Courageous Mod 3: Battery Monitors/USB

[fredthorne]

So we’re preparing to acquire a second battery, and I decided to fabricate a battery monitor out of an old wooden cigar box. Since I had the extra room available, for good measure I installed USB ports (1 USB-A and 2 USB-C) ports on the side it. I’m pretty pleased with how it came out. I’m mounting it using double-sided Gorilla tape above the main battery compartment, where the upper cabin meets the hull on the port side. I had to fish three pairs of wires from there to the galley opening, and from there to my fuse box near the main battery (for the USB) and to batteries 1 and 2 for the monitors. While I was at it, I chose to run a fourth pair of wires as a spare—my future self will thank me and it wasn’t any extra work to string the extra pair.

Fred Thorne
Courageous (MacGregor 26X)
Coupeville, WA

[fredthorne]

Here’s the inside of the box, before I installed the USB ports.

[fredthorne]

…and the final product, installed.

[pitchpolehobie]

Very well done. I did a similar mod a year ago and Ive been really happy to have access to up to date info about battery status and a few extra charging ports that can be isolated from eachother. What lind of 2nd battery are you going for?

[Russ]

Nice work. I like the idea of monitoring your batteries independently.
I have a single battery voltage meter at my panel and it only reports the house battery.

Why did you run pairs of wires? Aren't your 12v grounds all combined?

[kmclemore]

Many years ago I installed a Xantrex Link 20 in my 26X, when I also installed my solar panel setup, and it has served me well. It monitors both batteries and gives me info on battery volts, amperage available, amperage being used, hours to discharge, etc. for both batteries, as well as a quick visual display of the battery levels.

The Link 20 isn't available anymore, but they still offer a good selection of battery monitor products for RV and Marine use. (https://xantrex.com/products/accessories/)

[March]

Yup, I used to have one too, and upgraded it to an even more sophisticated version. But when it went on the fritz, the Xantrex people were less than helpful-- sent them countless messages and phone calls and they simply said: "no longer made, no longer supported"
Replaced it with a Dutch Victron which is much smaller and does pretty much the same. It works great! The BlueTooth interface is also a bonus.I can check out the status of the batteries without having to climb into the boat

[fredthorne]

Very well done. I did a similar mod a year ago and Ive been really happy to have access to up to date info about battery status and a few extra charging ports that can be isolated from eachother. What lind of 2nd battery are you going for?

I’m not sure what second battery to buy. I reckon I’d just show the feller at Napa a photo of what Courageous already has (see image) and ask for another one like it. Do you have a better idea?

Fred Thorne
Coupeville, WA

[fredthorne]

Nice work. I like the idea of monitoring your batteries independently.
I have a single battery voltage meter at my panel and it only reports the house battery.

Why did you run pairs of wires? Aren't your 12v grounds all combined?

Hello Russ, and thanks for your comments. I ran two wire pairs through independent, in-line fuses directly to each battery so I could measure each battery independently. Was that wrong?

Fred Thorne
Coupeville, WA

[pitchpolehobie]

Nice work. I like the idea of monitoring your batteries independently.
I have a single battery voltage meter at my panel and it only reports the house battery.

Why did you run pairs of wires? Aren't your 12v grounds all combined?

Hello Russ, and thanks for your comments. I ran two wire pairs through independent, in-line fuses directly to each battery so I could measure each battery independently. Was that wrong?

Fred Thorne
Coupeville, WA

Id be careful about using an old battery and a new battery in a parallel setup to charge them. The older battery could have less capacity and induce resistance and potentially cause overheating. I have a common perko 1-2-all-off battery selector and was told to only purchase the batteries in pairs to ensure theyre the same age. I think having more advanced charging circutry could isolate the batteries and eliminate that issue...Maybe someone w more electrical knowledge can chime in. Mines based off 20yr old physics class...

[Be Free]

+1 on the old battery/new battery concerns

You don't want to put batteries that are not pretty close to the same specs in parallel. If you are trying to build a larger house bank with multiple batteries in parallel they should all be the same brand, same type, and have the same (or very close) manufacture dates. Always buy (and install) them in matched pairs.

Just in case you don't know and for "posterity": any type of "dual purpose" battery, even if it says "deep cycle" or "marine" on it is not a true deep cycle battery. Think of them as the "Macgregor" of batteries. We (the motorsailers) have the best sailing motorboat and the best motoring sailboat out there. The dual-purpose batteries are the best engine-starting house battery and the best "deep cycle" engine-starting battery you can have. They are a compromise but mostly they compromise the deep cycle part of the equation. For light house loads they are just fine.

[ris]

Yes if possible you should buy your batteries at the same time from the same lot. We bought 4 Trojan 105, 6 volt batteries in 2015 and use them every year in our boat or trailer for 7 to 9 months. They still are working just fine. Here is a pic of our electronics board in the Mac.



All our electrical stuff is on this board. Just know that we travel for months on our boat so it is set up different from a boat that goes out for 3 to 5 days. The empty space under the 12 volt plug and usb ports now has a solar controller for our 175 watt flexible solar panel that is attached to our dodger. We tie the flexible solar panel to the dodger.
Richard

[Herschel]

Guys, I envy your skill set when it comes to electrical and battery issues. I lag a tad behind you. I just bought one of these battery testers. Aren't I getting the same data you are when I hook up my meter to either my starting or my house batteries? I just don't get the ready, real time readout and have to open up my battery boxes and clamp the meter leads on. That's right isn't it, or am I missing something important?
https://www.amazon.com/your-orders/pop? ... B0BLH6PTTZ

[Herschel]

My new battery tester is as follows. Can't seem to copy the Amazon link for it and have it work.

Car Battery Tester 12V 24V AUTOPHIX BAS100【Easiest to Use】100-2000 CCA Automotive Battery Load Tester Cranking Charging System Alternator Tester Battery Analyzer for Car Truck Motorcycle SUV ATV Boat

[Be Free]

Herschel,
There is some overlap between what fredthorne built (very nice build by the way), what kmclemore installed, and what you have but none of them are identical.

From the picture and description it appears that what fredthorne has installed is a digital voltage meter for each of his batteries. The voltmeter has a graphical display which estimates the state of charge of each battery by using voltage as a proxy.

You are correct that your tester will work in a similar manner when you hook it up. I have a different brand but I suspect that they were both made in the same factory. Other than the color and the name on the front I don't see any difference. In addition to measuring voltage, your tester will also estimate the health of your battery, the voltage drop while cranking, the efficiency of your alternator, and a few other useful measurements.

The device that kmclemore installed is a battery monitor. It will also measure the voltage of two batteries (like fredthorne) but it also uses a shunt to measure the amperage in order to calculate the actual number of amp-hours that have been removed or added to the battery. I think I am ahead of him in that I'm pretty sure that I have two broken Link 20 monitors around here somewhere. I replaced mine with a slightly less-featured and significantly cheaper monitor that I have been very happy with.

TLDR:
fredthorne - digital voltmeter. Also estimates state of charge.
herschel - battery tester. Includes digital voltmeter. Also estimates health of battery.
kmclemore - battery monitor. Includes digital voltmeter and ammeter. Calculates state of charge by adding or subtracting amp-hours via measurement.