Link 10 Battery Monitor

[ssullivan]

As if this product needs a review. It's probably the de facto standard in battery monitors. I'll give it a shot anyway:

The Link 10 battery monitor goes for about $200(+/-). Hooking up the monitor requires a little extra wiring that makes it more than a 15 minute setup. There is a shunt that must be connected to the negative battery bank terminal, then all negative returns from loads must be run through that shunt. Nothing can be connected directly to the battery itself or come between the shunt and the negative of the battery bank. This requires you to buy an extra piece of battery cable and go through the install.

The wiring also requires a twisted pair of wires, which many hardware stores do not carry. Luckily, I remembered from my old NASA days building prototypes, that when we needed twisted pair, we tied an end of the wires to a fixed object and put the other end in a regular hand held drill. Blast away, and you have a perfect twister pair of wires. This is what I did to get my twisted pair for the install.

The whole install took me maybe an hour because I didn't have good wire cutters for the 1/0 battery cable I use and had to cut it the hard way - strand by strand with simple wire dykes.

Once the wiring was set up, the battery monitor came to life and worked instanly, out of the box. I only had to change the capacity of my battery bank (it assumes 200 amps of battery bank capacity out of the box). It was a simple function to access about 4 clicks away from the main display.

The monitor displays how many amps you have in your battery bank at any time, how many you take out, what the flow of amps in or out of your batteries are, voltage and how much time you have left on your batteries at a given load. Very useful info.

I can only find 2 negatives for my own install.

Negative #1: The monitor requries you to charge your batteries up to full to get it in synch. Since I'm on a generator and no near any other source of electricity, this is an impossibility (given gas prices!). I wish there was another way to get it in synch. I suppose, mathematically, there isn't though. Maybe this is more a limitation of physics than a limitation of the product. Either, way, I have to find somewhere to plug in for about 6 hours to run though the synchronization.

Negative #2: Again, this is probably not a negative for the product, but more for my own install. I have twin Iota 90 amp chargers. I had hooked them up to a set of 4 Trojan T105's in series-parallel. So... I hooked the chargers each up to a set of 2 Trojans. This means that when both chargers are operating, I do not see the charging effects of one of the chargers on the Link 10. Why? Because it is connected directly to one of the battery banks, and the current isn't passing through the shunt, which measures the flow of energy. So, I am going to connect the grounds (negatives) of both chargers to the shunt (currently only one ground is on the shunt).


Question: If I have a positive batterty charging cable on each of the Trojan battery banks, and tie both of the chargers' negative cables to the shunt (effectively also tying them together) will this cause any problem? The positives from the chargers will see different "distances" between their battery terminals and the common negative terminal. Does it make a difference that the charger current will travel through 2 batteries for one charger and through 4 batteries for the other? (I'm thinking this is a good question... ha ha ha) The chargers are "pulse" chargers, which makes me think there is a time component to the charger signal, which leads me to belive there is a problem if I wire it like this. Maybe it's better to just tie both positives and both negative together and let them charge all batteries in that configuration, allowing charging current to flow from one battery bank to the next, through the cables that interconnect the battery banks anyway?

Conclusion: I would by the Link 10 again in a second. It works exactly as stated and shows you an incredible amount of information about your battery state. No wonder they are so common. (and thanks to Rick in Seattle for the work done )

[Alan Wheeler]

I must make a comment on the advice of ALL equipment must go through the neg. This is correct, but also incorrect. As a large vessel here connected everything, including the 1000A starter. It was not a pretty sight so I have been told.
So what is the best course of action in this situation. Should tha anchor winch also be bypassed past the shunt??

[ssullivan]

Ooooh! Very good point, Wheels.

Not *all* loads should go through the Link 10, unless you want to track them and they are suitable sizes. It is meant to be used on your house bank, not your starting battery. I handn't even thought of that idea.

I am pretty sure you can send any windlass through it though. Its ratings suggests the Amp meter will display as follows:

Low Range: 0 to 40.0 amps @.1 amp resolution
High Range: +500 amps @1 amp resolution

How many amps does a windlass use at a given moment?

[Pblais]

How many amps does a windlass use at a given moment?

The fuse will probably cut out at 50. A windlass is more like a toaster using a lot of amps over a very small amount of time. If the load isn't much it won't take as much as if you snag the chain on something. Then it can go pretty high and should trip the breaker before starting the wiring on fire.

[Jentine]

A 1000 amp starter.....c'mon lets be reasonable. I have the entire boat connected through the Link 10 negative shunt including the 90 amp windlass, starter, inverter and all other equipment on the boat on the discharge side and also all charging equipment on the input side. I see no need (since it is the ground, not the supply side) to be concerned by the loads.

[cal40john]

Originally Posted by Jentine

A 1000 amp starter.....c'mon lets be reasonable. I have the entire boat connected through the Link 10 negative shunt including the 90 amp windlass, starter, inverter and all other equipment on the boat on the discharge side and also all charging equipment on the input side. I see no need (since it is the ground, not the supply side) to be concerned by the loads.

It's a circuit, everything that goes out on the positive wire has to come back on the negative wire. If you have a smaller engine, your starter is probably not drawing 1000 amps.

John

[cal40john]

Originally Posted by ssullivan

As if this product needs a review. It's probably the de facto standard in battery monitors. I'll give it a shot anyway:

The Link 10 battery monitor goes for about $200(+/-). Hooking up the monitor requires a little extra wiring that makes it more than a 15 minute setup. There is a shunt that must be connected to the negative battery bank terminal, then all negative returns from loads must be run through that shunt. Nothing can be connected directly to the battery itself or come between the shunt and the negative of the battery bank. This requires you to buy an extra piece of battery cable and go through the install.

The wiring also requires a twisted pair of wires, which many hardware stores do not carry. Luckily, I remembered from my old NASA days building prototypes, that when we needed twisted pair, we tied an end of the wires to a fixed object and put the other end in a regular hand held drill. Blast away, and you have a perfect twister pair of wires. This is what I did to get my twisted pair for the install.

The whole install took me maybe an hour because I didn't have good wire cutters for the 1/0 battery cable I use and had to cut it the hard way - strand by strand with simple wire dykes.

Once the wiring was set up, the battery monitor came to life and worked instanly, out of the box. I only had to change the capacity of my battery bank (it assumes 200 amps of battery bank capacity out of the box). It was a simple function to access about 4 clicks away from the main display.

The monitor displays how many amps you have in your battery bank at any time, how many you take out, what the flow of amps in or out of your batteries are, voltage and how much time you have left on your batteries at a given load. Very useful info.

I can only find 2 negatives for my own install.

Negative #1: The monitor requries you to charge your batteries up to full to get it in synch. Since I'm on a generator and no near any other source of electricity, this is an impossibility (given gas prices!). I wish there was another way to get it in synch. I suppose, mathematically, there isn't though. Maybe this is more a limitation of physics than a limitation of the product. Either, way, I have to find somewhere to plug in for about 6 hours to run though the synchronization.

Negative #2: Again, this is probably not a negative for the product, but more for my own install. I have twin Iota 90 amp chargers. I had hooked them up to a set of 4 Trojan T105's in series-parallel. So... I hooked the chargers each up to a set of 2 Trojans. This means that when both chargers are operating, I do not see the charging effects of one of the chargers on the Link 10. Why? Because it is connected directly to one of the battery banks, and the current isn't passing through the shunt, which measures the flow of energy. So, I am going to connect the grounds (negatives) of both chargers to the shunt (currently only one ground is on the shunt).


Question: If I have a positive batterty charging cable on each of the Trojan battery banks, and tie both of the chargers' negative cables to the shunt (effectively also tying them together) will this cause any problem? The positives from the chargers will see different "distances" between their battery terminals and the common negative terminal. Does it make a difference that the charger current will travel through 2 batteries for one charger and through 4 batteries for the other? (I'm thinking this is a good question... ha ha ha) The chargers are "pulse" chargers, which makes me think there is a time component to the charger signal, which leads me to belive there is a problem if I wire it like this. Maybe it's better to just tie both positives and both negative together and let them charge all batteries in that configuration, allowing charging current to flow from one battery bank to the next, through the cables that interconnect the battery banks anyway?

Conclusion: I would by the Link 10 again in a second. It works exactly as stated and shows you an incredible amount of information about your battery state. No wonder they are so common. (and thanks to Rick in Seattle for the work done )

I need more info. Do you have the batteries set up in two banks?
Why do you think the second charger see all 4 batteries when you move the the negative lead across the shunt, why don't you think the one on the shunt now sees all four? A drawing might help.

Going through the shunt, if it is a 50 mV drop for 50 amps shunt, that means that there will be .1 volt drop across the shunt at 100 amps. If the charger doesn't have separate sense wires that are supposed to be directly connected to the battery, then the voltage that the battery sees is .1 V less than the charger is putting out, or you can say the charger thinks the battery voltage is .1 V higher than it really is. Of course as the output falls, so does the drop lost across the shunt.

Some chargers say that you cannot connect them in parallel, others like my Guest charger say you can parallel the outputs, but since the two chargers in the one box aren't perfectly identical, one of them cuts back to acceptance or float while the other continues to do the majority of the work after a time. Other chargers have a communication cable to parallel them effectively. I didn't see anything offhand at the Iota site about paralleling their chargers.

John

[AnchorageGuy]

We have had the Link 10 for a few years and love it. Two items are not connected and that is the windlass, since it only runs when the engine is on, and the Icom SSB which sometimes has issues with the Link. But neither of these would make a big difference in our power usage. This is after all a monitoring system and we don't really need to know the numbers down to the .1 volts or AH. It gives us more than enough info to keep the systems up and the batteries happy. We do have it on two banks, it just takes a bit of extra wiring to make it all work. There is a Link system for two banks.

[Rick]

Any battery monitor (including those built in to power tools and computers) must have a shunt that passes any and all current in/out of the battery. No "sneaker" wires should be in place bypassing the current shunt for any reason. Therefore, you can inspect your battery bank to see that only negative interconnects between cells exist on the "battery side" of the shunt with no other external wires.

If the positive connections between series cell strings are opened by a switch (or any other means) while current flows then the monitor cannot present a valid state of charge indication of either string although there will always still be a valid indication of the energy (and Amp-hours) removed or charged to the bank. You just will not know the percentage of charge applying to which string.

I have tested the standard shunt provided with the instrument to destruction. The shunt will handle current overloads just like a fuse in that there is a current-time integral that is temperature dependent.
The temperature dependence is a combination of ambient as well as conducted. The larger the copper cables connected to the shunt the greater is the current rating, up to a point because the copper conducts the heat away from the shunt.

The standard shunt with about two feet of 2/0 copper cable connected to each end will survive 2000 Amps for about 15 seconds (I don't have the data in front of me). There are larger shunts available that will handle more current if necessary. Obviously the Link10 measures up to 500A before "saturating" a reading and will not be able to show a starter current in excess of that amount, however, a battery bank with an internal resistance required to drive say 1000 A with sufficient hold-up voltage will not necessarily suffer by the loss of indicated energy during the few seconds of current delivery above the 500A level for the few seconds that a starter cranks. In fact, a normally started engine that has a peak starter current of 1000A will have an "error" on the Link 10 of less than 1/2 Amp-hour.

Sean, the Link 10 does not have to be initially connected to a "full" battery in order to "synch" up with the battery on charge/discharge cycles. In fact, it should take as little as one charge cycle to do so as long as the battery is charged until the charge current falls below 5% of the bank Amp-hour rating as a scalar value for over an hour. One way to tell if the bank is full after that condition is met is to force an acceptance voltage to 14.4V or above @ 20-25 deg C and observe the charge current. If the battery is indeed full and not hot it will not charge accept much current. Not much current means on the order of 1Amp per 100Amp-hours of rating. For one to determine if the battery has recovered lost capacity due to cyclical discharges the charge acceptance should even be less than that.

Hope this clears up some of the questions.
Regards,
Rick

[ssullivan]

Sorry. I did not see the responses to this post. They were very helpful.

I have now set up the dual Iotas so that they see the 4 Trojans as a single battery bank. I cleared this with Iota tech support. There is no interference between Iotas when using them in parallel. They both split the charging duties evenly, as can be seen using the Link 10 as well.

Rick, I guess the "synch" I was talking about was more for my specific case. I have 4 brand new Trojan T105s and they had (until this weekend) never been charged to the level of having the charging current drop to 5%, or below, of the Ah rating. They haven't seen that type of charge because I'm charging from a genset, and did not have an opportunity to run it for many hours at a time to get the batteries up to that state of charge - until this weekend.

This weekend, I was able to plug into shore power and get the charging current down to 4 amps for a 440Ah bank. This situation (when the Link 10 meets the charged paramaters) is what I meant by getting it in "synch". Probably a bad choice of words. I was really referring to the chargeup required to meet the charged parameters for the first time, which shows in the LED bar readout at the top of the unit.

Anyway, I did get down to 4amps (float charge state on the Iotas) this weekend after about 5 hours of charging. The Link 10 had a blinking green light indicating a fully charged bank, as the charge parameters were met.

All has worked well, and I have been amazed at how much power I am saving now that I have the Link 10. I can't imagine not having one.

[Therapy]

Originally Posted by ssullivan

I have been amazed at how much power I am saving now that I have the Link 10. I can't imagine not having one.

How do you save power by having a monitor?
Just by seeing you are using it and just stop?

[Pblais]

How do you save power by having a monitor?
Just by seeing you are using it and just stop?

In a way you can't save power, but you can manage it better. Once you know exactly how much you are using and the pattern you can also manage the charging as well. In that sense you can save power in terms of running the engine to recharge the batteries. Ideally you want to drain no more than 50% and charge back fully. This provides the most power usage for the longest period of time.

Without a monitor you are always guessing. When you guess wrong it costs you something. It also saves you from adding more batteries to the bank when you don't need them.

[Ex-Calif]

This has been a great thread. I am lusting after some solar panels and a battery monitor. Especially as we gear up the boat.

For us poor folks however - I stuck in one of those cheap cigarette lighter plugs with 3 lights.

Having a general idea of what we are drawing and then having those three lights has been very enlightening. Green is "fully charged", yellow is "normal" and red is discharged.

It reads whatever bank is hooked up - start, house or both. It's nice in that you can get a snapshot of the state of things. We hovered in the yellow for a while and last weekend got about 3 hours of motoring and the banks came up to the green.

I know it has a lot of limitations, hence the lust for the upgrades, but it can be useful.

[ssullivan]

Originally Posted by Therapy

How do you save power by having a monitor?
Just by seeing you are using it and just stop?

Just as Paul said above. I am using maybe .1 to .2 amps per hour to run the meter, but the data coming out of the meter has helped me to cut my genset run times literally in half. I was charging twice as much as necessary by guessing. The meter will pay for itself in short order at $200 for the unit.

BUT...

I am having what appears to be a problem. I think I am getting negative amps hours accumulating.

I charged up to 4amps input current (met "charged parameters" for my batts and the Link 10) a week or two ago. Since then, I have been attempting to charge up the batteries from 50% to 90%, using them down to 50% in between charge cycles. (remember - I'm on a genset)

So... what I'm getting now is a very long genset run today where the charging current dropped to 15amps, but yet the Link 10 told me I was still at -105Ah, or at less than 80% of my battery bank's capacity. I am finding this figure hard to believe given that the charging current was down to 15amps and the load on the genset was next to nil.

I used to determine if the batteries were charged by listening to the load on the genset. If the genset did not change power when I switched off the chargers, I could hear that the charge current was down pretty low and I could assume the batteries were mostly charged since little power was going into them.

Now, I use the Link 10 to observe the charge current, but the observed charge current doesn't seem to be adding up with the number of negative amps I am seeing in the Ah display reading, or with the bar graph (which does agree with the Ah display).

Question:

1) Do these figures sound right? Am I really at less than 80% charged on a 440ah bank when the charging current drops to 15amps and the battery temp is approx 40deg F? (thanks to my Dickenson! ha ha)

2) Is the bar graph display derived from, or logically linked to the Ah totals? Is that how it determines how "full" your battery is, or does it do something else to come up with how many bars to light up?

Thanks for any input. It's a tricky thing to get used to, but it's VERY handy. These are questions I didn't even know I had before I could see the data. ha ha

[Therapy]

I see what you mean about the savings.

I don't have one. I only know from reading. I have read some of the manual and lots of threads.

One question I am waiting to have answered is when setting up the first time and all the information is being "given" to the Link, how is one to know if the information is correct or just a best guess.

To me, a best guess could equal "garbage in - garbage out".

I don't even know enough to ask the right questions I think.
Watch (read) this;

My battery is 1 year old.
It is 500ah capacity.
I obviously don't know all of it's previous charge/discharge cycles.
I don't know what it's true capacity is at this exact point in time.
I think I have it all the way charged up right now.
I am pretty sure I know the battery temp - thermometer on top of it.
I am going to hook up the link now and set it up.

I know the unit is very accurate (more than most need?) so I should be good-to-go right?