Can A Lithium Battery Destroy Your Alternator? – Jalopnik

We can reply our personal premise for this story very simply. Yes, a lithium-ion battery can destroy your alternator. However, “can” and “will” aren’t the identical factor, so let’s unpack another questions — like how and why this vitality storage brick would possibly fry your alternator within the first place. First, let’s set the taking part in subject. There are professionals to lithium batteries, and a few RVers and boaters need to have a lithium battery along with, or instead of, a lead-acid one as a result of they work nice for energy storage and have a tendency to last more.

Most mild-hybrids that mix gasoline engines with 48-volt hybrid programs already include lithium batteries and alternator-starters. Some of those run a reasonably small motor between the engine and transmission instantly off the lithium battery, and the motor can present slightly added oomph, along with the gasoline engine. Obviously, these vehicles are designed to make use of that lithium battery, they usually get what’s known as a DC-to-DC converter that steps down the 48-volt system to run the automobile’s 12-volt parts. This can also be why pure EVs have further small 12-volt batteries.

But if all this has you pondering you would possibly need to run a lithium battery beneath the hood of a automobile engineered to cost a lead-acid one, hit pause. A lithium unit has one thing known as a battery administration system (BMS), which is designed to forestall anomalous occasions from harming the battery — however that BMS might additionally destroy your alternator. Also, lithium bricks have distinctive charging capabilities and points it is best to perceive earlier than contemplating the swap.

To shield its guts, a lithium-ion battery’s BMS acts like a kill swap. If there is a fault within the battery, the temperature will get too low, or the battery voltage spikes too excessive (often known as overvoltage), the BMS will all of a sudden open its switches to disconnect the battery, inflicting the voltage within the alternator to briefly spike (load dump), doubtlessly past 100 volts, even when the alternator is engineered to push simply 14 volts. That spike may cause the diodes within the alternator to fry.

Diodes convert AC present from the alternator to DC present that your automobile (or boat) makes use of for its electronics. Diodes are additionally single-direction; they forestall a battery from being drawn down when the engine is off. A nasty diode might be a parasitic drain that kills automobile batteries. Anyway, we now understand how and why the homicide has occurred. But is there any method to forestall it? Kind of. We’re hedging as a result of not all alternators are the identical or of the identical high quality. 

If a BMS fault fries the diodes within the alternator, that is most likely as a result of the alternator wasn’t capable of regulate the sudden voltage spike in time. Aside from going the usual route and hooking up a DC-DC charger, there appear to be different workarounds, too. An organization known as RELiON, which sells lithium batteries for RVs, boats, and different outside utilization, recommends utilizing a voltage regulator to backstop the problem.

Most late-model vehicles have already got computerized voltage regulation by way of what’s known as the powertrain management module. But is that sufficient? For the sake of your alternator, possibly you’d take RELiON’s recommendation and get a redundant voltage regulator simply in case. But once more, they make batteries for boats and RVs, which are not passenger vehicles, and lithium batteries for these purposes are engineered for deep-cycle supply, not for immediate cranking {that a} lead-acid battery delivers when it begins your automobile. This turns into an excellent greater deal within the chilly.

For the sake of argument, as an example you are good with the redundant voltage regulator concept and go along with a lithium-ion battery as a substitute of a lead-acid one. In the case of a contemporary automobile, its computerized voltage regulation might be enough to cost the lithium battery. Also, talking of contemporary vehicles, many of the electronics are going to be protected against a voltage dump within the occasion that the BMS within the battery results in the alternator sending huge juice by the automobile’s electrical system. Modern vehicles can even forestall over-voltage injury attributable to, say, connecting your automobile battery backwards. Further, Ford and GM documentation to suppliers exhibits that they require circuitry that may deal with such over-voltage. But, importantly, there’s nonetheless no assure that your alternator will not die if a lithium battery detects a spike.

There’s a last challenge with endangering your alternator and going the lithium route: the chilly. Lead-acid batteries are nice delivering juice in freezing temperatures, although anybody who’s heard a starter struggling to kick over when it is -5 levels is aware of a lead-acid battery will ship diminished voltage. But, it could nonetheless function and might be charged effectively under freezing. Meanwhile, lithium batteries will solely work all the way down to roughly -4 levels Fahrenheit, however they’re much less forgiving on the charging facet. 

A 2015 examine within the Journal of Power Sources discovered that making an attempt to cost a lithium battery under freezing led to a phenomenon often known as lithium plating, which may cut back the battery’s most capability, trigger short-circuiting, and presumably create a security hazard. Meanwhile, a separate 2018 examine printed within the Journal of Energy Storage additionally confirmed that making an attempt to cost a lithium battery within the chilly broken the battery’s electrolyte and electrode, lowering the battery’s cost capability. Low temperatures drastically enhance the inner resistance in a lithium-ion battery, and these batteries have low-temperature cutoffs that forestall them from charging at low temperatures, which may result in the aforementioned load dump contained in the alternator.

The gist is that whereas a lithium brick is likely to be the precise alternative battery to your previous Harley-Davidson, and possibly helpful as a home battery to your boat or RV, it is not superb to your automobile designed for a lead-acid battery. It’s simply all too more likely to assassinate your automobile’s alternator.