CD 25 Dual motor 12v upgrade

A

Aurelia

New member
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
 
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.
 
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
 
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?
 
Aurelia":14g43zvu said:
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?
Click to expand...

That triple VSR switch looks like it will solve a lot of problems without a lot of re-engineering on your system, just some re-wiring.

The lead-acid batteries are not all that dangerous, IMHO, if the space around them is ventilated and they are well secured in battery boxes that are themselves tightly secured.

Are you sure it was a fuel pump and not a bilge, livewell, washdown, or freshwater pump?

I don't think the fuel pump would run for more than a few seconds or so, and there are two of them, one on each motor, no?

It was a "whirr" like sound, indicating a circular pumping motion, not a diaphram like reciprocating sound, or a clicking sound, right?

I'd try connecting it again and see if I could locate the beast that's making the noise!

Joe. :teeth :thup
 
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!
 
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
 
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?
 
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.
 
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
 
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??
 
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
 
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 ... -1465.html



Greg
 
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
 
I will admit to not having read everything above, but wanted to make one very important point-

The Honda's probably cannot charge an AGM battery effectively. This means that after a year or two you may have a couple of very expensive paperweights.

AGM battereis require a different charging curve, and more voltage, so chargers must be set up for AGM use.

Yamaha specifically says on their small motors that you can not use AGM battereis with them.

A pair of 6 volt golf cart batteries will give more amp hours, for less investment, and match the charge curve of the starting battery more closely. Putting them inside the boat is not a good idea, because they off gas when charging.
 
The engine charging is simply push the power further along during a trip for us. The vast majority of the time, it is at the dock and plugged in happily charging with a AGM friendly charger specifically for the house bank. That should give our Sea Mate AGMs a good chance at a long life. I left the original 10 amp Guest unit in place for the regular lead acid deep cycle starting batteries at the dock.
 
Matt has a good point--and that is if the older 90 hp outboards only have a 16 amp alternator, then you will have a difficult time topping off the batteries. One of the problems is that you will be using a certain amount of current for the running of the boat--this includes the outboards, any electronics; lights etc. If you have a refigrator then the 4 days is optimistic. You have 400 amp hours of batteries, but only 200 useful. More than 50% discharge will shorten any battery's life--even an AGM.

I would have digital volt meters on all battery banks to moniter the voltages. We had a Link system, which also showed amps used and amps charged to the AGM bank. If possible, you might consider running one starting battery/house bank for all of the boat electronics and running needs. The other goes to the AGM house bank to give the full 16 amps (if possible) to that AGM bank. Granted that it will take some time to recharge what the refer has used--assuming that there is a refer....

I'll have to slightly differ with Matt on the subject of the Honda not being able to charge the AGM batteries. The alternator (we will call it that for simplicity) will put out enough voltage--it will be about 14.4 volts plenty for the AGM. The AGM has different (more effecient) charging characteristics--and will accept any charge which is available. We used a large AGM bank on our C Dory 25, with a single 130 (40 amps) and had not problems charging the AGM's. Now, we did stop every 3 or 4 days at a marina and used the specific charger to top off the batteries. But never lacked for battery power in Alaska, where we were running light and heat every night, and often radar during the day.

If you treat the batteries well they should last a "normal" time. The reason for AGM's is that you can put them in the cabin, in unusual positions or you cannot get to them for maintance. Matts point about Golf carts is well taken.
 
Right now I do have all "running" items feeding from the house bank and I do use a digital meter at the helm to monitor its health which I monitor to keep from dipping below 50-55 percent. We have a large bank AGM specific slow charger/maintainer built in for charging that set while the boat is at our dock and a separate quality AGM capable 30amp charger for quicker charges or charging with our honda generator while at anchor. The factory Guest unit still handles the starting batteries at the dock. The majority of our trips are no more than five days in length but we like to spend most of the time at anchor so this should be adequate for us. We do have a refer and use it about half of the time but we also have a 1-2amp (weather dependent) solar charging system that pumps enough juice into the boat to nearly offset our use of the fridge in the warmer season. In winter we use a cooler primarily and keep the refer items basically outside.

Immediately after starting, the VSR was already pushing power into the house bank so I think we are getting a decent amount (maybe 20 amps on a good day at cruise) directly into the house bank while running. I can always used the switches on the unit to tie a starting battery to the house bank for a bit more reserve capacity. We also have a 10AH battery built into the pudgy I could jump from possibly in a pinch plus a 55ah optima we often carry for more electic dinghy time and don't forget that honda generator with three onboard chargers plus the DC cable set for direct charging from the generator. There is more power options on the boat than needed really. Of course there is also a toaster and microwave with inverter to siphon off excess juice.

You know I have always liked battery systems so this is actually fun stuff for me.
 
Sorry I'm late tuning in, but I had to go back to the beginning & read the whole discussion and something seems missing. My question is how much battery do you need? I don't see where you have quantified it. I spent years reading sailing magazines with topics about going around the world and the power needs on a multi-year trip. What they taught is that first you have to determine your power uses. First you determine your amp hours per day needs. That is done by the amp draw(usually found on a label or instruction booklet) of every electrical device x hours needed (per day or per charge cycle). Add the amp hours for each device, (lights, stove, chart plotter, hair dryer & etc , add a fudge factor, and then see how well your existing batteries meet that projected draw.

I bought a '07 22 cruiser last year and began to worry about my electrical power use, especially with the 120/12 volt refrigerator since I usually anchor out. Those two batteries really looked small and insignificant. I really worried about failing to turn the switch at the end of a day and pulling both my starting and house batteries down and being "stuck" in some remote anchorage. I was worrying about buying a generator or adding batteries and worked myself into a lather. Then I did a test. It turns out that I have a very frugal refrigerator and it ran for 50 hours making ice cubes and keeping food cold before it drew down the house battery from 12.8 to 11.9 volts. Just a few hours running recharged it.

Conclusion: much ado about nothing. I've since found other things to worry about.

Chuck
 
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