New converter/charger if I use lithium?

[Mx468]

Do I need to change out my converter/charger to a lithium battery compatible one even if I have solar panels and a Victron 30 mppt controller? Also if I do change to a new converter can I go bigger than 30 amps which my vintage airstream came with? Is that a hazard? I installed a progressive smart charger 30 to replace my old univolt.

[dieseleagle]

The answer is probably yes. A regular converter/charger, even a smart one, bulk charges at 13.6v. The lithium batteries want to be charged at a constant 14.4v. The battery management system internal to the batteries does the smart stuff rather than relying on the charger. Given the high cost of the lithium batteries giving them maximum TLC is probably what you want. The difference in the maximum charge is significant to the cycle life of the batteries. Having said all that, the solar panels get the job done the vast majority of the time and don't need an additional boost from the shore power charger. The 13.6v from a regular charger will get you through an occasional period of low sunlight and won't harm the lithium batteries too much. (Emphasis on occasional). Still, after spending several thousand dollars on solar and lithium its a good idea to complete the system properly. A lithium charger is less than $200.00 with shipping and will extend the life of your investment.

[Mx468]

Originally Posted by dieseleagle

The answer is probably yes. A regular converter/charger, even a smart one, bulk charges at 13.6v. The lithium batteries want to be charged at a constant 14.4v. The battery management system internal to the batteries does the smart stuff rather than relying on the charger. Given the high cost of the lithium batteries giving them maximum TLC is probably what you want. The difference in the maximum charge is significant to the cycle life of the batteries. Having said all that, the solar panels get the job done the vast majority of the time and don't need an additional boost from the shore power charger. The 13.6v from a regular charger will get you through an occasional period of low sunlight and won't harm the lithium batteries too much. (Emphasis on occasional). Still, after spending several thousand dollars on solar and lithium its a good idea to complete the system properly. A lithium charger is less than $200.00 with shipping and will extend the life of your investment.

Yeah I plan on switching the converter out, do you think it’ll be ok to use a higher amp converter/charger? My 72 airstream used a 30amp converter, can I go up to a 45amp, 60? Does the higher amp chargers charge the batteries more efficiently or does size matter? The line I have running from my current converter charger to the batteries is 6awg. Thanks

[waninae39]

we move to Battle Born Lion battery
we moved them inside

we use this model. MultiPlus 3k VA
https://www.victronenergy.com/invert...48v-800va-3kva

plus we have salor MMPT

[rwnash]

Do some investigation regarding lithium batteries. I don't know about them, but lead acid batteries like slow discharges and slow charging. I changed to a smaller 30 amp converter when I replaced mine years ago. But, I don't use a great deal of electrical energy and don't have an inverter. 30 amps overnight is more than I need to recharge 2 batteries.

Whit Nash

[Mx468]

Originally Posted by rwnash

Do some investigation regarding lithium batteries. I don't know about them, but lead acid batteries like slow discharges and slow charging. I changed to a smaller 30 amp converter when I replaced mine years ago. But, I don't use a great deal of electrical energy and don't have an inverter. 30 amps overnight is more than I need to recharge 2 batteries.

Whit Nash

Yeah I have a separate 2000 pure sine inverter, which I use for a microwave, tv, and a coffee maker when I’m not connected to shore power. My airstream uses 30 amps but I did switch it out to a 60amp progressive charger/converter which seem to work great with my current battery configuration and dc electronics. Just didn’t know higher amps in a converter is better with lithium’s? I thought I read somewhere that with a higher amp converter/charger it will charge the lithium batteries quicker and more efficiently.

[uncle_bob]

Hi

Lithium's will accept a *lot* of charge current. A pair of 100AH BB's can be charged at a 200A level and still run for a very long time (>3000 discharge to zero cycles and > 80% capacity). Charging the same pair at 50A will get them to last for about 2X that.

If you decide to go with 200A charge current, you will need some hearty cable to handle that. You also will be putting around 25A at 120V into the converter / charger. Indeed you will be able to re-charge completely dead batteries in just over an hour.

That example assumes two batteries. If you are going to more than that (I have 4 in this trailer) then the numbers all scale accordingly.

Ideally (there are *long* threads here about this) you want to run up to about 14.4V with the charger and then cut back to about 13.5 or 13.6V. A programable charger (which your Victron solar MPPT is) will be happy doing this. There are not a lot of low cost converter / chargers out there that can be programmed to work this way. A Victron inverter charger is a common "solution" to the problem.

One other reason to prefer a programable device - we all may find out three years from now that the voltages need a tweak. There is no way to predict the future so who knows ....

Bob