Battery Configuration Help

[Willo B]

Not to stray off subject but im looking for suggestions. I'm replacing my bow thruster batteries (2 12v=24v 288ah sweeper) flooded with Agm. No room for 6v so looking at two Northstar g31agm 102ah,1150cca. i realize that ill be losing some reserve capacity. Also no 24v recharge except from shore power or generator. Am i going wrong here? Any input appreciated.

 

[john61ct]

Not to stray off subject but im looking for suggestions. I'm replacing my bow thruster batteries (2 12v=24v 288ah sweeper) flooded with Agm. No room for 6v so looking at two Northstar g31agm 102ah,1150cca. i realize that ill be losing some reserve capacity. Also no 24v recharge except from shore power or generator. Am i going wrong here? Any input appreciated.

Worth starting a new thread

 

[john61ct]

Just wonder,

The house deep cycle batts do an OK job of engine starting, even a 40-50% SOC if the bank is large , and has good plate area.

This might make it possible to forgo an actual start style batt and simply add to the house bank.

Great, till OOOPS the house bank gets too dead to crank the engine.

Has anyone attempted a main engine start with the small nicad power pack booster made for cars?

I personally prefer a Main house bank design, then a smaller Reserve. Engine cranking can easily be switched to either, good way to confirm Reserve is good every once in a while.

You could make Reserve a subset of Main, usually combined, just isolate it with an adjustable high-current LVD when SoC falls low. Long as cycling is shallow, SoC normally high, you gain big Peukert benefits of higher total AH capacity, thus less voltage sag and longer life overall.

_____
Yes there are portable power packs sized to crank big diesel truck engines.

I believe mostly lithium-based chemistry these days. Great for belt & suspenders redundancy, but **only if** kept fully charged and regularly replaced when getting worn / old.

It's very tempting to cycle them as laptop etc rechargers, if you do this then get two so one is always set aside left full.

 

[john61ct]

All significant charge sources should feed House / Main directly. Starter / Reserve need hardly any recharging since they (should) normally be used for trivial loads only, like cranking which usually .00x% DoD.

All significant loads (potentially drawing lots of AH while in use) should be wired from House. If the wiring run length makes the gauge required too big, then consider a dedicated bank for that function, with a DCDC charger or current-limiting ACR to handle keeping that properly recharged. But KISS, fewer deep-cycled banks the better, if at all possible.

Most VSR/ACR will only remain closed (combine) while a charge source is active, but they may be rated for lower current than ideal.

True, a pricey Blue Sea ML-ACR eliminates that, but do introduce a bit of voltage drop. But charge sources with dedicated Voltage Sense wires should def be installed only to House.

 

[dhays]

I personally prefer a Main house bank design, then a smaller Reserve. Engine cranking can easily be switched to either, good way to confirm Reserve is good every once in a while.

You could make Reserve a subset of Main, usually combined, just isolate it with an adjustable high-current LVD when SoC falls low. Long as cycling is shallow, SoC normally high, you gain big Peukert benefits of higher total AH capacity, thus less voltage sag and longer life overall.

I have seen this recommended before (possibly by you) and I frankly didn't understand it at the time. Now that I've had a few years of dealing with larger banks and higher power draws, I am beginning to understand it more.


If I understand it, a LVD simply combines two battery banks into one until the voltage of that large bank drops to a set level, then it separates the two banks. So in my case where I have a separate bank for thrusters and windlass, I could set the LVD at say 12.6 volts and have the advantages of a 1100 Ah bank but when the SOC drops I would have a 700 Ah house bank and preserved 400Ah thruster bank.


I'm not clear about how the LVD works when that house bank is being charged. Does it then work the same way an ACR does, connecting the two banks when the voltage reaches a given level? And if so, is that level the same as the disconnect voltage?

 

[john61ct]

If I understand it, a LVD simply combines two battery banks into one until the voltage of that large bank drops to a set level, then it separates the two banks.

Exactly. Really same as a VSR/ACR does, but an adjustable LVD lets you tweak at what voltage point the Reserve / Starter gets isolated.

And yes since the setpoint is **below** a VSR's any charging level voltage on Main / House will close / combine the connection. And yes, there is usually a hysteresis "gap" between open and close, to prevent chatter.

Obviously similar batts across both banks makes more sense, but the banks won't wear evenly if you frequently drop below the setpoint. Reserve / Starter would always be healthier though, which is A Good Thing.

 

[BruceK]

I have answered you wrt such questions before via PM last year. I only share what I choose about what I consider personal info. Do with that what you will.

John, it seems Al did not receive your PM. You could so easily "resend" it to him and resolve his inquiry.

 

[JDCAVE]

Not to stray off subject but im looking for suggestions. I'm replacing my bow thruster batteries (2 12v=24v 288ah sweeper) flooded with Agm. No room for 6v so looking at two Northstar g31agm 102ah,1150cca. i realize that ill be losing some reserve capacity. Also no 24v recharge except from shore power or generator. Am i going wrong here? Any input appreciated.

I’ll bite. I have a 24 VDC bow thruster. The PO installed 2 X Northstar NSB M-12-210’s with 1830 CCA’s. According to my marine electrician, they are probably the most expensive battery of this type I could buy. I phoned a dealer and was told they were about $900 CDN each. The Dealer asked if I could make do with smaller ones with a 1200 CCA. They would be less than half that price. I think your best approach would be to talk to the manufacturer of your thruster and ask if smaller batteries such as Group 31’s would be acceptable.

I think you are on the right track as AGMs are preferable, as your batteries are probably located under a forward berth, where gassing of FLAs would be an issue of concern. Also cable length and the complexity of combining batteries using a relay, I believe the best approach is a separate thruster bank.

BTW, there are several threads on this topic. Some advocate using a massive house bank. But it’s not clear to me how one selectively partitions a 12 volt house bank for occasional 24 volt service.

Jim

 

[FF]

Hot rods and some old trucks with new engines have been using 6 v to start 12v engines and 12v to start 24v engines for decades.


Many systems OTS.


https://www.google.com/search?clien...jeAhXCm-AKHTG-Du0Q1QIIzgIoBQ&biw=1366&bih=654

 

[garycasey]

Here's my thought on the matter, not that my thoughts are worth any more than you just paid for them... I would connect the engine starter directly to the start battery, along with the engine controls. I would also connect the thruster and windlass to that battery. The idea is that those motors are never run without the engine running and the alternator output combined with the surge capability of the start battery will do a good job. The alternator will rapidly replace the charge lost. Then run everything else off the "deep cycle" batteries. Then the battery selector will always be on the "house" battery. Then add a combiner so that the banks will be connected when the engine is running. The icing on the cake would be to add a "smart" voltage regulator that will push the alternator output up to the max for much of the time. That's what I did to a past boat and plan to do with my current one. Yes, lithium would be nice.

 

[Wil]

Surge from Start to House Bank?

One issue with having the alternator output routed primarily to the start battery is that there will be a LARGE surge from the start bank to the house bank when they are combined via ACR and the house bank is depleted? Need a current-limiting ACR or similar....

 

[FlyWright]

One issue with having the alternator output routed primarily to the start battery is that there will be a LARGE surge from the start bank to the house bank when they are combined via ACR and the house bank is depleted? Need a current-limiting ACR or similar....

It depends on how the systems are cabled.

If your cabling separates the charge from the alternator(s)/shore charger from the respective battery bank loads, no load sharing will occur with the ACR since the ACR would only share the charge, not the loads.

On a boat where the load and charge use a common cable (typically the starter cable), then the load will be shared until the start battery voltage drops below the specified voltage plus any time delay built into the system (if applicable).

My boat came wired like this until I changed it while modifying/improving my electrical system for a larger battery bank capacity, better charging, load reduction and enhanced control.

CMS covers the topic of relay chatter much better than I can in this post.

 

[Wil]

I'm trying to understand your concept. I attached a rough, simple diagram of my concept of a House/ACR/Machinery bank charging setup. With a depleted House bank, when the ACR turns on, the higher charge voltage/state of the Machinery bank will ?massively? discharge into the lower voltage House bank, even though the alternator is charging? Or maybe the alternator charge voltage being higher than both banks prevents the discharge? Not sure here....

How is your Machinery bank load (starter, windlass, thruster, etc.) separated from your Machinery and House bank charging circuit? I believe it is simple, but I'm not getting it. No manual switches, I want it to be as automatic (old guy short-term memory...) as possible.

If you could draw a brief wiring diagram of your evolved/upgraded charge/load system, and how they are separate, it would really help.

It depends on how the systems are cabled.... My boat came wired like this until I changed it while modifying/improving my electrical system for a larger battery bank capacity, better charging, load reduction and enhanced control http://www.trawlerforum.com/forums/showpost.php?p=625151&postcount=90.

 

[FlyWright]

Here's the basic configuration before many of the final components were upgraded, but the distribution is the same.

 

[garycasey]

Battery wiring configuration

First, I don't see where there is a "large surge" of current when the ACR is activated. If one battery is being charged to some voltage and another battery is connected to it, there will be a current flowing between the two, but it won't be dangerously high current. Maybe I'm missing something.

The other issue that concerns me is the wiring of the start battery. My Nordic Tug 32 is pretty typical, I think. The alternator power wire is connected directly to the starter power lead. That, along with the engine control and all other loads, is connected to the common terminal of the battery selector. There are two problems:

One is that the connection from the start battery to the starter is less than direct, increasing the voltage drop and therefore reducing the cranking speed.

The second, and I think the more important problem, is that the alternator is then in a position to be disconnected from its battery. If the engine is running and the battery selector switch turned to the "off" position the alternator will be disconnected.

Since the field current cannot be instantly reduced to zero, the alternator voltage will spike to often well over 100 volts. Not good for the alternator or anything else to which it might be connected. My plan is to connect the engine and engine control (as well as the windlass and thruster) directly to the start battery, just as it would be in any road vehicle. Some would say that they want the option to start the engine from either battery bank. But in my case, the other battery bank can still be connected in parallel to the start battery, just as when "jump-starting" a car. I think this also has an operational advantage in that in normal operation the battery selector never has to be moved. When the engine is to be started the key is simply turned on. After the engine starts and the starting battery voltage rises, the ACR will tie in the house battery bank. Any problem with this methodology?

 

[FF]

'The second, and I think the more important problem, is that the alternator is then in a position to be disconnected from its battery. If the engine is running and the battery selector switch turned to the "off" position the alternator will be disconnected. Since the field current cannot be instantly reduced to zero, the alternator voltage will spike to often well over 100 volts."


Some better rotary switches have field disconnect terminals built into the switch.

It is a "break before break" setup so the field is cut before the battery is disconnected.

Keeps guests children from blowing the alt diodes while playing underway.


"After the engine starts and the starting battery voltage rises, the ACR will tie in the house battery bank. Any problem with this methodology?"


Why bother? The ancient RV system using the acc terminal of a key switch does the merge at 1/5 the price , with no transistors to worry about .

 

[Wil]

Here's the basic configuration before many of the final components were upgraded, but the distribution is the same.

Thank you for the schematic, helpful. I see that a Yandina Combiner is the same thing as a Blue Sea ML-ACR, which is what I'm looking at using.

It depends on how the systems are cabled.
If your cabling separates the charge from the alternator(s)/shore charger from the respective battery bank loads, no load sharing will occur with the ACR since the ACR would only share the charge, not the loads.

What I'm not getting in your schematic is how the load (Windlass & both Starters) cabling is separate on your "8D Start Battery #2" from the charge (ProMariner Charger, 55A Port Alternator & Yandina Combiner to House Bank #1) cabling. They all go to the positive post on the 8D Start Battery #2. Then when the Yandina Combiner activates, both battery banks and all loads are combined (paralleled). So, if your 660AH House bank was at 50% SoC, and your 8D Start Battery #2 was at 98% SoC, would there be a large flow of current from #2 battery to #1 battery, even though they both are being charged at say 14.4v?

BTW, I'm not doing this as a thought exercise. I have a 900Ah House bank and a 220Ah Machinery bank that I want to use an ACR/Combiner on, in order to eliminate the present manual alternator charge-switching setup (1,2,Both,Off (no field disconnect)) I have now.

 

[Wil]

First, I don't see where there is a "large surge" of current when the ACR is activated. If one battery is being charged to some voltage and another battery is connected to it, there will be a current flowing between the two, but it won't be dangerously high current. Maybe I'm missing something.

I realize this is might be a basic question to ask. To make my ACR house/start (machinery) bank question clearer: take two 12v batteries, one 900Ah, the other 220Ah. Discharge the 900Ah to say 50% SoC, the other 220Ah battery is 98% SoC. Jumper them together with jumper cables--let the jumper cable melting process begin, no? That's my understanding.

Now take the same two 12v batteries in the same SoCes as above, but both being charged at 14.4v in parallel by an alternator. Now create a direct connection (jumper cables) between the two batteries. The ground circuits are all tied together. Do we get the same jumper cable melting process?

It seems to me that it doesn't happen, otherwise we'd have heard many stories about that, if it could happen. I'm having a hard time working out the thought of what happens if two batteries in very different states of charge and capacities are jumped together.

 

[FlyWright]

Thank you for the schematic, helpful. I see that a Yandina Combiner is the same thing as a Blue Sea ML-ACR, which is what I'm looking at using.

The Blue Sea ACR is a much more robust combiner than the Yandina. It's a good choice.

What I'm not getting in your schematic is how the load (Windlass & both Starters) cabling is separate on your "8D Start Battery #2" from the charge (ProMariner Charger, 55A Port Alternator & Yandina Combiner to House Bank #1) cabling. They all go to the positive post on the 8D Start Battery #2. Then when the Yandina Combiner activates, both battery banks and all loads are combined (paralleled).

CHARGE:
The charge from the alternators go directly to their respective battery banks (fused). If (and only if) a single source charge needs to be shared with the offside bank, the combiner can be switched on for the purpose. This is the CHARGE side of the circuit, not the LOAD side. LOADS are still pulled from their respective banks through the switches or hardwired devices like bilge pumps and windlass. In normal (95%) operations, the combiner is OFF, the CHARGES are split and the LOADS are sent only to their respective switches/bilge pumps/windlass.

LOAD:
If the LOADS need to be shared with a single battery bank, i.e. dead start battery and need to parallel the house bank to start, I can tie the banks at the Batt Switches located outside the ER. This also provides me a way to cut ALL 12V power from the busses in the event of an electrical fire. I have full flexibility to run house loads from start batt or start from house batt or isolate any battery or buss from the LOADS.

So, if your 660AH House bank was at 50% SoC, and your 8D Start Battery #2 was at 98% SoC, would there be a large flow of current from #2 battery to #1 battery, even though they both are being charged at say 14.4v?

My Balmar charges my house bank which carries the house loads while charging. The more LOAD I pull via the house circuit, the less CHARGE I receive. The PORT alt charges the start battery which carries the load from the starter and windlass.

When the CHARGE is shared via the combiner, i.e. alternator failure, the voltage of the banks will equalize and the START and HOUSE LOADS will be replenished by the single charge source.

BTW, I'm not doing this as a thought exercise. I have a 900Ah House bank and a 220Ah Machinery bank that I want to use an ACR/Combiner on, in order to eliminate the present manual alternator charge-switching setup (1,2,Both,Off (no field disconnect)) I have now.

If you're a single alternator vessel, then the Charge from the alternator should be sent first to the HOUSE bank and shared to the START bank via the combiner. This is covered in detail on CMS's post here. It's a long but worthwhile read. I've printed this and highlighted the most salient points for my future reference aboard. Points #4 and #5 address this issue directly.

 

[PMF1984]

Yandina ACRs come in many sizes. And the warranty is unbeatable. I just had my 1996 unit fixed at no charge.

 

[garycasey]

All the posts were interesting, but I think I'm commenting primarily on the post from FlyWright. I tried to add a figure, but it didn't work. In my single-engine system, the as-modified system The start battery(bat2) connects directly to the engine starter, engine panel, thruster and windlass. It also connects to the manual selector switch and the combiner. The alternator is connected directly to the starter and there to the start battery. There is a previously-installed inverter/charger that connects directly to the house battery(bat1). The house battery is also connected to the combiner and manual selector switch. There are various fuses in the system, but the alternator output is not fused. If it fails in a short mode I expect the internal wires will burn open or the external wire, which is short and not near other wires, will melt open. It is a fairly simple system and seems to work in any known mode without fault.

 

[garycasey]

One comment I read was about connecting batteries with significantly different charge states or voltages. While under charge (current coming in) the voltage will be fairly high - like 14+ volts. When below full charge the voltage can be as low as 10 or 11 volts. Connect the two together and, yes a fairly high current will be observed - but not a cable-melting current. The voltage of the two will essentially instantly come to the same voltage and the high-voltage battery will charge the other. No problem.

 

[FlyWright]

All the posts were interesting, but I think I'm commenting primarily on the post from FlyWright. I tried to add a figure, but it didn't work. In my single-engine system, the as-modified system The start battery(bat2) connects directly to the engine starter, engine panel, thruster and windlass. It also connects to the manual selector switch and the combiner. The alternator is connected directly to the starter and there to the start battery. There is a previously-installed inverter/charger that connects directly to the house battery(bat1). The house battery is also connected to the combiner and manual selector switch. There are various fuses in the system, but the alternator output is not fused. If it fails in a short mode I expect the internal wires will burn open or the external wire, which is short and not near other wires, will melt open. It is a fairly simple system and seems to work in any known mode without fault.

That's how mine was cabled when I bought the boat, except I have twins. I didn't like the losses from the small gauge wire from the alternator to the start cables or the fact that the dual-purpose start cables prevented me from splitting the CHARGE from the LOAD. The high output Balmar needed beefier cabling and my aviation background pushed me into building a system to allow complete and independent control of all CHARGES and LOADS.

I asked myself, "How would you control an ER electrical fire?" Without full control of the CHARGES and LOADS from outside the ER, I had little control. As I sit now, I can control all from the lower helm controls and the Perko switches at the bottom of the steps leading to the ER. (3 steps away from the lower helm) I can shed ALL LOADS without affecting the alternator charges (or burning alternator diodes) and I can shed all CHARGES without affecting LOAD distribution or burning up alternator diodes.

I'm not faulting the stock electrical systems at all (no pun intended). They work great for thousands of boaters worldwide. I just wanted a system that worked better for my intents and purposes.

 

[FF]

"Jumper them together with jumper cables--let the jumper cable melting process begin, no?"


NO PROBLEM.

 

[Wil]

Ok, good to know. I'm going from a large-frame alternator to the (fused) house bank, then via RBS & ACR to the start bank.

Thanks for the reference, CMS said it:
"#3 Combine voltages of the Blue Sea ACR are above the full charge resting voltage of a 12V battery. With 13.0V or 13.6V applied to the battery terminals current can only flow INTO the banks not out of the banks.
The Blue Sea ACR will combine / parallel the banks at 13.0V for 90 seconds or 13.6V for 30 seconds. Any time the battery terminal voltage is above the batteries SOC voltage, current can only flow in one direction, and that is into the battery.
The idea that a start battery or house battery can drain into one another, with an ACR, is not possible other than for 10 seconds or 30 seconds maximum. It takes voltage differentials to move current between batteries and the the energy that can move between the batteries in 10 seconds at 12.35V or 30 seconds at 12.75V in beyond minuscule."

 

[Seevee]

Back to the OPs question.....

I have a very similar set up at to what you want. Mainship 400, Single Yanmar 370 and goal to have enough battery power to carry me through an anchor stop without running the genny overnight.

I have the following:

80 amp alternator (built by RC Collins)
Balmar MC-614H - High Performance External Alternator Regulator

Magnum MS2812 charger/inverter

4 6v Lifeline AGM deep cycle 220amp batteries wired in series/parellel to give 220 usable amps at 50% SofC (12.2v)

1 12v Lifeline GPL3100T Starting battery

Blue Seas ACR

emergency start switch that combines house and start batteries.

Victron battery monitor
========

The thrusters work off the house batteries, as does the windlass.

The generator battery is separate and dedicated to the generator. Genny is a 8kw Kohler.
========

This gives enough power to set the anchor, shut down the engines and all non essential electrical items.
And I have enough power to supply computers, iPads, phone, and LED lights. I can microwave a short dinner, usually heating up leftovers, make morning coffee and heat something in the micro and then start the engines. It's a relatively small system but works great!

Now, if I wanted a fresh or hotter meal I'd use the crock pot underway, or perhaps micro something that took a bit longer. If I needed the grill or the stove, that would require the genny.

If I wanted more power, might consider a solar charger of sorts.

While I have a reasonable knowledge of electrical stuff, I hire an ABYC electrician for the inverter install, which included the monitor and making sure everything played well together.