DC to DC charger with Argofet splitter

[Bob666]

Hi!

Standard setup:
Generator B+ to start battery.
Start battery to DC to DC charger
DC to DC charger to LiFePO4 domestic bank.

My setup:
Generator B+ to 3-way Victron Argofet splitter.
Argofet to 3 lead acid battery banks.
Bank 3 to DC to DC charger.
DC to DC charger to LiFePO4 domestic bank.

Assuming all 3 lead acid banks are fully charged. Will I get equal current going into LiFePO4 bank with my setup as with standard setup?

Cheers

[YANDINA]

Since a splitter will feed the lowest battery first, if the DC to DC load drops the Bank 3 voltage it will take up to 100% of the available current once the other 2 banks are fully charged. In fact if it keeps Bank 3 from fully charging the other 2 banks will also not be fully charged.

[PaulCrawhorn]

Originally Posted by YANDINA

Since a splitter will feed the lowest battery first

Can the charger even be getting accurate feedback on battery voltage, without a separate voltage sensor wire when going through that splitter?

[smac999]

how big is the alt and how big is the dc to dc?

[moseriw]

It is said that a A2B Charger from the alternator(you said generator) is very very useful.
Though I bought a 200A A2B on an 160A alternator and connected the A2B to the ArgoFet-3 assuming that the 2xAGM and 3x2 Trojans are getting charged.

+2x Victron MPPT

Puhh - I do have the same problem to keep it simple...
Chargers, Chargers everwhere steering everyone right into a complete MESS!

Well I want a 90-280VAC >> 14,4VDC 200A unit to feed the A2B to reduce the damn chargers but it looks like I am running into the next mess....

Lot of people are having approx 1000-1200 Ah to get charged but even the best alternators reduce charging within 10 minutes to 100-110A.

So.. how to enable recharging of say 360Ah within 2 hrs on the 720Ah FLA house bank?
Nearly impossible.

btw: I think the LiFePo4 are NOT the solution but the oncoming Na-Ion will be.
We should wait for them and the oncoming PV's with maybe 40% harvest instead of the 21% we do have now.

[goboatingnow]

Loads determine current that’s the general rule.

[moseriw]

Originally Posted by YANDINA: Since a splitter will feed the lowest battery first

Sorry, No, the purpose of the argo fet are bank seperating diodes and every battery takes what it needs. There is absolutely no scrap IOIIIIIIIIIIIIII loading in it.

Well and this brings it to a point. No these IOIOIO chargers are not scrap as they try to charge the batteries gentle. The important question is which one as I am sure that the charger is not able to determine which one the argo fet feeds.

Therefore the charger before the FET charges something - best the bank with maximum Voltage (FLA) and after the FET one would need extra B2B chargers for the others AGM, SLA, LiFePo4...

LiFePo4 14 - 14,4V
AGM 14,4V
SLA < 14,3V (gassing voltage https://www.powerstream.com/SLA.htm) Sealed Liquid Acid
FLA 14,8V Trojan Flooded Liquid Acid

= running into trouble instantly = RTFM


And it looks like AGM, SLA, LiFePo4 can be charged via the FET without additional chargers but nobody knows if the IOIOIO thin is effective or not. PFFFFFFF what a MESS!

[CharlieJ]

@moseriw # 7

No, the purpose of the argo fet are bank seperating diodes and every battery takes what it needs.

This is not correct. The Victron ArgoFET uses FET's to isolate one battery from the other. FET's are generally preferable to diode isolators because there is virtually no voltage drop across an FET isolator and there is about 0.7VDC voltage drop across a good diode isolator.

There is absolutely no scrap IOIIIIIIIIIIIIII loading in it.

What does this even mean?

@moseriw #5

Though I bought a 200A A2B on an 160A alternator and connected the A2B to the ArgoFet-3 assuming that the 2xAGM and 3x2 Trojans are getting charged.

I am trying to understand your problem. If the alternator is controlled by an external regulator, than a single charging profile can be programmed. If the installation is comprised of several batteries with mixed chemistry, then an A2B is required to take the output from the alternator and adjust it for the charging profile required by the served battery's chemistry. You will need a separate A2B for each different battery chemistry.

Battery isolators, either FET or diode based, do nothing to adjust the charging profile as delivered to the input of the isolator.

[YANDINA]

They charge the lowest battery first because the source voltage will be pulled down to slightly above the lowest battery which will be less than the next highest battery so nothing will flow to it until the voltage on the lowest rises to equal the second, at which time they will share the current in proportion to their internal impedances.

[PaulCrawhorn]

Thanks Ann-Marie, makes sense never thought of it that way. Nice to let nature take its course.

It's a privilege to have you hanging out here!

Any chance you could have a quick look at this post? I suspect I'm being too conservative and maybe your combiners could be a solution rather than overkill investing in high-current DCDC chargers.

https://www.cruisersforum.com/forums....php?p=3552247

..

Originally Posted by YANDINA

They charge the lowest battery first because the source voltage will be pulled down to slightly above the lowest battery which will be less than the next highest battery so nothing will flow to it until the voltage on the lowest rises to equal the second, at which time they will share the current in proportion to their internal impedances.