Lithium Battery Voltages

[woods]

Bought myself my first lithium battery a couple months ago. Pretty neat. Haven't been on many rides with it yet. Yesterday was a solid day when I noticed what the volts were.

What are the voltages supposed to be though? Mine kept going down as low as 12.9 for a split second, to a high of 13.7 for split second. Floated between 13.1 and 13.5 for the most part.

is 14.2v not a thing with lithium batteries?

 

[MVI]

My Honda CRF450 has LI as OEM IIRC, 14.1v, 14.2v is normal with low beam (always on).

Run the high beam and the aux lights, you get 13.5v for hours on end

 

[ZoomerP]

Bought myself my first lithium battery a couple months ago. Pretty neat. Haven't been on many rides with it yet. Yesterday was a solid day when I noticed what the volts were.

What are the voltages supposed to be though? Mine kept going down as low as 12.9 for a split second, to a high of 13.7 for split second. Floated between 13.1 and 13.5 for the most part.

is 14.2v not a thing with lithium batteries?

See if you can find a data sheet for that battery. There's some variation on what resting voltage constitutes 100% state of charge. Once you have that, you can check battery voltage with the bike off and have a better idea about its state of charge. There are also generic charts available that should be fairly close to your battery's specs.

Lithium based batteries typically accept whatever amps a charge source can deliver up to at least 80% SOC. What you described may be due to your bike dumping all it could into the battery, with the voltage varying because of the bike's output. In some setups (RVs & boats), a lithium battery bank can even put enough load on an alternator to destroy it.

Unlike lead-acid batteries, lithium batteries have a very flat discharge curve until they drop below 20% or so. Also unlike lead-acid, they have very low self-discharge rates, and prefer to be stored at 50-80% SOC.

 

[woods]

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That's the battery there. Definitely did not hit 14v.

Then there's that. Quite the jump in .1 volts.

 

[Tripped1]

Bought myself my first lithium battery a couple months ago. Pretty neat. Haven't been on many rides with it yet. Yesterday was a solid day when I noticed what the volts were.

What are the voltages supposed to be though? Mine kept going down as low as 12.9 for a split second, to a high of 13.7 for split second. Floated between 13.1 and 13.5 for the most part.

is 14.2v not a thing with lithium batteries?

Was that with the engine running?

If so that isn't the battery voltage you are seeing that is the R/R output and I would be concerned about the state of my Regulator and/or stator if it was bouncing around like that without a significant change in electrical load.

 

[ZoomerP]

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That's the battery there. Definitely did not hit 14v.

Then there's that. Quite the jump in .1 volts.

Check the resting voltage in the morning to see the battery's SOC. Also, try a different meter in case something is wrong with the first one.

Like Tripped said, the charging system may be struggling. Check all connections. It's possible something came loose or was otherwise disturbed during the recent battery install.

 

[woods]

Was that with the engine running?

If so that isn't the battery voltage you are seeing that is the R/R output and I would be concerned about the state of my Regulator and/or stator if it was bouncing around like that without a significant change in electrical load.

Running and at different speeds.

Now, the issue may be that the voltmeter is run off of the wires by the ignition- not directly to the battery. I believe my heated grips are tied into the same circuit that the voltmeter is attached to. Not entirely sure if that matters.

 

[Tripped1]

Check the resting voltage in the morning to see the battery's SOC. Also, try a different meter in case something is wrong with the first one.

Like Tripped said, the charging system may be struggling. Check all connections. It's possible something came loose or was otherwise disturbed during the recent battery install.

Yup, test the battery voltage after trickle charging disconnected from the bike overnight should read something a 12.8 or better
Test at idle, the disconnect the ground and check the leads (this gets the battery out of the charging circuit) should read right around 14VDC

Visually inspect the connectors for the R/R and the Stator looking for heat damage (cracked brittle connectors, any discoloration on the plugs OR contacts) then clean it out, and add a little dielectric grease

 

[Tripped1]

Running and at different speeds.

Now, the issue may be that the voltmeter is run off of the wires by the ignition- not directly to the battery. I believe my heated grips are tied into the same circuit that the voltmeter is attached to. Not entirely sure if that matters.

Not sure what bike you are talking about but I know the last four bikes I have had would read about the same voltage running from idle to redline, and when I say about the same less than half of a volt difference. I can make the super duke read 13.8, but that also takes running all of the lights, heated grips, AND heated top/bottom.

This isn't always the case with older (like 90s and before) and a number of smaller engines that only have a couple hundred watt stator outputs. From a 12 volt system it only takes 14amps to start maxing out capacity, my heated gear alone can draw that turned all the way up (which I would last about 90 seconds before turning it back down).

 

[Amos Malone]

What you are seeing is normal(ish). Better Lithium batteries have DC/DC converter inside. The Lithium cells connect to the bikes electric system through that. You're measuring the output from the DC/DC converter, not the cells.

 

[ZoomerP]

What you are seeing is normal(ish). Better Lithium batteries have DC/DC converter inside. The Lithium cells connect to the bikes electric system through that. You're measuring the output from the DC/DC converter, not the cells.

Are you referring to a Battery Management System (BMS)?

 

[woods]

What you are seeing is normal(ish). Better Lithium batteries have DC/DC converter inside. The Lithium cells connect to the bikes electric system through that. You're measuring the output from the DC/DC converter, not the cells.

ya, so if I ran my voltmeter on the dash directly to the battery, I'd probably be seeing a different reading right? Or no, because it won't have the DC/DC converter?

 

[Amos Malone]

Are you referring to a Battery Management System (BMS)?

That is part of its function. You could say it's a BMS with more features. Sort of super BMS. Standard BMS does not step voltages up, in or out, like the system I've found in Lithium motorcycle battery (the one that I've taken apart). Standard BMS only monitors and controls charge and discharge levels, it does not actively step up voltages.

 

[Amos Malone]

ya, so if I ran my voltmeter on the dash directly to the battery, I'd probably be seeing a different reading right? Or no, because it won't have the DC/DC converter?

I mentioned "Better Lithium batteries". That is because not all Lithium batteries are the same. I've run a cheap (no circuit) Lithium RC battery in my dirtbike. I don't recommend you do that, but I had it lying around and it worked perfectly. I never measured the voltage. I've also take apart and fixed a broken Lithium battery that my friend had in his Yamaha. Those were completely different.
What is the meaning of "battery"? One meaning is the Lithium battery box. Another is the battery of Lithium cells on the inside. There is often a circuit inside the Lithium battery box and by measuring the battery terminals you're measuring the output of the circuit, not the actual battery of cells inside. With Lead Acid you're measuring the six two volt cells directly.

 

[ZoomerP]

That is part of its function. You could say it's a BMS with more features. Sort of super BMS. Standard BMS does not step voltages up, in or out, like the system I've found in Lithium motorcycle battery (the one that I've taken apart). Standard BMS only monitors and controls charge and discharge levels, it does not actively step up voltages.

As illustrated by the link in my earlier post, some BMS do more than monitor & control discharge levels. What you described is battery balancing, which isn't a rare BMS feature.

 

[ZoomerP]

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That's the battery there. Definitely did not hit 14v.

Then there's that. Quite the jump in .1 volts.

Looking at the RMATVMC Q&A, your battery at least has balancing. It'd be more helpful if they provided a link to the spec sheet, but I haven't found that yet. Given the price and application, it most likely uses passive balancing between cells.

When you press the battery level indicator button, what does the light show?

 

[woods]

When you press the battery level indicator button, what does the light show?

This is on my DR and I have to remove a few things to get to the battery. Its tucked in there. I've been soloing parenting this past week so I won't be able to tackle that until Momma gets back. I'll throw the multimeter on it too and see if there is a difference between that and the voltmeter on the dash.

 

[Amos Malone]

As illustrated by the link in my earlier post, some BMS do more than monitor & control discharge levels. What you described is battery balancing, which isn't a rare BMS feature.

What I described is DC/DC step up/down transformer. With BMS.

 

[Anders-]

Voltages jumping up and down can very well be caused by some powered stuff using pwm circuits - i.e. a varying load on the electrical system.
(heated grips are a good example of this)