Which Battery Monitor ?

[Maine Sail]

Originally Posted by Cheechako

You can not effectively measure state of charge without letting the battery come to a resting voltage. This takes time. How long do you ....

Gee, Time was not a problem when I was cruising...... but now I'm curious..... does the Link account for resting voltage when it does it readings amp hours and calculations?

Resting voltage is time with NO, NADA, ZERO, ZILCH input or output even milliamps.. NONE. A resting voltage is like your battery has been disconnected and is sitting on a bench for 4-8 hours min. Most sailors, when on the boat, are reluctant to spend 4-8 hours waiting to get a voltage reading and I've yet to meet one who takes an accurate resting voltage as there are often draws on the bank even with the batt switch in the off position.

Having worked on many, many charging systems and having installed a fair number of battery monitors every single person I installed one for had NO CLUE what had been going on even when they claimed to be checking state of charge at "resting voltage".. Comments like "I think you need to come because my regulator is broken, it does not put out 100 amps?" Are all too common once folks can actually visualize input and output in terms of amps and the aggregate total of used amps..

The battery monitors do not calculate state of charge on resting voltage but rather what has been put in or taken out based on your pre-programmed bank size..

Ten out of ten times, when I've asked people to show me how they have been measuring state of charge with a DVM, it has been flat out wrong...

[lookoutnw]

Thanmks for all the input folks. I am looking at putting in battery monitors on mine. I have 2 house banks, 2, 4 golfcarts linked by a combiner, and 1 , 2 grp 27 starting banks. The 1 grp 27 is separated and only can be used if the disconnect is engaged and the battery selector is on 2 or both. It is for starting the generator in a battery emerg. The other 2 grp 27 are for starting the main engine, and a bilge pump. The 2 golf carts are for the frig and plan to have an Aerogen 4 air/hydro unit for it. teh 4 golf carts I plan to have 2 120W solars for. The combiner combines when either gets to 13.5 volts and disconnects at less than that. This way either will get teh other charged as conditions allow.
I was thinking of a separate battery monitor for each of the house banks so I can see 'exactly' what teh staus is. I understand that they only show +/- amp on 1 and voltage on 2 or more. Thanks for your time and comments in advance here. I will hopefully be leaving this coming summer and plan on getting it all done before then. I am well onmy way alreay.

[Cheechako]

..every single person I installed one for had NO CLUE what had been going on even when they claimed to be checking state of charge at....

If they dont have a clue about that, they are really going to be confused by a link system! :>)
I think they are nice systems, as I said in the beginning I have one. I'm just saying you dont really need one. Bottom line when you are off the grid is, you pick a time of day to run the gen or main engine to recharge. You dont even need a voltmeter to know that, because you know the fridge and that video you watched last night pulled the amps out. You charge for maybe an hour or so. After the first 20 minutes of charging you are putting in amps very slowly and are asking yourself if it's worth running the engine. Also, your buddies are alongside the boat ready to go snorkeling. SO you stop charging after an hour and live with what you have. A fancy meter will not solve that situation. If really running low you might recharge for half an hour that night to pound in the good part of the charge cycle. It's really not about a bunch of complicated equiptment, it's about putting amps in as best you can.... I am an engineer, have built diesel charging systems and water makers, but bottom line is it's real world not theorhetical.
Nuff said "peace"..........

[theonecalledtom]

Originally Posted by lookoutnw

I understand that they only show +/- amp on 1 and voltage on 2 or more

Hi,

I just ordered a Link20. This monitors Amps, Volts and Ah across two banks (but not further info on your third). Personally I'm going to monitor the starting bank too for peace of mind (we only have one house bank) [Though I did appreciate your video Acoustic - are you a teacher?].

Cost $300 for the unit [defender] including P&P. Now I'm playing that annoying waiting game with the post and wishing I'd paid for express delivery!

[Delezynski]

Just a few notes on the Link 10. First, I think they are GREAT. I have and use one. I have considered getting a spare to take along as I value it.


Having said that....
They ONLY keep track of Amps used and Amps put back in to the bank. They DO NOT take into account the battery voltage.


They keep track of the amps that it takes to fully charge the bank. Each time you use amps, say 20, it then keeps track of how many to fill it back up, like 21. It then computes the efficacy and computes a state of charge.


Every once in a while you need to connect up and do a FULL charge until the LEDs start blinking. This tells you the meter has done a reset. In most cases, this will take a marina stay. OR a VERY long engine run (like 8+ hours).


Now, if you are out for months at a time, and do not get a reset, the meeter can be off by quite a bit.


We were out and after about 4 months, I was only watching amp usage and did not flip over to voltage reading and that was an error on my part!


At one point, the amp gage was saying I was 75% charged, but reading voltage, I was down to 11.5 V!


So, use the Link, but also set it to read voltage.


Greg

[Sandero]

I am on a shore power charge for the past 2 months (TruCharge 20). But I am using the batts when I on board each weekend working there - I use lights, the stereo, the water pressure pump and the Espar heater, the bilge pump is on too bit rarely draws anything.

My link doesn't flash on either the house bank NOR the start bank on an echo charge.

The voltage reads 13.70 or there abouts and as low as 13.35 but no flashing displays. One would think that they would be topped up eh??? and flashing - at least the start bank.

What gives?

[Celestialsailor]

I had bought a Trimetric 06/08 and worked fine at the dock but as soon as we got into the mix at Point Conception, Ca. and water was everywhere, it failed horribly. The electronics are not potted and lends itself to salt water intrusion. They were kind enough to replace it and when asked if they planned on potting the exposed electronics, they were "looking into it". I would not buy another one.

[Delezynski]

Defjef,

I had the same problem when I was prepping to go cruising. After a long time I thought the unit was bad.

Try turning off your charger for a day and use a normal load, (Reefer, lights, radios etc...) make sure you draw your batteries down 20% or so. Then plug in your charger and let it top up. You should then get the flashing.


The unit does not work all that well if you are always charging or if you don't ever fully charge. Working the system makes it all work the best.



Greg

[Sandero]

Greg,

I think you nailed it. In fact I have a "beef" with their "charge" algorithim for precisely the condition I am describing and you have experienced. It's not possible that the batts under the described condition are not effectively 100%.

What this implies is that there is some sort of resistance which manifests and it is only "erased" by a deep discharge and then a ramping up to full voltage supplied by the charging source.

My understanding is that as the battery tops off it becomes resistant to more amps being shoved in. This resistance can perhaps be interpreted as being less than fully charged. Bad batteries won't take amps either! So my theory is that the Link get confused when it does not see the charge start out "big" and ramp down which is what a healthy battery will do. When it's essentially topped off, the link doesn't see that charge "parameter" of big amps ramping down and so it just won't flash full! If this theory is correct, then those "flashing" lights are a rather primitive and flawed means to tell when the batts are topped up.

Perhaps Bill Trayfors can explain this.

Many people have charging going on continuously - wind and solar and so they don't get discharged but remain close to full up or DO get full up and I bet they don't get the flashing lights!

[camaraderie]

defjef...Xantrex out of the box defines "fully charged" as 13.2 Volts AND less than 2% of battery capacity in amps flowing (for a minimum of 5 minutes. Thus, with no draw on a set of flooded batteries of 400ah's...one you get to 13.2 volts and draw less than 8 amps from your charger for 5 minutes...you are fully charged whether or not the last light is flashing. The only way to get the light to flash is to discharge 10% or more and then re-enter the recharging mode.

[Sandero]

Cam,

If I understand you correctly the flashing light signal really applies to the case where you are recharging from at least 10% discharge based on the capacity input and the rate of charge is less than 5% of batt capacity for more than 5 minutes. This flashing signal is like telling you I am not going to take more charging, thanks.

However, my charge program on the trucharge 20 is set for bulk absorption and float (IIRC) and it's on float most of the time because there are no loads which bring the batts down and call for bulk charging. I have noticed that when I use a lot of juice I the TC20 kicks up the voltage into the 14's but pulls back pretty quickly because the discharge was shallow, not for long and the batt doesn't seem to want to take more. It then returns to the mid 13's settling in at 13.3 or so (float). My sense is that the batt is basically topped up, but this flashing light I do not see.

When I have seen it, IIRC it's been after a day of lots of use and then motoring back to the anchorage with the alternator kicking out lots of amps and reaching 100% and then getting the flasher.

In the end I basically use the link as an accurate volt meter and to read the draw in amps or the output of the charging sources. The other stuff I consider BS.

[camaraderie]

defjef...well the link10 and 20 served me well on two boats. I tended to disregard the flashing light but took my time setting the right parameters initially and found them to be pretty reliable amp hour usage as well and helped me know when I needed to charge and not drain the batts too deeply on the hook.

[theonecalledtom]

Link20 just turned up but has a big bubble in the plastic cover so is going back. Doesn't give too much confidence in the build quality of the unit. To add insult to injury someone (defender.com?) added a big yellow sticker to the box claiming "inspected". Guess it didn't claim "passed".

Oh well, now I'm not going to get a chance to install it until next month, assuming the next unit is in better shape.

Humpf.

Whoever commented on current Xantrex build quality please hold your tongue now.....

[Pelagic]

This Victron Monitor complimented the other Victron remotes I installed and does everything I need

Power on the move - Victron BMV 600 Battery Monitor - quallty, ultra high resolution, lower cost.

[Pelagic]

If you study the manual and set up parameters you can see that it does a lot more than “ballpark” the state of your battery

BMV-600 and BMV-602 - Victron Energy