2008 R25 battery replacement

[jimbeam]

The boat has 4 five year old lead acid batteries and would like to replace them. I am thinking that I could tie in the thruster battery to the starter battery and save weight and plan on AGM's size 29, which is the size of the old batteries. Sounds like a plan but need input as to the idea and if it is practical.
Jim

 

[scross]

Jim,
At five years old it’s probably a good idea to be replacing your batteries.
Our 2009 R25 Classic uses group 27 size batteries not group 29s. Will the 29s fit?
Also, the prior owner added two extra house batteries to Our Journey so we have 6 batteries in total. I’m happy with that because I think it gives us more time on the hook during our cruises. I’m not concerned about the extra weight of the additional batteries. Until the price of AGM batteries come down more I’m sticking with the conventional lead acid type batteries.
Using a single battery for both thrusters and engine starting is an option but you are somewhat reducing your options to respond to battery problems when in remote areas.

 

[knotflying]

Here is my humble opinion, keep it as simple as possible: a) I would keep the engine battery as a single entity so that if on the hook should any electrical issue arise from other systems it will be less likely that the engine battery will be drained. b) when all systems are working correctly and the engine is running all batteries are joined via the relays so why join the engine and thruster. c) if I were to join batteries I would tie the thruster to house and have a switch between them so you can isolate the thruster battery from the house or join it for additional amps when on the hook. d) your batteries are are most likely group 27, You may be able to fit Group 31 to get more amperage, but I would check the sizes to make sure they will fit. e) I am a proponent of flooded on the 25 and 27. They are easy to access. There are many things that we cruisers do unintentionally that can destroy the charge on the batteries and AGM, although tolerant, can also be destroyed. Hence, I would rather destroy a $90.00 Walmart battery than an AGM.

Just some thoughts to consider.

 

[Cutwater28GG]

i wouldnt tie thruster to engine. do thruster to house but only as a last resort.

your thrusters will kill the battery after some use and take hours to recharge to full.
house electronics like the garmin dont like large voltage drops and hence ranger keeps the thruster off the house battery.

 

[Red Raven]

I replaced the Thruster battery switch with one that includes a combine positIon to combine it with the house. It gives us 50% more house when on the hook and I only use the Thrusters and Windlass when the engine is running. I have left the Thuster battery combined even when under way for days and never had the electronics complain when using the thrusters or windlass.

Curt

 

[j&lgray]

I agree with Knotflying on his theme of battery choices and engineering.

Having had an R-25 for 7 years and now have a classic R-27, what worked very well to increase the house battery capacity was to replace the two 12-volt house batteries with four 6-volt batteries that added a lot more amps. Pay attention to how these are wire together, in two pairs of 6 volts each. I put two of the 6 volts on the starboard side of the boat which helped in weight distribution. With this solution, a solar panel nor a generator was needed to be at anchor for 3 full days.

 

[knotflying]

I agree with Knotflying on his theme of battery choices and engineering.

Having had an R-25 for 7 years and now have a classic R-27, what worked very well to increase the house battery capacity was to replace the two 12-volt house batteries with four 6-volt batteries that added a lot more amps. Pay attention to how these are wire together, in two pairs of 6 volts each. I put two of the 6 volts on the starboard side of the boat which helped in weight distribution. With this solution, a solar panel nor a generator was needed to be at anchor for 3 full days.

Just keep in mind that when joining batteries in parallel volts stay the same but amperage doubles.
When batteries are in series voltage doubles, but amperage stays the same.

Hence changing to four six volt deep cycle batteries will accomplish two things; a) the batteries are truly deep cycle and will hold a much deeper charge and b) there will be double the amperage available because of the added batteries.
With that said, I would first think about how you are using the boat and what your needs are with regard to amperage required. If you anchor out for long periods, say longer that 2 days, you may want to consider the six volt conversion route. On my R-27 with thruster joined at anchor, 135 watt solar panel. refrigerator on all the time in hot weather I can squeeze by for three days and then it is either move on to another spot and charge up the batteries on the trip or go to a marina and get on shore power.
Sometimes better is not what is needed and just adds complexity and cost to the situation.

 

[BB marine]

The boat has 4 five year old lead acid batteries and would like to replace them. I am thinking that I could tie in the thruster battery to the starter battery and save weight and plan on AGM's size 29, which is the size of the old batteries. Sounds like a plan but need input as to the idea and if it is practical.
Jim

The answer to your question is more opinion based. Everyone has an opinion on the best way to utilize batteries and get the best performance and longevity. Many have a reason why they use a certain type of battery and how many. The best answer to the question is based on how you use your boat. If higher amp hours for the house battery is important ( anchor out most of the time) then install the highest amp hr deep cycle batteries available or use 6 volt in series. If having a dependable high cranking amp battery for a start battery is important look for a High CCA amp battery ( it will have a lower amp Hr rating.) If you are concerned about the weight of the batteries and are comparing the pluses and minuses of Flooded to AGM's make your decision based on how you use your boat.

I was on the fence between Flooded and AGM batteries. I originally had flooded maintenance free group 27 92 amp hr.dual purpose deep cycle house and thruster and a 900 CCA starting battery for the engine. I tied the thruster battery to the house circuit with a battery switch ( option to use it in the house circuit or not) in case I needed more amp hr capacity if we were at anchor. The house batteries lasted 3 full boating seasons. Cost of replacement around $600.00 if I shopped around $450.00. Weight of of the 4 batteries 3 dual purpose 43lbs each the cranking battery 48 lbs total 177 lbs. I started shopping AGM's ,reasons, better longevity ? faster charge rate ? fully sealed and not vented (yes) weight 67 lbs all four rated duel purpose 92 amp hrs and 930 CCA total 268 lbs 91 lbs more in the aft section of a boat that is stern weigh sensitive. Cost $1200.00.

The biggest reason for switching to AGM is the battery venting. Ranger and Cutwater boats do not have a true marine ventilation system designed in their boats. The cockpit area is the continuation of the engine compartment and ventilation. I have a full enclosure for my cockpit. If a flooded battery vents gas the only way for this gas to escape is through the openings between the hull and the cockpit liner into the cockpit. There is no flow of fresh air in and compartment air out. Normally the amount of gassing is minimal and should not propose a problem unless a battery fails. This happened on my boat. I had a failed battery, the charger was charging all batteries at the rate needed to maintain the failed battery, ACR all closed. The charger output started "cooking" the batteries. I had the enclosure closed up except the transom door opening and I was working inside for hours. A marina technician was walking by the boat and yelled out a "hi" to me. I started talking to him and he asked "what's that smell?" "It smells like rotten eggs " I didn't smell anything I had become use to it as the gases increased. He said " it is hydrogen Gas. " I immediately opened the battery compartment and the gas concentration was very high and batteries were warm one was hot. I lifted all hatches and opened the side curtains to vent off this gas. AGM's in an over charge condition will gas too if the pressure inside the battery gets to 3 psi. There is an internal relief valve. The flooded will vent continuously. This is rare but it happens. I chose AGM's for this reason. Probably not the reason of most.
I have increased ventilation into the compartments and installed exhaust blowers to help move fresh air in and pull air out. Batteries should be installed in well ventilated storage compartments.

Jim we all have our reasons for battery types and configurations. If reducing battery counts to 3 works for you based on the way you use of your boat do it. I would caution using the thruster and engine combination though. The engine if common rail injection which most if not all Ranger and Cutwaters are have battery requirements. Having a voltage spike when operating the thrusters may or may not effect the operation of the engine. I would not want to take that chance. Using the house would be my choice if I was eliminating the thruster battery. My opinion.