Lead Acid Battery Bank

[TiggerTwo]

Can I have a bigger House Battery than the Starter ?
Do problems occur when I have the main changeover switch turned to both and the charging starts ?
I have a stirling smart charger..

[Pete7]

Oh good a question that can be answered unlike the NWP 2018 thread

Yes, the house bank should be sized to meet your daily needs which if you don't know needs calculating. Do a search on here for previous examples posted by members.

The house bank also needs to be sized to take into account space (on a 28ft yacht) and the cost.

Ours is 220 Ah and consists of 2 x 12v batteries. This easily meets our daily requirements for about 40 Ah or 60 Ah if we run the diesel heating.

In terms of batteries the majority of members are American and favour 6v golf cart batteries. These are not necessarily cost effective in the UK. Also as we found out won't fit our existing battery box space. Our solution was a pair of Varta Hobby 110Ah batteries which are a good compromise between cost and quality.

Think twice about any battery in the UK which claims to be deep discharge but is sealed, the words snake oil spring to mind. The ability to top up the fluid level in a house bank is very useful.

The Sterling chargers are fine but the rotary switches not great. they are fitted to boats because they are cheap and easy to wire up for the manufacturer. If you move the switch when the engine is running and there are no batteries connected to the charging circuit and alternator it can take out the diodes in the alternator.

A better switch solution is the BEP range of switches, but they are not cheap:

Battery Switches: BEP 701-pm Panel Mounted Battery Switch 275a On/off (701-PM) (8-90035)

I replaced our rotary switch when the switch failed to disconnect the batteries even though the lever had been turned. It discharged a pair of batteries and wrecked them, hence the move to BEP swithces.

Pete

[Zil]

Yes you can have a larger house bank than starter battery. Both do need to be the same voltage, ie; 12V or 24V. Some problems are covered by Pete7. I'm willing to take a bet that most house banks are larger in capacity than starter batteries. Although I know a few are the same.

[Sailmonkey]

Our house bank is 450 (was 450 8 years ago), and our start battery is a group 24. No problemsz

[GTom]

Originally Posted by Sailmonkey

Our house bank is 450 (was 450 8 years ago), and our start battery is a group 24. No problemsz

450Ah@12V on a 32'-er, wow

[Sailmonkey]

Originally Posted by GTom

450Ah@12V on a 32'-er, wow

It’s only 4 GC2’s.......it’s a heavy boat in the first place too[emoji16]

[S/V Alchemy]

Originally Posted by GTom

450Ah@12V on a 32'-er, wow

I don't consider that excessive, and not because I'm a power hog. I like for the bank to discharge only down to 75% or so SOC to extend longevity. Daily discharges to 50% and back up to fully charged (or close enough) will shorten battery life as my manufacturer informs me. That means a big bank with fairly trivial cycling can go (with proper maintenance) for more years. We have 1,185 Ah capacity (six L-16s FLAs) on a 40 footer. Right in the middle of a steel boat, mind. That 350 kgs. of weight is part of the internal ballast!

[stormalong]

In addition to the already good responses a voltage controlled relay would be a good replacement for the 1-2-both battery switch. These are made by several companies and automatically join the two battery banks when a charging voltage is sensed on either battery. When the charging voltage goes away the batteries are separated.

This means no forgotten switch settings. Charging sources can be wired to either battery bank making wiring easier.

Battery switches are still needed to isolate the batteries for service but a simple on-off switch meets that need.

Mine is made by Yandina and has been in place for about 20 years now with no problems. I have even used it to join the banks together to start the engine when the engine start battery died. It has the option of wiring a switch up to disable the combiner or manually connect the banks. Although not a great idea for a 120 amp combiner my engine starts quickly.

[GTom]

Originally Posted by S/V Alchemy

I don't consider that excessive, and not because I'm a power hog. I like for the bank to discharge only down to 75% or so SOC to extend longevity. Daily discharges to 50% and back up to fully charged (or close enough) will shorten battery life as my manufacturer informs me. That means a big bank with fairly trivial cycling can go (with proper maintenance) for more years. We have 1,185 Ah capacity (six L-16s FLAs) on a 40 footer. Right in the middle of a steel boat, mind. That 350 kgs. of weight is part of the internal ballast!

You are right. I estimated our daily power budget around 100Ah which should be provided by mostly solar, meaning that around 2/3 of the consumption will happen under non-ideal condition (I don't expect much charging before 10am and after 3pm) = about 70Ah would burden the bank. If I aim to 75% SoC, that's 250-300Ah (@12V).

[Teknishn]

On my Hunter 27 I have 3 House Banks. 2 of the house banks consist of two size 24 90Ah marine deep cycle batteries connected in parallel and the 3rd "house bank" is actually two size 24 90Ah marine start batteries. The Start battery for the Yanmar 1GM is a single size 24 marine start battery.

My daily amperage requirements are usually less than 90-Ah...so it's a bit of overkill, I know.

Charging for the deep cycle batteries is via two 200-watt solar panels, each with a separate controller to enable charging of the separate battery banks if so desired using 200-Amp Blue Sea battery switches. To charge the 3rd House Bank, I connect a 3-Amp Start Charger and Maintenance unit to the batteries which is powered by the 2500-Watt inverter installed for 110-VAC throughout the boat. The 3rd House Bank (start batteries) can be placed in parallel with the engine start battery or used independently to start the engine. Again, using Blue Sea battery switches.

This all may seem a bit complicated for most, but for me it has served me well for the past year that I have been living and cruising on the boat. Last time I connected to shore power was in April 2017 to test the shore power cable and receptacle.

[hzcruiser]

Originally Posted by TiggerTwo

Can I have a bigger House Battery than the Starter ?

Sure, no problem there, as they have separate functions. Comparing them just by looking at Ah capacity might be difficult, as a starter batt is "designed" to provide lots of Amps for a few seconds only, with a house batt it's the other way around. That's why they often quite cold cranking apms, or CCA, on starter batts.

Do problems occur when I have the main changeover switch turned to both and the charging starts ?
I have a stirling smart charger..

Technically it's not a problem, although some people would say only combine batts of same type/chemistry/age etc...

As mentioned, a VCR would prevent you from forgetting to turn the combiner off again after charging.