KISS or Smartbank Pro charger

[Garry & June 'Friendship']

Along with other upgrades to our boat before setting off for the sun, I have been looking at our power needs. I have upgraded our batteries to 450 ah AGM domestic which at present we are operating through a large and simple rotary switch, 1, 2, both,off. I have installed 300w of solar to hopefully keep these topped up once in the Med with occasional boost from mains hook up and 90 amp alternators. My question is do I actually need a Smartbank Pro charge controller or would I be better off keeping things simple with the old manual switch. I presume if fitting a smart controller it does away with the switch. In that case what happens if the controller malfunctions. Would I be over complicating things at the cost of little benefit.

 

[duncan99210]

Presumably the 1,2 both switch connects your domestic bank and engine battery together so that you can use the domestic bank to start the engine in an emergency? Looking at what the Smartbank does, it seems to be a battery isolation system, which takes the output from the alternator and directs it to your batteries in a manner that you have programmed it to do. It also has the ability to join both batteries together in an emergency by way of an additional plug in extra. That's the same basic function as your current arrangement, but automated.
You could achieve the same effect by using a simple VSR to separate the alternator output, preventing cross discharge of the engine battery at lower cost. The VSR will direct current to the engine battery until it reaches a set level, then it also charges the domestic bank. The overall effect is the same as the Smartpro but lower cost. You'd also have to wire in an additional switch to enable paralelling of the batteries in an emergency.
Frankly, I'd spend the money on a large smart charger so that when you have access to mains power you can fully charge your batteries as fast as possible rather than a complex version of a VSR.

 

[Garry & June 'Friendship']

many thanks for that Duncan. I'm beginning to think you are right. Leave my present system as it is, as its worked so far with no problems so why mess with or over complicate things. Beefing up my charging equipment would be the better investment.

 

[Mistroma]

I thought that your 1,2,both,off switch was most likely used to simply select which battery is currently in use. You can direct charge from your alternator to either or both when the engine is running. Switching to both at anchor would draw power from both batteries for domestic use or engine starting.

I'd agree with the comments above. Smartbank will just automate what you do at present and remove the risk of forgetting to select the correct battery for charging/discharging. It won't do anything to speed up charging. Spend the money on something to improve charging.

One point:
If you already have a decent mains charger then it will probably have outputs for battery and domestic and this by-passes the manual battery selector. So Smartbank or VSR does nothing for you in that case. Improving engine charging would give most return on your money.

Working a bit blind here as I don't have details of your system (you can find my setup on my profile if you want to compare). You have 300W of solar and I assume that this either charges the domestic bank or regulator has outlets for start & domestic. Again, Smartbank does nothing for you in that case apart from probably linking start/domestic when sun is shining. This means that you actually lose the advantage of sep. charging if your controller already provides it.

 

[Garry & June 'Friendship']

Many thanks Mistroma ... I have addressed the mains charger and moved up to a larger sized unit. I have set up my solar to charge the domestic bank only but this could be switched easily if the need arises. My system is a little more complicated as we are a multi and thus have twin engines. Strangely the previous owner, (we have not owned long hence presently carrying out upgrades) has different sized alternators on the engines so as far as I can see most of the charging work is carried out by the port engine. This seems a bit strange so I am definitely looking now at not only beefing up the alternators but also matching them so I can switch the charging load from one engine to the other. I am hoping the solar will provide most of our needs once in the sun and maybe run alternate engines once every 3 or 4 days to give the battery banks a boost and keeping the engines working every so often which will benefit them.

 

[duncan99210]

I've come across a number of cats with large alternators on one engine, standard on the other. One chap I met said he switched the big alternator over every winter to even out the running hours, only running one engine to charge batteries when at anchor. Others just lived with the imbalance of engine hours, accepting that the engine with the large alternator would be run a good deal more than the other...

 

[RichardS]

I've come across a number of cats with large alternators on one engine, standard on the other. One chap I met said he switched the big alternator over every winter to even out the running hours, only running one engine to charge batteries when at anchor. Others just lived with the imbalance of engine hours, accepting that the engine with the large alternator would be run a good deal more than the other...

Why not just put a larger alternator on both engines like mine. Extra cost seems trivial compared to cost of boat.

I only use one engine when charging but can alternate as necessary.

Richard

 

[duncan99210]

Hey, I wasn't seeking to justify what other folks do just reporting it!

 

[RichardS]

Hey, I wasn't seeking to justify what other folks do just reporting it!

No problem. I've never seen that so just thought the guys you've spoken to might have mentioned why their set-up was like that. :encouragement:

Perhaps someone else has the answer?

Richard

 

[halcyon]

Along with other upgrades to our boat before setting off for the sun, I have been looking at our power needs. I have upgraded our batteries to 450 ah AGM domestic which at present we are operating through a large and simple rotary switch, 1, 2, both,off. I have installed 300w of solar to hopefully keep these topped up once in the Med with occasional boost from mains hook up and 90 amp alternators. My question is do I actually need a Smartbank Pro charge controller or would I be better off keeping things simple with the old manual switch. I presume if fitting a smart controller it does away with the switch. In that case what happens if the controller malfunctions. Would I be over complicating things at the cost of little benefit.

Option, small bank engine start, large bank service.
Connect starters via output of 1,2, both allowing starting from either bank, while maintaining clean service power supply during starting.
Connect service loads via single isolator switch and connect both alternators direct to this bank.
Connect start bank to service bank with VSR, when service bank on charge, engine bank is charged.

Gives a auto system with manual over-ride.

The reason for odd sized alternators is to avoid hunting. As the two alternators will have a different regulation value, may only be small, but when the lower one reaches it's regulation point it cuts out leaving only the higher one. The load increases, so the voltage drops a little, so low alternator cuts back in and so the cycle repeats. Fitting a single high output alternator avoids the hunting problem.

Brian