Monitoring LiFePO4 Lithium Batteries

[Hyprdrv]

What "seems" to be one of the better meters is a JLD 404 Intelligent AH Meter

EVTV Motor Verks Store.

EVTV is a good source of info, the pricing is a little high but they include a complete kit rather than just a meter. See if this does what you want. They have another meter on the same page that is suppose to do a more acurate job by kWh.
Individual battery monitoring is a little bit different and more complex. I'm not sure if there really is something out there that just does that. The issue is drawing down a pack with parasitic loads from the meter. Often mentioned is a Powerlab 8 and another one from Powerlab which I don't know if that will do a large pack.

Steve in Solomons MD

[goboatingnow]

Originally Posted by Caracal

Please read what Panbo writes. He had the time to try things, and not just listen to sales speak.

I think Ben himself has mentioned several times he is not a technical person, more a reviewer. Sometimes his blog responses from people do contain gems. In the case of the Victron Colour Controller, I believe he was using the Victron site for data.

As for METS, given its a trade only show, I find a high proportion of technical sales people there. usually the info is reliable.

I meant that good LiFePo batteries, say, a 12V LiFePo4, has current/voltage monitoring on the individual cells within the battery. A nominal 12V LiFePo4 battery consists of 4 cells in series (and more in parallel, depending on the Ah).

I know we use this term "cell' , but I always assume a "cell" is a anode and cathode in a continuous electrolyte. Large prismatic form factor LI "Cells" , actually consist of large number of parallel Li pouch cells. Technically there fore they are a "battery", but its a minor semantic issue

In any case, my point is, that if you want to use LiFePo4 batteries, you had better get some proper digital monitoring and control of it, in order for the expensive batteries last as long as possible, and in order for you to be able to tell as precisely as possible how many Ah is left. You can't rely on a simple voltmeter.

There are two differing requirements for Li monitoring

(a) Cell !! protection. Here simple cutoff voltage monitoring is sufficient , i.e. a voltmeter with preset limits and either alarms or preferably cutoffs.

In a parallel configuration, you could monitor the group of "cells" as one cell.

(b) SOC determination, best done by amp counting


Dave

[sparrowhawk1]

Dave can you tell me what amp meter and what voltage cutout device you are using. I was hoping to find them both on one device and I'm searching. I'm doing my homework but it sure is taking a while

[sparrowhawk1]

Originally Posted by Hyprdrv

What "seems" to be one of the better meters is a JLD 404 Intelligent AH Meter

EVTV Motor Verks Store.

EVTV is a good source of info, the pricing is a little high but they include a complete kit rather than just a meter. See if this does what you want. They have another meter on the same page that is suppose to do a more acurate job by kWh.
Individual battery monitoring is a little bit different and more complex. I'm not sure if there really is something out there that just does that. The issue is drawing down a pack with parasitic loads from the meter. Often mentioned is a Powerlab 8 and another one from Powerlab which I don't know if that will do a large pack.

Steve in Solomons MD

The powerlab 8 v2 does 40 amps but it cost $250 and doesn't have an amp meter. The problem with the Jld is it doesn't measure individual cells. And to me the whole point of a high voltage and low voltage cut off are for the unlikely event that the cells become unbalanced. Thanks Joe

[ColdEH]

Originally Posted by sparrowhawk1

The powerlab 8 v2 does 40 amps but it cost $250 and doesn't have an amp meter. The problem with the Jld is it doesn't measure individual cells. And to me the whole point of a high voltage and low voltage cut off are for the unlikely event that the cells become unbalanced. Thanks Joe

You need to look at the CleanPowerAuto LLC for individual cell HVC and LVC cut off

There is also other things on there site , lots of the guys here use this system

Its the one I will be using .

Im still trying to figure out the best way to calculate state of charge, since the good old voltmeter is gone the way of the Doo Doo for that .

Regards .

[darylat8750]

I bought a Victron BMV 600S from Compass Marine for monitoring the bank. I haven't chosen the individual cell protection unit yet but when I do it will have alarm then cut off of high and low voltage separately and will not be able to balance the cells as I see that as something that is not required and is a possible failure mode.

[sparrowhawk1]

Originally Posted by typhoon

You need to look at the CleanPowerAuto LLC for individual cell HVC and LVC cut off

There is also other things on there site , lots of the guys here use this system

Its the one I will be using .

Im still trying to figure out the best way to calculate state of charge, since the good old voltmeter is gone the way of the Doo Doo for that .

Regards .

The link goes to the homepage. What model exactly are you using? Thanks

[ColdEH]

Originally Posted by sparrowhawk1

The link goes to the homepage. What model exactly are you using? Thanks

Sorry, I will be using this , MiniBMS Cell Module - CleanPowerAuto LLC with this , HousePower BMS - CleanPowerAuto LLC

There are manuals on the site that show how to wire them and explains there usage .

Regards

[SteveSails]

First thing to remember is that volts are volts and amps are amps, and amp hours are just amps x time, doesn't matter if that's from FLA, AGM, LiFePO4 or whatever. If you have an older shunt type battery monitor like the Xantrex Link series no reason to dump it. While the voltage based SOC function won't mean much it still can keep track of amp hours and that should be your 'fuel gauge'. The Linklite monitor and I suspect others have programmable alarm contacts for low battery voltage, programmable from 8-33V. You could use that for a low voltage shutdown or to start charging, very useful IMHO.

Steve

[Maine Sail]

Originally Posted by sparrowhawk1

Dave can you tell me what amp meter and what voltage cutout device you are using. I was hoping to find them both on one device and I'm searching. I'm doing my homework but it sure is taking a while

There really is no "one device".. You will usually have a BMS that monitors cell level and an Ah counter that measures pack level SOC. Unless you want to pony up HUGE money for a fully gourmet $1000.00 + BMS then you build it from components. I listed them in post #10 here.

A Cell Log 8s can be configured to do some cuts using external relay but this IMHO it is a toy best left to visual monitoring of cell voltage and perhaps triggering audible alarms. Personally the Cell Log 8S is not something I would trust a $4000.00 system to. I do not trust one on my boat other than for visually monitoring my cell voltage. YMMV....

The Clean Power Auto House Power BMS and cell boards gets you HVC & LVC plus pack main relay if you choose to use it. If you use HVC the shunt boards will never come into play because it HVC is below where shunting would occur. HVC occurs at 14.2V with the House Power BMS...


Victron BMV-600
Xantrex Link Lite
Xantrex Link Pro

And other Ah counting battery monitors will give you Ah counting. I have discussed how to keep them accurate below..

Battery Monitor Manual Re-Sets To keep Calibrated

The Victron BMV-600 has a relay port as do others and these could be used to drive a "pack voltage" level relay but cell level is much more important because cell drift always happens most at the bottom and top...

The House Power BMS is the best value I have found to set up for cell level HVC and LVC...

[sparrowhawk1]

Thanks Maine sale for the review. Now I can stop my search for one that does it all. I already looked at the victron amp meter and really like the remote display. And high amperage shunt. Now I thought you and Terry agreed that a balancer is not necessary and even possibly a liability. Thanks Joe. edit. is there something that will just give me HVC and LVC on 4 cells I guess i shouls say 4 banks of the paralleled cells

[goboatingnow]

Originally Posted by sparrowhawk1

Dave can you tell me what amp meter and what voltage cutout device you are using. I was hoping to find them both on one device and I'm searching. I'm doing my homework but it sure is taking a while

I think Maine sail has answered this post, but suffice to say there isn't " one device to control them all" ( with apologies to frodo )

Dave

[ColdEH]

Hey guys what do you think of this for a SOC gauge?

EV Display - CleanPowerAuto LLC

Seems to be the right fit , has any one used one yet ?

Regards

[Maine Sail]

Originally Posted by sparrowhawk1

Thanks Maine sale for the review. Now I can stop my search for one that does it all. I already looked at the victron amp meter and really like the remote display. And high amperage shunt. Now I thought you and Terry agreed that a balancer is not necessary and even possibly a liability. Thanks Joe

I don't agree BMS balancing is not good or perhaps not necessary... In some cases it could be a good thing to have mid season to push your cells CAREFULLY into shunt balancing if they became out of balance.. I would not however aimlessly want someone to read the Chinese manual and think it is okay to continually push a bank to shunting levels every time they charge...

The House Power BMS can shunt but if you use the HVC function it will not be activated unless you do it manually because HVC cuts out before shunting level voltage is attained....

I keep my bank out of BMS range but I do believe in one as part of a safe and sound system design and to protect your investment..

I use it as an insurance policy above and beyond my system design because things happen especially on boats...

[sparrowhawk1]

I also found one on ebay that shows voltage and amp hours at the same time and has a 100 amp shunt and goes for $40. There are also ones with higher amperage shunts for slightly more Sorry I don't know how to post links. But I googled 12 volt amp hour meters. and the eBay site came up