Batteries on opposite sides of boat?

[Graham376]

If anyone knows a better way of mixing batteries in parallel, please post a link or diagram, rather than negative posts and opinions.
Finally I would remind anyone constructing a large parallel battery bank that in the end using another battery selector to divide them up is definitely the way to go,
PS: I don't base my posts on anything I find in the internet, but what I try to do is provide links to confirm my opinions and to provide more information.

Having read your posts, I really can't understand where your advice is coming from. Diodes have no place in paralleling batteries and switching every battery is unnecessary and just complicates matters. The OP's question was answered in post #2, parallel them together preferably alongside each other. It is of course better if both are identical and the same age but not crucial. I speak from a few decades of practical experience, not theory, having tried most combinations of battery connection.

 

[TNLI]

Having read your posts, I really can't understand where your advice is coming from. Diodes have no place in paralleling batteries and switching every battery is unnecessary and just complicates matters. The OP's question was answered in post #2, parallel them together preferably alongside each other. It is of course better if both are identical and the same age but not crucial. I speak from a few decades of practical experience, not theory, having tried most combinations of battery connection.

Diodes have no place if the batteries are of the same type, and I'm not suggesting installing an extra switch for every battery. For example if you have 4 house batteries, then I would just install one switch.
It's a bad idea to mix different age batteries in parallel, and I'm surprised anyone would say it's not.

 

[Graham376]

It's a bad idea to mix different age batteries in parallel, and I'm surprised anyone would say it's not.

It depends on how wide the difference is. I would not parallel a new one with a 5 or 6 year old one except on a temporary basis but wouldn't worry about a good battery a year or two old.

 

[Tranona]

Diodes have no place if the batteries are of the same type, and I'm not suggesting installing an extra switch for every battery. For example if you have 4 house batteries, then I would just install one switch.
It's a bad idea to mix different age batteries in parallel, and I'm surprised anyone would say it's not.

You really do seem to have little understanding of how house banks in small yachts are wired up, instead you keep on about the problems of mixing battery types and then dreaming inappropriate solutions to a non existent problem. The Ops question was simply whether it was sensible to have the batteries in the bank in different locations.

The almost universal way of building house banks is to parallel two or more batteries of the same size and type, usually multiples of 100-130ah capacity to achieve the desired total capacity. This size is chosen because it is relatively easily handled and packaged in the restricted space on yachts. The bank is then treated as one battery, with one isolator switch and charged as one from the charging systems the boat has - engine alternator, solar, wind, towed or whatever. There may well be a split charging system to enable a completely separate engine start battery to be charged from one or more of the same sources, although this was not what the OP asked about.

Why do you find that so difficult to understand?, given that it has been explained to you in some detail already?

 

[jwilson]

To add to Tranona - the correct way to parallel 2 batteries into one bank is as shown here - this exactly splits the load between them. Boat load leads going to the same battery gives the other battery slightly less work due to the (hopefully small) resistance in the leads.

The OP should probably put two house batteries one side (wired as shown) and the engine start on the other, to minimise lengths of heavy cabling. I would not want very long or thin leads between paralleled batteries.

 

[TNLI]

VICTRON ARGO DIODE BATTERY COMBINER 80A FOR 2 BATTERIES CAMPERVAN BOAT MOTORHOME 8719076020974 | eBay

That way of combining batteries of different types or ages is used for caravans and fairly cheap, BUT is of no use if you need to use a house battery for emergency starts, due to max load limits. It also provides a type of expensive emergency short circuit protection for the battery, as diodes melt when shorted!

My last 2 yachts both had normal battery installations with a house battery consisting of 2 sealed batteries wired in parallel of the same type purchased at the same time, although I would try to avoid using more than 2 batteries in parallel, as they all need to be replaced together if one fails before the others.
I'm presently building an offshore lifeboat and the regulations as regards engine starting are better than for an offshore yacht, so I have 2 start batteries. I also have 2 house batteries controlled by a second battery selector.

In safety or reliability terms it's always best not to put all your eggs in one basket, which is why I don't like house battery systems that consist of too many batteries wired in parallel. Battery selectors are not too expensive and are an easy way of improving the efficiency and reliability of a large bank of house batteries.

I would note that the build regulations and standards of most yachts are very poor in safety or reliability terms, so just because most manufacturers only fit one start battery and one battery selector, does not mean that is how it should be done. The same clowns that wrote them think it's a good idea to only fit one bilge pump. My lifeboat will have 6 bilge pumps for 3 watertight compartments, even though it's only 27ft.

 

[PaulRainbow]

VICTRON ARGO DIODE BATTERY COMBINER 80A FOR 2 BATTERIES CAMPERVAN BOAT MOTORHOME 8719076020974 | eBay

That way of combining batteries of different types or ages is used for caravans and fairly cheap, BUT is of no use if you need to use a house battery for emergency starts, due to max load limits. It also provides a type of expensive emergency short circuit protection for the battery, as diodes melt when shorted!

Good heavens, that's just complete nonsense, again. Yes, you could connect different battery types to your domestic systems, but they would likely have different resistances and one battery would do most of the work, potentially being depleted to an unacceptable SOC whilst the other battery doesn't do much at all. This is not the purpose of the device.

You can still start an engine if one of these is fitted, you simply fit the emergency switch before the diode.

Using diodes in place of fuses is stupid, plain and simple. If the diode fails closed circuit, which they can do, you could very easily have a fire. If a circuit needs a fuse, fit a fuse.

My last 2 yachts both had normal battery installations with a house battery consisting of 2 sealed batteries wired in parallel of the same type purchased at the same time, although I would try to avoid using more than 2 batteries in parallel, as they all need to be replaced together if one fails before the others.

That also makes no sense. Not paralleling batteries in case one fails and you have to replace them all is daft. If you fit one battery and it fails, what do you do, change half of it ?

I'm presently building an offshore lifeboat and the regulations as regards engine starting are better than for an offshore yacht, so I have 2 start batteries. I also have 2 house batteries controlled by a second battery selector.

SOLAS regs cover lifeboats and are not any better than a decent yacht system:

3. Starters
3.1 The engine shall be provided with either:
(LSA 4.4.6.2)
− a manual starting system, or
− a power starting system with two independent
rechargeable energy sources

Any yacht that has a domestic battery bank can and should comply with that regulation by having an emergency parallel switch. Every battery installation i have ever installed has had such a system and my installations are far from unique in that respect.

In safety or reliability terms it's always best not to put all your eggs in one basket, which is why I don't like house battery systems that consist of too many batteries wired in parallel. Battery selectors are not too expensive and are an easy way of improving the efficiency and reliability of a large bank of house batteries.

You cannot improve the efficiency of a large battery bank by splitting it up, in fact, you make it less efficient.

I would note that the build regulations and standards of most yachts are very poor in safety or reliability terms, so just because most manufacturers only fit one start battery and one battery selector, does not mean that is how it should be done. The same clowns that wrote them think it's a good idea to only fit one bilge pump. My lifeboat will have 6 bilge pumps for 3 watertight compartments, even though it's only 27ft.

Given the posts that you make, that's really funny.

 

[CapPugwash]

Seems to me that TNLI is very concerned about being unable to start the engine due to lots of flat batteries. I have never experienced a flat starter battery with my traditional Domestic Bank plus Starter Battery setup. However I do carry the following device for peace of mind. It also charges my phone sometimes.

NOCO Jump Starter

 

[PaulRainbow]

Seems to me that TNLI is very concerned about being unable to start the engine due to lots of flat batteries. I have never experienced a flat starter battery with my traditional Domestic Bank plus Starter Battery setup. However I do carry the following device for peace of mind. It also charges my phone sometimes.

NOCO Jump Starter

My engine battery suddenly failed in 2016, i simply turned the emergency parallel switch on and started the engine from the domestic bank.

Straightforward two bank setup, would even comply with the SOLAS regs for lifeboats that TNLI keep droning on about.