Lithium

[Tim W]

i have a Lithium battery question. Im sure this has been asked a million times. So I have a 36 volt ultrex. Is a single 36 volt lithium battery all I need instead of 3 agms

[k3fishing]

It will work but the amp hours are usually low on those, but the thing I don’t get is people will sell a 36v 50ah battery and buy 3-50ah batteries. It’s the same thing by the numbers. And they say they are better. Makes no sense.

[C130]

It will work but the amp hours are usually low on those, but the thing I don’t get is people will sell a 36v 50ah battery and buy 3-50ah batteries. It’s the same thing by the numbers. And they say they are better. Makes no sense.

I just recently bought three 12V 50ah batteries and the cost was way cheaper than buying one 36V lithium. I initially thought one 36V battery was the way to go but not at the added cost. Others have stated if the one 36V went bad you were done and with three you might could finish the day, not 100% sure on that though and was not a concern with me. I have fished twice with my lithiums, both 8 hour days, used spot lock while fishing, finished the days with 89% and 83%, but not a lot of wind. Second day was maybe 10-12 mph, no current.

[Dropdeadfred]

Depends on your motor. I have A garmin force that doesnt care if it is 24-36 volts. Just gives you the power it can.
For me,, 3 12's make more sense. If one takes a dump I can still fish. I can still fish while waiting on replacement.

[toofy]

For a single 36v battery, how will you measure the state of charge?

[flyinghappy]

For a single 36v battery, how will you measure the state of charge?

Lithium batteries are a bit different in general for measuring state of charge. Voltage doesn't tell you as much as it does with a lead acid, so the most accurate way to measure the amperage going in and going out and figure it out from there (called coulomb counting). There are meters out there that do this, the power pole charge can do it and some lithium batteries like the Ionic have a bluetooth app that reads that info from the BMS.

[Ann-Marie]

If you want to charge your 36 volt Lithium battery(ies) from your alternator at up to a maximum of 100 amps using the Trollbridge 36 it requires 3 x 12 volt batteries.

[toofy]

Lithium batteries are a bit different in general for measuring state of charge. Voltage doesn't tell you as much as it does with a lead acid, so the most accurate way to measure the amperage going in and going out and figure it out from there (called coulomb counting). There are meters out there that do this, the power pole charge can do it and some lithium batteries like the Ionic have a bluetooth app that reads that info from the BMS.

Exactly. That's the biggest weakness of lithiums right now. I pulled 4 LithiumPros out of my boat and replaced them with Ionics for that reason.

[bobcoy]

I will take those batteries off your hands, no charge. There are all kinds of battery monitors you can hook to any batteries as flyinghappy mentioned. It also matters if you got the bare minimum size battery or bank you needed. The ionic having that feature is a big convenience. But not the only way to know how much is remaining. Bob

[Tim W]

I have the power pole charge so I can monitor the battery's life. So basically there is a good chance a single 36 volt battery is not gona work as good as my 3 12 volts now. My TM is a ultrex 112

[toofy]

I will take those batteries off your hands, no charge. There are all kinds of battery monitors you can hook to any batteries as flyinghappy mentioned. It also matters if you got the bare minimum size battery or bank you needed. The ionic having that feature is a big convenience. But not the only way to know how much is remaining. Bob

These 4 Lithium Pros batteries I removed were two 36v 40ah and two 12v 110ah batteries. I paid another $240 for a Victron BMV-712 battery monitor to know how much charge they had. Turns out I can only monitor 1 battery reliably with the Victron.
These Lithium Pros are sitting in my garage and I will give you a screaming deal to take them off my hands. I would have to charge and test them first though to verify all is good, since the BMS system has probably turned off the batteries.


https://www.lithiumpros.com/product/...m-ion-battery/

https://www.lithiumpros.com/product/...m-ion-battery/

[rfdong]

I will take those batteries off your hands, no charge. There are all kinds of battery monitors you can hook to any batteries as flyinghappy mentioned. It also matters if you got the bare minimum size battery or bank you needed. The ionic having that feature is a big convenience. But not the only way to know how much is remaining. Bob

Bob, what’s a good system to use to monitor 4 batteries? I looked into Victron but as Toofy stated only monitors 1 battery so would need 4 of them or be able to move it.

[bobcoy]

You can do one per series bank. But it is not actual amps from all batteries. I have 3 100 ah batteries in series. I monitor 1 battery(with a $40 victron knockoff) I have checked several times using an accurate meter to see if they are all at the same state of charge at 24 hours after charger removed and they are. I am satisfied that one battery represents the state of charge of the bank very well. There some very expensive setups to have a monitor that has several shunts and can show individual state of charge for all. I don't want 3 or 4 different monitors somewhere on the boat but you could do it for about $150 for 3 batteries. Link on amazon: https://www.amazon.com/AiLi-Battery-...0727525&sr=8-9
I should also say I waited a day after use, without charging and did an OCV state of charge and they were also still at identical state of charge. At that point they were only 6 months old and identical ( within 1% SOC). Bob

[rfdong]

You can do one per series bank. But it is not actual amps from all batteries. I have 3 100 ah batteries in series. I monitor 1 battery(with a $40 victron knockoff) I have checked several times using an accurate meter to see if they are all at the same state of charge at 24 hours after charger removed and they are. I am satisfied that one battery represents the state of charge of the bank very well. There some very expensive setups to have a monitor that has several shunts and can show individual state of charge for all. I don't want 3 or 4 different monitors somewhere on the boat but you could do it for about $150 for 3 batteries. Link on amazon: https://www.amazon.com/AiLi-Battery-...0727525&sr=8-9
I should also say I waited a day after use, without charging and did an OCV state of charge and they were also still at identical state of charge. At that point they were only 6 months old and identical ( within 1% SOC). Bob

thanks Bob. Seems pretty simple, but maybe you can answer 2 more questions if I may, how do you manage the small amp draw via the monitor. I want to use it for a lithium battery and don’t leave them plugged in all the time. Just wondering how you mange that unless you’re using for lead acid and keep them plugged in continuously. Or is that sleep consumption so minimal that unless the boat sits for months it’s not an issue? I’m not “electrical” enough to know if that sleep draw in uA is per hour?

#2. If I use on my cranking battery, do all of the negatives have to come off the shunt? Including the motor, charger etc? Seems like it only needs to be in line with 1 negative? I was watching a You Tube video on installing that unit and he said all negatives had to come through the shunt, which is counter to most of us trying not to stack connections. TIA

Rob

[Team Colibri]

i have a Lithium battery question. Im sure this has been asked a million times. So I have a 36 volt ultrex. Is a single 36 volt lithium battery all I need instead of 3 agms

Yes it is.
But you might want 3 lithiums instead. The reason is that a LiFePo4-battery has a much longer expected lifetime then the lead-based batteries you are used to. A good lead based battery will give you 500-ish cycles (one cycle is one discharge and one charge) while a good LiFePo4 will give you 3000 cycles. (In my case, that means that the LiFePo4 will outlive its owner...) The two main reasons for a LiFePo4-battery to fail, are issues with the BMS, or a failing cell, and in both cases you are looking at a new battery. If you have a 36V-battery and that happens, you will be replacing the whole battery, if you have three 12V you will be replacing just the single battery that failed and one 12V is a lot cheaper then one 36V.

[skigill]

I bought 2 of these. https://www.amazon.com/dp/B07KS1G585...p_mob_ap_share. I set one for 36v and one for 12v.

[toofy]

Also, if you have a 36v battery, you cannot use it to jump off your 12v starter battery.

[bobcoy]

RF,
Yes all input and output devices need to be on the -lead before the shunt. Use of a Buss for the negative wires is needed. The monitor drain is miniscule(Victron is .004 Amps or 17Ah over 6 months). I am putting a link on here from How to Marine which I feel is very good. Bob
Link: https://marinehowto.com/installing-a-battery-monitor/

[rfdong]

Thanks Bob. Much appreciated!

[Tim W]

Yes it is.
But you might want 3 lithiums instead. The reason is that a LiFePo4-battery has a much longer expected lifetime then the lead-based batteries you are used to. A good lead based battery will give you 500-ish cycles (one cycle is one discharge and one charge) while a good LiFePo4 will give you 3000 cycles. (In my case, that means that the LiFePo4 will outlive its owner...) The two main reasons for a LiFePo4-battery to fail, are issues with the BMS, or a failing cell, and in both cases you are looking at a new battery. If you have a 36V-battery and that happens, you will be replacing the whole battery, if you have three 12V you will be replacing just the single battery that failed and one 12V is a lot cheaper then one 36V.

Ahh that makes sense. I just cant justify the cost. My set up isnt broke so I better leave well enough alone lol