

 

[Paulyc]

Sorry for the late reply.
Thanks for the advice on the different ones.

After speaking to an auto electrical friend, he’s advised to get one of these
https://www.12voltplanet.co.uk/victron-orion-tr-smart-1212-18a-isolated-dc-dc-charger.html

He is going to fit this at the weekend so hopefully all will be ok.

Will update after its fitted.

 

[alexanderfoti]

Yes, they are the best type