Battery monitor

[boatmike]

The smartgauge monitor certainly has its merits but on the downside it does not measure current, as other battery monitors do.

If a display of charge or discharge current is important then the Smartgauge is not the one

Thats perfectly true but interfacing the Smartguage with their split charge relay system (SmartCharge I think its called) gives a degree of battery management I have not seen in other systems. Advantages are 1 No voltage drop over diodes 2. The ability to tandem both battery banks for emergency engine start 3. Totally automatic system splits batteries when they are up to charge and wont allow services to drain engine start battery. You don't need to do anything. On my boat I fitted a separate analogue ammeter shunt on the service side to monitor charge/discharge. With a total cost of around £250 its more expensive but a brilliant system.

 

[pvb]

Thats perfectly true but interfacing the Smartguage with their split charge relay system (SmartCharge I think its called) gives a degree of battery management I have not seen in other systems. Advantages are 1 No voltage drop over diodes 2. The ability to tandem both battery banks for emergency engine start 3. Totally automatic system splits batteries when they are up to charge and wont allow services to drain engine start battery. You don't need to do anything. On my boat I fitted a separate analogue ammeter shunt on the service side to monitor charge/discharge. With a total cost of around £250 its more expensive but a brilliant system.

A decent VSR would do the same, eg the Victron Cyrix at about £45.

 

[MAURICE]

slightly off topic but if you have a bow thruster with a fuse of 300amp. What battery monitor do you use? The Nasa ones BM2 needs all your lecky to flow through a 200 amp shunt.

 

[pvb]

slightly off topic but if you have a bow thruster with a fuse of 300amp. What battery monitor do you use? The Nasa ones BM2 needs all your lecky to flow through a 200 amp shunt.

Nasa shunts (indeed all shunts) will withstand excess current for short periods. Anyway, most people would have a dedicated battery for a bow thruster, so the shunt wouldn't monitor it.

 

[noelex]

slightly off topic but if you have a bow thruster with a fuse of 300amp. What battery monitor do you use? The Nasa ones BM2 needs all your lecky to flow through a 200 amp shunt.

Assuming the bow thruster is operated from the house bank rather than a dedicated battery the shunt size needs to be considered carefully. The 200A shunt rating will be for continuous operation and the bow thruster will not operate continuously so it may still be OK. You need dive into the specifications looking at intermediate ratings. The durations etc.

However, often the specifications are for best case conditions, adequate cooling, large gauge wires (these help dissipate heat from the shunt) etc etc. Even if the shunt is just OK it will be very marginal so personally I would forget the calculations and purchase a battery monitor with a 500A shunt. There several battery monitors that can be fitted with 500A (or larger) shunts.

 

[pvb]

Assuming the bow thruster is operated from the house bank rather than a dedicated battery the shunt size needs to be considered carefully.

It's rather unusual to try to run a thruster from the domestic bank - cable sizes are massive.

 

[noelex]

It's rather unusual to try to run a thruster from the domestic bank - cable sizes are massive.

It depends on the configuration of the boat. The installation position of the domestic bank is the most critical factor.

It is usually cheaper to install a bow thruster battery so this method is increasingy used, but I would not agree that it is “unusual” to power a bow thruster from the domestic battery. Powering the bow thruster from the domestic bank is preferable if it is practical.

Anyway, Maurice will know if he has a bow thruster battery or not so can decide if the domestic batteryy shunt needs to be rated for this load.

 

[boatmike]

The VSR you mention would certainly have many of the functions of the Smartcharge but interfaced with the Smartguage I think you would find that functions are available that cant be achieved with a VCR alone. The Smartguage puts information on the display that tells you exactly how and when the relay is operating and has an inbuilt learning program that recognises the capacity and condition of each battery bank. As I said however, it is expensive and if you are happy to pay £45 for a Victron plus another £100 or so for a cheap battery monitor I would not argue. My own opinion however having had one is that the extra functions of the system are worth having. Its entirely a matter of preference however and I would not argue that standard VCR systems are no good. They are infinitely better than diode bridges or manual switching.

 

[boatmike]

Assuming the bow thruster is operated from the house bank rather than a dedicated battery the shunt size needs to be considered carefully. The 200A shunt rating will be for continuous operation and the bow thruster will not operate continuously so it may still be OK. You need dive into the specifications looking at intermediate ratings. The durations etc.

However, often the specifications are for best case conditions, adequate cooling, large gauge wires (these help dissipate heat from the shunt) etc etc. Even if the shunt is just OK it will be very marginal so personally I would forget the calculations and purchase a battery monitor with a 500A shunt. There several battery monitors that can be fitted with 500A (or larger) shunts.

While I think 500A might be OTT I would certainly not fit one with a 100A capacity. Many vessels have inverters fitted these days and if the service batteries are ever switched in for engine start that current also runs through the shunt. 200A should generally be OK but 100A in my view is risky unless your system is very basic.

 

[noelex]

While I think 500A might be OTT I would certainly not fit one with a 100A capacity. Many vessels have inverters fitted these days and if the service batteries are ever switched in for engine start that current also runs through the shunt. 200A should generally be OK but 100A in my view is risky unless your system is very basic.

I think it is a little dangerous to generalise. Electrical systems have grown more sophisticated. Inverters, anchor windlasses, bow thrusters can all draw more than 200A in some installations. Of course on some occasions these items will be used together with other high draw appliances, so I think it is important to check rather than assume. 200A is not a large shunt these days.

Certainly for our boat, a 500A shunt is needed despite running on 24v, which halves the current needed.

 

[crocks]

These are £25 on eBay, including shunt.

 

[MAURICE]

Hi all thought id let you know that i have 2 house batts. under my bunk in the stern and 1 house bank at the bows all connected as one house bank 12v. The forward one is due to the bow thruster and windless and i connected them all as it seemed a waste not to use this battery except for the odd occasions. All the batteries are deep cycle marine lead acid 180ah. the system works very well and without the front battery the bow thruster struggles. All fuses are at the bow. I shall have a look at 500 amp shunts thanks

 

[Mistroma]

The VSR you mention would certainly have many of the functions of the Smartcharge but interfaced with the Smartguage I think you would find that functions are available that cant be achieved with a VCR alone. The Smartguage puts information on the display that tells you exactly how and when the relay is operating and has an inbuilt learning program that recognises the capacity and condition of each battery bank. As I said however, it is expensive and if you are happy to pay £45 for a Victron plus another £100 or so for a cheap battery monitor I would not argue. My own opinion however having had one is that the extra functions of the system are worth having. Its entirely a matter of preference however and I would not argue that standard VCR systems are no good. They are infinitely better than diode bridges or manual switching.

I was lucky and got a good deal on Smartgauge and Smartbank advanced way back around 2012. I seem to remember that the 3 battery system was only a few pounds more than the bare Smartgauge.

I added a fan, wiring and diode to get variable ventilation for negligible cost. Fan off when discharging, half speed on initial charge and full speed when Voltage is high enough to get significant gassing.

It also has another nice feature which lets me charge different battery types. Everything is connected when charging starts but batteries disconnect once Voltage gets to 14.5V. I have a Silver/Calcium start battery, Spiral Redtop bowthruster battery and a T105 based domestic bank. Start and bowthruster only charge to 14.4-14.5 and Trojans continue up to 14.8V.

Start and Redtop can take the higher Voltage at a pinch (especially the start) but it is probably better to disconnect them below 14.8V. Useful feature but I did have to compromise on some things. Solar and wind only charge the domestic bank and that allows T-105s to get to 14.8V. Alternator only gets to 14.4V and doesn't trigger a disconnect.

 

[Mistroma]

Hi all thought id let you know that i have 2 house batts. under my bunk in the stern and 1 house bank at the bows all connected as one house bank 12v. The forward one is due to the bow thruster and windless and i connected them all as it seemed a waste not to use this battery except for the odd occasions. All the batteries are deep cycle marine lead acid 180ah. the system works very well and without the front battery the bow thruster struggles. All fuses are at the bow. I shall have a look at 500 amp shunts thanks

I have a bowthruster battery in the bows but couldn't use is for domestic. The domestic bank are deep cycle Trojan T-105s which are great but not at all suited to a bowthruster. The forward battery is a spiral wound Redtop designed to give very high current for short periods and not at all suitable for deep-cycling.

What type of deep-cycle battery do you have in the bows? It must be a little unusual to combine very high current output with deep-cycle qualities.

 

[Mistroma]

These are £25 on eBay, including shunt.
View attachment 79879

I've seen these recently when searching for the model I bought. A friend was interested in buying one similar to mine but I could only find the type shown in your picture.

Mine had some nice features:
1) No shunt, sensor just slips over the wire
2) Bluetooth so results displayed on my phone. I mounted the box in a locker and never even look at the LCD.
3) Cheap at only £18

I don't think they are available just now and I could only find versions with a shunt, often without Bluetooth.