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Battery Charger -> House -> DC/DC Charger -> Lithium?

The Victron DC to DC charger has adjustable cut off voltages. He can just set it to drop off the AGM circuit at whatever voltage he is comfortable with.

You even tell it what voltage you want it to wait for, before it comes back on.

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If you don't use the ignition sense the won't the Victron charger use the start battery as an input. So at most 18 amps out. With 5 amps max in from the shore charger, you could deplete the start battery before the house battery is charged. You really need the second charger.

Is the 5 amp charger bolted in or portable? It was fine for a maintenance charger when both house and start we're Lead Acid, but overkill as a maintenance charger just for the start battery.

Just to give you another rabbit hole to go down...
I have LA and Lifepo4 in my RV.
When plugged in, I have a separate lifepo4 charger for house and run a small 2 amp DC-DC charger off of the lifepo4 as a maintenance charger for the Lead battery.
I'm leaning to upgrading the charger regardless of how I run it, whether to the AGM or directly to the Lithium and as you mentioned another rabbit hole, I'd like to ask you what your small 2 amp DC-DC charger product is? Because I think that could be the answer to this. So to recap I'll:

  1. Remove existing 5 amp lead acid charger.
  2. Buy the 25 amp Victron charger and connect it to the Lithium house bank.
  3. Buy the 2 amp DC-DC and let the Lithium keep the AGM start topped off while on shore power.

While running the engine, the alternator will charge the AGM start battery, which will power the Victron DC/DC/12/12/18 which will top off the Lithium house bank.
 
The Victron DC to DC charger has adjustable cut off voltages. He can just set it to drop off the AGM circuit at whatever voltage he is comfortable with.

You even tell it what voltage you want it to wait for, before it comes back on.

View attachment 106326
Yes, I was planning to set the drop off at 12.5 so the AGM would never get run down.
 
Yes, I was planning to set the drop off at 12.5 so the AGM would never get run down.
This will still result in the AGM being cycled by the dc charger. Starter batteries arnt good for that. Some form of engine run/stop signal could be used to disable the dc dc unit. Cars do this.

Secondly adding a mains charger to the AGM will confuse the dc dc unit. Best add a Li mains charger.
 
Lyypggh
This will still result in the AGM being cycled by the dc charger. Starter batteries arnt good for that. Some form of engine run/stop signal could be used to disable the dc dc unit. Cars do this.

Secondly adding a mains charger to the AGM will confuse the dc dc unit. Best add a Li mains charg
 
I found this charger that can handle two banks of different chemistries at the same time, then I dont have to worry about going through the dcdc charger while on shore power.

NOCO GENPRO10X2 12 Volt, 20 Amp Genius 2 Bank Battery Charger
 
I found this charger that can handle two banks of different chemistries at the same time, then I dont have to worry about going through the dcdc charger while on shore power.

NOCO GENPRO10X2 12 Volt, 20 Amp Genius 2 Bank Battery Charger
reading the manual there seems to be no way to set different profiles for each bank. The selected profile seems to apply to all banks ( they do a 3 and 4 bank version )
 
I'm not the biggest fan of NOCO, because I think I got one that is messed up and I haven't felt like dealing with support to exchange it... but from the description of it, and how they function, it should be able to do different profiles on each.

Independently charge and control each battery bank with selectable charging modes - including 12V, 12V AGM, 12V Lithium, and 12V Repair Mode - for all types of lead-acid and lithium-ion batteries.
 
reading the manual there seems to be no way to set different profiles for each bank. The selected profile seems to apply to all banks ( they do a 3 and 4 bank version )

Go to 2 minute mark, he's got different profiles selected at the same time.
 
Despite my suspicion I have a defective Noco Genius 10, the build quality and packaging on them seems top notch. Just in case you are debating buying it or not, they are like the Apple of the battery charger world.
 
I had one a few years ago and was impressed with the build quality. They come with a 3-year warranty too
 
I had one a few years ago and was impressed with the build quality. They come with a 3-year warranty too
given that can do multiple chemistries , that's an advantage , personally i see no need, as my starter will charge from the Li bank via a simple DC DC trickle charger , all other charge sources are charging the Li bank directly
 
given that can do multiple chemistries , that's an advantage , personally i see no need, as my starter will charge from the Li bank via a simple DC DC trickle charger , all other charge sources are charging the Li bank directly
Whats your simple DC DC trickle charger product called?
 
i Use these low cost buck boost DC DC units from https://www.aliexpress.com/item/4000544391002.html?


These can be set to a trickle charge voltage and current limit

Interestingly these survived my recent lightening strike and all the victron gear didnt !!!!

also useful for equipment that needs a fixed steady voltage and the high input voltage tolerance means the alternator protection spike post APD doesn't kill it
 
for other components I have one of these on order https://www.connectorconcepts.com/lare12.html as the bi-stable relay has little current , but the issue is how to make it " fail safe "

as I have used Te connectivity 2219561-1 500A EV relays but these have a 600mA operating current ( which I drop to 300mA after initial pullin ) these are nice because they can fail open when the power fails

I have a design for a very rugged MOSFET using STY145N65M5 Mosfets ( 650V 138 A) switch that I will build later in the year but component availability is killing me right now
 
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i Use these low cost buck boost DC DC units from https://www.aliexpress.com/item/4000544391002.html?


These can be set to a trickle charge voltage and current limit

Interestingly these survived my recent lightening strike and all the victron gear didnt !!!!

also useful for equipment that needs a fixed steady voltage and the high input voltage tolerance means the alternator protection spike post APD doesn't kill it
Thats damn clever so what setting do you put the thing at to trickle charge your starter?
 
for other components I have one of these on order https://www.connectorconcepts.com/lare12.html as the bi-stable relay has little current , but the issue is how to make it " fail safe "

as I have used Te connectivity 2219561-1 500A EV relays but these have a 600mA operating current ( which I drop to 300mA after initial pullin ) these are nice because they can fail open when the power fails

I have a design for a very rugged MOSFET using STY145N65M5 Mosfets ( 650V 138 A) switch that I will build later in the year but component availability is killing me right now
No idea how this relates to the topic? Can you explain
 
around 13,6 -13.7 and I set the CC to 5A ( they get too hot other wise , so if the battery discharges the draw from the Li is set to 5A max) most f the time little current flows as the starter is rarely depleted ( nothing else runs from the starter other then the starter relay , glow plugs and the starter itself ) , my next rewire will change the engine panel to be powered from the domestics
 
No idea how this relates to the topic? Can you explain
relay based battery disconnects , around $100 for 500A a bit less $80 for 200A, used as BMS disconnects , just showing thir are good alternatives to things with "marine " stamped on them, but I should have posted that in the other thread
 
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