Battery/inverter problem

[OldSailor41]

Our boat is a 2014 Ranger 31S, new to us last autumn, but had 2 previous owners. Engine hours when I bought boat were 250. First noticed that inverter would stop working a while after turning off engine and mooring without shore power. Only switches on were the refrigerator and maybe the water pump. Read inverter manual and noticed that a possible reason is low battery voltage. Voltage on #1 was down to 12 or so when this happened. I am wondering if maybe the house batteries are not holding a charge and I need all new house batteries or if there could be some other problem. If it is batteries, why would the batteries be failing so soon? What kind of batteries should I buy and where is a good source? BTW, the solar system seems to be working OK. Thanks for any help.

 

[SGIDAVE]

Our boat is a 2014 Ranger 31S, new to us last autumn, but had 2 previous owners. Engine hours when I bought boat were 250. First noticed that inverter would stop working a while after turning off engine and mooring without shore power. Only switches on were the refrigerator and maybe the water pump. Read inverter manual and noticed that a possible reason is low battery voltage. Voltage on #1 was down to 12 or so when this happened. I am wondering if maybe the house batteries are not holding a charge and I need all new house batteries or if there could be some other problem. If it is batteries, why would the batteries be failing so soon? What kind of batteries should I buy and where is a good source? BTW, the solar system seems to be working OK. Thanks for any help.

Hello OldSailor41,

If your house battery bank is original and you are the third owners, then there's a good chance the bank is shot. I'm saying you don't know the degree to which your boat's batteries have been abused prior to your term of ownership. Every time they are discharged below 50% SOC or left for intervals at less than 100% SOC shortens their lifespan.

HOWEVER, it's always good to know what is going on, so before randomly replacing stuff, get out your VOM (volt/ohm meter) and start checking voltages...of your batteries to start. For instance, what's the voltage when you shut down the engine on a mooring (no shore power)? Then, a while later when the inverter has stopped working...what's the voltage then (you said 12 above). Load testing your batteries is a good way to know if they are the problem...or, at least, ONE of the problems.

Second, from a philosophical standpoint, WHY is your inverter 'on' when all you have running is the fridge and water pump? These are both 12vdc devises, yes? And since the inverter's primary job is to change 12vdc into 120VAC....wha? why do you want that on? The inverter is not 100% efficient, that is, it consumes some amps whilst inverting the DC into AC...so it's a net consumer of your batteries 'juice.' Maybe do a little test...turn on the inverter and use some AC power. Start with something like 400-600Watts, like a curling iron maybe. See how long your batteries last doing that.

Let us know what turns up,

dave

 

[OldSailor41]

Dave, thanks very much for the advice. Very helpful and we will try your suggested battery tests. The reason for using the AC power is mainly only for a coffee maker and occasionally the microwave, both necessary (?) luxuries.

 

[knotflying]

Dave, thanks very much for the advice. Very helpful and we will try your suggested battery tests. The reason for using the AC power is mainly only for a coffee maker and occasionally the microwave, both necessary (?) luxuries.

I never leave my inverter on unless I am using 110v power. And when I use it I start my engine to compensate for the loss of amperage. Using the microwave and a percolator will deplete the batteries. Additionally, as Dave said, you don't know the condition of the batteries and if they have been abused or not. Once fully charged and rested you should do a load test. You can save yourself some trouble and buy an inexpensive load tester from Harbor Freight or even Advanced Auto or one of the other automotive supply stores.

 

[Nellie Too]

Never have your battery charger on with your inverter.