Battery charger only charging Genet battery?

[km1125]

Source of the post
... When I went to the boat Friday I turned off the main battery switch so there is no longer any drain on batteries to see if they would recover. ....

That will not stop all loads from the batteries. There are a few (notably bilge pumps, CO detectors and perhaps fume sensors) that usually bypass the main battery switch. There could be others too that a previous owner installed.

There are three breakers on that panel you posted. In the pic, it's the upper right (but the pic is upside down). Those should be the ones isolating the charger from each of the batteries. While that location makes sense for the starting batteries, it doesn't really for the genset battery, but it's probably there for convenience. There probably should be another breaker/fuse in the line to the genset battery located closer to the battery. The other two are within close proximity to the master switch, and provided the big lines from the master switch to each battery are protected from physical damage, would meet the ABYC requirements for location.

[bud37]

Good to see the original location.....that may mean the original harness is being used. If that is the case then those breakers are the only thing between the charger and the batteries as the #1 and #2 breakers are wired to the main battery iso switch......the gen has its own charge cable that runs to the gen battery from the breaker. In the bilge the main cables are labeled #1 and #2 if the tags are still there....that corresponds to 1 and 2 on the switch.
The generator battery has its own on /off main switch mounted on a stringer near the gen which also charges itself while running.
The breakers that say bilge and the CO breaker are hard wired to the batteries, I forget which one, but there is a diagram in your manual.....also on the other side is the stereo memory which is also hardwired.....non of these are controlled with the main battery switch.

Lets say that is how my boat was as original. Lets see what you find out today.

[Dark Horse]

Here is the pamel

[Dark Horse]

Okay. Just measured voltage at batteries with main switch off. Both engine batteries at 9.63v. Genset battery at 12.07v.
Turned off battery charger with main switch still off. Engine batteries at 6.77v geset still at 12.07v.
Turned charger back on measured volts at terminals on charger. Both engine cables at 9.63v. And genset at 12.07.v.
This all leads me to think charger is bad because it's not putting anywhere close to the 12 v o need to keep batterys charged.
I have main batteries on regular charger now but keeping master switch off.
Pretty sure I need a new charger.

[bud37]

So it does seem bad for the charger but did you clean all the terminals especially the grounds at the batteries and the charger ground as Viper suggested ?? Was there any flashing warning lights on the charger when you first checked it, have you reset the charger by shutting the 120vac off to it then turning back on ?

I guess the other question for me would be, is this something that just started or have you been fighting this since you got the boat ?
Don't condemn that charge yet , try it when you get the batteries fully charged....that means 12.8vdc. If the charger is good it will just go to float around 13.2 vdc.

Your gen battery at 12.07vdc is effectively dead......if this has been going on for a long time these batteries may be sulphated.

Regarding the panel....the stereo memory is on...turn it off when you leave for now, it is parasitic for sure especially with old stereos. If you decide to replace, my advice would be to go with a promariner 1250P, plug and play except for an extra case ground, your original for that boat was 50amps.

That is all I got .....good luck man

[Dark Horse]

Yes sir terminals clean when I put new batteries in 2 weeks ago. Cleaned ground no difference. The bank numbers flash when batteries are low but that's it. Did turn off 120 to charger and back on. Waited for it to reset, no change.
This issue has only recently popped up. First 2 years with boat i never had a problem. Couple week ago engines wouldn't start. Figured the batterys were toast so bought the new ones. Now I'm thinking it was the charger all along but hey got new batteries in It.
Guess I was hoping for a better answer but it looks like a new charger on the horizon for me.

[Viper]

Have you measured the supply voltage to the charger at the charger's inlet terminal block yet? There should also be an internal fuse for the AC side. Check to make sure the input terminals are tight and clean and make sure the fuse block contacts are free of corrosion and the fuse is tight. I would also measure the fuse to ensure there is no appreciable resistance.

You may also want to check the troubleshooting section of the manual, they may have something pertinent to that model that might offer some insight. You can also contact Mastervolt and ask to talk to a service tech, there might be an issue they're aware of on that model, they may even offer to help you remedy the problem in some way with either a repair or replacement. BTW, if you do call them, they'll likely want the answers and results to similar recommendations and questions we've made here so I would follow through on those first so you have some answers before you call.

[Midnightsun]

Really sound like the charger is toast if you want my opinion however it sounds like it is not very old as it is not the original Charles charger. That being said, I agree a call to Mastervolt may help you locate an internal fuse or get some trouble shooting tips from them. It does sound like it's getting power though since you do mention charge indicator lights in the initial post. Does it look like this?

https://www.mastervolt.com/products/pow ... -12-40-31/

[Dark Horse]

Yes that's the one. I have reached out to Mastervolt but no response yet. (But it is a holiday for some companies today so i don't expect a response yet)

[Dark Horse]

Final update (sorry for the delay).
After much conversation with Mastervolt, they have determined the charger is no longer functioning correctly.
However the cost of repair outweighs just buying a new one which is what I ended up doing.
Installed new charger and all is good once again!