CD 25 Dual motor 12v upgrade

Aurelia · Posted: Sun Dec 06, 2009 2:04 am Post subject: CD 25 Dual motor 12v upgrade

I have been reading like crazy and tearing into my boat to learn what I have and how different it is than the rest of the others I can find. We want to increase our house capacity for anchoring away from power sources. We are not looking for solar supplementation at this time and we do have a honda eu1000 onboard and are not afraid to use it for charging.

We have twin 2005 Honda 90s with 16A each of charging capacity.

We also have one 5/5 guest charger with one bank connected to the starboard starting battery (switched) and one bank connected to a port starting battery AND a group27 house battery doing a poor job of keeping up with demand both in usage and replacement obviously. I plan to add 2 group31 optimas or 3 group34 optima deep cycle batteries paralleled in the cabinet under the passenger seat for a total of about 150-165ah of capacity. I will route that port side Guest charging bank only to the port starting battery as it should be. It seems to do a decent job of maintaining a couple of group24 starting units.

I carry a Schumacher 2-30 amp variable portable charger that I would like to use for pushing power back into the new house bank when connected to generator or marina power. I carry the charger anyway for a portable trolling motor battery (that I would also like to parallel with the house when needed) and feel confident that we can manage the manual nature of charging the house bank in this slightly less convienient fashion. The low discharge rate of the optimas would mean that I would not need to keep the schumacher connected for longer periods when un-attended and I would use a light gauge (6) wire in the charge connection to act as a safety switch in case of overload issues as recommended in the charger manual.

I know we could get another installed charger and wire that into the set but I would like to try using this portable option first if it can work.

I plan to wire the new house set back to the current house connection on the Port side and basically just as it was wired with the 1/2/both switch between that and the port starting battery. I also think a VSR would be great to pass the excess charging capacity (after the starting battery is topped off) from the engines back to the house bank when available. I am not confident that both engines charging outputs are combined at present so I will have to figure that out and it would be great to draw from both.

I am not sure of the relationship between the current 1/2/both switch and a VSR unit or if they need to both exist.

I don't plan to put a third battery back in the current house position because I would like the additional space back there and it would complicate wiring I think.

I know some 12v basics but this stuff is just a bit outside my current training level so I am looking for suggestions. I keep finding diagrams of simple systems with few components (which is appealing) then I read the next webpage and it has twice the components to do basically the same job. I know I am builing a system but I like simplicity and practically thrive on inconvenience as long as I understand what I have and how to use it.

If you can chime in on just a piece of the puzzle, that would be great as well.

I appreciate any help,

Greg,

keeper of Aurelia

NewMoon · Posted: Sun Dec 06, 2009 8:59 am Post subject:

Hi Greg,

Not having a twin engine setup I can't provide much advice on best interconnection of your setup, but I would offer one suggestion.

If you are considering 3 g34 Optima's for your house bank, you might do better with 2 g31 AGM's from East Penn Mfg (Deka), model 8A31DTM. The Deka Sea Mate AGM's are those sold by West Marine and under several other labels. For about 138 pounds vs 125 you get a lot more AH capacity (210). Ours are 9 summers old and going strong.

Similarly, Odyssey (or Sears Platinum) g31 AGM's would provide a more robust and long-lasting house bank for not many additional pounds.

We've had great success with Optimas as starting banks in multiple vehicles (boats, truck, etc), but their specs for use as a sizable deep cycle bank aren't very good for the price and weight.

You can get the Deka's at an industrial battery supplier for far less than at a marine store.

journey on · Posted: Sun Dec 06, 2009 11:33 am Post subject:

If you're adding that many batteries, let me make a suggestion

First, I've added 2 ea 6 volt golf cart batteries (GC2 ?) in the starboard lazerette. See photos in Journey On . The port batter is used for backup. Worked great for 5 years. They are REALLY deep cycle and outlast the marine deep cycle by years.

Second, what's wrong with regular wet batteries? They're a lot cheaper, I only check & add water every 2 mos. or so. They don't leak under normal rolling, and if you turn the boat over, you're got other things to worry about. Difference in price is $100 per battery. Wet golf cart is ~$100 ea.

Third, if you have those amp-hrs, you'll want to use them. And some of that use will be AC, right? I have a 1000 watt Xantrex SINE wave inverter, which has worked well for years. I also have a seperate 40 amp Xantrex battery charger from a past life. A 20 amp charger is all you'll need. One can buy a combination inverter/charger for ~$1500. Separate might be a little cheaper.

Boris

BRAZO · Posted: Sun Dec 06, 2009 12:17 pm Post subject:

Aurelia · Posted: Mon Dec 07, 2009 12:39 pm Post subject:

I will be looking into the lifeline batteries as well as other larger sizes. I just wish the AGM units were a bit more common in the marketplace. I plan to install them in the cabin and do not want lead acid traditional units although the cost and output would be great.

I like that combined triple switch VSR unit and may be ordering that one very soon.

I had the 12v power switched off on the boat overnight and when I hooked a battery back up, I heard a humm noise that I think is the fuel pump. It ran steady for about 5 minutes without the motors running so I disconnected teh power again. Is that normal after a long loss of power to have it run so long?

Sea Wolf · Posted: Mon Dec 07, 2009 1:18 pm Post subject:

Aurelia · Posted: Mon Dec 07, 2009 1:32 pm Post subject:

I reached down through the access hatch and put my hand on the bilge and that was not the source of the sound. Is there a second bilge back in the cockpit that I haven't noticed on my 25? It was below freezing last night if that makes a difference. definitely a whirring sound...

Actually, that just reminded me that my daughter was on the boat and may have flipped a switch on the panel that I did not notice until I connected power. I plan to get out there again tonight and check.

Maybe it was the cabin bilge and It just sounded like it was under the cockpit floor!

Great Lakes skipper has the switch assembly for $199. Just ordered one and thanks for the suggestion BRAZO!

Doryman · Posted: Mon Dec 07, 2009 2:41 pm Post subject:

I have found it quite difficult to find specific brands of batteries, such as those recommended above, other than Sears, Optima, etc. Any tips?

Warren

Aurelia · Posted: Mon Dec 07, 2009 4:02 pm Post subject:

I found 2 group 31 AGM's (Deka Sea Mate) at Sportco here in Fife, WA for $219 each which is a bit cheaper than some other local options. I just bought them at lunch and will have a bank of 210AH soon! Thanks for the tip Cindy Sea! I would not have guessed they would carry them but its a fishing/hunting store and they sell alot of trolling batteries.

Without making phone calls and visiting stores, it has been hard to know what I might find at different locations. Even the chain stores vary in what they keep on hand. Costco has great pricing on group34 optimas but they don't carry the larger models. The Exide Obital 50AH batteries can be found for about $100 each if you look around at Exide distributers. Cabelas sells some AGM batteries for decent prices as well and that was my next move. West Marine had a good set for $280 each but I will put what I saved into good wire and connectors.

I just need to study up on wire/connectors and get ready for the re-construction.

I am not too thrilled with drilling into the hull for hold downs inside the cabinet so I plan to incorperate something drilled into the side walls. Has anyone tried using adhesive to attach material for battery hold downs?

thataway · Posted: Mon Dec 07, 2009 11:57 pm Post subject:

To address your last question first--don't drill into the hull for tie downs. I would put the batteries in boxs, with have lids, or on trays with hold downs. If you need to afix any fitting to the hull, epoxy a block of wood, glass or PVC material to the hull and drill into that. You don't want to allow water access to the core, and the sides of the hull are too thin to drill and screw into.

You don't have a lot of charging capacity--and you can use at least a 20 amp/maybe even a 40 amp charger with the AGM's you are putting in. Running outboards just to charge batteries at 16 amps (you are really charging at far less than that)--is not effecient.

Also VSR does not kick in when the starting battery is topped of. It kicks in at a set voltage. This is usually about 13.7 volts. In my experience this occurs in a few seconds up to a minute or so. No significant charging in that peroid. The VSR acts more as an isolator, to protect the starting batteris.

In the 25's (at least the one I owned). The foreward round access hole is the fuel tank guage sender access, the aft round access is the bilge pump. There is also a macerator pump for the black water (sewage) tank under the aft Port hatch. Newer boats will have a water tank aft, rather than the sewage tank.

You are better to charge specific batteries from outboard alternators, rather than combine the two alternators. You need a marine battery charger of adequate size for the house bank--keep the 5/5 for the engine starting--don't combine with a house bank. It is just not enough charging capacity.

Good luck with your design and application. The AGM's can be put outboard, and thus not take up any usable room--remember that AGM's can be put on their sides, or ends--but not upside down.

Aurelia · Posted: Tue Dec 08, 2009 1:27 am Post subject:

The side drilling I was referring to was the sides of the cabinet. I won't be drilling through the hull at any point if I can help it. I have adhesives at the ready and may build the trays myself. With the combined output of 32A from both outboards minus losses, I am not betting on that source to keep my house batteries up to snuff on their own. I will take the limited excess they put out and plan to use the house batteries a bit like a reservoir of power and really replenish it with generator +30A charger or shore power and 30A charger.

I like the PVC mount idea for hold downs and I may end up using some of the tough joint pieces and good epoxy and run straps through them.

Thanks for the advice all,

Greg

starcrafttom · Posted: Tue Dec 08, 2009 8:01 pm Post subject:

I have to ask what are you trying to power. susan and I spent a lot of time on the hook last summer with just two start batteries. we have nothing to run but the wallas and a laptop while sitting at anchor, oh and the radio. We run to a different stop everyday even if its to sit on the hook. so the battiers get charged then. So what are you guys running that you need all that juice??

Aurelia · Posted: Wed Dec 09, 2009 12:26 pm Post subject:

Two 1500 watt space heaters because Cindie gets cold! Kidding of course.

We have the Wallas, laptop, DVD player charging, lighting to keep a toddler from getting worried, radios, GPS for anchor alarm, limited fridge running, and also a small microwave/inverter used for short periods. We will need to sustain ourselves for up to three days without running the motors but we do have a generator to fill in the gaps as needed.

Greg

Aurelia · Posted: Wed Dec 23, 2009 2:08 am Post subject:

The batteries are in the boat and the old 12v system is in pieces, but I have the following question if anyone can help.

I order one of the twin VSR units but it seems to be labeled for 24volt systems. The info in the package lists both 12 and 24 on the specs. If you have one, do the two VSR boxes on your unit list a cut in voltage of 27.4 on the front of them? I don't see any specific 12 volt version available in the bundled sets on BEPs site:

http://www.bepmarine.com/Twin-Outboards,-Three-Battery-Banks-180-1465.html

Greg

Aurelia · Posted: Thu Mar 03, 2011 10:29 am Post subject:

I love this site!

I got the BEP VSR system installed last winter and moved on to other projects. Since then I have watched my volt meter on the house bank and although it seemed to be doing pretty well supplying our needs, I felt like we needed more from the charging systems on the outboards. I never did see the voltage switch over from charging the starting batteries to charging the house bank, but based on my large house bank and the relatively low output from the older Honda 90s, I figured it likely pushes over the top at a higher RPM so we were likely getting some charge while at cruising speeds only at which times I am usually not back at the transom with a meter. Watching the meter on trips, usually with some kind of activity in the system, I never got the solid feeling that the system was working right. I did some more research and found some folks with blown regulator/relay switches so I though maybe that was my problem. In talking with another Brat with the same BEP unit (Sea Angel), I picked up on an unfamilar detail and investigated it last night. See message to Sea Angel below.

"I listened to your experience and investigated my VSR setup last night. I did not recall the small ground wires coming out of the BEP unit you mentioned. I finally tried some various RPM testing and found no lights and no voltage switchover up to 3000RPM. I looked at the wiring diagram and it did not show any ground wires coming off the unit. So I start dis-assembly to investigate and learn enough to change out the regulators for new units thinking maybe I screwed up and blew them both on installation.

Inside the cases of the little regulator boxes at the top corners was a ground wire all coiled up with nothing connected to it. I connected them to eachother and tied them to my grounding bar. Now I have lights and a charge even at idle carrying over to my house bank and the voltages all look correct. Thanks for the insight, it made my night!

I was thinking I must have missed a detail on the diagram but I remember studing that thing for a long time to design a new DC system around it last winter. I checked the diagram supplied with my unit again and it really did not show those wires existing. What the hell, it works now."

We though we were doing pretty well for power during the last year and that was with only the solar charger really working away from the dock house battery charging. I can't wait to see the power resources now. I hope for easily 4-6 days at anchor without running a generator and thats what nearly 400 amp hours should get you.

Greg