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Installation of Lithium, DC Charger, AGM with a Boat Switch assistance

Hi all. I wonder if I should just replace my current flooded lead batteries with AGM in the current system. I want to minimize gassing on board (I believe AGM's can vent). Any recommendations? I have also heard of GEL but not sure if they can replace the flooded ones.

Please let me know. thanks!

 
Do you have an over gassing problem now? I've only seen that with overcharging issues. In which case you have to solve that first.
Switching to lithium and/or a hybrid system takes $$$ and commitment. If you're not all in yet, I'd replace the existing lead with AGM's until you are. You'll get 3-5 years to decide. There needs to be a reason to switch.
 
HI again. No current gassing problem, but concerned if there would be in tight quarters. I think I need more experience with the boat, switches - hybrid systems etc so AGM replacing the current batteries might be the best route. Still learning. This DC stuff is a bit of a challenge for me - but the folks on here have been a big help! I am currently using a BlueSky SB3000I MPPT and very happy with it. Got up to 16A with my 340W of STC rated power the other day!
 
Hydrogen atoms are very small compared to Nitrogen (in the air) and so dissipate very quickly with minimal venting or airflow. Massive gassing can be an issue, but it would take some effort to get there.

AGM batteries are much more easily damaged that Flooded. Make sure you understand all of your charging and proper battery care before buying them.
 
Hello, I am in the exact same situation now, where I am introducing a Lithium house bank #1 and have an AGM start #2. I don't want to undergo a huge rewiring project, so I believe if I follow the following rules, it should not be a problem.

1) Never combine the batteries in the "Both" position
2) Only ever start the engine with the AGM, with switch in #2 position

If the AGM dies for some reason, put switch in #1 position, turn on the inverter and charge the AGM with a battery charger using the Lithium as power supply

I have the Victron 12/12 18 amp DC-DC charger, the AGM will charge the Lithium through this device while the engine is running.

One thing I wanted to do was connect an alarm with a loud annoying sound, that would only sound if the battery switch was in the "Both" position. Does anyone know if this is possible?
 
1. - I wouldn't saw never.
In an emergency, if your AGM was low, you could directly boost it in "both"
Switch it to #2 after starting, just make sure not to rotate it through "off"
You are talking emergency situation correct? No need to charge it through the inverter.
You could, but it's a lot of wasted energy.

2. - I guess it depends on the engine. I start my 60 HP outboard with my lithium all the time.
 
1) If I started the engine in "Both" and then switched to #2 AGM after it starts would that cause any problems? Yes, I was talking about an emergency situation where the AGM was dead

2) I have a 200ah Lithium battery rated for 100amp discharge, and the engine I have is a 8hp Yanmar diesel, not sure how much the starter draws though

Alternatively, if I did want to use the #1 Lithium bank to start the engine, I'd want to rewire the alternator to directly charge the AGM, so that would be a minimum amount of re-wiring
 
I think your over thinking this. Start on #2, switch to #1 on shut down.
You said your alt charges the AGM and have a dc-dc for the house battery.
Get a lithium jump pack for emergencies. They're like $50 on sale. I've started many a friend's diesel truck with it.
 
Thanks, yeah I tend to obsess, mainly because I'm a noob and don't wanna screw anything up. Thanks for the tips.
 
I have two lifpo4 batteries as house. Both are charged from my Sterling alternator to battery charger using the lithium setting. In addition I have a lead battery as a starter battery also charged from the sterling charger with a lead profile. I do have an alternater saver in the event the BMS shuts down. The lifpo4s charge at 20 amps each.
I also have a duo solar controler to tricle charge the batteries when in the marina.

My panda generator 240v has two battery charges lithium and lead and there is always shore power If needed.

Its all been running for over a year without a hitch despite being told my alternater will burn out / overheat and bearings may collapse. Its a 20 year old 100 amp v belt alternater on a Nanni 50hp diesel. Was thinking of a second alternater and sterling BtoA charger.

I am now looking to install two more 280ah po4s in series so 24v with an inverter to run the combi oven and induction hob. Am also looking at a lynch motor for silent electric running from the same 24v supply. Charging will be fun.
 
Question for you all. So I'm planning to re-route my alternator to ONLY charge back to the starter battery, even if the Lithium House is used to start the engine in an emergency. Here is the original wiring diagram for my boat and I've marked where I'll cut the alternator "B" wire, and re-route directly to the starting battery. The blue line on the battery switch is the toggle showing which bank is selected. In this drawing the starter battery is selected and the lithium house bank is isolated. Does anyone see any problems with what I've got here? I'll be adding fuses to this, so this is just a basic drawing. The only change I'll be making to the original boat wiring is the re-routing of the alternator charging wire which originally went back through the starter connections. Many thanks
reroute-alternator.jpg
 
Err , presumably normally you want the starter to be powered by the starter battery. This switching arrangement seems to suggest you then turn over the switch to then connect the house loads to the Li and also this brings the alternator with it.

If so there are lots of issues.
 
Err , presumably normally you want the starter to be powered by the starter battery. This switching arrangement seems to suggest you then turn over the switch to then connect the house loads to the Li and also this brings the alternator with it.

If so there are lots of issues.
I believe the original plan was to not switch to house battery until after engine shut down.
I don't think he's picked s path yet, just feeling out options.
 
I believe the original plan was to not switch to house battery until after engine shut down.
I don't think he's picked s path yet, just feeling out options.
Well the drawing doesn’t make sense as it’s depicted , firstly you are relying on your alternator to power all loads when the starter battery is in circuit , that’s the way a car works but boats often have much higher peak dc loads then cars. This will damage the starter battery

Secondly you have to remember to switch modes on shutdown and engine restart as you can’t switch modes during engine running

Thirdly your alternator will either have a Li capable profile which will be wrong when switched to the starter and or will fry the alternator if it’s a LA profile , and it ends up inadvertently switched into the Li bank and the engine is started

I note that even with the engine off the dc dc convertor will remain charging the Li, using a cheap starter orientated battery to charge a big Li bank will rapidly kill the starter battery
 
The house loads are minimal on my boat. There is a depth sounder, and a radio, and perhaps some running lights if it's nighttime. The 35amp alternator can handle that load fine.

Once engine is shut off, I'll switch the house loads to the Lithium.

This is standard (if a bit prone to forgetting) setup on old boats. I'm not interested in rewiring a bunch of stuff. Just trying to make sure that by hardwiring the alternator to the AGM starting battery only, even if I choose to start the boat in an emergency with the Lithium bank, the alternator will not be charging the Lithium bank. It will be charging the AGM

Because normally the alternator on old boats charges back through the starter and back into whichever battery that was used to start the engine. I want to avoid that.

Specifically I wanted to see if my drawing had any red flags, for instance, I believe I don't need to rewire the alternator negative, as that goes back to the common ground (engine). Just rewiring the positive, I believe.
 
The house loads are minimal on my boat. There is a depth sounder, and a radio, and perhaps some running lights if it's nighttime. The 35amp alternator can handle that load fine.

Once engine is shut off, I'll switch the house loads to the Lithium.

This is standard (if a bit prone to forgetting) setup on old boats. I'm not interested in rewiring a bunch of stuff. Just trying to make sure that by hardwiring the alternator to the AGM starting battery only, even if I choose to start the boat in an emergency with the Lithium bank, the alternator will not be charging the Lithium bank. It will be charging the AGM

Because normally the alternator on old boats charges back through the starter and back into whichever battery that was used to start the engine. I want to avoid that.

Specifically I wanted to see if my drawing had any red flags, for instance, I believe I don't need to rewire the alternator negative, as that goes back to the common ground (engine). Just rewiring the positive, I believe.
If your loads are so small there’s no advantage to using Li at all.
 
I forgot to say I have a refrigerator / freezer. But that can be turned off or on. It only draws 4 amps I believe. But the reason I got the Lithium is because I want to be able to anchor out for a few days at a time.

The diagram shows the switch is on the start battery. The Lithium is isolated
 
I forgot to say I have a refrigerator / freezer. But that can be turned off or on. It only draws 4 amps I believe. But the reason I got the Lithium is because I want to be able to anchor out for a few days at a time.

The diagram shows the switch is on the start battery. The Lithium is isolated
How will you ensure the DC dc converter will stop charging the lithium when the engine stops.
 
How will you ensure the DC dc converter will stop charging the lithium when the engine stops.
The victron converters are pretty good at detecting that they watch for the voltage to be obviously high enough that the alternator is running.
 
The victron converters are pretty good at detecting that they watch for the voltage to be obviously high enough that the alternator is running.
Typically stock alternators are set to about 13.8v , so let’s say you set the set point at 13.5V , fine

But when the engine stops you will tend to discharge the AGM until the cut off point is reached. AGMs hate partial discharges. It reduces their life considerably.

A better way is to establish a engine run stop signal and switch the Victron dc dc on off ( it’s has that ability )
 
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