question

gregsut avatar image
gregsut asked

Batter to Battery Dc charging without alternator or switch

Scenario

I have a 175ah Lithium battery powered by solar via Victron MPPT

I want this unit to charge a spare 120ah Lithium battery I have

If I use a Dc-Dc Smart charger with isolation 12/12v - 18a would be plenty, will it work and what would be the L H Pinouts.

I live down under plenty of sun and the solar keeps the 175ah topped up most days

orion dc-dc
2 |3000

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

4 Answers
kevgermany avatar image
kevgermany answered ·
It's not clear how you're going to wire this or use the output from the second battery. Ideally it has separate loads and the only connection to the 175Ah is through the Orion and ground. I get the impression you're wanting the Orion to provide safe isolation between the batteries, but provide constant charge without sharing loads.

If you want it on 24*7, L and H should be bridged as it is from the factory.

Using engine detection allows you to let the Orion charge when solar charges the first battery.

As already stated you can tweak input voltage settings to make it charge continuously. The BMS for the first battery should prevent over discharge.


2 |3000

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

Alexandra avatar image
Alexandra answered ·

@Gregsut

The use of the HL pins are in the manual.

How you signal it without the alternator or switch depends on your other system components

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.

gregsut avatar image gregsut commented ·
Thanks but there is no alternator just another Lith battery charged by Solar
0 Likes 0 ·
Sarah avatar image
Sarah answered ·

Hi @Gregsut One option to control the Orion is to use the engine detection feature and set it to be slightly lower than the absorption and float voltages on the mppt. Other options include using the relays in a Cerbo or BMV712 or the relay on your mppt (if it has one). Each device has slightly different ways to trigger the relay (for the bmv and mppt you can have a look at the demo library in victron connect).

2 |3000

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

gregsut avatar image
gregsut answered ·

No Engine detection needed as this will be charged by a separate battery isolated from the engine and charged by solar only, so I need it to be on 24x7.


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.

mvas avatar image mvas commented ·

You are misunderstanding what "engine detection" does. It prevents the main battery from being discharged, when it's voltage is below a threshold. This feature can be used, when there is no engine.

1 Like 1 ·

Related Resources