DC to DC charger - not needed for boats with proper alternators.

[CaptainRivet]

You don't need a wakespeed in 80% of cases. Eg a Nordkyn VSR200 for 300Euro is enough and its not even necessary to modify the alternator for external regulator as nordkyn works via original sense wire. Thats especially great for newer volvos as you get around the d+ problem too and keep the internal temp protection.
The way i go and throw out lead. One hull hybrid starter/house 1088AH LFP and other hull 60-80AH LTO starter/backup.
So VSR200 is cheaper then a 30A Victron DC2DC and you get 80A from a 115A Mitsubishi for the same amount of money.

[newhaul]

Originally Posted by CaptainRivet

If you stay at around 40-60A at 12V or half at 24V a DC2DC may make sense if you want to keep lead.
But if we talk about charge of 70-100A @24V or 100-200A @12V a DC2DC makes no sense at all. Then charge directly LFP and if you wanna keep lead use a small DC2DC to trickle cahrge lead.

A pair of 60 amp dc-dc and lifepo4 sounds just fine to me . For a big system.
A single 12v is good for my system .

[newhaul]

Originally Posted by CaptainRivet

You don't need a wakespeed in 80% of cases. Eg a Nordkyn VSR200 for 300Euro is enough and its not even necessary to modify the alternator for external regulator as nordkyn works via original sense wire. Thats especially great for newer volvos as you get around the d+ problem too and keep the internal temp protection.
The way i go and throw out lead. One hull hybrid starter/house 1088AH LFP and other hull 60-80AH LTO starter/backup.
So VSR200 is cheaper then a 30A Victron DC2DC and you get 80A from a 115A Mitsubishi for the same amount of money.

Still more than the renogy dc dc I'm installing
Currently sale priced at $170
https://www.renogy.com/12v-60a-dc-to...ttery-charger/

[Simi 60]

Originally Posted by CaptainRivet

You don't need a wakespeed in 80% of cases. Eg a Nordkyn VSR200 for 300Euro.

Unavailable


https://nordkyndesign.com/product/no...ce-controller/

Wish I knew of them earlier
But, if I couldn't get them it would have been dc2dc x2

[CaptainRivet]

Originally Posted by newhaul

A pair of 60 amp dc-dc and lifepo4 sounds just fine to me . For a big system.
A single 12v is good for my system .

A VSR200 Nordkyn is cheaper, charge directly and get rid of lead. Sounds better for me and the VSR regulates while DC2DC you guess and altrrnator can still burn out when you guess wrong.

@Fuss: the cheap way is instead DC2DC just put a resistor into sense line and limit this this way to 60A or whatever you figured is the current your alt can savely handle in your environment, it is the same then a DC2DC. Surge and spike protector and you are done.

[newhaul]

Originally Posted by CaptainRivet

A VSR200 Nordkyn is cheaper, charge directly and get rid of lead. Sounds better for me and the VSR regulates while DC2DC you guess and altrrnator can still burn out when you guess wrong.

.

When I'm wrong about what?
My start battery is a u1 350cca a 75 amp alternator a 60amp dc dc detectable by half . a switch in sense wire and on the other side is a 250ah lifepo4 bank I built from raw cells .
There is a refit thread where I detail the bank .

[CaptainRivet]

Originally Posted by Simi 60

Unavailable


https://nordkyndesign.com/product/no...ce-controller/

Wish I knew of them earlier
But, if I couldn't get them it would have been dc2dc x2

For your setup you need 1, you can run up to 3 alternators parallel on 1 VSR if they are on the same engine.
Surprised not many know about the VSR200, genius product.
Soon back in stock, and 2 are mine :-)
Also good to read all his article, Eric is very knowledgeable.

For me no seperate starter or lead needed anymor. put starter directly on your house, put LCV on 3.0V that switches all off except starter and you can always start.
Use a small LTO+active balancer, as buffer battery for nav station and a victron isolated 12V to 12V dc converter. This isolates and protects your nav equipment from spikes of starter or windlass and works as top up charger for LTO.
In absolut emergency that LTO can also start the engine.
No need for lead anymore.

[CaptainRivet]

Originally Posted by newhaul

When I'm wrong about what?
My start battery is a u1 350cca a 75 amp alternator a 60amp dc dc detectable by half . a switch in sense wire and on the other side is a 250ah lifepo4 bank I built from raw cells .
There is a refit thread where I detail the bank .

Wrong sbout your current limit of DC2Dc.
Expect 60A setting on 1500RPM and a normal 75a Alternator is definitly toast. Remember yours is hefty modified.
Get rid of starter and add more LFP instead.

[Putt-Putt]

Originally Posted by newhaul

When I'm wrong about what?
My start battery is a u1 350cca a 75 amp alternator a 60amp dc dc detectable by half . a switch in sense wire and on the other side is a 250ah lifepo4 bank I built from raw cells .
There is a refit thread where I detail the bank .

Am I right in concluding that you intend to charge your U1 (35 Ah.+/-) battery with the 75 amp alternator and at the same time ask the battery to deliver up to 66 amps to the DC-DC (it is about 90% efficient) so it can modify the voltage and apply 60 amps of charge to your 250 Ah LiFePO4 bank? For what, 2 or 3 hours?

Seems like a tall order for a small lead battery to me.

What is the manufacturers recommended charge current for this U1 battery which is often found in small tractors or riding mowers?

[newhaul]

Originally Posted by Putt-Putt

Am I right in concluding that you intend to charge your U1 (35 Ah.+/-) battery with the 75 amp alternator and at the same time ask the battery to deliver up to 66 amps to the DC-DC (it is about 90% efficient) so it can modify the voltage and apply 60 amps of charge to your 250 Ah LiFePO4 bank? For what, 2 or 3 hours?

Seems like a tall order for a small lead battery to me.

What is the manufacturers recommended charge current for this U1 battery which is often found in small tractors or riding mowers?

No the renogy dc to dc connects direct from alt to dc dc to lifepo4 the u1 is kept in its position and connections to the alternator . Just like any start battery

[newhaul]

Originally Posted by CaptainRivet

Wrong sbout your current limit of DC2Dc.
Expect 60A setting on 1500RPM and a normal 75a Alternator is definitly toast. Remember yours is hefty modified.
Get rid of starter and add more LFP instead.

Where are you getting the 1500 rpm from my westerbeke is 2200rpm engine with a 2.5 to 1 pully set from crank to alternator which is speed to optimum of 6k rpm
Somreal close not worried about heat .

How is my system heavily modified?

please explain to an engineer how his engineering is wrong.

[wholybee]

Originally Posted by Putt-Putt

Am I right in concluding that you intend to charge your U1 (35 Ah.+/-) battery with the 75 amp alternator and at the same time ask the battery to deliver up to 66 amps to the DC-DC (it is about 90% efficient) so it can modify the voltage and apply 60 amps of charge to your 250 Ah LiFePO4 bank? For what, 2 or 3 hours?

Seems like a tall order for a small lead battery to me.

What is the manufacturers recommended charge current for this U1 battery which is often found in small tractors or riding mowers?

That isn't how it works. The alternator output, DCDC input, and start battery are all connected together.

The alternator can produce 75Amps. At full load, 66ish Amps will go to the DCDC, and 10ish will go to the start. Those numbers will move based on state of charge, if the start battery is full then it will take 0, and everything will go to the DCDC. You are not putting 75 amps into the battery at the same time as taking 66 Amps out, it's only the net of what that battery needs that will go into it.

FWIW, I have the (almost) exact same setup, 70A alternator, Renogy 60A DCDC, and a built from cells LFP. One of the reasons I did it this way is because I have enough solar, and the DCDC is selectable between 30A and 60A, and can be turned off. So, I have a switch on my panel, 30A-Off-60A, and that switch lives in the off position with solar normally providing enough power. If I need a fast top off, I can run at 60A for an hour, or if I am stuck motoring for hours anyway I can run it at 30A.

[newhaul]

Originally Posted by wholybee

That isn't how it works. The alternator output, DCDC input, and start battery are all connected together.

The alternator can produce 75Amps. At full load, 66ish Amps will go to the DCDC, and 10ish will go to the start. Those numbers will move based on state of charge, if the start battery is full then it will take 0, and everything will go to the DCDC. You are not putting 75 amps into the battery at the same time as taking 66 Amps out, it's only the net of what that battery needs that will go into it.

FWIW, I have the (almost) exact same setup, 70A alternator, Renogy 60A DCDC, and a built from cells LFP. One of the reasons I did it this way is because I have enough solar, and the DCDC is selectable between 30A and 60A, and can be turned off. So, I have a switch on my panel, 30A-Off-60A, and that switch lives in the off position with solar normally providing enough power. If I need a fast top off, I can run at 60A for an hour, or if I am stuck motoring for hours anyway I can run it at 30A.

Thats a great idea thanks the 3 position switch .

[wholybee]

Originally Posted by newhaul

Still more than the renogy dc dc I'm installing
Currently sale priced at $170
https://www.renogy.com/12v-60a-dc-to...ttery-charger/

I have the same one and am happy with it. It has a connection for the keyswitch to turn it on/off, and a connection for 30A/60A. I connected both to a dpdt on-off-on switch, for 30A-off-60A operation. (and also still to the key switch) I don't think any other DCDC will allow this.

I have not had overheating issues with my 70A alternator, although it is a Balmar, so should be good for 70A continuous. It will do 90A if I ask it to.

[newhaul]

Originally Posted by wholybee

I have the same one and am happy with it. It has a connection for the keyswitch to turn it on/off, and a connection for 30A/60A. I connected both to a dpdt on-off-on switch, for 30A-off-60A operation. (and also still to the key switch) I don't think any other DCDC will allow this.

I have not had overheating issues with my 70A alternator, although it is a Balmar, so should be good for 70A continuous. It will do 90A if I ask it to.

Mine is a 75 amp chevy alternator on a mitsubishi k2b engine but it is my 4th backup charge source . ( solar first, wind , then generator and my inverter charger. Then last is the alternator. ) mainly top off when leaving an Anchorage or marina.