Multiple charging sources

[marciaanddave]

So this is a simplified drawing of my system.

I am unable to bring lithium batteries up to full charge. It was pointed out that I may have a conflict with the charging sources. They all think the batteries are full and then go into “float” charge. At this time I have the wind and solar turned off, and I am running the engine. The dc/dc charger is set to 20amp. I have a backup alternator on that is 80amp. Voltages are; starter battery 13.92, dc/dc input 13.76, dc/dc output 13.36, lithium battery 13.25.

Before I started the engine, with the solar on and wind off I had 13v at the lithium and the charger was in bulk stage.

I suspect the house batteries are so low that it will take a while to bring them up.

Should I just make it procedure to turn off the solar when using wind generator and wind off when using solar?

Is there a better wiring plan that would allow both solar and wind to work simultaneously?

We are cutting our Bahamas trip short and headed back to the states so I will at least have access to parts and local experts. Just looking for a little helpful advice.

[Stu Jackson]

Just adjust the target voltages for each controller/regulator a slight bit differently.


This method has been used for like forever.


Good luck.

[AnsleyS]

Is there a reason to route the alternator output through a wet cell and the dc/dc charger before getting to the lithium house bank?


I believe that a conflict between voltage regulators is your issue. Your alternator puts out the most so rewire that straight to the lithium with the voltage regulator set to the lithium settings and turn off the others before you start the alternator output. When you are not motoring start the solar or wind that you think will put out the most energy with the other turned off. The voltage regulators of the wind and solar should also be set for the lithium bank. You can then turn the other one on and its regulator will probably set it in float pretty quickly.

[marciaanddave]

My alternator’s regulator did not have a lithium setting and I was afraid I would smoke it. So I went to the FLA first, then let the dc/dc take care of the lithium. But I’m starting to think that I’m my attempt to save money I should have just bit the bullet and got the correct regulator…. Ugh

[CarlF]

How big is your lithium bank?

Your 80amp alternator is working fine and has fully charged the start battery. Now it’s just charging at 20 amps to the DC-DC charger.

The drawback of DC-DC chargers is they don’t deliver enough amps to make a real dent charging a big lithium bank. And if there’s any load on the lithium bank from other things the 20 amps may get used up before it makes it to charge the battery.

But it’s probably fortunate that you wired it as you did. Most 80 amp alternators would overheat and be destroyed if connected directly to a lithium bank.

For now get the wind and solar turned on and try to fully charge the lithium bank. It may take a long time.

If you don’t already have one, I’d install a battery meter that shows how many amps are going into and out of the lithium bank - and the state of charge.


https://www.amazon.com/Victron-Energ...13197219&psc=1

[marciaanddave]

We have 400ah of lithium. I see your point. I am leaning towards a new belmar regulator that has lithium profile. Then charge the lithium with that and then use the dc/dc to charge the fla. I think then the solar and wind will be able to keep up.

[smac999]

if the batteries are below the bulk set point (which is around 14.2-14.4v for lith all chargers will be trying to charge full out. and none will ever go to float (if they started in bulk). there is no issue having multiple chargers

once bulk ends and chargers go to absorb. at that point some might go to float early. but with lithuim when bulk ends you'll at 99% battery.... so it's not an issue. it's a minor issue with agm or flooded because that point is around 85% instead of 99%.

if the dc to dc is in bulk at 13.2 volts you'll probaly have many many hours of running to get it up to 14.2. if it's only charging 20a. since 13v (charging off) is a very low lith battery if the lith bank is 200a that's 10 hours of running... or 20hours for a 400ah bank

[HeywoodJ]

There should be no problem running multiple charge sources if the batteries are at a point where they can accept a bunch of current. The question would be settings on the solar controller, if it does think the batteries are already full and won’t go to bulk then voltage settings need to be adjusted.

What kind of solar controller? What kind of controller (if any) on the KISS? Settings on both? Can you watch current on any of the controllers to confirm that they are not putting out anything when the engine is running?

For reference, we have engine, solar, and wind all charging at the same time, the only time there’s a little bit of issue is when the batteries are above 90%, then one or more controllers may drop out, but at that point it’s OK because the batteries are full enough to start limiting current.

[marciaanddave]

Update. So today we left the marina with fully charged batteries. Sailed all day. Solar and wind were doing a fair job of putting amps back in. Wind finally died so we turned on the engine… and the alternator (running through the dc/dc charger REMOVED amps from the house batteries!!! So there must be something wrong with the alternator? I have tried two different alternators with the same outcome. So is it a bad dc/dc charger?

[HeinSdL]

Originally Posted by marciaanddave

Update. So today we left the marina with fully charged batteries. Sailed all day. Solar and wind were doing a fair job of putting amps back in. Wind finally died so we turned on the engine… and the alternator (running through the dc/dc charger REMOVED amps from the house batteries!!! So there must be something wrong with the alternator? I have tried two different alternators with the same outcome. So is it a bad dc/dc charger?

Sounds like it, and I hope so (regarding the last question)! I just installed a DC/DC charger on my boat and my key assumption is/was that: 1. it won't charge unless the engine is running, ie the start battery is above some preset voltage 2. there cannot be any current flowing from house to engine battery.

So far I am satisfied that the charger is operating as intended but I would be interested to hear what you find out. What charger is it? Common ground/isolated?

[MWGDVC]

13.36V DC-DC output seems low for lithium charging. Is this where you have it set? What does your battery manufacturer recommend? I run alternator to FLA start battery, DC-DC to 12V300AH lithium house bank, no trouble. I believe my DC-DC charger is set to 14.4V output. Not currently on the boat, so I can’t verify.

[brazenarticle]

The Victron Dc to DC charger manual mentions "When the engine shutdown detection has been switched off in Victron Connect (‘forced charging’) current will be drawn from the starter battery even if the engine is not running."

[markcouz]

Originally Posted by marciaanddave

Update. So today we left the marina with fully charged batteries. Sailed all day. Solar and wind were doing a fair job of putting amps back in. Wind finally died so we turned on the engine… and the alternator (running through the dc/dc charger REMOVED amps from the house batteries!!! So there must be something wrong with the alternator? I have tried two different alternators with the same outcome. So is it a bad dc/dc charger?

I dont think that current can be reversed through a DC2DC, either the DC2DC has failed in some bizzare manor or source/target wiring is reversed.

[markcouz]

... or your DC loads exceed the output of your DC2DC, is which case you would still see discharge current with alternater running

[marciaanddave]

It’s a renogy 40amp dc/dc charger. It is set for 14.2 volt output. It worked properly when using shore power to charge the FLA and then I have a switched wire to excite the dc/dc charger. All was well until the alternator came on and we were off of shore power. I’ll make a diagram of how I have the chargers hooked up and post that.