Battery Isolator Replacement Options

[UK Ade]

Recently fitted a Balmar ARS 5 Regulator to max our OEM 120Ah Valeo Alternator.
To ensure max sensing of the House Bank have wired Pos & Neg ARS-5 to House Bank (650Amps AGM - only less than 12 inches away) in accordance with best practice for cruisers.

Now have to resolve the distribution from the Alt output to two other battery banks. Engine (Start) 120Amp AGM & Aux Bow Thruster 120 Amp AGM.
Currently Alt output goes via a Cristec Diode Battery Isolator which splits into the three Batt Banks.

I will need to separate the Engine and Aux Banks from the Alt output which is only 'sensing' the House Bank. Otherwise they will immediately go into high voltage when charging from the Alt.

Options which have been suggested:
1. Replace inefficient Diode Battery Isolator with Victron FET Isolator (less voltage drop) and re-wire ARS-5 onto Alt Output post. (Easiest, but then charging not optimised as voltage being 'sensed' does not reflect true House v)
2. Alt output via Bus Bar direct to House Bank and then use x2 Bluesea ACRs (Engine Batt & Aux Batt) to combine respective banks with House during charging voltage. (Impact of combined batts not sure?)
3. Use DC - DC Chargers or Balmar Duo Charge (or equivalent) x 2 (Costly but no combined risk and charging follows profile).

Think I'm aiming for Option 2, but would be grateful for any thoughts, considerations, risks etc before deciding.

[smac999]

unless the banks are really far apart the voltage on all 3 should be simular when using the argofet. but the house will likely be the lowest since it'll have the must current drop and the engine voltage may be a little high. I have seen this before where the engine battery was over 15v when the house was 14.6 but the engine battery was also much closer to the alt then the house.

the dc to dc would be the best

[UK Ade]

Thanks SMAC999. Really helpful to get your views. I was thinking the same re the Argofet Isolator. i.e. potential high voltage to Engine and Aux (Bow Thruster). Aux is 40feet away but Engine is close and would over charge if I left the Smart Regulator ARS-5 sense wired to the House Bank. Would have to put the Balmar ARS-5 sense/+ & - back onto the Alt output post. This would stop over charging but defeat the objective of the Smart Regulator maximising House Bank charging. But might be what I have to do.

Re the DC-DC Charger, I'm concerned about spike load draw from the Engine and Bow Thruster banks from Engine Start and Bow Thruster activation. These are resolved with the BlueSea ACR's through their 'load' sense wires (via starer motor & bow thruster) which make the ACR go open circuit instantly to protect combined banks getting spikes. How does this work with a DC-DC Charger? Although the charging draw would be minimal, would a spike high load cause the 30amp fuse on a DC-DC Charger to blow?

I'm having this same conversation with qualified marine electricians but getting too many differing answers, so good get some other views please from anyone.

[tkeithlu]

I've approached the same problem by having the engine and the genset batteries charged by their own alternators, so the engine has two - one big Balmar and Balmar controller to charge the house bank and one for it's own starter battery.

In the unusual case that something fails - most frequently a weak starter battery - I have a jumper cable to connect the other starter battery in parallel or the house to a starter battery to get things going.

It's a simple system, it avoids complex wiring, and it works.

[smac999]

Originally Posted by UK Ade

Thanks SMAC999. Really helpful to get your views. I was thinking the same re the Argofet Isolator. i.e. potential high voltage to Engine and Aux (Bow Thruster). Aux is 40feet away but Engine is close and would over charge if I left the Smart Regulator ARS-5 sense wired to the House Bank. Would have to put the Balmar ARS-5 sense/+ & - back onto the Alt output post. This would stop over charging but defeat the objective of the Smart Regulator maximising House Bank charging. But might be what I have to do.

Re the DC-DC Charger, I'm concerned about spike load draw from the Engine and Bow Thruster banks from Engine Start and Bow Thruster activation. These are resolved with the BlueSea ACR's through their 'load' sense wires (via starer motor & bow thruster) which make the ACR go open circuit instantly to protect combined banks getting spikes. How does this work with a DC-DC Charger? Although the charging draw would be minimal, would a spike high load cause the 30amp fuse on a DC-DC Charger to blow?

I'm having this same conversation with qualified marine electricians but getting too many differing answers, so good get some other views please from anyone.

On the case I was working on, I ended up moving the sense to the engine battery. which made it safe. but then the alt went into absorb really early as the engine battery would be at 14.6v and the house only at 14.2 or so when going into absorb. which made the whole upgrade less usefull. but the whole job was done and being tested at that point... hard to change everything after it's done.

on that boat should have run the alt straight to the house, then put a dc to dc from house to engine. the engine battery and argofet was beside the engine but the house battery was 20' further away. if the banks were side by the side the issue would have been less

[Stu Jackson]

Originally Posted by UK Ade

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Options which have been suggested:
1. Replace inefficient Diode Battery Isolator with Victron FET Isolator (less voltage drop) and re-wire ARS-5 onto Alt Output post. (Easiest, but then charging not optimised as voltage being 'sensed' does not reflect true House v)
2. Alt output via Bus Bar direct to House Bank and then use x2 Bluesea ACRs (Engine Batt & Aux Batt) to combine respective banks with House during charging voltage. (Impact of combined batts not sure?)
3. Use DC - DC Chargers or Balmar Duo Charge (or equivalent) x 2 (Costly but no combined risk and charging follows profile).

Think I'm aiming for Option 2, but would be grateful for any thoughts, considerations, risks etc before deciding.

I agree Option 2 makes the most sense (pi ). Have you considered the Yandina combiners in lieu of the BlueSeas ACR? I have a Yandina combiner, in since 1999 and works great. I also installed a simple toggle switch in the negative wire to the combiner and can shut it off whenever I want to. My house and reserve bank are right next to each other.


I agree that the sense should go to the house bank. But unless the voltage is higher than what your batteries are designed to take, wouldn't battery acceptance limit charging to the start and aux batteries? As Maine Sail has taught us, the only thing that can "overcharge" batteries is too high a voltage, because the batteries themselves limit the current.

[CarinaPDX]

I think your choices are between various levels of goodness: they all will work fine, but some are slightly better than others. The "better" need not be the enemy of the "good". I would guess that in terms of efficiency and battery longevity you would never in practice notice the difference. So how much is it worth to you to get closer to perfection?

1) The old silicon diode isolators work just fine - I used them for 30 years and you have used them too. They are inexpensive (free for you since you have them), very simple and very reliable. The supposed downside is inefficiency; if the diode drop is 0.6V and the alternator is putting out 100A then the power loss is 60W (and most of the time it is going to be much less current so less loss). My 38hp diesel is rated at 27.9kW, so 60W is 0.2% of the maximum engine output, at maximum charge rate. Put your own numbers in and see how tiny the issue is. The other potential downside is that the lesser-used start battery will be charged at a higher rate than optimal because the house battery is sensed; true again, but in practice I never found that the start battery had a short life - did you? Part of that is that while the charging may be less than optimal, the usage was much lower than the other batteries. Any concern you have about voltage spikes at one battery reaching the others is a non-issue as the diodes block that. They also prevent a blown alternator from flaming with power coming back from the battery. All things considered a pretty good solution. And easily the most reliable.

2) Battery combiners also work well, and assuming they are using relays (usually true) they are slightly more efficient than diodes. OTOH diodes don't wear out but relays do - given the rate of contact closures it is not likely a problem though. Unless they have some smarts in them they don't solve the (non?) problem of over-charging the start battery. And they lack the protection of diodes that prevent back-flow of current (shorted alternator/cable, spikes reaching all batteries). Because of the larger total capacity the spikes should have less effect though. ProMariner makes a line of smart ACRs that I think would be better than two ACRs; you can buy them for two or three bank systems and they switch the different banks in/out as needed, while switching the voltage sense lead for the regulator. While no ACR can adapt the alternator voltage to the differing needs of the different banks, the smart ACRs can at least control the time charging. So an ACR will be slightly more efficient and slightly better for the batteries, with less protection and reliability than simple diodes. It does provide excellent charging for the house bank.

3) Directly charging the house bank while charging the other banks with 3-step DC-DC battery chargers is the best technical solution to date. Each battery can be charged optimally, the house with the smart alternator regulator and the other banks with their own battery charger settings. And the banks remain isolated from one another. If starting from scratch and money is no object this seems to me to be the best solution. Whether it is worth it to buy two battery chargers to replace the diodes is a personal decision, but with this as an option I don't see the ACRs as competitive. Full disclosure: I bought one of the ProMariner smart ACRs and will stick with that - I don't think it is worth the cost to change now. And I still think that keeping the diodes would have been a good solution...

Greg

[YANDINA]

Originally Posted by CarinaPDX

<SNIP>
. OTOH diodes don't wear out but relays do - given the rate of contact closures it is not likely a problem though. <SNIP>

Greg

Relay life in Combiners:-

Having sold over 200,000 Combiners in the last (nearly) 30 years ALL with unconditional warranty I can confirm that relay life is not a problem. Based on warranty returns and average life the Mean Time Between Failures of all returns works out to be over 1,000 years, and no failures to date have been due to relay contact failure.

In fact a fishing boat customer in Charleston SC complained about the "buzzing" sound his combiner made. It turns out the timing capacitor had a bad connection so instead of cycling once per minute at the threshold it had been cycling about 300 times a minute for 6 months, equivalent to 150 years of normal use. Inspection showed the contacts to be about 25% degraded and still in good working condition.

[sv_pelagia]

Anyone have experience with/knowledge of

Sterling Power ProSplit-R – Zero Voltage Drop Isolator
https://www.sterling-power-usa.com/P...olator-13.aspx

I have one but haven't installed it (to replace my diode - - the old "don't fix it if it aint broke" problem).

Sterling Power products in general?

[Bowdrie]

Originally Posted by CarinaPDX

So how much is it worth to you to get closer to perfection?

1) The old silicon diode isolators work just fine - I used them for 30 years and you have used them too. They are inexpensive (free for you since you have them), very simple and very reliable. The supposed downside is inefficiency; if the diode drop is 0.6V and the alternator is putting out 100A then the power loss is 60W (and most of the time it is going to be much less current so less loss). My 38hp diesel is rated at 27.9kW, so 60W is 0.2% of the maximum engine output, at maximum charge rate. Put your own numbers in and see how tiny the issue is. The other potential downside is that the lesser-used start battery will be charged at a higher rate than optimal because the house battery is sensed; true again, but in practice I never found that the start battery had a short life - did you? Part of that is that while the charging may be less than optimal, the usage was much lower than the other batteries. Any concern you have about voltage spikes at one battery reaching the others is a non-issue as the diodes block that. They also prevent a blown alternator from flaming with power coming back from the battery. All things considered a pretty good solution. And easily the most reliable.

And I still think that keeping the diodes would have been a good solution...

Greg

Agreed,, my system is perhaps somewhat reflective of me; Not yet ancient, and still reasonably operational.
The ~30 years old Powerline isolators, and the same vintage Ample Power regulator work just fine.
Never felt the need to get involved in the never ending chase for minimal increases in efficiency.
Diode losses are a non-issue.
Oh,, on another note, this site may be worth a view;
https://www.emarineinc.com/

[goboatingnow]

If you are battery sensing , then the diode drop is immaterial. The power loss due to heat is as was shown largely irrelevant. Ideal diodes are useful where you can’t battery sense. In my case I make my own splitters using Schottky diodes which are lower drop voltage and hence lower power loss.

Diode splitters are easier to manage and do a better job then combiners imho. It’s a fit and forget. The spikes and droop from each battery won’t propagate into the other battery neither as there isn’t a common feed which there is if a “ commoning “ relay is used.

If you are considering high voltage absorption cycling on a regular basis ( ie you have a smart alternator regulator ) Then the starter battery will tend to be subject to some extra stress. This doesn’t happen with stock alternator regulators as they don’t have an absorption setting. That extra stress can shorten the starter battery life but you’ll not really notice. The same issue happens with multi output battery chargers.

[waterman46]

My advice is don't use any isolator which uses mechanical relays. The contacts get more resistive with.age and it happens gradually so you
may not notice it unless you see the max charge current from alternator gradually dropping over the years. .This can also be caused by a sulfated battery so you need to monitor the voltage drop across the relay.if you suspect problems.

I like the Victron FET isolators.

[CarinaPDX]

Originally Posted by Bowdrie

The ~30 years old Powerline isolators, and the same vintage Ample Power regulator work just fine.

I had two Ample Power regulators - some of the earliest that they made. One regulated the alternator and the second the solar panels (at that time 3-step solar regulators were not available IIRC). My thinking was that if the alternator regulator failed I could re-purpose the solar regulator. As it happens both regulators served flawlessly for 30 years.

As GoBoatingNow pointed out, when using diodes it is desirable to have a remote voltage sense for the regulator. Personally I think installing a 3-step regulator with remote sense is the first electrical upgrade for cruising boats as it has a major impact on engine run times for charging and battery longevity. My new Volvo engine came with a 115A Mitsubishi alternator which has remote sense standard; in addition to compensating for diode voltage drops it allows for a Nordkyn VRC-200 external regulator (no modification to alternator required).

Greg

[Bowdrie]

Originally Posted by CarinaPDX

As GoBoatingNow pointed out, when using diodes it is desirable to have a remote voltage sense for the regulator. Personally I think installing a 3-step regulator with remote sense is the first electrical upgrade for cruising boats as it has a major impact on engine run times for charging and battery longevity.
Greg

Yes, the regulator has battery sensing.
I'm going to leave well enough alone, and not fix what ain't broke.

[YANDINA]

Originally Posted by waterman46

My advice is don't use any isolator which uses mechanical relays. The contacts get more resistive with.age and it happens gradually so you
may not notice it unless you see the max charge current from alternator gradually dropping over the years. .This can also be caused by a sulfated battery so you need to monitor the voltage drop across the relay.if you suspect problems.

I like the Victron FET isolators.

30 years of experience of Yandina "isolators with mechanical relays", all with UNLIMITED warranty proves you are totally wrong. Where did you get this information, Victron? We have never had a warranty return that showed relay contact exhibiting increased resistance. Does Victron have the integrity to offer UNLIMITED warranty? Does the FET have zero voltage drop?

If it ever did happen, our red "overload" LED would come on and warn you so you already have a voltage drop monitor.