Please critique my electrical diagram (12v system | 4.8kw bank | 2kw inverter | DC-DC charging) *UPDATED!*

rboothe

New Member
Thanks for clicking in and having a look.

Electrical diagram is attached but you can also go here: to view it.

My main question is in regards to the battery-to-battery charger which is not connected to the Victron Lynx Distributor currently. Because it will have an inline fuse (and the Victron MEGA fuses for the Lynx are too large), I was wondering if I could hook it up on the same positive and negative bolts that the Solar Charge Controller is using. Dumb question but would I need to add bus bars or can I just place the wire terminals on top of each other?

Any other comments are appreciated as well. Thanks for your time and consideration.

Electrical diagram v4.jpg
 

Diysolar123

Solar Addict
when you try and charge batteries from two different sources, well, they each have no idea the other is there and follow whatever their algorithm to charge is. The mppt and smart charger are both watching the voltage to decide what to do and make sure they protect hte battery from over charge. If the settings (absorb/float)are exactly the same then there will only be small differences in which device is providing what current. They will act different even with exactly the same settings for, well, lots of reasons. This is the same for chargers which are designed to work with batteries that are under load, all they can do is raise the voltage and monitor the outgoing current.
Keep in mind some BMS units will disable the charging fets if you hit the top voltage limit and they KEEP THEM OFF until a much lower voltage. This is the kind of thing you want to watch out for and the best bet is to avoid hitting charge cutoff voltage of the bms (set lower absorb/float voltage).

you can place more than one cable lug on a connection, if the connection and lug are strong enough.
 

rboothe

New Member
when you try and charge batteries from two different sources, well, they each have no idea the other is there and follow whatever their algorithm to charge is. The mppt and smart charger are both watching the voltage to decide what to do and make sure they protect hte battery from over charge. If the settings (absorb/float)are exactly the same then there will only be small differences in which device is providing what current. They will act different even with exactly the same settings for, well, lots of reasons. This is the same for chargers which are designed to work with batteries that are under load, all they can do is raise the voltage and monitor the outgoing current.
Keep in mind some BMS units will disable the charging fets if you hit the top voltage limit and they KEEP THEM OFF until a much lower voltage. This is the kind of thing you want to watch out for and the best bet is to avoid hitting charge cutoff voltage of the bms (set lower absorb/float voltage).

you can place more than one cable lug on a connection, if the connection and lug are strong enough.
Thank you. I thought about this multiple charging problem. My solution was to only have one charger going at one time. And to shut off the other two when not in use. But if it's possible to have either the mppt and AIMS charger going at the same time or mppt and DC-DC charger going at the same time, what would you recommend for the charging profiles? Are you saying I'd keep them the same but on the BMS I would set a lower absorb and float voltage? Are there articles out there recommending these types of charging profiles?
 

HRTKD

Boondocker
The multiple charge sources situation is a case where using components from the same vendor could help. Within the Victron landscape, many components can either talk between themselves or can be controlled from a central controller like the Cerbo GX.

My two Victron solar charge controllers can coordinate. The Victron BMV-712 makes that communication possible I believe.

I don't have the Cerbo GX, so I can't confirm features except for what I read on the Victron website.
 

rboothe

New Member
The multiple charge sources situation is a case where using components from the same vendor could help. Within the Victron landscape, many components can either talk between themselves or can be controlled from a central controller like the Cerbo GX.

My two Victron solar charge controllers can coordinate. The Victron BMV-712 makes that communication possible I believe.

I don't have the Cerbo GX, so I can't confirm features except for what I read on the Victron website.
Thanks @HRTKD. I checked in with a Victron sales rep who said the Cerbo only works with Victron components. So, unfortunately, the components I have will not be compatible with the Cerbo. I think I can either do what @Diysolar123 said and slightly lower the float and absorb voltage profiles on my non-dominant charging source (probably the solar charge controller) and leave the dominant charging source the correct "normal" profile. Or potentially, slightly raise the dominant charging source by .1 for it's max voltage...
 

Freqz

Solar Enthusiast
Thanks @HRTKD. I checked in with a Victron sales rep who said the Cerbo only works with Victron components. So, unfortunately, the components I have will not be compatible with the Cerbo. I think I can either do what @Diysolar123 said and slightly lower the float and absorb voltage profiles on my non-dominant charging source (probably the solar charge controller) and leave the dominant charging source the correct "normal" profile. Or potentially, slightly raise the dominant charging source by .1 for it's max voltage...
I’d let the solar handle the top off/absorb portion and only use the AC mains charger for “bulk”. Ou don’t *need* to take them to 100% every single day but just use the day’s excess to take care of top off/balancing :) It’s a “poor-boy” version of Victron’s ESS.
 

HRTKD

Boondocker
Thanks @HRTKD. I checked in with a Victron sales rep who said the Cerbo only works with Victron components. So, unfortunately, the components I have will not be compatible with the Cerbo. I think I can either do what @Diysolar123 said and slightly lower the float and absorb voltage profiles on my non-dominant charging source (probably the solar charge controller) and leave the dominant charging source the correct "normal" profile. Or potentially, slightly raise the dominant charging source by .1 for it's max voltage...

It really shouldn't be a big deal to have multiple charge sources active. I fire up my generator or connect to shore power, which activates my converter and my solar charge controllers don't complain.
 

rboothe

New Member
I’d let the solar handle the top off/absorb portion and only use the AC mains charger for “bulk”. Ou don’t *need* to take them to 100% every single day but just use the day’s excess to take care of top off/balancing :) It’s a “poor-boy” version of Victron’s ESS.
"poor boy" version of Victron is what I'm shooting for ;)
 
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