Battery Charging parameters

colbysmith · Posted: Fri Jun 30, 2023 9:06 am Post subject: Battery Charging parameters

C-Travelers outboard was set up with charging to the start battery, through a 50A CB, from a point on the Yamaha 150 that looks like an electronic module with several wires running into it. I’m concerned this may be overcharging the battery as the Victron BMV714 is showing a voltage of 15.6 at higher RPMs and around 14.3 or so at idle. I can average this voltage down by placing the battery switch in both or Batt 2, thus paralleling with the regular battery charging…off the alternator?. For this reason I’ve routinely switched to both after starting. However sometimes I would like to just switch to Batt 1. Does anyone know what that electronic module is for and if it should be hooked up this way to the battery? I’m wondering if it has something to do with spark control…. I believe this was done by a shop the previous owner used. Colby

jkidd · Posted: Fri Jun 30, 2023 10:03 am Post subject:

Got a picture of it?

colbysmith · Posted: Fri Jun 30, 2023 10:54 am Post subject:

thataway · Posted: Fri Jun 30, 2023 11:12 am Post subject:

Colby, no ACR? I have been using these for years, That way you do not have to do the battery switch. Also safer for the batteries. When you are under way, there should be a load on the house battery.

I am a bit puzzled that the charging circuit comes thru a 50 amp breaker. Normally the charging lead does not have a breaker. If the breaker trips, then open circuit to the alternator, and risk of damaging the diodes.

Outboards generally are not as well regulated as many other charging circuits and convinces, so that seeing a high voltage is not that unusual. If it persists, just add a resistive load such as turning on the navigation lights.

It is possible that the lead you have is the auxiliary charging lead, and the main charging is done thru the start battery cable--as in many outboards.

colbysmith · Posted: Fri Jun 30, 2023 11:57 am Post subject:

thataway · Posted: Fri Jun 30, 2023 2:55 pm Post subject:

Yes, it is very likely that this cable is the auxiliary charging cable. If that is the case and it is hooked up directly to your house battery (2 batteries certainly better for a well equipped C Dory 25.). If it is not the auxiliary charging cable, then you should be using an ACR. Check your engine manual to see if this is the aux charging cable.

colbysmith · Posted: Fri Jun 30, 2023 4:26 pm Post subject:

An ACR just does the same thing my switch does, but automatically. The problem is, it won't allow you to chose when and which battery is being charged or used. Thus, I'll stick with my old fashioned switch. The house batteries can only be charged through their main battery cable, and chosen at the main battery switch. (1, 2, both). The separate wire I'm talking about is on the starter battery and I think I remember the previous owner said his shop wired it up this way to make sure it stayed charged.... Anyway, here are some photos of the area on the top of the Yamaha F150 I was talking about.

Looking at the second and fifth photos, I would need to trace the wiring again, but I'm pretty sure it is the red wire where two are hooked together on the terminal post on the second photo. That wire is coming in from the CB (8 gauge, then spliced to a 10 gauge in the front of the engine cowling), the other wire is the red one in that last photo at the starter relay. I didn't get a photo of the CB that the wire goes thru on the way to the starter battery, but it's one of those thermal CB's with the push button that pops the "arm" that can be reset, so used as a switch as well. They come with the Lewmar windlasses. Colby

Robert H. Wilkinson · Posted: Fri Jun 30, 2023 5:52 pm Post subject:

15.6 is in the equalization range and will boil a FLA battery dry. Keep an eye on the acid level - if it goes below the plate level it causes irreversible damage. On the plus side you shouldn't have to worry about sulfation!

Regards,

Rob

Dora~Jean · Posted: Sat Jul 01, 2023 3:16 pm Post subject:

I have a separate Link 10 monitor for each starter battery which are DIRECTLY connected to their respective engine (twin Yami 80’s). I typically read 14.5-14.8VDC on each engine. That’s just a tad higher than automobile regulators are set for (older ones at least). I believe they run outboard regulator voltages a bit higher to account for generally shorter runs than say an automobile. One of my batteries is almost 6 years old and seemed still fine even on the trip to Friday Harbor and PLI. I have a 1-2-Both switch to select which battery will be the house battery for the day (or days).
I agree with Dr. Bob, your engine should be directly connected to your start battery, not through a switch or CB. Too much risk for engine (alternator or regulator) damage.

rogerbum · Posted: Sat Jul 01, 2023 9:25 pm Post subject:

colbysmith · Posted: Sun Jul 02, 2023 1:35 am Post subject:

colbysmith · Posted: Sun Jul 02, 2023 2:10 am Post subject:

Doing some more internet research, it appears that the Yamaha F150 does have an auxiliary charging lead. I had not heard about that until Bob mentioned it. (Thanks Bob!) And from what I can gather, the 50 amp fuse, which happens to be close to the battery, is just protection from any current the battery can put back through the wire. I still haven't been able to find out anything as far as what voltage should be running from that aux output. So with that lead going to my starter battery, it seems like it negates the need for an ACR. My battery switch allows me to choose which battery is powering stuff, and which battery is getting charged from the outboard's main charging system.

thataway · Posted: Sun Jul 02, 2023 7:51 pm Post subject:

That is correct. But beware of the infernal combustion engine. They fail. Need to have a sail or oars, just in case...