Using thruster battery as part of house bank

A

Annie Time

Well-known member
Joined
Apr 19, 2010
Messages
136
Fluid Motion Model
C-28
Hull Identification Number
FMLT2710F819
Vessel Name
Annie Time
I remember reading a thread where someone had joined the thruster battery into to house bank. I have searched for the topic but can’t find it. Any help would by appreciated

Perry


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Perry,

I recently had a post regarding this issue:

viewtopic.php?f=5&t=15510

I also just communicated with the factory and here is there response:

I do not see an issue combining the thruster to the house. Just be aware that running a thruster with everything turned on the house could pose some power issues to the electronics or other devices. These take high bursts of power and why we don’t combine them.

Hope this helps.

Bob
The Doghouse 2
 
Hey Bob, thanks for the quick reply. That is the thread I was looking for. What did you do in the end? Did you worry about the battery charger? I’m thinking one switch in between the banks. When on the hook, engage the switch to combine and add the capacity. When the engine or shore power are on, disengage the switch, running in normal mode as delivered.

Perry


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Perry, why not just add an extra battery or two to the house bank? We have four house batteries. Easy to add more batteries! Adds weight but the extra Amp Hours really helps us going days at a time on the hook or mooring buoy.
 
The Doghouse 2":2dqfvs9q said:
I do not see an issue combining the thruster to the house. Just be aware that running a thruster with everything turned on the house could pose some power issues to the electronics or other devices. These take high bursts of power and why we don’t combine them.
Click to expand...

My opinion on this response is I agree but disagree ! The thruster, house and engine batteries are usually all connected in parallel when the engine is running and battery voltages are above 13V. The ACR are closed and the quickest disconnect is 10 seconds if the voltages fall below 12.35V or 30 seconds if the voltages fall below 12.75V. When you are coming into a dock and activate the thrusters all banks would be parallel and the voltages may drop from the spike from thruster activation but not enough to effect the electronics or set off a low voltage warning to the electronics.

I would not have the thruster battery permanently paralleled to the house bank. I would have a battery switch to do a physical disconnect. I don't need the house bank for thrusters ( actually most of the time they are connected (ACR)). I need the thruster battery for the house battery to extend battery capacity at anchor.

In theory the response is correct but in the operation and installation of the Ranger and Cutwater electrical 12V system the batteries are combined anyway via ACR.

If a boat owner had the house and thruster permanently combined there would be times when this could present an issue to the electronics when activating the thruster. ( Batteries in a discharged state).

In 5 seasons of using the thruster and house combined parallel via a battery switch I have never had an issue and have increased my house battery capacity by using a battery that rarely gets used. I have an additional 103HA battery capacity with no additional weight.
 
BB, I agree to take advantage of a battery that gets rarely used. I’m going to put a disconnect switch between the house and thruster, but like you may never need it.


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There’s a photo of my switch setup under the modification tab in my album. It’s been a great modification.
 
Chino, do you switch yours or leave it on all the time like BB.


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I use a battery switch for a physical disconnect. House and thruster battery. I do not keep it parallel all the time.
 
Annie Time":381lvui4 said:
Chino, do you switch yours or leave it on all the time like BB.

I switch to combine with the house batteries when I’m anchored etc. I disconnect before raising the anchor because the engine is running and the diesel alternator provides enough current for that using the thruster battery alone.
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Click to expand...
 
An update to this thread in case anyone is interested.

I just replaced the original 5 yr old batteries with three 105 Ah Lifeline AGMs and a dual purpose blue top Optima for starting. I also installed the Victron Smart shunt. I didn’t want to run wires and drill holes and the information displayed on my iPad is great (and large scale). So, equipped with new toys I went out yesterday and am on the hook (buoy) in Bedwell Harbour. When I arrived I switched the thruster battery in with the house. All batteries fully charged.

A couple of comments and findings after the first 24 hours.

I turned house and thruster power off. Pretty sure the ACRs were combining batteries anyway because the solar was keeping things at 13.4V. I was showing a discharge of 0.44A, presumably the direct wired items. Consumption showed at 52.3Ah. And SOC at 81% with the Victron set to 210Ah capacity 2 batteries or 89% from 315Ah. This would be influence by the solar which was kicking out 6A and showing it had produced 28.9 Ah total split 24.8 house to 4.2 engine as expected. I had also run the microwave for 3 minutes in the morning to make tea, with the engine running as usual.

That last item made me experiment later with the engine charging rate. I have asked whether anyone has an output/rpm curve for the d3 in the past. Seems it’s certainly not linear but load dependent.

With engine off and all dc off I was then showing 13.56V on both battery banks, net 57Ah consumed and 79% SOC (set for 2 batteries). I started engine and there was no immediate change in the readings when I turned on the inverter but I showed about 21A charging from the engine. I quickly turned on the microwave (boiling water) and ran it for 4 mins. The engine went under load but stayed at 700 rpm. Charging current went to between 110 and 106A as the microwave cycled. That’s obviously net of the microwave demand. I then ran the engine an additional 2 minutes with the microwave off before shutting down, total engine run approximately 7 minutes. At the end my net consumption had dropped to 49.6Ah and my SOC increased to 82%. That’s 89% of my three batteries.

Thoughts: The Victron is a fun toy.
The engine alternator really puts out power, even at idle. 13% reduction in Ah consumed in 7 minutes is useful to know.
The new batteries seem good. I know they are new and will deteriorate but the last 24 hours are not kind to them. I have the fridge set at 4 and minimal lighting +radio overnight but it’s 84 deg (28 C) inside the boat right now and it only dropped to 68 (20) overnight.

Maybe someone would like to run the same experiment for comparison? Maybe a d4 or and outboard? It may help some understand the systems on board and the advantage of running the engine or motor when running the inverter.
 
Additional commentary on combining the Thruster and House banks... this describes the modifications to my 2012 R27 done in 2013 and which are still in use. I've had the boat 1 year (batteries are 3 years old but in good shape showing specific gravity in all 24 cells of 1.25 or higher) and so far the thrusters work great (even both at the same time) and I've not had any other electrical equipment drop out. Hope this helps. GF
 
I've also combined the house with Thruster batteries, via the addition of another terminal switch. I enjoy the increased amp hours. I, too, have not had any electrical problems on other things when using the thrusters.

Best,
Bobby
 
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