Lithium battery charger problem help

[Cbprov]

I have a 36 volt lithium pro battery and there on 36 volt on board charger .os there away to check if it is charging properly .how many volts should it show on a meter while it is charging battery when it is low .thanks .

[toofy]

This is exactly the reason I just took out my Lithium Pros 36v batteries. There is no way to know the state of charge. Voltage is not useful for a Lithium battery. You can use the Victron BMV-712 battery gauge, but you have to purchase one for every battery, and the installation is not straight forward.

[Phisherman]

You shouldn't be using a 36v battery to begin with. Its not recommended. for 36v systems, pertaining to trolling motor set up. 3 12v batteries is what I have been told and read. As far as charging goes, you should be able to hook a volt meter to measure battery voltage at the terminals while charging and then if you wan to check amp output, place the vdom between the battery and charging output wire. Lithium is no different when it comes to checking stuff like this. As far as chargers go, with a MK anything that is PC in the model number is okay to charge. I know of one other charger that will charge the batteries without having to send out for modification but they have not come out and said that their algorithm will charge lithium, but I know it will because I had used it.

[Cbprov]

You shouldn't be using a 36v battery to begin with. Its not recommended. for 36v systems, pertaining to trolling motor set up. 3 12v batteries is what I have been told and read. As far as charging goes, you should be able to hook a volt meter to measure battery voltage at the terminals while charging and then if you wan to check amp output, place the vdom between the battery and charging output wire. Lithium is no different when it comes to checking stuff like this. As far as chargers go, with a MK anything that is PC in the model number is okay to charge. I know of one other charger that will charge the batteries without having to send out for modification but they have not come out and said that their algorithm will charge lithium, but I know it will because I had used it.

i ahe read many threads and never heard u should run 3 batteries instead of one

[toofy]

You shouldn't be using a 36v battery to begin with. Its not recommended. for 36v systems, pertaining to trolling motor set up. 3 12v batteries is what I have been told and read. As far as charging goes, you should be able to hook a volt meter to measure battery voltage at the terminals while charging and then if you wan to check amp output, place the vdom between the battery and charging output wire. Lithium is no different when it comes to checking stuff like this. As far as chargers go, with a MK anything that is PC in the model number is okay to charge. I know of one other charger that will charge the batteries without having to send out for modification but they have not come out and said that their algorithm will charge lithium, but I know it will because I had used it.

Voltage has NOTHING to do with state of charge for Lithiums and is completely unreliable.
This is the first I have heard that three 12v batteries are any different than one 36v battery.

[Phisherman]

I was referring to reading voltage while charging,which you can do using a vdom. Now you can get a "charged" reading once the charge is believed to be completed,to give you some type of idea where you stand in regards to voltage status. When load testing you can load test using a load tester that reads in recoverable time,which is what i have and was told by a Relion engineer is okay to do. I run lithium in my my cat, Relion batteries. I am just passing along what was told to me. I have used this information and seems to be accurate regarding my set up. Hope it helps someone down the road.

[charliey]

Google E712 victron monitor....it's a gauge to monitor lithium batteries.....tells you everything you want to know about the status of your battery....% used....time left as well as voltage.....best thing since sliced bread when it comes to lithium batterie

[toofy]

Google E712 victron monitor....it's a gauge to monitor lithium batteries.....tells you everything you want to know about the status of your battery....% used....time left as well as voltage.....best thing since sliced bread when it comes to lithium batterie

I DO have that monitor and I disagree it's anything special. I can only monitor ONE battery, so what do you recommend I do for the other 3 batteries? It says 2 batteries but it only gives you voltage for a second battery which is almost worthless with lithium. Lastly, the installation is not simple, with drilling on your boat and running wires. I would prefer to just look at my phone app.

[retieoften]

My lithium 36v batteries are 42.6 volts when fully charged the lowest Ive ever seen them is 39.2 volts.

[toofy]

My lithium 36v batteries are 42.6 volts when fully charged the lowest Ive ever seen them is 39.2 volts.

And at 39.2 volts, how much charge did you have left? It's nowhere near the same answer as if this was a lead battery.
Voltage gives very little info about how much charge is still remaining. Most of us are thinking about lead/AGM batteries where the discharge is fairly constant and predictable.
The discharge curve for lithiums is very different. Lithiums hold on to their voltage until the very end, then your battery is suddenly dead.
Look at this chart to see why.

LiFePO4-vs-Lead-Acid-Discharge-Curve-EN.png

[ammdrew]

That is not accurate. We have been using lithium's as our power source for race cars for over a decade now and you can very clearly see voltage/amount of charge. While this is a much different curve then lead acid it is always the same and very predictable. If you are running lithium's to voltage cut off then the BCM is cutting power at a specific voltage. This is to protect the battery from over discharge(reduces human error). LiFe batteries can be discharged to 2.5 v per cell with a max voltage of 3.6. As even the basic curve you displayed has a constant drop in voltage over time.
While the crude voltmeters we have all been using in our marine applications may not show accurate enough information to know rate of charge as simple $9 voltmeter will tell you everything you need to know for battery state of charge. For simplicity every 12volt battery consists of 4 battery packs in series = a fully charged battery of 14.4 and discharged at 10.. The current BMS defiantly come on before 10 volts but I am not sure of what that voltage is. The first part of the voltage comes down rather quickly, say 10% of capacity. The battery is fairly stable voltage just slowly loosing voltage until cut off. It would not be too hard to document voltages and have a good working knowledge of when you are getting close to voltage cut off. I can currently fish about 3 normal days on my 75 amp hr lithium's before cutoff. Lithium's peak charge much faster then lead acid. Just a few hours every couple of days will get you back to full capacity vrs the 12-14 hr soak lead acid require to be fully charged. So much less down time and quicker turn around.

[toofy]

I agree there are rough equivalents that can be developed from lithium voltage to determine how much charge is left. But it would be so much simpler if the battery manufacturer provided a way to accurately gauge the state of charge of each battery. Or at least provided some guidance.

[retieoften]

And at 39.2 volts, how much charge did you have left? It's nowhere near the same answer as if this was a lead battery.
Voltage gives very little info about how much charge is still remaining. Most of us are thinking about lead/AGM batteries where the discharge is fairly constant and predictable.
The discharge curve for lithiums is very different. Lithiums hold on to their voltage until the very end, then your battery is suddenly dead.
Look at this chart to see why.

LiFePO4-vs-Lead-Acid-Discharge-Curve-EN.png

I get it bud your super excited you just bought lithium batteries, all be it the cheapest ones out there. Enjoy your app..

I am NOT asking for any information here. I know how lithiums work, I did my research.

I dont care how much charge I have left, Ive fished up to 11 hours and never seen lower than 39.2 I dont ever plan to fish 24 hours.

According to Danny at Stealth 1 when my voltage reads 37.2 I need to charge, I DID not hook up the gauge he sends in his kit to monitor them, I have been using a loose voltage gauge to check all year just for my knowledge.

[retieoften]

I have a 36 volt lithium pro battery and there on 36 volt on board charger .os there away to check if it is charging properly .how many volts should it show on a meter while it is charging battery when it is low .thanks .

37.2 volts on your 36 system is what danny at stealth one says indicates you need a charge.

[188Musky]

I get it bud your super excited you just bought lithium batteries, all be it the cheapest ones out there. Enjoy your app...

...and you enjoy your overpriced ones with the external volt meter, and no app.

[proptwister]

I don't quite get all the worry and wonder about exactly how much charge you have left in the TM battery? I too have tried my best to kill my pair of 36 volt 40AH TM batteries in a day and can't get it done. I installed Danny's gauge on my dash, and I have the factory Basscat one at the TM, so either place I can take a quick glance and know that, unless I'm nearing 37 volts, I can keep on fishing.

Run the hell out of em', fish you *ss off, head back to the dock at the end of the day, plug em' in.

Are we over-complicating this? Just curious.

[188Musky]

Are we over-complicating this? Just curious.

Yes!

However, in some situations, like trips to remote areas, and times when one cannot or does not charge up after every session, power management can be very important, just like fuel management.

[toofy]

I don't quite get all the worry and wonder about exactly how much charge you have left in the TM battery? I too have tried my best to kill my pair of 36 volt 40AH TM batteries in a day and can't get it done. I installed Danny's gauge on my dash, and I have the factory Basscat one at the TM, so either place I can take a quick glance and know that, unless I'm nearing 37 volts, I can keep on fishing.

Run the hell out of em', fish you *ss off, head back to the dock at the end of the day, plug em' in.

Are we over-complicating this? Just curious.

I had the Lithium Pros 36v batteries. Two of them to give me 80ah. I ran them dead 3 times. Stealth 1 charger on the two 12v batteries (one for electronics and the other was a starter), then had the DC charger from Lithium Pros to charge the 36v batteries when the others were full.
The problem is that I had no way of knowing when the 36volt batteries were fully charged.

[proptwister]

I had the Lithium Pros 36v batteries. Two of them to give me 80ah. I ran them dead 3 times. Stealth 1 charger on the two 12v batteries (one for electronics and the other was a starter), then had the DC charger from Lithium Pros to charge the 36v batteries when the others were full.
The problem is that I had no way of knowing when the 36volt batteries were fully charged.

Wow. That is very similar to the system I'm running and I've only ran it dead once (2 40 AH 36 volt batteries) but that was on a week long dedicated fishing trip to Minnesota after 3-4 days of hard fishing. It does feed back to the TM batteries as we move around the lake so that helps. As a matter of fact we leave Friday for the exact same trip!

I have two separate AC chargers with 3 of the leads connected to my start battery (a 24 AH lithium race-style battery) that then feeds that 45 amps to the DC side to charge the TM. I know its done charging when all three banks feeding the start battery turn green. Most of the time takes an hour or two at the most. The fourth lead goes to the 100 AH house battery that feeds the graphs, radio, ect.

Hate to hear you having trouble. I've ran mine for a year and half now and have had no troubles at all.

[proptwister]

However, in some situations, like trips to remote areas, and times when one cannot or does not charge up after every session, power management can be very important, just like fuel management.

I agree.