Is it possible to limit the charge to the lithium batteries?

[hawk232]

I have read through the Kisae Abso manual and nothing stands out. Is it possible to limit the charge (to 70-80%)? When storing the boat I would like to keep my engine and thruster AGMs topped off (like they like) while limiting my lithium to a lower SOC (like they like). Right now i occasionally go turn on the charger then once its done, run the water heater to deplete the lithium bank some. I am hoping for a more automated solution.

 

[hawk232]

With no responses, im guessing its not possible. So does everyone with lithium just let them charge (and stay) at 100% SOC?

 

[Bruce]

I had asked Dakota that question. They said it does not hurt their lithium batteries to stay at 100% SOC. I asked if it hurt to plug in to shore power each night as if staying at a marina? They said that it is fine. My question is what should the voltage be at 100% SOC? Mine reaches 100% at 13.7. I shut off the charger at 100% for fear of overcharging. I have asked Dakota what it should be but have not heard back yet.

 

[Levitation]

Most of the large LFP batteries (roughly anything bigger than 18 AH) have built in charge controllers. Give them a 14-15 volt source and let the controller run the railroad. If your large LFP battery does not have a controller then follow the manufacturers advice.
If you wish to store the battery at 80% SOC then pull 20% off a charged battery and call it good.

 

[freedomvango]

Unless you are storing for long periods, its not really an issue

 

[hawk232]

Most of the large LFP batteries (roughly anything bigger than 18 AH) have built in charge controllers. Give them a 14-15 volt source and let the controller run the railroad. If your large LFP battery does not have a controller then follow the manufacturers advice.
If you wish to store the battery at 80% SOC then pull 20% off a charged battery and call it good.

This is what i was doing, but its pretty hands on. I want the engine and thruster battery at 100% (they are AGM) and the lithium at 80 or so. The charger charges the lithium bank before moving on to the engine/thruster batteries, so i HAVE to charge the lithium to 100 in order to charge the engine/thruster batteries. i have been turning on the water heater afterwards to draw them down but it seems like such a waste.... and time consuming!

 

[hawk232]

Unless you are storing for long periods, its not really an issue

what counts as "long periods"? it may be a couple of weeks at a time that I am away from the boat.

 

[freedomvango]

what counts as "long periods"? it may be a couple of weeks at a time that I am away from the boat.

months more often than not.

Your battery manual spec sheet will be more specific. But its really a thing for the 4+ month situation

I have 1200w of solar on 630ah of lithium and its almost always at 100%. If I'm not going to use the van or boat for a few months, ill discharge to 80% and turn the solar controller off (i use all victron so its easy to do in the app)

 

[hawk232]

Good to know, thanks! I guess I am just overthinking it.