question

badrock avatar image
badrock asked

Lithium SuperPack drop-in replacement feasibility

Hi, I've been reading though all the posted questions but can't find a clear answer.

I'm considering replacing the current AGM house bank on my boat with SuperPack batteries, and I'm trying to understand what it would involve.

Below an attempt to visualize my current setup:

electrical.jpg


I understand that I'll have to replace the shore charger for a Lithium one, but beyond that, is there anything else I would have to replace/modify, or will the SmartPacks be a simple "drop-in" replacement?

My main doubt is:

Since the BMS is integrated, what will happen if the batteries are fully charged and the engine/alternator is running? Is there a risk the BMS will trigger the over-charge protection and disconnect all the loads (e.g. loosing plotter and instruments when approaching an anchorage/marina)


Any other suggestion/input is highly appreciated, like: does the Argo Fet still make sense with the SuperPack, or should I replace it with an Orion-Tr DC-DC charger? Do I need a separate external BMS to protect the batteries from overcharging?

Thank you!

Lithium Batterysystem designSuperPack
electrical.jpg (243.8 KiB)
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

3 Answers
bramdvries avatar image
bramdvries answered ·

What is the max. output A of your alternator? If greater or equal to 18, on of the Orion Smart series DC/DC converters could replace your argo fett

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Sarah avatar image
Sarah answered ·

@badrock provided the MPPTs and charger are configured correctly for lithium you should not have a situation with overcharging. For the alternator I would suggest leaving the Argofet in place and installing an additional Orion DC charger. The Argofet is a nice way to prevent unintended discharginging of the house battery (while there are multiple ways of doing this the Argofet has zero additional cost as it is already installed and requires no additional configuration) the Orion can be configured with a Lithium profile to allow for improved ‘regulation’ of the charging voltage while also limiting the load on the alternator. This last point depends a lot on the brand of your alternator and presence of any internal regulation - most of the time an Orion with half the rated output of the alternator is recommended to prevent any overloading.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

badrock avatar image
badrock answered ·

Thanks for the answers.. not really relevant since it's been almost 2 years :-).

For everyone one else following, my main question was around the behaviour of the BMS in case of overcharge. To be honest, there is no way around it, since the charge and load are on the same circuit, is the overcharge scenario triggers, you loose all the loads.

Adding a dc-dc charger with a lithium profile is one way of solving it, but to me it this solution looses the main advantage of lithium, like the fast charging rates, and degrades the battery life, since it will tend to keep the batteries at full charge.


My solution, which I implemented a couple of months after writing this, was to build my own battery out of 12 individual cells. I have my own BMS that controls two different circuits, one for all the loads and one for all the charging sources. It also sends a "fake" voltage to the alternator, in effect regulating it's output.

The result really works for me, but it's not a drop in replacement. There is no drop in without big compromises, and going for the 'proper' solution (regulated alternator/external BMS etc) easily doubles the price. With my current solution I got 90A from my 115 stock alternator, can control how much to charge the batteries (e.g. leave them at 70% charge when not using the boat) can control all the charging sources independently (e.g. motoring back there is no risk I loose the loads). Also, I'm currently working in being able to control everything via n2k and the plotter.

I'm a computer/electrical engineer, so to me it's doable, but it's absurd the solutions of the market at ~10x the price of a DYI.

Hope this helps someone :-)

Cheers


2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

Additional resources still need to be added for this topic

Additional resources still need to be added for this topic

Battery Compatibility

Did You Know - How to create a battery profile for non-Victron batteries?