Can my system support Lithium Batteries?

[paticus]

I recently bought a houseboat with Solar, and this is my first solar system. I need to replace the current batteries. They are 6 Trojan L16HAC (6v) batteries wired in 36v series.

I am thinking about going to 4 Lithium 36v 67ah batteries wired in parallel, so I can cut weight, and reduce trips to the boat for battery maintenance. Also provide flexibility to add more amp hours if needed.

I am trying to figure out if my current system will charge Lithium batteries.

Controller: Outback Flexmax FM60
Inverter/Charger: Xantrex Freedom Marine 30

Neither manual even mentions the word Lithium.

 

[MisterB1959]

My motorhome (RV) charger doesn't have a lithium profile so I use it in the Lead Acid profile and it works just fine. It doesn't top up fully to 100% but solar usually provides for the missing couple of percent.
Just fitted a Renogy DC to DC charger and that also seems to do the job!

 

[NVS]

Looking at your inverter/charger it is a 12vdc not 36vdc. So I would look at your batteries again. Connecting 36vdc to it will damage it. Common inverter voltages is 12v, 24v and 48vdc, I personally have not seen a 36vdc unit.

 

[12vDC]

Looking at your inverter/charger it is a 12vdc not 36vdc. So I would look at your batteries again. Connecting 36vdc to it will damage it. Common inverter voltages is 12v, 24v and 48vdc, I personally have not seen a 36vdc unit.

yes, that’s curious.
but in reading the OP it seems it’s already installed and functional with the inverter charger he listed and the 6V batteries he’s describing.

 

[12vDC]

I recently bought a houseboat with Solar, and this is my first solar system. I need to replace the current batteries. They are 6 Trojan L16HAC (6v) batteries wired in 36v series.

I am thinking about going to 4 Lithium 36v 67ah batteries wired in parallel, so I can cut weight, and reduce trips to the boat for battery maintenance. Also provide flexibility to add more amp hours if needed.

I am trying to figure out if my current system will charge Lithium batteries.

Controller: Outback Flexmax FM60
Inverter/Charger: Xantrex Freedom Marine 30

Neither manual even mentions the word Lithium.

for us non-houseboat people please explain the 36 V system and it’s necessity.

but maybe you have a series/parallel system for 12V instead? that is the more likely scenario given your inverter is only listed at 12 V in the manual you provided.

and if that is the case your inverter/ charger will work for lithium batteries, even though it does not contain a lithium profile. But if it has the TSC option, do not use it.

if your solar charge controller Does not have a lithium profile. I would say you can still use that as well.

in both cases, I would use the AGM profile.

 

[NVS]

The inverter also looks like it can operate at upto 15.5vdc. Lifepo4 batteries max voltage is 14.6 so you are good there.

You SCC looks like it is programable so you should be able to set the correct charge parameters for lifepo4 batteries. Your solar will top off the batteries so you wouldn't need to change your inverter/ charger. If your batteries also charge off the boat motor a DC-DC charger would be recommended. This will save your alternator from over heating.

 

[paticus]

Let me check the wiring on the batteries next weekend. They are definitely 6v batteries. I guess I just assumed they were all series since 6v wouldn’t make sense.

Is it common to do 3 banks of 6v + 6v series, in parallel?

 

[paticus]

BTW, no alternator hookup to the main system, there is a dedicated 12v starter battery for the engine.

 

[rodrick]

Let me check the wiring on the batteries next weekend. They are definitely 6v batteries. I guess I just assumed they were all series since 6v wouldn’t make sense.

Is it common to do 3 banks of 6v + 6v series, in parallel?

Yes 2s3p is a common setup, 36 volt in that application would be very unlikely

 

[mikefitz]

if my current system will charge Lithium batteries

Yes, however they will be set up for the Trojan so will need the charge profiles changing. With lithium you don't want temperature compensation or equilisation so disable these functions. The solar controller seems to be user programmable for all settings, the inverter charger need battery select, the wet cell setting at 14.4 volts charge, 13.5 float seems suitable, there is no auto equiljsation and temperature compensation is disabled by disconnection of the sensor.

3 banks of 6v + 6v series, in parallel?

Very common sail boats where weight is not an issue. Your batteries are 430Ah each so at 12v you have 1290 Ah and a total weight of 330 kg, 720 lbs.
With lead its common to limit used capacity to half total, thus the eqivilent lithium is around 700 Ah

no alternator hookup to the main system

Very unusal in a sailboat unless it is always in the marina with shore power.

Trojan L16HAC

These are expensive batteries and worth saving. If beyond useful life they still have scrap value, ( around $250)

 

[chrisski]

The best way is to use the voltages that @mikefitz says. If you can't program your SCC, choose a mode that does not equalize and is equal to or less than the voltage he lists. In my case, the charger I was using where I could not enter voltage was to set the charger to a gel setting.

 

[paticus]

Thank you everybody for the information so far! I can tell I am going to be a regular here..

Does my following battery logic make sense?

The current 6 Trojan L16HAC batteries are 435ah.
Each 6v + 6v pair produce 435ah x 3. The 3 parallel 12v banks have a total of 1305ah.

I am looking at 4x Big Battery OWL 12v 170ah units.

Those would produce 680ah in parallel at 12v. That is half of the amp hours of the Trojans, but the LiFePO4 should provide 2x capacity. So I should expect around 1360ah of "lead acid performance" with this configuration. Which aligns with my current configuration. And if I want, I can add 1-2 more batteries to this configuration in the future.

 

[chrisski]

Somewhat less than the max amp hours since the lead acid couldn't be fully charged. The math would be harder.

The Lead acid charge to a greater voltage than the lithium, so lead acid voltage could ruin the lithium batteries quickly. The Lithium lower voltage would cause a lead acid battery not to be charged enough. Also, no temp compensation in lithium.

There area a couple people on the forum who have successfully mixed lead acid and lihium batteries.

 

[NVS]

A lot of people have been using chins 280ah they are $649 there is also a $40 coupon on the listing, make sure to check the box. You can parallel upto 4 of them.

https://a.co/d/dmie48j