New Lithium Battery, DC-DC charger

[goldenstate]

I'm planning to upgrade my battery banks in the near future. Lithium seems to be an obvious choice for low lifetime cost, fast charging, and light weight.

Here is an example that appeals:

Amazon.com

Some counter-arguments:
1. Lithium has a higher absolute purchase price cost than lead acid. (Yes, but prices are coming down all the time. $190 for an AGM 100Ah battery vs $325 for the Lithium one).

2. You'll set your boat on fire. (No, the current drop-in LifePo batteries all have integral Battery Management Systems that prevent this sort of thing).

3. You'll burn out your alternator. This seems to be a reasonable concern. The Lithium batteries will accept a lot of amperage, so without some metering function, an alternator can be burned up by the excessive draw that a Lithium battery can accept.

One answer that seems widely adopted is to use a DC-DC charger. Your alternator charges your Lead-Acid high High-Cold-Cranking-Amps starter battery, and then that starter battery is linked to your Lithium bank via a DC-DC Charger:

Amazon.com

So the alternator is governed by the amount of amperage the lead acid battery will accept, which is the normal expectation for the alternator

Has anyone been down this path (using a DC-DC charger and a lithium bank of house batteries)?
I googled EYO forum topics and did not find much about DC DC chargers.

I know another choice is to buy a bigger, fancier externally regulated alternator (@$1,200 vs. $200 for the DC-DC charger).
I don't know much about the benefits of having a big alternator vs. simply having a DC DC charger to throttle the re-charging of the Lithium.
I suppose one tradeoff would be a longer recharging cycle?

Thanks for any ideas.

 

[Stuphoto]

Just a thought,
I have been watching some YouTube channels on off grid living and a few of them are getting used medical batteries and making their own battery packs with the.
It looks like these batteries are around the size and shape of a pop can.
They claim the batteries are more affordable than the cheap lithium batteries, and if you are lucky you may find a local source.
What I like about this is we can customize the setup to easily fit some pretty tight spaces.

I don't have access to YouTube at the moment, or I would post a link.

 

[David Grimm]

I did this! You'll need a dc to dc charger and you will have to keep a conventional battery in between the alternator and the charger to keep the alternator happy. Now when I say conventional I mean in battery type not size. Its really in place as a capacitor with resistance. I used the battery out of my 2010 Harley Road Glide. Lol

In short. Alternator-HD batt-renogy 60a charger-batt switch common + starter - bank1 2 (100ah mighty Max li) bank2 2(100ah mightmax li)

Alternator = Balmar 200a with k5 belt.

Works great. Lots of power!

 

[goldenstate]

I did this! You'll need a dc to dc charger and you will have to keep a conventional battery in between the alternator and the charger to keep the alternator happy. Now when I say conventional I mean in battery type not size. Its really in place as a capacitor with resistance. I used the battery out of my 2010 Harley Road Glide. Lol

In short. Alternator-HD batt-renogy 60a charger-batt switch common + starter - bank1 2 (100ah mighty Max li) bank2 2(100ah mightmax li)

Alternator = Balmar 200a with k5 belt.

Works great. Lots of power!

So the lead acid starter battery is relatively small in physical size, yes?

 

[Stuphoto]

David,

If you have a chance to snap a photo of your system I am sure we would all love to see it.

It's an upgrade I would love to work on soon, especially if I don't need to replace my lead acid battery right away.
It's only a few months old.

Personally I like the fact that we can expand the DC electrical systems a little at a time rather than dumping in thousands at once like with a new motor.

 

[David Grimm]

So the lead acid starter battery is relatively small in physical size, yes?

No, The small battery is only there to satisfy the alternator. The lithiums start the engine. They do it effortlessly!

 

[goldenstate]

No, The small battery is only there to satisfy the alternator. The lithiums start the engine. They do it effortlessly!

Do you know how many amps the lead acid battery permits to flow through the DC charger to the lithium?

As in, do you have long charge cycles if you are only allowing a small number of amps to flow through the lead acid battery to the charger?

 

[David Grimm]

Do you know how many amps the lead acid battery permits to flow through the DC charger to the lithium?

As in, do you have long charge cycles if you are only allowing a small number of amps to flow through the lead acid battery to the charger?

The conventional battery is in parallel with the input of the charger and the alternator. Meaning the current from the alternator flows around the battery not through. For example I drain bank 1 down to 85% I turn on the charger, set my 30/60 switch to 60 amps and with my Fluke dc clamp meter I read 59.9 amps going into bank one!

Now say your sailing all day and night and Bank 1 is pretty low. Like 10%. No worries. Switch to bank 2 and start the motor. Say bank 2 is at 80%. You're headed into a tough marina to dock for the night. Save your engine power and keep the dc-dc charger off. The alternator will happily keep the conventional battery at float. No load on the belt giving you all the engine power to dock. Uses shore power to charge. Or charge the next day when your motoring up the river against the wind lol. At 30 amps.

If you want a quick charge while sailing, pop her out of reverse and set it to 60 and take the battery bank up to 95. In an hour or so.

 

[David Grimm]

I made this video a while back. Youtube kept giving me problems. Got it tonight!

 

[David Grimm]

One thing about my system you have to be aware of because it could be dangerous. If you were to drain one bank of batteries down low and then switched the battery selector switch to (All), the current would run unrestricted from the charged bank to the uncharged bank. This could heat up your wires or cause a fire. You would probably be better not having the (All) setting. I have seen switches that way.

The more conventional way of doing this is having a conventional battery as your start batt. This wasn't for me because if that conventional batt went bad you would have no way to get the lithium power to the starter without a wrench!

 

[Shawn Rodel]

Hi and thanks for the good information, one question what if there are two alternators, one for the house and one for starting. The house is a high output with the smaller for charging the starting battery. There are 2 banks on the house 4 flooded batteries total and as previously stated 1 starting. I can charge all batteries with the battery switch set at the all position or select 1 or 2 depending on what bank is in need of a charge. Hear is the question, run the starting battery small alternator to a separate switch, off or on. Install a battery switch with 1 / 2 and off for the high output alternator keeping the system as you have set up unchanged. Wouldn't this eliminate the risk of current running unrestricted from the charged bank to the uncharged bank and utilize the second alternator. The starting battery would still be flooded or AGM with the house batteries as Lithium. I do like your system and have the similar boat 1988 38-200

 

[David Grimm]

Hi and thanks for the good information, one question what if there are two alternators, one for the house and one for starting. The house is a high output with the smaller for charging the starting battery. There are 2 banks on the house 4 flooded batteries total and as previously stated 1 starting. I can charge all batteries with the battery switch set at the all position or select 1 or 2 depending on what bank is in need of a charge. Hear is the question, run the starting battery small alternator to a separate switch, off or on. Install a battery switch with 1 / 2 and off for the high output alternator keeping the system as you have set up unchanged. Wouldn't this eliminate the risk of current running unrestricted from the charged bank to the uncharged bank and utilize the second alternator. The starting battery would still be flooded or AGM with the house batteries as Lithium. I do like your system and have the similar boat 1988 38-200

You state flooded as house bank or is it lithium? Two alternators would be a serious challenge to fit in our engine compartment!

My high amp Balmar with the mc614 regulator set to lithium hooked to two 100ah lith batts it overheats in seconds. Can't do it.

There is a more expensive rout to take using a Victron battery and an battery isolator. Still uses a conventional start batt. It automatically detects start batt voltage and won't charge the lithium house bank until the start batt hits its charge. It monitors the house bank bms as well. Its a way more expensive solution eliminating the battery switch altogether. Probably what you would find on a new boat today.

Downfall of this system is if the start batt fails, looses a cell or something you will be getting out some tools to start the boat off the house bank.


See in my system. The Balmar 614 is set to agm. Thats what the harley battery is. The mc614 monitors that battery for temp and voltage and switches to float soon after the engine is started. When I turn on the dc-dc charger its like turning the headlights on in your car. The mc614 sees the draw of current and ramps the power up out of the alternator.

When you stop the engine and the dc-dc charger is left on it will continue to pull from the Harley batt if you forget to shut the ignition off. Thats why I put a buzzer off the oil pressure switch. Engin stops buzzer starts and I remember to shut the ignition!

 

[David Grimm]

This chicken scratch diagram may help some understand.

 

[Shawn Rodel]

Sorry if I was not clear the engine has two alternators now 1 high output balmar and 1 standard alternator. My batteries at present are all flooded 4 house 1 starter. I understand what you have done and thought since I have two alternators why not dedicate the standard alternator for the starting battery [ AGM ] with a switch for on and off. Then add 4 lithium house batteries in the same configuration you have and add the dc to dc charger with a new battery switcher for bank 1 and bank 2 and no [ all ]

 

[David Grimm]

That would work great! And two alternators is good fail safe.

 

[Nick J]

After rewiring my distribution panel, the battery replacement project is next. I'm planning on going lithium with a DC to DC charger as well. I'll essentially be keeping the same start battery configuration with the stock dumb Hitachi alternator and 20 amp ProNautic charger. From there I'll add a 50 amp Renogy DC to DC charger with NPPT and a DIY 280 ah LiFEPO4 battery. Additional changes will be a 3 switch battery panel so I can switch the banks independently while still keeping the ability to combine if necessary and a 1000w inverter wired to the house outlets. Here's the design so far:



I have the battery built and the basics mocked up on my work bench with a charger acting as the start battery and a bench top power supply acting like the solar panels. It's working out really well, now I just have to find the time to install it on the boat....

Here's a link to some pics of the project so far:

Do you manage/switch house vs. starter batteries?

Did the PO also install an upgraded alternator with regulator? Alternator is 50A. Based on your earlier post, that should be a good deal bigger?

ericsonyachts.org

 

[jrlago55]

I'm planning to upgrade my battery banks in the near future. Lithium seems to be an obvious choice for low lifetime cost, fast charging, and light weight.

Here is an example that appeals:

Amazon.com

Some counter-arguments:
1. Lithium has a higher absolute purchase price cost than lead acid. (Yes, but prices are coming down all the time. $190 for an AGM 100Ah battery vs $325 for the Lithium one).

2. You'll set your boat on fire. (No, the current drop-in LifePo batteries all have integral Battery Management Systems that prevent this sort of thing).

3. You'll burn out your alternator. This seems to be a reasonable concern. The Lithium batteries will accept a lot of amperage, so without some metering function, an alternator can be burned up by the excessive draw that a Lithium battery can accept.

One answer that seems widely adopted is to use a DC-DC charger. Your alternator charges your Lead-Acid high High-Cold-Cranking-Amps starter battery, and then that starter battery is linked to your Lithium bank via a DC-DC Charger:

Amazon.com

So the alternator is governed by the amount of amperage the lead acid battery will accept, which is the normal expectation for the alternator

Has anyone been down this path (using a DC-DC charger and a lithium bank of house batteries)?
I googled EYO forum topics and did not find much about DC DC chargers.

I know another choice is to buy a bigger, fancier externally regulated alternator (@$1,200 vs. $200 for the DC-DC charger).
I don't know much about the benefits of having a big alternator vs. simply having a DC DC charger to throttle the re-charging of the Lithium.
I suppose one tradeoff would be a longer recharging cycle?

Thanks for any ideas.

Hello, Let me first say that I build my system to sustain my autopilot, nab lights and radio 24/7 while underway. Also, I will be relocating my boat to PR so I do not need zero degree disconnect. With this I installed a Renogy DCC50S box with 4 flexible solar panels and a 200ah ampere time battery. Even though outside of my requirement, I added a Renogy 2000W inverter which I connected with a manual transfer switch to the AC panel. My experience is that it works better than expected to the point that I’m no longer electrically tendered to the pier. Hope this helps

 

[Nick J]

Hello, Let me first say that I build my system to sustain my autopilot, nab lights and radio 24/7 while underway. Also, I will be relocating my boat to PR so I do not need zero degree disconnect. With this I installed a Renogy DCC50S box with 4 flexible solar panels and a 200ah ampere time battery. Even though outside of my requirement, I added a Renogy 2000W inverter which I connected with a manual transfer switch to the AC panel. My experience is that it works better than expected to the point that I’m no longer electrically tendered to the pier. Hope this helps

That sounds really close to what I'm doing. Do you ever trip with over current protection in your BMS with the 2000W inverter? I was worried about that, so I went with a smaller inverter. I'm sizing all of the cables and breakers to handle more if I change out the battery or add a second one to split the load. What solar panels did you go with?

 

[jrlago55]

No, but I have a double fuse (blue seas) on my battery terminal; one for the charging system which I use 130 amp and a 200 amp for the inverter. Also, all the 4 awful wires coming in have 75 amp breaker on them. Finally the batteries both house and starter and the solar panel all have disconnects switches.

 

[jrlago55]

I meat 4 awg wires not awful. Darn iPhone….