By Mike Sokol
Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM.
Dear Mike,
We really would like some more capacity for my RV while boondocking, especially to run my CPAP machine and residential refrigerator. But we keep getting conflicting reports about if we can simply swap in a Lithium battery to replace my current lead-acid batteries, or do we need to change out the charger/inverter as well. A local RV shop says you just stick in a Lithium battery and it will work just fine, but will that work? Do I really need to replace my perfectly good converter at the same time? That’s a lot more cost than we bargained for. —Connie and Jim
Dear Connie and Jim,
Lithium (actually Lithium Iron Phosphate) batteries are great, not only due to the reduced weight and increased number of charge/discharge cycles. But you get a lot more percentage of power out of this technology compared to lead-acid, allowing you to discharge them down to 20% or even 0% of their rated capacity without harming their life.
So while a 100-Ah lead-acid battery should only be discharged down to 50% of its rated capacity to keep from shortening its life (that would be around 600 watt-hours of power from a 100-Ah battery), a 100-Ah Lithium battery can provide 960 watt-hours (discharging to 20% of capacity) to 1,200 watt-hours (discharging to 0% is allowable with some Lithium Batteries) of power from the same size battery. Pretty incredible, but at a higher initial cost. When comparing costs of the lead-acid batteries to lithium iron phosphate batteries, the cost per kilowatt hour for a lithium iron phosphate battery over its lifetime is lower when compared to lead-acid chemistries even when the cost of potential chargers or other components are included. The lower long term ownership costs and increased power of having a lithium iron phosphate battery is one reason why many RVers are switching to lithium iron batteries.
And that cost is what?
Well, Lithium batteries are pretty picky about two important things: (1) They don’t behave well if you try to charge them at a low temperature; and (2) They don’t charge well from a standard converter/charger that’s only rated for flooded cell or AGM lead batteries. The first part is easy since many Lithium batteries have built in heaters or a heating blanket wrap that warms them up before they’ll accept a charge. But the second part is a bit more tricky (read – expensive), since most converter/inverter chargers that were installed in your RV beyond the last 5 years do not have a lithium battery charging setting.
Is that bad?
While you may not notice it at first, charging a Lithium Battery from a converter set for Lead or AGM batteries will ruin the battery prematurely. So instead of the 2,000 charging cycles and 10-year service life of that expensive battery, you can lose half (or more) of its life because one can actually damage the battery by using the wrong charger. And that means you could be replacing it again in a few short years, rather than getting the full service life you paid for. Doing so is just throwing your money away, and nobody likes to do that. The known exception to this is Progressive Dynamics, Inc.’s (PDI) converter charger. Their lead acid converter chargers will not damage lithium-iron phosphate batteries.
According to Progressive Dynamics (a long established manufacturer of converter charges for RVs and boats), charging times can also be affected. When a lead acid charger is connected to a lithium iron phosphate battery it will take 6 to 8 hours to charge only to 79%, while a lithium-iron compatible Progressive Dynamics converter charger connected to a lithium-iron battery will charge to 100% in 90 minutes. And fast charging times is a huge advantage for getting lithium-iron batteries that ought not to be missed.
What to do?
Well, first you need to identify the brand and model of your converter, inverter or charger that’s actually charging your existing RV house batteries. Then you need to see if they have a setting for Lithium batteries. Don’t take the word of an RV shop that’s trying to sell you an expensive Lithium upgrade. No, you need to confirm this yourself with the charger manufacturer.
If you don’t have a converter with a Lithium setting, then factor in the cost of a new converter, which should not cost more than $200 to $500. But if your converter DOES have a Lithium battery setting, then you’re in business and your RV shop can adjust the settings and literally drop in a new Lithium battery replacement. But don’t just take their word for it: Caveat Emptor (Buyer Beware).
For more information
Here’s the Lithium battery company I’ve been working with on my swing-compressor refrigerator project. For more information on their Lithium Ion-Ready™ batteries, go HERE. Or send an email to contact@briterproducts.com. [Note: Briter Products’ Lithium Ion-Ready™ batteries are Lithium Iron Phosphate (LiFePO4) Deep-Cycle 12V 100Ah batteries.]
I’ll write more soon on the differences between Lithium ion versus Lithium iron batteries, including their intended uses. Plus I’m gathering information on the various Lithium Battery manufacturers and will attempt to do an analyses of the pros and cons of each brand in the spring, but there’s a lot of information to wade through.
OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.
Let’s play safe out there….
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.
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Since their new vans have lithium batteries, I asked a rep from our RV manufacturer about installing lithium batteries in ours and he said we would have to rewire the whole van.
Regarding replacing a charger, I’m going to guess that if your current charger was also used to charge the chassis batteries you would leave that in place and require to have new charger work with house batteries?
Hi it has taken campervan and motorhome users (RV’s) years to decide which type of lead acid battery to fit ? So they are really going to get confused with the Lithium v lead acid saga. In the end though they will go for the cheapest option ? as usually ?
Eric Roberts http://www.batteriesontheweb.co.uk/blog/
Good overview on replacing a flooded battery with a lithium, Mike. Since my charging system charges both the house and chassis batteries (in some magic way), will there be a problem using the lithium for the house and staying flooded in the chassis? Thanks.
Everyone…. Remember I’m not telling you that you HAVE to buy Lithium Batteries, or even that you SHOULD buy Lithium Batteries. This is an introductory article showing some of the design variables you need to consider before integrating this technology into your RV. Any shop that just wants to sell you a Lithium battery without being able to discuss even the simple points I discussed in this article is one you should stay away from. This is WAY more complicated than slapping in a pair of 6-volt Trojan batteries and wiring them in series to increase capacity. And two of the drivers for this discussion are CPAP machines and Residential Refrigerators while boondocking. The holy grail seems to be having enough solar and battery capacity to power a full size Residential Refrigerator and at least one (maybe two) CPAP machines overnight, all without using a generator. It can cost a lot of money to do this properly, so that’s why I’m studying all the variables. I’m sure this topic will have a lot of discussion in my RVe Master Classes this year, so you’ll certainly want to attend one if you can. Right now they’re scheduled in Live Oak, FL and Enumclaw, WA. Looks like I’ll be doing a Master Class in Phoenix and a few others, so bookmark and keep watching my 2020 RVe Seminar page for updates: https://www.rvtravel.com/rv-electricity-2020-seminar-schedule-sokol/
I can’t find my battery in 2013 39p charokee where would it be located
I appreciate you getting into the meat of the matter on the new lithium batteries. The coach charging apparatus seems fairly easy to adapt but I would like to know more about integrating those batteries into the Sprinter AGM system.
Interesting discussion on converters, but I am curious of what happens when I plug into my tow vehicle? My alternator is a high output 135 amp model but I presume is designed to charge lead acid batteries.
I don’t even know where the “physical location” would be to see whether or not I have a converter with an inverter option! 🤪
(2017 Lance 1475)
As RV tech’s know , Rv batteries discharged to 11.5 volts is fully discharged, 50% discharged is 12.volt and a fully charged acid battery is 12.6 so most RV appliances and inverters will shut done at 11 v. to 11.5 volts . on the other side, RV’s can be harmed by to much voltage , about anything above 15.3 volts. Lithium batteries do not do well in that range , they require a higher voltage to charge and will draw down to a low voltage, you can buy lithium batteries for RV’s but they will only give you a 15% to 20% more and the cost compared to deep cycle acid Batteries is not worth it . by the way RV power converters do not have settings for what type of batteries you have.
Some of the newer RV’s are coming out with Lithium batteries but have a completely different elec system than most of past and present RV’s. some of the new Motorhomes don’t have Gensets ! they run off lithium batteries, solar cell, and the motorhome motor!
For more 12 v. power for the cost, spend the money on solar cells, the price has dropped a lot lately.
The COST per killowatt basis for being a bargain vs. lead acid is calculated on the THEORETICAL battery cycle life of thousands of recharges vs, lead acid batteries. This means you must CYCLE your batteries daily for MANY years (10 years daily is less than half of the claimed cycle life!). So unless you live aboard, BOONDOCK rather than plug in, and cycle daily for over a decade…you will not see a COST per Killowatt (or amp hour) advantage. Consider this when you decide to put your $$.
Now as the article points out, you may like all the other advantages in Lithium so it may be worth the money to you to achieve your goals. I caution however that DROP IN LifePo batteries with built in BMS’s are NOT a complete system and even charger/converters with a lithium setting are not proven to take care of them over the long term. Experienced professionals are seeing many thousands of dollars of Lifepo’s destroyed by lack of end to end system design. NOT just a battery and lithium setting on the charger.
I would urge anyone with a technical bent to read and consider the long and detailed article on Lion technology and focus on the passages on” what about LiFePo drop ins ” on marinehowto.com…
https://marinehowto.com/lifepo4-batteries-on-boats/
Don’t be put off by the marine focus since RV’s face a similar envronment…particularly in the aspect of both heavy amp loads and shock and vibration. Hope some find this useful.
Mike Gondek, what is the basis for your statement: “Briter Lithium ION-Ready batteries are more costly, but so worth it. They are engineered with superior internal components and are built to last. “? I haven’t seen any technical reviews of these batteries and as I mentioned earlier their technical spec doesn’t show a low temp cut off which is standard for most other suppliers.
Briter Lithium ION-Ready batteries are more costly, but so worth it. They are engineered with superior internal components and are built to last. I have 6 of them in my DP. When you are passing through Elkhart, IN go 20 minutes east to South Bend, and drive-in. They will go through your entire rig’s electrical system and make 100% sure that your rig is ready for their batteries. It cost more, but SO worth it.
it is my understanding that if you have a LiFePO4 battry with a BMS (battery monitoring system) built in that you can use any charge controller and the battery will not be damaged. in the battleborn website here is what they say
https://battlebornbatteries.com/buy-special-charger-lifepo4-batteries/
Do I have to buy a special charger for LiFePO4 batteries?
“You do not need a special charger to charge your LFP deep cycle battery. As I mentioned above the battery prefers to bulk charge at 14.4 volts and float at 13.6 volts. Most standard chargers can handle these settings. There are some made for lithium chargers available on our store page and they will charge faster than a regular charger in most cases.”
Could you elaborate on this!
I couldn’t find the pricing for these batteries on their website but I seen the previous post of $1399 . I’ve been following this technology for a long time and Will Prowse is the most knowledgeable man on YouTube. I will be using BattleBorn Batteries when I build out my system, it’s hard to beat their price and 10 year warranty.
I’ve been following this new battery technology since I first heard of it several years ago. It has always intrigued me because wifey and I are big boondockers, and battery power is what gives us freedom. Prices on this new technology keep coming down, but not fast enough for my taste – ha. I will continue to ‘love’ my Trojan Golf Cart Batteries until such time as the prices are ‘affordable’ for everything we need to convert. This new technology is still young.
Besides the converter/charger you also need to be aware that the solar charger is set for lithium if you have solar panels.
“Some of my colleagues say that Briter Products may have the best Lithium battery technology available,” I haven’t seen much supporting evidence for this. If you look at Briter’s technical specs their BMS doesn’t have a low temperature cut off. Not impressed with that.
Will Prowse (DYI SOlar Power with Will Prowse) on youtube does actual testing and tear down of Lithium batteries. He hasn’t done Briter as yet but has done some of the others. He was impressed with the Battle Born batteries and construction.
I always enjoy reading Mike’s Articles.
I have been considering my next set of Batteries for the RV. Will probably go with AGM Batteries, verses the current Flooded ones I have now.
Going to the information website Mike Provided, these ION Ready batteries are Very COST prohibitive! At $1399.00 per battery and then you would have to purchase a Lithium Charger too.
Thanks Mike for the information, but NO Thanks to the Cost!