Just an observation on batteries

[knotflying]

Over time I have seen several posts regarding adding supplemental batteries, changing to golf cart type etc. I was discussing this with a fellow Tugnutter and our conclusion was if it works don't fix it. I did a calculation and when on the hook I consume about 80 amps in a 15 hour period. A simple inexpensive task of Joining my thruster battery to my house bank gives me way more than I need and in the morning before my solar panel kicks in I am at about 80%. So, my point is, before you start changing configurations and adding batteries, do a consumption calculation and determine if you really need to make the change.

Mike Rizzo

 

[LADYBUG TOO]

Right on! Everyone has a different situation depending on equipment options and habits.

Pat & Carolyn, Ladybug, Too

 

[Boatdreamer]

Mike I agree with your thoughts. He's how we do it if we are alone in an anchorage. We will run the gen for an hour in the morning while making breakfast to charge the batteries and heat the hot water heater for morning showers. Then we let the solar panel do it's deal thoughout the day. Depending what we are making for dinner, we might run it again for another hour in the late afternoon. I haven't made any changes to our system yet, but I like the idea of using the thuster/windless battery to make a larger bank at no real cost the me.
All that said, we stopped at the Vero Beach City Marina to let that storm roll through Monday night and we're still here. Now I know why they call it Velcro Beach, once you're here, you don't want to leave!

Tim and Donna

Gratitude

 

[pugtug613]

It makes perfect sense to use the thruster/windlass bank. You would never use them unless the engine was running. As long as you monitor the battery bank closely. I like checking the voltage and never letting it get below 12v. I am new to the R27, I had a big fancy 38 sailboat with all the bells and whistles. I had to have a monster house bank to go 24 hrs on the hook, then I would run the generator or engine if I needed hot water for 1 hr. Sometimes 2 times each day. I guess I will find out this year. I heard with the solar panel, you should be able to stay on the hook for at least 24 hrs. That's with fridge, lights, CD player and normal stuff running. Some people even say 48 hrs??
Pugs Tug Long Island

 

[Don and Brenda]

Be careful saying you would never use the thruster/windlass unless the engine was running. Over the summer the engine died out in a channel and we had to drop the anchor and await a tow. On getting to the dock we used the thruster getting into a slip I was towed to.

Don

 

[RProffer]

All that is fine for the bigger boats. The R21Classic and R21-EC do not have a dedicated battery for the thruster. Nor does the boat have a generator or solar panel. And I sure hate getting woke up in the middle of the night with a low battery alarm. The solution is to add more/bigger batteries.

 

[knotflying]

Mike I agree with your thoughts. He's how we do it if we are alone in an anchorage. We will run the gen for an hour in the morning while making breakfast to charge the batteries and heat the hot water heater for morning showers. Then we let the solar panel do it's deal thoughout the day. Depending what we are making for dinner, we might run it again for another hour in the late afternoon. I haven't made any changes to our system yet, but I like the idea of using the thuster/windless battery to make a larger bank at no real cost the me.
All that said, we stopped at the Vero Beach City Marina to let that storm roll through Monday night and we're still here. Now I know why they call it Velcro Beach, once you're here, you don't want to leave!

Tim and Donna

Gratitude

Well, I don't have a built in generator. I carry a Honda 2000 and have used it 3 times just to exercise it. When I get up in the AM I am at 75 to 80 percent charge. If I want to use the Microwave I turn on the engine and then the inverter. I have power and hot water, done deal. If you want the ability to isolate your thruster battery for that rare occasion then put a switch in between the lead and you are golden.

 

[Tugalong]

With the R21EC it is difficult to increase the size of the batteries because of the limited area.

Where do you fit an extra battery ? in the stern compartment or under the bunk in the forward cabin area ?

I have fitted 2 x 10 watt solar panels to the cabin roof to help extend the available power. Haven't yet tried them out on an overnight stay to see what is gained. I also changed all the lights to LED's again I don't know what difference this has made either.

The 10watt panels fit perfectly in front of the roof hatches.

Geoff

 

[RProffer]

Geoff,
For the R21-EC, the factory installs two batteries under the aft bench seat, port side, for the air conditioner. I had the batteries installed when I bought the boat, but I did not get the air conditioner. I later changed out the two type 24 batteries for two 6 volt golf cart batteries to get the extra amps. The factory suggested installing an inverter under the aft bench seat, but I figured there was too much moisture there. I installed the inverter under the helm seat.

I would not install batteries in the cabin unless they were completely sealed and vented to the outside. Flooded batteries can produce caustic gasses when they charge.

 

[Levitation]

Just a comment on the comment about discharge to 12.0 volts. That is too low.
12.0 is a 25% charge state and frequently going this low decreases life.
12.2 volts is 5o% charge and is as low as you want to routinely - that 0.2 volts makes that much difference. Which is why you want a digital meter that is known accurate for calibrating the cheesy analog meter they install.
You also need to be young and flexible with perfect eyesight to read the ferslugginer meter on the 25. :| :mrgreen:

 

[HRowland]

Denny makes a good point about the accuracy of the voltage reading. The inexpensive digital meter that I keep in my on board electrical bag is only 1% accurate for DC voltage. A 1% error is .12V, this can make a huge difference when determining state of charge using voltage alone! The meter I use at home on my electronics work bench is better but even it is only 0.5% for DC voltage accuracy. The Victron battery monitor I installed on my tug is 0.3% accuracy for voltage measurement. However, for its state of charge calculation it is measuring both current and voltage. It also compensates for Peukert's law and charge efficiency. I have an alarm programed to alert if I get to 50% SOC.

Voltage alone is only an approximate measure for state of charge, to be most accurate the battery must be idle (no charge or discharge current) for several hours and the voltage must be compensated for temperature. If you have a flooded battery with removable caps you can do a specific gravity measurement to check charge level. This also needs to be compensated for temperature.

For the marine deep cycle batteries most of us are using even a 50% SOC is pretty severe, these batteries are usually hybrid or dual purpose (even if labeled Deep Cycle) and repeated discharges to 50% will noticeably reduce life. I avoid going below 60% SOC to help improve cycle life. A true thick plate deep cycle battery can be repeatedly discharge to even 40% SOC and last many cycles.

In my usage the most severe operation is actually day trips with some friends. Some of our friends enjoy cooking and will bring an extravagant lunch, some of which has been prepared in advance. While on the hook they will say "just microwave this for 10 minutes and this other item for 5 minutes". Of course they are thinking of a full power home microwave, not the small one we have on board. To make matters worse the on board microwave has slightly reduced power when running on the modified sine wave inverter so even more minutes are required. For noise and vibration purposes while we are in the cockpit I do not want to start the generator so I use the inverter. I also use the invertor for the blender and coffee maker, so by the end of the day I have put a big dent in the house bank SOC. I have permanently connected the thruster and house banks and re-cabled with new heavy duty 600A bus bars which has helped significantly. A nice side effect is that the thrusters work better, voltage is higher with 3 batteries in parallel. I am still using the factory installed Centennial batteries which are 90AH. Unfortunately they are the maintenance free type so I am unable to check specific gravity or check electrolyte level. I will get traditional flooded batteries as replacement, SG can be checked and they can also be equalized periodically to improve lifespan.

Howard

 

[knotflying]

Howard,

Nice explanation on meters and batteries! I actually never use the inverter for hi wattage items like the microwave and such unless I have the engine running since I do not have an installed generator. This has two benefits, my batteries stay topped off and my guests never come back. :lol:

 

[Tugalong]

Knot flying,
You wouldn't get rid of me that easily

 

[pugtug613]

I've been boating since 1989. I always had a sailboat and mainly did coastal/local cruising. My normal weekend was finding some friends and rafting up, drink beer, bulls**t, and just chill. I have been through many battery banks. The last one was a powerful 6v golf cart set up. I had 4 Titans with 110 AH each at a cost of $460. After 6 years they needed replacement. (I did not do anything but check the water level) I replaced them with the cheap COSCO $89.00 batteries. They work just as well. I monitor the voltage and don't allow it to go under 12.25v. I would bet the cheaper alternative pays off?? On my Ranger, I will go with the cheaper alternative when it comes that time again.

 

[bill j]

Mike - how are you joining the thruster battery to the house bank? are you using jumper cables? thanks - bill

 

[knotflying]

Bill,
I made up a cable equal to the gauge of the thruster cable and then the length I needed and this depends on where you may be mounting the optional isolation switch. If you are installing the switch you will obviously need two lengths of cable of appropriate length, one into the switch and one out. I hooked it up to the positive side of the house bank and positive side of the thruster bank. I put the optional switch in so that if I wanted to isolate the thruster battery for any reason I could just switch to off. A pretty easy installation.

 

[nzfisher]

So a detailed description (or photo) of how to wire the thruster battery to the house battery as well as a source of connectors used would be a big help to me as well as those who are as not familiar with electrical systems.

Thanks for your help

 

[HRowland]

Be very careful with a project like this and be sure you know what you are doing. The batteries are capable of delivering well over 1000A into a short circuit and will act like a powerful arc welder and start a fire. A battery explosion can shower you with sulfuric acid.

When I did my house/thruster bank merge and battery monitor installation I wore protective goggles and took great care with the sequence of the final connections to the batteries.

This was a much more extensive project and I made my own cables. Details are here: viewtopic.php?f=5&t=3665

Howard

 

[nzfisher]

Thanks for your thorough examination of the merge of house and thruster batteries. I appreciate the work it takes to document a process like this. I have tried to do it when cutting out the access panel to the Yanmar water pump and replacing the step- it is a lot of work. It is great to have access to such expertise on Tugnuts. I am especially interested in your set up to monitor the batteries during discharge. So far my battery experience has been satisfactory. Should it become less so, I will review your information again and see if it makes sense for me. Perhaps when the batteries are being replaced.

Thanks Howard