Battery Management (yep, again....)

[RobMcClain]

I have a concern regarding the battery configuration on our 2006 CC Venture 23. The existing configuration might be just fine, but I'm not sure and have no meaningful electrical expertise. A few months ago I wrote the technical support folks at both Perko and Blue Sea Systems describing the current setup. They both responded that the description sounded reasonable. The only thing they each expressed was that our current setup requires that we use the Perko battery selector switch to monitor battery system use and charging. I am curious how our current set up sounds to you guys and any recommendations you might have. Please excuse the simplicity of my explanation...

Our boat has 2 relatively new Interstate batteries, purchased last July. One is the "marine cranking" Group 24 starter battery, while the other is the "marine deep cycle" Group 27 house battery. These are controlled by a traditional Perko selector switch with 4 positions: Off - 1 - All - 2. Each battery has the expected positive and negative wire that comes off it, but also attached to the negative terminal of the Group 24 starter battery are several other wires that connect to other systems. These systems include the Tundra refrigerator, Raymarine electronics (chartplotter, radar, & depth finder), Guest 10 amp battery charger, Xantrex XM1800 Pro Inverter, house lights, etc. There is no negative bus bar so all of the wires are just slipped onto the Group 24 negative screw post. Coming off the Group 27 house battery are just the 2 traditional wires. The positive wire goes to the Perko selector switch, while the negative wire goes to the screw post on the Group 24 starter battery. No other wires connect to the Group 27 house battery.

When the battery selector switch is in the #1 position for the starter battery I can still run everything from this battery, including all house items. Similarly, if I put the battery switch over to the #2 position for the house battery I can still run everything. Frankly, this confuses me. I always assumed the starter battery would just power the engine and nothing else, and that the house battery would then be used to power the electronics and house systems. I took the boat to a local dealer a few months ago to fix a leak in the hydraulic steering and while there I asked them to check the battery management. I specifically told them I wanted to assure the starter battery was only for the engine while the Group 27 house battery would be used to power everything else. When I picked up the boat they told me they had checked the configuration and that it was just the way I had said I wanted it. I know I should trust them, but I am still confused as to why I can power the house from the starter battery.

I'm supposing it's all in the position of the battery selector switch and that my system setup is just fine, but I am still concerned and just want to double-check with the C-Brats experts. Is this system normal? Once we are at anchor I always assure the battery switch is set to #2 for the house so that I don't mistakenly run down the starter battery. Perhaps it is as simple as assuring the switch is where it should be, as the folks at Perko and Blue Sea wrote in their e-mail responses. I am aware from postings on C-Brats that I need to be careful with battery charging because I am using 2 different types of batteries. The representative from Blue Sea Systems recommended that I install a voltage regulator that will monitor charging of the 2 batteries and automatically switch off a battery once it is fully charged; thus, alleviating concern that I could overcharge the starter battery. This certainly sounds like a very good idea and it is something I am definitely planning on doing. There are 2 voltage regulators I am considering. One is sold by Blue Sea Systems (http://bluesea.com/products/7610/SI-ACR%20Automatic%20Charging%20Relay%20-%2012_24V%20DC%20120A) while the other is sold by BEP, which I believe is associated with Marinco (http://www.bepmarine.com/home-mainmenu-8/product-714/digital-voltage-sensing-relay-dvsr). Based on my limited knowledge and understanding I think these 2 regulators do the same thing. The other thing I appear to be missing is any sort of battery gauge that would allow us to easily monitor usage, level of charge, etc. I welcome any suggestions in this regard in terms of type, capability, options it should have, etc...

I know these sorts of issues have been addressed many times before and I am sorry for raising them once again, but getting my head to understand these concepts has been challenging to say the least. It's like trying to learn a foreign language and it makes me feel even older than I already am

Thanks for any thoughts!

Rob

[lloyds]

I would have to draw the diagrom but on the surface, to me, it seems like the batteries are reversed, not in polarity but in use.

[journey on]

Goodie, yet another battery problem.

First, you've got every return/negative wire tied to the negative terminal of the starting battery. Nothing wrong with that, those negs have to be tied somewhere. You might put in a return buss bar to clean up the wiring.

You don't say, but I assume that the positive lead from the starting battery goes to the battery switch, too. So far everything seems OK. The switch controls the power to everything since it's the only place the 2 ea positive leads connect. BTW, I assume that the outboard alternator/starter cable connects to the output of the battery switch, and the alternator return/negative to the neg post on the starting battery. I assume that you use the battery switch to select the starting battery for starting and then switch to the house battery or both for running?

The inverter on Journey On is wired through a separate switch and breaker, because for 1000 watts, you're pulling >80 amps (1000watts/12.4 volts), and for 1800, that'd be 150 amps. Is the Xantrex XM1800 Pro Inverter wired through the battery switch that you mentioned?

Battery chargers, are usually wired separately, directly to each battery.. I thought that the Guest 10 had a 2 bank output, with a separate wire to each battery (through a fuse.) But that's not what you said.

As far as monitoring the condition of those batteries, I'd get a good panel analog voltmeter with a switch and connect the switch directly to the batteries. that way you could monitor the condition of each battery. 12.3 Vdc is low, 13.6-14.0 Vdc is charging, 15 Vdc is high. That's all I've used for years. Analog meters are chaep, get one at Radio Shack. Years ago, I had a fancy digital integrating amp meter which told me the ~exact state of charge of the batteries, but I found out that a voltmeter did better and I didn't worry as much.

Charging relays are just something added to the electrical system and so far I've avoided them.

Also, not everybody will agree with my comments about voltmeters and relays. However they've worked for me.

Boris

[potter water]

Well, if you've had a couple knowledgeable folks look your system over, and they are happy with it, then don't worry, you be happy too.

"Still Crazy" has a complicated system with voltage sensitive relays and all, and it works great. The whole lot was installed by Weffings when the boat was new. I have 3 batteries, one for starting each engine and one house battery. Each is on its own master switch which I really like. When I'm not running the engines, I turn off both engine master switches and leave only the house battery live for living functions. I'm always assured that way that the start battery (s) haven't been accidentally drained, powering house functions. My electrical system will allow the motors to charge each start battery and the house battery with either or both motors running. The whole system makes battery management idiot proof, but being an electrical engineer, if I were to spec the system, I'd leave out a lot of the idiot proof stuff and go with something simpler like you seem to have.

The only worry I have about what you've got is I'm not hearing anything about separate fusing for each and every subsystem you have drawing power. They are probably fused there somewhere, but if not, you are courting trouble eventually.

[NewMoon]

Hi Rob,

If I understand your system description correctly, it sounds much like mine, except that I would strongly recommend connecting all the negatives via a bus bar, which is then connected to the negatives of both batteries. The idea of a setup like ours is that whichever battery is connected by the master switch runs everything, and gets all the recharging input as well.

We are cruisers who anchor overnight a lot, with no charging source on. Here's our low-tech method, which has worked for us without fail over 22 summers and ~40,000 nm of cruising:

Our boat has the typical 1-both-2-off switch, one bank of starting batteries and another of deep cycles. To take best care of the batteries, and be sure we always have enough juice for starting our diesel, we set the switch to the house bank almost all the time. When we're ready to start the engine, we switch to the starting bank. We keep it there for the few minutes (10-20) after starting needed to thoroughly re-charge the starters. Then we switch (through the both position, not through off) to the house bank, and leave it there until the next time we want to start the engine.

On the very rare occasion when we've let the start batts get drawn down enough without sufficient recharging that they can't crank the engine by themselves, we switch briefly to both for starting, then back to the start bank to recharge it, then back to the house bank for continuing normal operations.

Adding an ACR or VSR or combiner (different names for pretty much the same thing) can avoid the switching.

[BrentB]

A battery switch purpose is to isolate one battery from others
and yours is not isolating them

see

http://assets.bluesea.com/files/resources/instructions/6007_web_version.pdf

Do you have a diagram showing every connection?

You can use Word, Powerpoint or Paint (other options too) and make a drawing

[thataway]

Several issues a couple of which have been addressed:
You definitely need a negative bus bar. You don't want 6 or more wires off one battery terminal. Tie both negative battery terminals together with a 1/0 or bigger wire. Then a 1/0 to a good bus bar, and run all of the functional circuits off that. In fact you really should be running a pair of # 8 or #6 to the console and fuse block/breaker block for the positive of electronics--(red) and a negative for a bus bar up there for the electronics etc (Yellow).

Your VSR or ACR do NOT disconnect the battery after it is charged. What they do is to add the second (house) battery after the start battery is up to about 13.6 volts, and disconnect it if it drops below 12.7 volts. There may be ones which will protect from over charge or under voltage, but I don't believe the models you link to are those. The ACR--VSR is a great idea.

You will want to run the switch in #2 position most of the time for house battery use--and the main wire off the "out" terminal of the Perko switch will go to another positive bus bar: This will have the #6 or 8 red to the console, it will have the inverter (heavy wire--probably 1/0 depending on length of run-- and maybe a second bilge pump or Wallas stove, if you have one.

Battery chargers will have plus and minus to both battery respective terminals.

Now to the inverter. 1800 watts will pull that group 27 down to 50% discharge in about 15 minutes (if you are really using 1800 watts--about 200 amps @ 12 volts). Assume that the group 27 is close to 100 to 110 amp hours, and your cut off point you want is no lower than 12.2 volts.

I agree that you need to draw out the circuit so we all can be sure.

I may be a little more modern than Boris, in that I prefer a digital gauge, and they are not much more expensive than Analogue. (I have a wonderful old Analogue volt meter (mirror behind the needle ) which belonged to my father who was an EE and I suspect it was used for checking out a lot of start ups on the Edison company generators etc....but that was a very expensive instrument in its day, and is a collector's item now. You can get a volt meter which reads to the 12.XX and that is what I really want. I actually use a "link" system, which has amps used, cumulative amps etc--but that is not necessary.

I think that if you are going to be using the inverter much, you better re-think the battery system, and make the "house" bank larger.

Also an inventory of what power use you will have will be important. You have a refer, and several electronics--maybe fans, stereo etc--and you want to know what the overall drain will be--and how long you can sustain this without damage to the battery.

Your ideas are solid.

Also--no wing nuts, no wire nuts--Bolt down any lugs to the battery, and they should be lightly torqued. Also consider anti corrosive gels or sprays in the battery compartments.

Keep the questions coming and you will have a great system.

[Bill K]

As Bob knows, I just bought a 1989 22' and am having Wefings install a second battery and charger and have no idea how they will wire it till I go back down and bring it home to Ohio.

That being said I may be sticking my nose in this post for info also.

Bill Kelleher

[RobMcClain]

I greatly appreciate all of this feedback! I've not done an actual diagram of the entire configuration and it makes complete sense that I should do this. One of those "Duh!" moments... No doubt once it is on paper it will be easier to understand and identify any possible weaknesses. Design of the necessary fixes can then flow from there. Sounds like the negative bus bar and VSR are necessary components for sure. I will start on the diagram, but I suspect it is going to take a bit of time before I have this complete since my wife is having her 2nd knee replacement surgery on Friday. I wonder if I have my priorities right?? Once I have the diagram done I will repost on this thread with more specific information. I am excited to get this project done since we want to enjoy some overnight voyages this spring without worry that we're depleting the batteries.

Rob

[BrentB]

A hand drawn sketch on a napkin is acceptable.

Everyone just wants to see the connections.

Your switch could be mis wired or faulty

[Sunbeam]

What I sometimes do (not being real handy with diagrams or having programs for such on the computer) is just to draw something out by hand on paper, then photograph it, and then post the photo to my album (so I can put it in the post).

[NewMoon]

Rob, I have a diagram of my boat's main wiring you might look at, or use to start from. I didn't think it was worth the trouble to diagram all the small circuits that go from the distribution panel to every individual device.

It's a Word doc, and if you like I could email it.

[Tim & Dave Kinghorn]

Rob,

I think Lloyds has called it correctly. If you reverse the labels of start and house to what you describe, it then works normally.

When the positive lead of the battery you label as the house battery is run directly to a switch position, and has no other loads, it appears to be the start battery. The second battery with all the house loads attached would seem to be the house battery.

1. Therefore, when you select what you call the start battery (the one with all the house loads), it will start the engine and all the house circuits will work.

2. When you select what you call the house battery (the one with the positive lead going directly to the switch terminal with no other loads), it will start the engine, and the house circuits are still hot off what you call the start battery.

3. The alternator will only charge the battery used to start the engine. If you are using the house battery under the assumption it is a start battery, it will both start the engine, run the house circuits, and be charged when the engine is running. However, the battery you call the house battery will not be charged. Also, it is not a good idea to have your electronics on when using what appears to be the house battery to start the engine as it can cause damaging voltage spikes.

4. I suspect you have incorrectly traced the house and start battery leads to the switch. If not, then you are using the deep cycle as the start battery and the start battery as a deep cycle.

That said, I use a VSR. you can check out my solution in the Forum Section, Electrical and Wiring , page 3. Tim & Dave Kinghorn an Electrical Control Module for a two battery system for a 23' Venture.

I have a guest charger which charges separately the two batteries. I have a switch to disable the VSR during charging as The VSR will automatically switch its charging to the second battery. My quest charger monitors each battery and adjusts the charge per its needs. Therefore, when I'm using the charger, I do not want the VSR in the circuit.

You can go the Venture photos to see the schmatic of the unit and its construction.

Tim & Dave Kinghorn

[thataway]

It seems as if some may be mis-interupting the negative and positive terminals. The OP said that all of the negative leads came off the "starting battery, and the house battery was connected to it with a single lead. What this means is that there is no bus bar, and that the negative terminal of the start battery is used as a common ground or negative point instead.

This has nothing to do with where the positive and the fused side of the circuits come from. We have to assume that there is a positive bus bar, and that this is connected to the "out" terminal of the battery switch and that this is wired properly. This would be proper wiring, and not put all of the load on the start battery or mean that the house and start were not properly wired.

Yes, a rough diagram works fine. Few of us have CAD available to do diagrams--and electrical diagrams are not easy to do, even for experienced people, because of wires which cross vs don't connect, and wires that connect when they cross.

Sketching out the battery, VSR, fuses, buss gars, in block (not electrical symbols) works well and puts all of us on the same page.

[Jake]

Learned so far in this thread:

1. Electrical connections on a multiple battery setup should be left to the experts.

Jake