series-parallel combination circuits, now is time to screw it up

[SanDiegoChip]

Hi,
I have searched the forum and read many posts but so far have not come up with the answers. A lot of conflicting data it seems.
We have just relocated our house battery bank. We left the batteries setup exactly as they were only moved them. Everything is working fine now, the engine starts and all else is good.
So it is time to screw it up.

We have four Interstate batteries that are 220 ah each all 6 volt.
They are set up in a series-parallel combination by the PO.
We do not know how old they are but seem to all work fine. I did a cell test not long ago and they all passed.
All the boats functions run off these four batteries.
I am trying to figure out this circuit for ah usage and setting up a Link 2000 and a new battery charger inverter.
At present we are running the original 1978 charger into a selector switch and hooked to each series, that’s how it was configured.
Also are adding a H3 Lewmar windlass 1000w which draws about 85amps will be operating from the house bank. The windlass would need the 12 volts.
We will be adding a separate starting battery.
How should we attack this?
Should we first install a starting battery then re-configure these batteries?
Should we leave them as a series-parallel combination circuit and simply add a starting battery?
How can we get good windlass usage and at the same time get good ah out of the house bank?
So with the series-parallel combination would we then have 440 ah?
That would be 220 in each series?
Are we asking too much from the house bank?
We will be OK with 440 ah for now.
The picture is of the old setup in the old location. The new location they are setup the same only they are one behind the other.
OK the pictures are not the best.
Old location

New location


What is a series-parallel circuit? : SERIES-PARALLEL COMBINATION CIRCUITS
Thanks,
Chip

[Gene T]

I understand your dilemma. My recent boat came with 10 batteries. 8 6v for the house bank with 2 series 2 parallel twice for 2 house banks. 2 group 27's in parallel for the starting battery. So 880 house AH and ? for starting, but starting also runs windlass.

The inverter/charger is a 2500 and there is an additional alternator.

I was really nervous about all this at first but am warming up to is. Still haven't had time to figure out all the controllers yet.

Advice - such as it is - add a starting battery. You will need to run the engine when you use the windlass anyway so you can run it off the starting battery. I would use the house bank until you have a problem with one of the batteries. Then I would probably split it in two for 2 house banks. The problem with parallel setups is if one battery goes bad you need to change them all.

But: there are so many ways of doing this I would take the time to research figuring in your needs. There is a great spreadsheet on sailnet somewhere for calculating your needs. Do a search you will find it.

Gene

[Gene T]

I found the spreadsheet, it is not on this board. Try here Amp Hour Load Calculator - Did I Miss Anything? - Cruisers & Sailing Forums

Gene

[sailingdog]

Originally Posted by SanDiegoChip

Hi,
I have searched the forum and read many posts but so far have not come up with the answers. A lot of conflicting data it seems.
We have just relocated our house battery bank. We left the batteries setup exactly as they were only moved them. Everything is working fine now, the engine starts and all else is good.
So it is time to screw it up.

We have four Interstate batteries that are 220 ah each all 6 volt.
They are set up in a series-parallel combination by the PO.
We do not know how old they are but seem to all work fine. I did a cell test not long ago and they all passed.
All the boats functions run off these four batteries.
I am trying to figure out this circuit for ah usage and setting up a Link 2000 and a new battery charger inverter.
At present we are running the original 1978 charger into a selector switch and hooked to each series, that’s how it was configured.

Why was the selector switch needed? Were these treated as two different banks? If so, combining them at this point may be a mistake, as they may have significantly different usage histories.

Also are adding a H3 Lewmar windlass 1000w which draws about 85amps will be operating from the house bank. The windlass would need the 12 volts.
We will be adding a separate starting battery.
How should we attack this?
Should we first install a starting battery then re-configure these batteries?
Should we leave them as a series-parallel combination circuit and simply add a starting battery?

Unless these batteries are all of the same age and use pattern, I would recommend getting new batteries for the house bank if you can. If not, combining them into a single large house bank is really your only option. Then add the starting bank.

How can we get good windlass usage and at the same time get good ah out of the house bank?
So with the series-parallel combination would we then have 440 ah?
That would be 220 in each series?

Windlass usage doesn't much matter as you really should be running your engine whenever using the windlass. This is for two reasons...first, you may need to move the boat under power... second, the windlass requires 13.5 volts, which you will really only get when the engine is running and the alternator is putting out electricity.

Are we asking too much from the house bank?
We will be OK with 440 ah for now.
The picture is of the old setup in the old location. The new location they are setup the same only they are one behind the other.
OK the pictures are not the best.
Old location

New location


What is a series-parallel circuit? : SERIES-PARALLEL COMBINATION CIRCUITS
Thanks,
Chip

Again, the Link 2000 will give you a lot of information on whether the battery bank is really properly sized for your usage and charging patterns.

[SanDiegoChip]

At present we do not have many needs. Our refrigeration is a work in progress. At this time we are using a Koolertron cooler for it. Our instruments are a hand held chart plotter.
We removed the old engine driven refrigeration and that’s where we are installing the starting battery.
We have installed but have not wired up our new charger\inverter.
We have but have not wired up our new solar controller.
We have installed one 135 watt solar panel so far but have not wired it up yet.
We have almost installed the windlass. It will get fiscally installed this weekend. Have just cut the mounting boards etc.
It will not be wired up for a couple weeks.
We have converted most bulbs to Led and replace old fixtures.
We have a bunch of fluorescent lights that I am not sure how to convert or replace them. Replacing would leave ugly old mounting places.
We will be getting a wind generator but that’s later.
We have a new Honda 2000 generator.

So as you can see it is a mess.
We want to start anchoring soon. So we are going to add the starting battery and use a trickle charger on it.
We will keep the battery bank the way it is for now.
We will hook up the link 2000 and see what’s going on with the batteries.
The anchor windlass wires would need to run through the engine room to get to the starting battery. We could lose up to 20% because of heat in the engine room.
The alternator is hooked to the house batteries.
I think going to the house bank will be fine but I will make sure we have enough length in them to move them to the starting battery if we change our mind. Have not ordered them yet. Next week we will. There is not much difference in length.
On replacing the batteries, $$$$
They seem fine now. We want to cruise in 2 ˝ years. So if we could get a couple more years off them that would be great. We would like to replace them with AGM’s. However I have heard that AGM’s need to be cycled and sitting at the marina on charge all the time will not make them last. Also like I said $$$.
Sounds like a plan.
Thanks
Chip