New WattCycle mini 100ah(BT) battery stats & questions.

[dkwas]

This new post is in response to a prior thread and a contributor thought best to start a new thread so here we go. I am responding to Chuck7454's previous questions in this thread below.

I purchased (March 16th 2025) 3 Wattcycle 100ah mini (BT) batteries and don't know what numbers are good/bad. All batteries have never been used or connected to anything but the charger. The 3 are listed below with numbers from my multi-meter.

I connected a Dakota Lithium Marine 4 bank 10-amp charger. Each bank is 10-amps totaling 40amps.
I tested the batteries while the charger was powered on and then removed the ring terminal connectors from the batteries. Testing took place immediately after charging.

Battery 1 While charging Test 1: 14.37 ; Powered Test 2: 14.25. Removed from charger: Test 1: 13.70; Test 2: 13.47
Battery 2 While charging Test 1: 14.37 ; Powered Test 2: 14.25. Removed from charger: Test 1: 13.14; Test 2: 12.90
Battery 3 While charging Test 1: 14.34 ; Powered Test 2: 14.33. Removed from charger: Test 1: 12.96; Test 2: 12.94

The numbers above were measured with the multimeter pins touching the M8 screw terminals as well as without the M8's screwed in.


I also purchased a Humsienk 100ah (Group 24) 2 weeks ago on March 9th. I didn't do any testing on this battery as I didn't have a lithium charger until I got the 3 Wattcycle batteries, and Dakota charger earlier this week. I tested this by connecting the multimeter leads to the screw-in M8 terminal screws. The results are unlike all 3 of the Wattcycle batteries.

Humsienk Battery: Test 1 While charging test 1: 14.25 and 14.24. Removed from charger: Test 1: 14.24; Test 2: 14.09.
When I charged this battery it was the only battery on the DL charger and it was charging at 10amps. I did not connect all 4 banks at once.

When I received all 4 batteries they were all between 12.90-13.11v (based on the multimeter readings).
After unboxing, the 3 new Wattcycle batteries were showing 52, 54, and 55% charged in the Wattcycle App on my iPhone 15 ProMax. I didn't happen to notice the voltage in the app.

I didn't run any tests at all until I connected all 3 to the Dakota Lithium charger and the lights turned from solid red to solid green, which took almost 5hrs. The DL charger got pretty hot while charging all 3 batteries.

The DL charger is not adjustable and there are no switches, buttons or anything else to change on it. You have the 4 sets of wires coming out to the unit with the SAE quick connects going to ring terminals directly to the batteries. I don't have a clamp meter or anything like that, just a multimeter I just bought.

I have not tested since yesterday evening (around 9pm EST). When I get home I will test. That would give it about 20hrs since it was on the charger.

 

[sunshine_eggo]

Place a load on the 12.XV batteries for about a minute. Remove load and then check voltage.

In some cases, batteries will present a falsely low voltage when the batteries are in charge protection mode.

 

[Enketchum]

What is your question?

 

[robbob2112]

Note - this is the other thread he is referring to

J

Thread 'Watt Cycle Batteries.'

Jan 31, 2025

I ordered 2 of the Watt Cycle mini batteries with blue tooth and both batteries were reading 5+ volts. I never was able to wake up the BMS. I e-mailed Watt Cycle and sent them pictures as per their instructions, and immediately they said they would send 2 new batteries. Watt Cycle is a company that stands behind their product. I thought I would be screwed because I bought the batteries in November from Amazon and I never checked them out until January, even then, Watt Cycle never hesitated or tried to get out of their warranty. The 2 new batteries work great and the bluetooth...

• JettyDaddy
• Replies: 28
• Forum: Vendor Review Corner

• 

 

[dkwas]

What is your question?

Are the variance between each battery normal? The Humsienk when off the charger basically stayed the same as when it was being charged, 14.25 on charger and 14.24 off the charger. The Wattcycle were vastly different going from 14.34 while on the charger to as low as 12.90 off the charger. All are 100ah batteries. Just seems weird that 1 Wattcycle off the charger can be 13.70 and another one at 12.90. All of the Wattcycle are 100ah mini (BT) models. And compare that with the off charger Humsienk (group 24) measuring 14.24 seems like quite a difference.

Maybe all of this is normal, I am just ignorant at this point what is normal and what I should be concerned with. Especially since they are all new I want to make sure I'm not going to have problems from the start. If a variance between 13.70 on 1 battery to 12.90 on another is normal then fine. I would just like to know more that's all.

 

[robbob2112]

They should all end up around 13.6 or so when fully charged and rested for a few hours... They ones reading 12.9 are either in protection mode or not fully charged. Or the cells inside are badly imbalanced and it is hitting over-volt protection for one well before the other 3 cells are full.

14.24 doesn't seem real or valid -

Answer for each battery -
Where are you measuring the voltage and how? You should be using a multimeter of some sort and not the bluetooth
Does it allow you to discharge it when you put a load on just it? Can you measure with a clamp meter or shunt the current?
Does it allow you to charge it and can you measure current going in with either a shut or clamp meter?

 

[dkwas]

They should all end up around 13.6 or so when fully charged and rested for a few hours... They ones reading 12.9 are either in protection mode or not fully charged. Or the cells inside are badly imbalanced and it is hitting over-volt protection for one well before the other 3 cells are full.

14.24 doesn't seem real or valid -

Answer for each battery -
Where are you measuring the voltage and how? You should be using a multimeter of some sort and not the bluetooth
Does it allow you to discharge it when you put a load on just it? Can you measure with a clamp meter or shunt the current?
Does it allow you to charge it and can you measure current going in with either a shut or clamp meter?

After leaving the batteries alone since fully charging them last night I came home from work and pulled out the multimeter and off the battery charger all 3 Wattcycle batteries read: 13.36v, 13.38v, and 13.39v from the M8 terminal screws.

I haven't connected it to anything since I'm just going to use it on 36v trolling motor. I don't really have anything else to try the batteries out on, nor do I own a clamp meter or shunt.

I haven't hit the Humsienk with the multimeter since yesterday but here's what it shows on the multimeter now. Measured at the terminals.

 

[robbob2112]

Great 3 out of 4... next step... put a load on the Humseink and drain it a few hours.... hook up a 12v inverter and see what happens.

 

[dkwas]

Great 3 out of 4... next step... put a load on the Humseink and drain it a few hours.... hook up a 12v inverter and see what happens.

So last night I connected it to my trolling motor and ran it for 2.5hrs at 50% or so. On a 36v system that of course is shared with the other batteries but should have pulled some energy out of the one in question as well. This morning I brought it in from the 38 degree temps sitting in the garage all night, let it warm up for the last few hours and now it reads 13.33v on the multimeter. I don't have an inverter or anything else like a clamp meter or shunt either so all I can go by is the multimeter at this point. I suppose I can put it back on the charger and see if it charges back up to the 14.20v like it did Friday. I just don't want to get stuck with a bad battery if I can get it sent in for an exchange within the 30 days I bought it in. Sure it was only $150 but still if it's not working like it should then I'm not going to just throw money away. I've been reading a lot of these posts and it seems like a lot of varying opinions exist. For example, my 3 Wattcycle all read within .02 of a volt of one another but it's lower than the 13.6v that people say it should be. Mine only show 13.36, .38, .39. So does that mean these are "bad"? And the Humsienk seems to be way too high. I'm not sure what that even means. Can a battery be rated incorrectly? Are the batteries inside holding more capacity than they are rated? Is the BMS not doing what it should be an allowing it to overcharge? I apologize for all of the questions but I'm new to all things lithium and what things should and shouldn't be. I'm just a fisherman who wants these things to work right and not pay $3600 in the process. I'm not an electrician so I don't have all of the tools that one might use for measuring electrical things. I just have a test light and a multimeter in the house for regular troubleshooting around the outlets in the yard or basement and stuff. I trust what someone here has to say and what to look out for, and what should and shouldn't be as many are experts in this field. I just want the items I have to work and hope to get the right answers (if possible) to ensure that they do. Thank you for your time on these questions and I'll be eagerly waiting on what to do next.

Daryl

 

[robbob2112]

Sounds like you are doing fine.

Your wattcycle batteries just have an internal imbalance that should clear itself while in use over time as they cycle --- This means you have a runner cell inside that is hitting the cutoff voltage ahead of the other and it is turning off charging. pretty much ALL LFP batteries come with this sort of imbalance .... So just check back in a few months and see how it is going.

On the Humsienk - that seems very reasonable as a voltage now verse the 14.x that was to high and probably false... I would assume it is awake and probably functioning just fine. Before you put it back on the charger drain it to 13.0v or so by using it and you should be good. If after it is charged again it switched to 14.x you can assume the imbalance inside is pretty bad but will self-correct with use and to wake it up you just put a load on it.


If you are going to do anything more with solar or batteries than what you are now you might consider this $29 meter -- will save a lot of guess work.

https://www.amazon.com/ANENG-Multimeter-Capacitance-Resistance-Continuity/dp/B0BKVVFP21

When LFP batteries are new they typically DO hold more than the rated energy -- between 7% and 10% more energy --- this will go down to the rated capacity after a month or so of daily use.


Here is a sample reading from inside my wattcycle I just replaced the BMS with a bluetooth version --

What I suspect is happening inside your Humsienk is one cell instead of being 3.394 is reading something line 3.65 while the others are down in the 3.3v range - so when that single cell hits 3.65 the BMS cuts off the charge current and puts a false voltage on the terminals. So when you drain it with a load, that comes back down to 3.50 or so and then it turns back on the ability to charge.

 

[dkwas]

For less than $30 that's a good investment. Solar or otherwise knowing what you're getting into with KNOWING what your batteries are doing is important. I don't want to be 12 miles offshore and "wonder" is it going to work properly and will I be able to get home? I have to know it's not going to just cut out on me and I'll be stranded. I know lithium isn't quite like lead-acid in that it will get lower, and lower then cut out. Lithium looks like it works great and then BAM you're out of power. So with your recommendation I just bought that meter you referenced above. You have over 6,000 messages and I've read many of your posts so it seems people trust you and you know what you're talking about and I find this comforting since I'm new to all of this. Thank you for the info and I'll run that Humsienk down some more and see what happens.

Thanks again,

Daryl

 

[robbob2112]

I have one other suggestion -

Get something like this

Amazon.com

Ideally it would be hooked between the batteries and the charger on the negative side and left connected. But it sounds like you haul your batteries in and out to charge them.

So,, you leave this out hooked up in the boat.... and when you reconnect the batteries you set it to 100% SOC and for the capacity of your batteries... 3 in series of 100ah each means they are 100ah * 38.4v = 3840Whrs....

This is your fuel gauge so you never run out of power out on the lake, you can just keep an eye on it.

There are fancier ones but this would do the job for you.


SO, when you hook it back up you hold in the % key and it is set to full

 

[dkwas]

I have one other suggestion -

Get something like this

Amazon.com

Ideally it would be hooked between the batteries and the charger on the negative side and left connected. But it sounds like you haul your batteries in and out to charge them.

So,, you leave this out hooked up in the boat.... and when you reconnect the batteries you set it to 100% SOC and for the capacity of your batteries... 3 in series of 100ah each means they are 100ah * 38.4v = 3840Whrs....

This is your fuel gauge so you never run out of power out on the lake, you can just keep an eye on it.

There are fancier ones but this would do the job for you.


SO, when you hook it back up you hold in the % key and it is set to full

View attachment 287130

And what would be the easiest way to draw down these batteries without having to run my trolling motor for hours on end and put wear and tear on it? My GPS/Fish Finder only uses 2.1A/Hr so it will take quite a bit of time to draw down the battery so what would be a way I could connect something directly to my battery posts to run down the power in each battery fast? Since I don't have an inverter I would want something inexpensive just to draw down the battery in quick fashion.

And what would you think if I also purchased one of these?
Would this help me troubleshoot or see how my battery is doing?

I am planning on mounting the batteries in the boat and not dragging them into the house when I need to charge them as I purchased a 4 bank 10Amp onboard charger for the boat but it's pretty basic. Red light charging, green light charged up. So that battery monitor looks like good insurance as I don't know how much you can trust the phone battery apps. After looking at these items on Amazon it seems I could have bought some of these as combo units. Oh well, who knew...

 

[robbob2112]

I don't see what use you would have for a dc powersupply unless you plan to build batteries or to nickel plate copper or other metals at home.

I would get a 20amp charger or make sure the 10 amp version you get is in an aluminum case and has a fan.

Don't trust the phone app connected to the BMS any farther than you can throw it... they are notoriously inaccurate.... a battery monitor based on a shunt is really good.

Avoid the hall effect sensor version of the monitor...it has a loop around the cable verse a shunt... simpler to install but can be very inaccurate

 

[JerryK]

So last night I connected it to my trolling motor and ran it for 2.5hrs at 50%

Not sure what brand trolling motor you have
Many of them depend on water to cool the armature/prop shaft as it comes through the rubber seals and the water also helps lubricate it just a bit.
Very similar to the water pump of an outboard you don't run them dry very long as they heat up and wear the rubber.

 

[dkwas]

Okay I'll scratch the power supply and get the battery meter only.

The battery charger is a 10amp x 4 (40amp total) bank Dakota Lithium charger. It is an onboard charger for the boat.

Marine 4 Waterproof Onboard Battery Charger with 36v Wiring | West Marine

Check out our Marine 4 Waterproof Onboard Battery Charger with 36v Wiring and more from West Marine!

www.westmarine.com

Jerry, I had the motor submerged in a 25gal fish tank as to keep it cool. I just don't like the idea of the wear and tear on the motor as well as being away from it while it running. It's a Minn Kota Ultrex 36v 112lb bow mounted trolling motor. That's why I was asking what type of 12v device I could connect to one of the lithium batteries to run it down a bit instead of my Trolling Motor or GPS/fish finder.

 

[Enketchum]

Okay I'll scratch the power supply and get the battery meter only.

The battery charger is a 10amp x 4 bank Dakota Lithium charger. It is an onboard charger for the boat.

Marine 4 Waterproof Onboard Battery Charger with 36v Wiring | West Marine

Check out our Marine 4 Waterproof Onboard Battery Charger with 36v Wiring and more from West Marine!

www.westmarine.com

View attachment 287231

Jerry, I had the motor submerged in a 25gal fish tank as to keep it cool. I just don't like the idea of the wear and tear on the motor as well as being away from it while it running. It's a Minn Kota Ultrex 36v 112lb bow mounted trolling motor. That's why I was asking what type of 12v device I could connect to one of the lithium batteries to run it down a bit instead of my Trolling Motor or GPS/fish finder.

I use one of these to test battery capacities when I get them. They can discharge up to 150 watts and turn it into heat while measuring the capacity.

Amazon.com

 

[dkwas]

I use one of these to test battery capacities when I get them. They can discharge up to 150 watts and turn it into heat while measuring the capacity.

Amazon.com

That that sweet! I think that will be perfect. I appreciate the info.

Daryl

 

[dkwas]

I have one other suggestion -

Get something like this

Amazon.com

Ideally it would be hooked between the batteries and the charger on the negative side and left connected. But it sounds like you haul your batteries in and out to charge them.

So,, you leave this out hooked up in the boat.... and when you reconnect the batteries you set it to 100% SOC and for the capacity of your batteries... 3 in series of 100ah each means they are 100ah * 38.4v = 3840Whrs....

This is your fuel gauge so you never run out of power out on the lake, you can just keep an eye on it.

There are fancier ones but this would do the job for you.


SO, when you hook it back up you hold in the % key and it is set to full

View attachment 287130

Would I need one of these for each of my batteries? Or since I'm going to be running 3 of them in a 36V configuration can I use 1 meter on that config?

 

[robbob2112]

No, you just wire the battery monitor across the 36v connection and it will tell you how much power is left.... the shunt connects to the most negative pole of the string in line and there is a small wire to the positive post for running the electronics....

So once you get the batteries fully charged you just hold in the % to set to full and after that it should stay in sync .... most have a menu option to program in the min/max voltage and AH of the batteries --- Most will also reset to 100% every time you charge the batteries and let them top off

 

[dkwas]

No, you just wire the battery monitor across the 36v connection and it will tell you how much power is left.... the shunt connects to the most negative pole of the string in line and there is a small wire to the positive post for running the electronics....

So once you get the batteries fully charged you just hold in the % to set to full and after that it should stay in sync .... most have a menu option to program in the min/max voltage and AH of the batteries --- Most will also reset to 100% every time you charge the batteries and let them top off

Awesome, then I'll put it on order today along with the battery fan tester device enketchum talked about. I'll have everything I need soon enough . Thanks so much for your help on this as I don't know who I would have asked for help with stuff like this.

Daryl