Lithium batteries

I’ve got a 25A Redarc DC-DC charger in my camper, and I really like it. It has dual inputs, so it can connect to the truck battery and your solar panels, and will prioritize using solar whenever available. It supports lead acid, gel, AGM, and lithium. I currently have a single group 31 AGM battery, but anticipate that someday Li will hit a price point that’s attractive to me.

It also has one benefit that I wasn’t anticipating before installing it, but have come to appreciate. If you have a 3-way fridge in your camper, the DC mode will work noticeably better due to the voltage being maintained about 2.5 volts higher than than it would be with no DC-DC charger.

I like mine enough that I recently noticed that Redarc now has 40 and 50 amp dual input DC-DC chargers, and I will be upgrading mine to a 40 amp.

:):)

pianotuna wrote:

Nope.lifepo4 don't like to be charged to 100% at least for storage--which is where most RV's are.

It is academic for me--as I need -40 temperature tolerance and only one LI chemistry that can do that. So I'll be going SiO2

-30-

Another link

Nothing about it being "bad", they just might last a bit longer. "Bad" is storing a battery with zero charge as that will damage the battery.

Most RV's have parasitic loads that are constantly drawing power even while in storage. While my camper sits in the driveway each day the solar panels will give it a charge and each night the loads will suck some energy out.

Back on topic: some users will employ a DC-DC supply on their truck charge line to step up the voltage to at least 13.6V or 14.2V-14.6V so that their LiFePo4 battery can be charged while driving.


- Mark0.

https://www.power-sonic.com/blog/how-to-charge-lithium-iron-phosphate-lifepo4-batteries/

Mork0,

Nope.lifepo4 don't like to be charged to 100% at least for storage--which is where most RV's are.

It is academic for me--as I need -40 temperature tolerance and only one LI chemistry that can do that. So I'll be going SiO2

-30-

pianotuna wrote:

mbloof wrote:

pianotuna wrote:
Since Li don't want to be taken to 100% I can't see why a dc to DC booster would be particularly useful.

Since when? Can you quote a source for that information?

The Battleborn battery I own and even the DIY LiFePo4 cells I bought along a with proper BMS have no issue with being charged to 100%.

- Mark0.

Many many many sources.

Some BMS systems have the 90% set to read as fully charged. Battleborn might be one of them.

The ideal is 40% to 90% for most Li chemistries.

They tolerate 20% state of charge well. But lifespan may be shorter.

Here is a source that suggest maximum of 80% SOC:

https://electrek.co/2018/05/04/are-you-killing-your-lithium-batteries/

Keep in mind that there are different Li chemistries and what might be recommended (via the link you provided) for other types does not apply to LiFePo4 batteries.

While LiFePo4 cells have a peek voltage of 3.65V (14.6V for a 4S pack) they can be safely charged to %100 with that voltage without degration. (this is also what BattleBorn recommends (14.2-14.6V).

They do however recommend 50A or less charge rate for a 100AH battery otherwise degration will occur.


- Mark0.

Thanks I think I will just rely on 510 watts of solar

mbloof wrote:

pianotuna wrote:
Since Li don't want to be taken to 100% I can't see why a dc to DC booster would be particularly useful.

Since when? Can you quote a source for that information?

The Battleborn battery I own and even the DIY LiFePo4 cells I bought along a with proper BMS have no issue with being charged to 100%.

- Mark0.

Many many many sources.

Some BMS systems have the 90% set to read as fully charged. Battleborn might be one of them.

The ideal is 40% to 90% for most Li chemistries.

They tolerate 20% state of charge well. But lifespan may be shorter.

Here is a source that suggest maximum of 80% SOC:

https://electrek.co/2018/05/04/are-you-killing-your-lithium-batteries/

pianotuna wrote:
Since Li don't want to be taken to 100% I can't see why a dc to DC booster would be particularly useful.

Since when? Can you quote a source for that information?

The Battleborn battery I own and even the DIY LiFePo4 cells I bought along a with proper BMS have no issue with being charged to 100%.

- Mark0.

Since Li don't want to be taken to 100% I can't see why a dc to DC booster would be particularly useful.

My "skinny" OEM wire is #8--perfectly capable of carrying 40 amps. It is not the wire that is the problem, it is the ECM of the chassis.

Are the battery management systems able to be set to stop charging at 90% state of charge?

We have 400Ah of lithiums and 640W solar on the roof. Plenty of juice and plenty of charging. We have no need to charge by truck which is measly anyway with the skinny wires and not even worth hassling with.

My Battleborn LiFePo4 battery is mostly charged by 136W of Solar and MPPT Li compatible charge controller.

I did not bother to upgrade or update the charging from the truck. My use needs don't need it.

When in a pinch, I have a 1000W Yamaha generator and can use the stock AC/DC converter to charge the battery. Granted it won't charge it fully or 'optimum', again, my use case(s) don't require or need that.

For those that travel a lot and go from place to place and only stay 1 night at each place maybe better truck charging makes sense for them. Not needed for me.


- Mark0.