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jko avatar image
jko asked

How to charge a lithium-only system with an alternator?

Project:

Replace lead acid batteries (3*180 ah) in the 12V house bank in my boat with lithium battery (1*300ah). Note: intention is to remove the lead acid batteries completely from the house bank.


Challenge:

How to charge a lithium-only house bank with an alternator?


House battery bank @ 12V:

Currently 12V house bank with lead acid batteries (3*180 ah) charged with Victron EasySolar 12/1600 charger (300W solar panels and shore power) and dedicated alternator. Alternator is from 1990's (nothing smart in this either).

Lead acid batteries to be replaced with single 300ah lithium battery. Battery charged with the Victron EasySolar 12/1600 charger (300W solar panels and shore power) and possibly with the alternator (based on advice).

House bank is used to power inverter (EasySolar 12/1600), bow thruster (thruster specifications 12V, max 350A, measured ~230A) and other house loads such as lighting, fridge etc.


Starter battery bank @ 24V (separate from the house bank):

24V Starter battery bank (2 * 180 ah, 12V lead acid batteries), charged with it's own 24V alternator and a shore power charger (24V/5A). Alternator is from 1990's (nothing smart in this).

Starter bank is used for engine start and 24V stern thruster.

Option 1:

Can the lithium battery be charged by placing a Victron Orion-Tr Smart 12/12V 30A DC-DC charger between the existing 12V alternator and the lithium battery (without lead acid battery in the circuitry)?

Note: intention is to remove the lead acid batteries completely from the house bank circuitry.


Option 2:

Disable the 12V alternator by removing the belt and disconnect it from the 12V system. Use the 24V starter bank as mediator between the engine charging by using Victron Orion-Tr Smart 24/12V 30A DC-DC charger (using the 24V alternator as charging source and starter bank lead acid batteries as buffer).


Option 3:

Keep single lead acid battery between alternator and DC-DC charger (typical setup seen in the Victron diagrams). This of not preferred due to space constraints and the wish to keep the house bank clean and simple.


Option 4:

Disable the 12V alternator by removing the belt and disconnect it from the 12V system and relying only to shore power and solar charging. This would simplify the system, but far from optimal especially considering unpredictability of solar power.


Are there other options?

What is the recommended approach/solution? Any diagrams available for reference? Anything else to consider especially if several approaches are equally good from technical perspective?


UPDATE

Project has progressed with installation of the lithium bank and Orion DC-DC charger. However I'm having a problem.

To summarise, the setup consists of an engine alternator (old style without any intelligence) which is connected directly to Orion DC-DC charger (isolated, 12 | 12, 30A) which in turn charges lithium battery bank (2 * 200 ah batteries). This setup was in advance verified from Victron by the local reseller/distributor.

Alternator is Bosch K1 14V, 55A 20 (original for the Volvo engine).

There is a problem where the input voltage from the alternator to the Orion fluctuates from ~9V to ~36V causing the Orion to intermittently go offline ("charge is disabled due to: Input voltage lock-out"). This happens regardless of the state of charge of the lithium batteries.

Is it possible that the fluctuating voltage is caused by insufficient resistance from the Orion DC-DC charger or is there something else that may explain such a phenomena?

Is it possible that the alternator is faulty, or is such a fluctuating voltage a common issue under some specific circumstances?

Any idea how to rectify this? Do I need to replace alternator and/or place a led acid or agm battery in between the alternator and the Orion (exactly the scenario I was hoping to avoid)? If an intermediary battery is required, what would be the recommended chemistry and size? Needless to say that I'd prefer small, lightweight and affordable solution...

battery chargingLithium Batteryalternator
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jko avatar image jko commented ·

Project has progressed with installation of the lithium bank and Orion DC-DC charger. However I'm having a problem.

To summarise, the setup consists of an engine alternator (old style without any intelligence) which is connected directly to Orion DC-DC charger (isolated, 12 | 12, 30A) which in turn charges lithium battery bank (2 * 200 ah batteries). This setup was in advance verified from Victron by the local reseller/distributor.

Alternator is Bosch K1 14V, 55A 20 (original for the Volvo engine).

There is a problem where the input voltage from the alternator to the Orion fluctuates from ~9V to ~36V causing the Orion to intermittently go offline ("charge is disabled due to: Input voltage lock-out"). This happens regardless of the state of charge of the lithium batteries.

Is it possible that the fluctuating voltage is caused by insufficient resistance from the Orion DC-DC charger or is there something else that may explain such a phenomena?

Is it possible that the alternator is faulty, or is such a fluctuating voltage a common issue under some specific circumstances?

Any idea how to rectify this? Do I need to replace alternator and/or place a led acid or agm battery in between the alternator and the Orion (exactly the scenario I was hoping to avoid)? If an intermediary battery is required, what would be the recommended chemistry and size? Needless to say that I'd prefer small, lightweight and affordable solution...

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3 Answers
kevgermany avatar image
kevgermany answered ·

Either 1 or 2 would be good. Personally I'd retain the 12V alternator. What amp capacity is the 12V alternator? If it's big enough, say over 100A, you could fit 2 Orions in parallel for faster charging. But don't overdo it.

One thing struck me. Is the bow thruster draw ok for your proposed battery?

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jko avatar image jko commented ·

The battery specs allow max discharge current at 200A with short peaks up to 400A (5s).

Discharge over current 1 protection 230±10A， delay time 25±5 S

Discharge over current 2 protection 400±20A，delay time 3±1.0s

----

Another option is to have 2 * 200ah lithium batteries. Those have over discharging current 205A~305A Delay 10S.


I was leaning towards the single battery solution for the sake of simplicity, but I'm torn if the extra capacity and redundancy would actually make it sensible to go for the dual battery solution. I'd very much appreciate good insight on this too.

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djsmiley avatar image djsmiley jko commented ·
Instead of the Orion, if the 12V alternator is a dedicated one, consider a alternator regulator like eg a Wakespeed 500. That allows you to maximize the charge from the alternator instead of only 30A from the Orion.

For the bow thrusters: those require massive amps, so you most likely need multiple batteries in parallel to get the required current. Most batteries are limited to 150-200A max, so you need at least 2 in parallel.


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kevgermany avatar image kevgermany ♦♦ jko commented ·
Yes, bigger batteries. You're on the limit already. If you like the Wakespeed idea, look in detail, I don't know if it is a charger or just a power source.
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jko avatar image
jko answered ·

First of all - I'm extremely thankful that both of you have taken time to give your thoughts and advice. This is very valuable to me!

If I understand correctly, I should rather go for a 2 * 200ah battery instead of the single 300 ah. This will help sustaining the large current draw by the thruster. Is that correct?

This is the 200ah battery which my local provider can offer:

https://www.suomenakut.fi/storage/product_files/0/78350-LFP12.8V200AhBatteryDataSheet_edb93ac9bef4a237b10bc88cd8e627e8.pdf


If you have time to have a glance and give your thoughts I'd really appreciate that before I'll make the purchase.


I'll look into to Wakespeed coming days to see if I can figure it out and if I can find a dealer shipping to my location. If you have some good sources for installation guidelines, diagrams etc. I'd very much appreciate tips.

Thanks again for all the help!



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kevgermany avatar image kevgermany ♦♦ commented ·
Battery looks good. When I saw the .fi link, I thought about lack of winter protection, but seems it has a built in heater.

Check charging. If the charger sees winter temperatures and doesn't recognised the battery temp, you will have no charge, even with a warm battery.


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jko avatar image jko kevgermany ♦♦ commented ·

My understanding is that the Victron system I recently installed has ability to measure the battery temperature (EasySolar 1600, Cerbo GX, battery protect and smart shunt).


Not sure though if the external sensor provides sufficient temperature reading to determine the battery core temperature to allow cold weather charging...

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hjohnson avatar image
hjohnson answered ·

Your other option is to modify your alternator for external regulation, and get yourself an advanced regulator such as the Wakespeed WS500. That's what I have on my boat.

The alternator directly charges my LiFePO4 battery bank. The WS500 gets its directions from my BMS (I have a DIY battery bank, controlled by a REC ABMS). But it will also work with Victron batteries (controlled by a Lynx BMS) and/or several other BMSs.

It really works well.

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jko avatar image jko commented ·
Do you have suggestions regarding what kind of alternator would work here? Which model you have used with the Wakespeed?

Is it right to assume that Wakespeed won't do the trick with my alternator from 1990's (basic one that has been shipped with the old Volvo truck engine)?

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