Boat electrical setup

[SteveJ]

Hi all, appreciate any views on the way the batteries have been configured on our boat: we've had it for less than two years so we've inherited the configuration. The boat is a CheoyLee 34' trawler (mid 1980s) with twin Ford Lees 120hp deisels. I have just replaced both the house bank (4x140AH AGM batteries) and the start battery (1x1030 CCA). This is a 'like for like' replacement for what was installed and was driven by the age of the batteries, measured and observed average performance from both banks and lack of knowledge of their lineage and history. The new batteries have been in a month and are working very well in comparison. My question relates to to the way they have been configured with a voltage sensitive relay. My understanding is that both engines charge the start battery, which upon reaching 13.3V closes a circuit through the VSR and allows the engines to push charge into the house bank. Both banks remain connected until the start battery reads 12.8V when the VSR opens and isolates the start battery. Which makes sense to me - keeping your start battery fully charged even if your house bank is discharged. With solar panels charging the house bank, it is usual for the battery banks to be connected. So... when it comes to starting the engines should I be concerned to do so if the banks are connected? I have a large capacity (1030 cold cranking amp) start battery - should I isolate this from the deep cycle AGMs (which I can do) or is it ok to leave the two banks (and two different types of batteries) connected when I start up? I've included a diagram of the setup. Thanks in advance for any advice.
Regards, Steve

 

[Lou_tribal]

Based your comment about your vsr and your schematic, start bat will never charge through solar so wondering why not everything is following the same path (meaning solar, charger, gen) so you know all batt charging whatever the source.

L

 

[O C Diver]

What amperage size are the alternators?

Is there a manual bypass for the VSR in case it fails?

Does the VSR only work when one of the engines is running or all the time?

It seems like your VSR would be cycling a lot as the alternators charge the start battery and then discharge it to the house bank. That's inefficient as you lose power in the process of changing and discharging a battery.

It takes significant amperage to start an engine, but very little amp hours. As a result, I would wire one of the alternators directly to the house bank.

Ted

 

[High Wire]

Your setup will work as is as long as the start battery gets charged fully once a month or so.
Are you sure the vsr doesn’t also close on house side voltage above 13.3 volts? If it does then the start batt will also get automatically charged.

 

[Bmarler]

i think it'd a fine setup. the start battery is first in line for charging. when it's been charged to 13 or whatever it will bring on the house bank. i wouldn't worry about charging the start battery with the solar, but maybe a manual parallel switch would be a good idea so you can start the mains with the house bank if needed, or if the relay fails.
it looks like there's a battery charger for shore power use, i'd want to be sure it charges both banks. if it's aimed at the start bank hopefully the relay will close and charge the start battery too. if not, moving it's output to the start battery will do the same thing as the alternators do, bring up the start battery first then do the house.
the other option would be to use a maintainer on the start battery when on shore power. i do this on one of my boats and it works well.
i like the idea of both alternators output tied together, cause if one fails, the other will keep things going. i'd want to have some sort of monitoring on them to be sure they were both working though. there must be some sort of combiner for the alternators right? like a balmar centerfielder or similar?

 

[Bkay]

I'm not familiar with Wise Owl, and there doesn't seem to be much on the internet that I can find. But the things I was trying to confirm are:

1) Does the VSR connect ONLY when there is charging on the start batteries, or when EITHER bank has a charge? In my experience (albiet limited) a VSR senses voltage in either bank and connects them. Than means your solar could be causing the VSR to connect the banks when the house batteries are charged. My concern would be whether two different charging profiles are needed for the banks (You didn't state this, but I got a feel the start were not AGM. I may be wrong on that.). Test with the battery charger connected to the house and see if the starts are connected at that time.

2) Generally there is a surge protection in the VSR - so if the banks are connected and you start the engines, the VSR will disconnect and not allow a rush of power to your house bank. The info I could find on Wise Owl references "ignition protection", so again, you could test this by monitoring house bank while someone starts the engine.

3) Someone mentioned the cycling of the VSR as it charged the house bank. My understanding is this is not an issue. When the VSR senses one bank has a charge going to it and connects, then the current flows to the path of least resistance or the lowest charged battery. Current does NOT flow from the charged battery to the discharged battery, so there is no on-and-off cycling. At least, this appears to be the case with my Blue Sea VSR - I hoped to check whether it was the case with your Wise Owl but couldn't find that info.

4) It does appear you have a manual switch to parallel the batteries in an emergency. Is that correct?

 

[tiltrider1]

This set up works and it is how things were done in the 80’s. The weakness of this arrangement is overcharging the start battery when the house bank is low. A better arrangement would be having all charge flowing directly to the house bank and then a Smart ACR between the house and start banks. This prevents overcharging of the start bank but allows the start bank to be charged from both shore or solar.

 

[SteveK]

The schematic shows shore/generator directly charging both the start and house. How are the two isolated from each other at that point?

 

[SteveJ]

Additional info…

Thanks everyone for your thoughtful comments. A few answers to the questions posed in the thread:
- original alternator is a Lucas putting out 55A (port)
- have replaced alternator on Stb with closest match possible and it puts out 75A
- VSR is active all the time (not just when the engines are running)
- VSR only closes on Start bank
- VSR has an over-ride setting which connects the banks irrespective of the charges
- House bank are AGMs and the Start battery (one) is a heavy duty truck battery (maintenance free lead acid)
- Switch board allows me to parallel the banks (eg for emergency start). I can also isolate each bank individually

Soo-Valley thanks for noting the manual shore / gen charging capability. Whilst the chargers are set to the profile of each bank the VSR will connect them virtually straight away (at 13.3V). Am wondering if it is sensible when back at the dock to isolate the start battery and connect a maintainer. The solar will keep the House bank topped up and I don’t have the cross-over charging problem?

 

[rgano]

This set up works and it is how things were done in the 80’s. The weakness of this arrangement is overcharging the start battery when the house bank is low. A better arrangement would be having all charge flowing directly to the house bank and then a Smart ACR between the house and start banks. This prevents overcharging of the start bank but allows the start bank to be charged from both shore or solar.

Especially with a single engine as I have, There is a manual parallel switch in my set up with full start current capacity between house and start. Had to use it once when boat was at a pier with no power for a few days and the old start batteries showed their weakness.

 

[SteveK]

with dual engines I favor one to start and one to house battery. As said I agree the VSR should be reversed so start is not overcharged, then in this case the solar will keep start topped up.

The shore/generator charging both start & house should be isolated.

 

[rgano]

My Blueseas ACR (VSR, if you like) operates in both directions. Hard to imagine a one way VSR, but ya never know.

 

[O C Diver]

- VSR is active all the time (not just when the engines are running)

That would be a conceptual problem for me. When I shut the engine(s) down, I want nothing drawing power off the start battery if at all possible.

The other consideration is if the VSR "sticks" closed.

It would also be interesting to know if the setup (combining the alternators, going through the start battery, going through the VSR, and finally reaching the house battery), acts as a flow restriction. Simply, do the alternators' regulators sense an elevated voltage and reduce charging amperage, as they are measuring the start battery voltage and not the house battery voltage.

Don't suppose the alternators are using external multi stage regulators to increase deep cycle charging?

If you have access to a clamp style DC amp meter, it might be worth checking the alternator outputs after a night on the hook and then getting underway.

Ted

 

[Bacchus]

When I was doing some charging system mods on our Mainship and eliminating diode isolators I researched several alternatives. I was concerned that if start/thruster bank & house bank were combined and thrusters activated I could get a hi amp flow through the VSR. ProMariner adviser that they would not recommend there ProIso charge in that application. I found and use a Sterling CVSR that is capable of handling and disconnecting when Hi amp flow is sensed.
For a more complete write up & component manuals, schematics etc see my Bacchus website - Projects - Page 4 - Charging System Mods

 

[Mischief Managed]

I would replace the VSR with a Blue Seas ML-ACR It combines when either battery bank is being charged (or manually from the helm or engine room), is rated at 500 amps (so combining for starting allows for a substantial boost), and if you connect your start circuit wiring to it, it will automatically disconnect (unless manual override is selected) the two banks when either engine is started. I replaced a battery isolator on my boat with one and it works great. I think it would address all of the shortcomings of the VSR in your setup and it's not very expensive.