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.
I noticed something on your Facebook Group last week about Lithium batteries not really being a direct replacement for my old batteries.
“Beware of ‘plug and play’ lithiums – you may not get their full capabilities without additional changes to your system…”
So what’s the scoop? Can I just drop in a new Lithium battery or not? After all, that’s a lot of money to goof up. —Kevin J.
This is something I’ve been studying for the last year or so, and I’ve reached a few conclusions. First of all let me say that this group posting was done by one of my very sharp moderators in the RVelectricity group.
So I would like to thank moderator Mike Ehlert for posting this screenshot from the Lion Battery website and starting this discussion. And you can read the full thread of this Facebook Group discussion HERE, including the response from Lion Energy. No, you don’t have to join Facebook to read this discussion, but you will need to join if you want to make any comments on this thread.
What does “plug and play” suggest?
The marketing literature for Lion Energy Lithium batteries (and many other brands) suggest that all you have to do is pull out your old battery, drop in a new Lithium battery, and begin enjoying all the benefits of this new battery technology. So is that all there is to it, or do you have to replace something else like the converter? And what happens if you don’t upgrade the converter at the same time?
What are the main benefits of Lithium Iron Phosphate (LiFePO4) batteries?
Well, first let’s do a little checklist of the important items for this discussion:
- Most Lithium batteries are designed to be discharged down to 0% without any damage to battery life. So you can get a full 100 amp-hrs of energy from a 100 amp-hr battery.
- Flooded cell batteries can only be discharged down to 50% of rated capacity without damage to battery life, so a 100 amp-hr capacity rating really only provides 50 amp-hrs of energy storage.
- Lithium batteries can be rapidly charged with up to 100 amps of current, allowing them to be recharged from 0% to 100% in less than 2 hours, or from 50% to 100% in less than an hour.
- Most flooded cell batteries should only be recharged at a maximum rate of less than 20 amps of current, so recharging a 100 amp-hr battery from 50% to 100% can take 3 to 4 hours.
What are the downsides of plug and play?
While you certainly can drop in a replacement Lithium battery in place of your original lead-acid battery, how well it performs depends on if your converter/charger has a Lithium setting, as well as its maximum available charging current.
Since Lithium Iron Phosphate batteries require a higher charging voltage to reach full capacity, your original converter/charger probably won’t be able to recharge your new Lithium battery to 100% – maybe reaching only 75% of full charge. So instead of 100 amp-hrs that you paid for, you might only have 75 amp-hrs of energy after recharging with your conventional converter/charger.
What about charging rate?
Secondly, if your converter/charger thinks this is a lead-acid battery it will limit the charging current to perhaps 1/4 of what a Lithium battery could actually accept. While that may not be a big deal if you’re plugged into shore power overnight to recharge your batteries, if you need to run a generator to recharge the batteries that could mean 4 to 6 hours of generator run time, when 60 to 90 minutes would do the job with a proper converter/charger. So Lithium batteries can recharge at a lightning rate, but only if your converter/charger is capable of providing all the needed amperes.
Does this hurt Lithium batteries?
UPDATE: I’ve recently learned that some RV battery chargers have a desulfator mode that can’t be disabled. This process uses high voltage or high-frequency pulses to “zap” the sulfates that have built up over time in a lead-acid battery. In a flooded-cell battery these pulses loosen the sulfates which drop back into the acid and dissipate. However, these same pulses can damage or destroy a Lithium Battery. So if you can’t disable the desulfation mode in a charger, you can’t us it for your Lithium battery.
But in general, connecting your new Lithium battery to an older charger/converter without a Lithium setting shouldn’t hurt anything (as long as you can disable desulfation mode). But you won’t be getting all the storage capacity you just paid for. And you can’t recharge your new Lithium battery in an hour or so. You’ll still be limited to the amperage rate of your converter/charger.
What is the solution?
If you’re planning on installing new Lithium batteries soon, first check the brand and model of your converter/charger to see if it has a Lithium setting. If not, then best practice is to have a new converter/charger installed with a Lithium setting that provides a higher charging rate and voltage profile to keep your Lithium battery investment fully charged.
So, is this misleading advertising as noted in the thread?
Yes, I would say it is. I don’t consider installing a Lithium battery to be “plug and play.” You really should do some research to find out if your existing converter/charger has a Lithium setting or not.
Of course, if you have a non-Lithium charger and know about the reduced storage capacity and less-than-fast recharging capabilities using an old charger, then that’s your decision. It won’t really hurt the Lithium battery, and you will get a little extra storage boost over your old battery (75% rather than the 50% of the rated capacity of a lead-acid battery). So you pay your money and you make your choice. However, if it were me I would install a new converter/charger during the battery installation that would allow me to reap all the benefits of a Lithium battery.
What’s the takeaway?
The key point is that if you simply replace an existing lead-acid battery with a Lithium battery without upgrading your converter/charger, you may not be getting all the battery performance you paid for. So yes, Mike E is exactly right….
Will there be more on this topic later?
Yes, I’m planning on making a full article and YouTube video discussing this topic in more detail next month, so stay tuned. In the meantime, find the model number of your existing converter/charger and you can discover if it’s Lithium ready or not by looking up the brand online, if you don’t have the information handy.
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.
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