Charging Lithium with 2018 Micro Minnie 2108DS

[KeithB]

I have a 2018 2108DS travel trailer. My question; when charging a lithium battery with my current controller, as I understand it will not do a full charge; 13.6 as oppossed to 14.4 needed for lithium?? if so, can I do a full charge lithium with my HQST MPPT 20 amp solar controller? In other words, when plugged in to 30 amp service, can I combine my solar charge at the same time to get the full charge? Over time I plan to upgrade my camper controller but would like to spread out the cost of converting to lithium.

[Marine359]

Your current controller will charge a lithium. Albeit, it will take a l-o-n-g time. Your charger is a 3 stage charger: bulk/absorption/float. Lithiums do not have an absorption stage, so the charge they receive during charger absorption phase will not be above 14v. I dunno for sure, but likely it will stay near 13.6v and continue charging. If the lithium is already at 13.6v, not much will be added to the battery. A solar controller will ad amps to the battery as long as the array voltage is 5v higher than the battery voltage. So, a 20v nominal array should charge a LFP until it’s near 100% SOC. If the array voltage drops below 18v, it may not help much with charging when battery voltage exceeds 13.6v. What really works good for topping off is a NOCO Genius. It’s programmable. 10 amps, so it’s not real fast, but will top off where your OEM charger leaves off. Leave it on overnight, and when you wake, you’ll be topped off. Before I got a 80 amp charger, the NOCO worked great. I did disconnect battery terminals from mains while using the NOCO.

[creativepart]

Keith... Your Travel trailer has a Converter that charges your battery when on shore power AND it has a Solar Charge Controller to manage battery charging from your rooftop solar panels. It's important to keep those two things separate - one is a Converter and the other a Controller.

So, reading your post I think you mean that your TT's OEM "Converter" (not controller) cannot fully charge your new Lithium batteries because it's not LFP capable. And you are asking if your solar charge controller can complete the charging when used in conjunction with your Converter.

Sort of, yes but that's really not a great way to treat your LFP batteries. You'll basically be under charging those batteries all the time.

You need to upgrade your TT's "Converter" (again, not your controller) to one that is compatible with charging LFP batteries so that that expensive new battery gets the charging profile it needs for long life.

[KeithB]

Originally Posted by creativepart

So, reading your post I think you mean that your TT's OEM "Converter" (not controller) cannot fully charge your new Lithium batteries because it's not LFP capable. And you are asking if your solar charge controller can complete the charging when used in conjunction with your Converter..

Yes, wrong terminology. You are correct in assuming my question. We plug in when camping 100% but I would like extra amp hours lithium would give me should we need a Walmart parking lot stop for a night. With lithium prices now down where the “commoner” can afford them, I figure this is the way to go. I’d like to wait until summer to upgrade the converter to spread out cost. I may just need to wait till summer to do it right. Thanks for your thoughts!

[creativepart]

Will you be using your TT between now and Summer? If not it shouldn't matter. If you will be using it a lot then maybe consider an external AC powered lithium compatible charger to augment your Converter. You can pick one up for about $50. So, when camping with shore power you can fully maintain your LFP battery.

But, changing out your current Converter to a lithium version is only $225 so, perhaps buying an external charger isn't very much of a savings.

https://www.amazon.com/lifepo4-charg.../dp/B09CGYLD8Z

[KeithB]

Planning 3-4 outings this winter/spring. May just go for the upgrade now. Probably dumb question, but…I have a 1amp charger with lithium option I use to trickle charge motorcycle, mower batteries in the winter. Would that get me by? Would be too slow of charge ??

[creativepart]

I dunno, maybe. Sounds like a maintainer for a charged battery more than a device to fully charge your chronically undercharged battery.

This is all just my opinion. It's likely not ideal to do as you are doing, but not the end of the world either. It's just not the way I would do things. But, you do you.

[Marine359]

This is the Noco Genius. It’s what we used when we were in your position (before upgrading our charger). We still use it to keep our lawn tractor up to snuff in winter. 10 amp programmable for LiFePo4. It will add 100ah to your battery overnight, and unlike your stock charger, it will charge the battery completely. Good value for $99.

NOCO GENIUS10, 10A Smart Car Battery Charger, 6V and 12V Automotive Charger, Battery Maintainer, Trickle Charger, Float Charger and Desulfator for Motorcycle, ATV, Lithium and Deep Cycle Batteries https://a.co/d/aLakm0k

[KeithB]

Originally Posted by Marine359

This is the Noco Genius. It’s what we used when we were in your position (before upgrading our charger). We still use it to keep our lawn tractor up to snuff in winter. 10 amp programmable for LiFePo4. It will add 100ah to your battery overnight, and unlike your stock charger, it will charge the battery completely.

Thanks for the tip! Would I need to unhook the battery cabling from the trailer before connecting the charger?

[Marine359]

Yes, you need to unhook battery cables when using the NOCO
To make it easy, put a set of Anderson style quick disconnects between battery and bus. Then just pull the plug when using the NOCO. It has alligator clips..

RVBOATPAT 350 Amp Battery Quick Connect Connector, 12V Towing Winch Quick Connect Wire Harness Plug Connector Kit - 2 Pack https://a.co/d/gneFC3s