DC-DC Charger vrs VSR set up

[brett62]

I am starting to try and work out my re-wire in the boat and have most items covered and sorted out. Before I started rebuilding I removed all the wiring and will be starting fresh.

One issue I am needing some information on is the batteries and recharging system that will suit my needs. Originally the boat was wired with 2 x 100 amp house batteries and 1 x 100 amp crank battery and these went through a BEP/VSR and had a switch to connect both battery banks if the crank battery was to die. I also have a solar panel and it has a sunsmart 10amp regulator connected to the charge system. The old motor was a mercruiser and not sure what the alternator output was. I also so have a battery monitor connected. This system was working ok and never had any issues for the short time I had the boat in the water. I am adding some new toys which will draw a little more power and want to get this right.

The new motor has a 120 amp alternator and the new configuration will be 2 x house batteries and 2 x crank batteries. Will be reinstalling the solar panel, battery monitor and adding a 2000 watt inverter. Will also install a onboard 40 amp battery charger to keep the batteries on float charge when parked up or on shore power.

After some research I am looking at installing a 40 amp DC-DC charger which the solar panel connects also instead of the BEP/VSR system. From what I have read the DC-DC system seems to do a better job regulating/charging than the VSR. The VSR set up is cheaper by about half and the intention is I will be out 2-3 nights and looking at what will give the best reliable outcome. Changing all the lights over to LED's and will be running a fridge and all the normal equipment. I have a microwave (240v) and a anchor winch which are only used when the engine is running and the microwave is only used to heat a meal up so not used for long.

Is anyone running something the same as real experience will be more truthful then the sales pitches.

[ranmar850]

All that a VSR does is close when it detects a certain preset voltage( 12.4v or thereabout) on the supply side, effectively paralleling your two batteries to charge together, just the same as if you had turned a conventionally wired switch to both.The VSR will be connected across the Both switch, and when the main battery voltage drops below the preset (12.4v?) the VSR will then open, so a properly wired boat will not draw down your Start battery--properly wired as in all your auxiliary load running off the House switch. From my understnding of it, and please correct me if I am wrong, a DC-DC charger is only needed for these newer automotive alternators that simply stop charging once a start battery is detected as having enough voltage--a VSR won't work properly on auxiliary batteries to keep them charged?

[TheRealAndy]

DC-DC is better in as much as its a proper multistage battery charger. They are typically used where there is a voltage issue, ie when there is a long run of cable and the voltage drop means you cant get a full charge in your house battery. As ranmar suggested, I think you can also get variants that overcome the issue of smart alternators. I use a smart charger on my caravan, because the cable run from the car battery to the battery in the van is via about 6m of cable.

If your house battery is close to your main battery, then a VSR is sufficient. I am using Enerdrive dual sensing VSR's on my boat, they detect the engine battery voltage and switch on when the motors are running. However they also switch on when the solar panels have charger the house batteries, so top up the start batteries also (which is handy for me given my boat lives on a hardstand).

[brett62]

Ranmar850 yes some newer alternators do pose a problem with a VSR set up and the DC-DC will help fix the problem. No I don't think I will have that problem as it is more for the auto world as you stated. I do like some of the smarts a DC-DC system has and I suppose that is why they are dearer. I particular like the way you can hook the solar directly into the unit and it sorts out the charging.

TheRealAndy my battery banks are about 3m in cable leaught at present but I am looking at moving the house batteries forward which will have the run at 6m. I haven't decided as yet but this will take a good amount of weight off the stern which this boat could do with. I have looked at the 40amp Edrive DC-DC which seems boat friendly at around $500. I did have concerns with not having the ability to switch the house bank over if the crank batteries died but I am told that there is a regulator you can install with a switch for such occasions.

I suppose one thing that has me looking at the DC-DC system is having a good quality VSR crap itself and not knowing. The Enerdrive tells you what is happening also having the monitor gives you a heads up which I put in after the VSR lost it.
I am also looking at the Enerdrive 2000 watt inverter and the 40 amp onboard charger. The onboard Truecharge 20 amp charger has see much water and I don't think it's will live much longer due to being installed in a area that can see water. I am in the process of waterproofing (but well ventilated) area at the stern to set the gear up.

I am not sure of the VSR set you have so I will google and have a read.

Thanks for the information Gents.

[scottar]

It will all come down to how quickly you need to get charge into your house bank - maximum you get out of your DC to DC will be 40 amps. The charger will do a better job of charging the batteries provided the duty cycle of run time against down time (I've never played with them but assume it will be set up to disconnect when the engine isn't running) allows it too

While I too have seen plenty of VSR's fail, personally I think the VSR with either a separate or integrated manual override would still be my choice. Knowing whether your VSR is functioning is as simple as a dual bank voltage gauge - if your volts don't come up on bank two once the engines been on for a bit - it has failed and you need to switch it manually. Even if I was to use a DC charger I would still want the volt gauge for the same reason - it's electronic and can fail. If it does fail you will have lost both the engine and solar inputs.

The distance to your house bank - just means bigger cables. If you want any sort of starting redundancy you will need them anyway - even if you do go with the charger.

[brett62]

Thanks for explaining that Scottar. You are correct that they disconnect once the engine is off and only charges with the solar. Also I see your point if the charger fails you lose all ability to charge which is something I didn't think about. I like the idea of the volt gauge which I also didn't think about. It would seem that the VSR and gauge in my set up would be the better idea. I know there are different VSR 's out there, is there a particular one I should look at ?

Also will the VSR fully charge deep cycle house batteries as one of the sales pitches is that a VSR will not fully charge ?

[scottar]

Not to the extent the charger will but once again it will be reliant on required charge and run time. Failures aside, VSR's have been used for years and the combination of that and a separate solar regulator will IMO offer the simplest option with maximum redundancy. I don't have a preference of brands for VSR's. When you look at the housings I suspect quite a few come out of the same factory anyway. Over the years I have used BEP, Blue Seas, Enerdrive and Hella. Have also used the Redarc on vehicles - these are a bit different with a solenoid and a separate sensor/controller.

[Marchy001]

I always thought 12v stuff was easy. Until I started messing with solar, multiple batteries, extended run times, large current draw and long cable runs.

My 2 cents. Good luck.

However I do like the DC/DC charger option with manual backup/override. Batteries are not cheap and if a decent DC charger gives you more time between new batteries then the purchase price of the charger disappears quickly. At a minimum a permanent smart charger that gets used regularly would be better than nothing.

Ps I will be watching and learning as this discussion continues.

[brett62]

Not to the extent the charger will but once again it will be reliant on required charge and run time. Failures aside, VSR's have been used for years and the combination of that and a separate solar regulator will IMO offer the simplest option with maximum redundancy. I don't have a preference of brands for VSR's. When you look at the housings I suspect quite a few come out of the same factory anyway. Over the years I have used BEP, Blue Seas, Enerdrive and Hella. Have also used the Redarc on vehicles - these are a bit different with a solenoid and a separate sensor/controller.

Thanks Scott. All I need to do now is see what type of alternator is used on the motor. I wouldn't think it is a smart one like used on many newer vehicles but I will confirm with the dealer. You never know as the engine is pretty well controlled by the ECU so may have a issue if that is the case. When the boat is sitting in the shed I will have it hooked up to the charger which will keep the batteries fully charged and it goes into float so it's really only when I am out for 3 nights I was concerned and also trying to keep the batteries in good condition. I have lost the three batteries I had in the boat which were new when I got the boat. I know it's been 3 years but I have kept them charged the whole time which didn't help save them.

[Alchemy]

Brett, I have a diesel inboard with 120 amp alternator. I have two crank batteries and 2 x 120 ah deep cycle. The deep cycle batteries are primarily to run my two 100 litre fridges/freezers. I can however run the house equipment via a switch from the deep cycle batts too.

I started out with a blue seas vsr and it died after two years. I now have a ctek d250s dual dc/dc charger, which pushes out 20 amps of charge (now 5 yrs old). I also have 2 x 130 watt solar panels. I too have an electric winch and like you only use it with engine running.

I find this this set up works very well and would never consider going back to a vsr.

Regards
Dave.

[scottar]

I always thought 12v stuff was easy. Until I started messing with solar, multiple batteries, extended run times, large current draw and long cable runs.

My 2 cents. Good luck.

However I do like the DC/DC charger option with manual backup/override. Batteries are not cheap and if a decent DC charger gives you more time between new batteries then the purchase price of the charger disappears quickly. At a minimum a permanent smart charger that gets used regularly would be better than nothing.

Ps I will be watching and learning as this discussion continues.

It's a funny one Marchy. I am about the slackest bugger in the world when it comes to maintaining my boat batteries but on average I get about 5 years out of a standard lead acid wet cell - can't say I ever recall being annoyed with what I would call a premature battery failure. About the only thing I have always been particular about is that when the boat is put away, the batteries via switch or otherwise are totally disconnected - no stereo memories etc at all. My typical charging regime could only be described as randomly intermittent - occasionally when I remember (probably once every 3 - 6 months) I hook up a low amperage maintenance charger for 24 hours or so. The rest of the time they get left to fend for themselves and if the boat is being run semi regularly (seems that happens less these days) the charge from the engine is all they get. Courtesy of the E-Tec I have now split my charging system so the house battery is charged independently but up until the recent rewire they were just run in parallel unless I was parked up overnight.

[brett62]

Brett, I have a diesel inboard with 120 amp alternator. I have two crank batteries and 2 x 120 ah deep cycle. The deep cycle batteries are primarily to run my two 100 litre fridges/freezers. I can however run the house equipment via a switch from the deep cycle batts too.

I started out with a blue seas vsr and it died after two years. I now have a ctek d250s dual dc/dc charger, which pushes out 20 amps of charge (now 5 yrs old). I also have 2 x 130 watt solar panels. I too have an electric winch and like you only use it with engine running.

I find this this set up works very well and would never consider going back to a vsr.



Regards
Dave.

Your set up is near the same as I will have except I am running a single solar panel. How long have your batteries lasted ?

[brett62]

Below is a snippet found on the web while researching what type of alternator I have. I have dropped a line to the dealer to see what it is but in the manual its calling it a variable voltage alternator. The engine does meet tier lll emissions so it could well be connected to the ECU to drop out once the crank battery reaches capacity. This takes load off the motor so less emissions produced and less fuel used which you would measure in cc's





Benefits of using a Battery-To-Battery charger for auxiliary battery charging Battery-To-Battery chargers are becoming increasingly common in leisure, commercial and marine applications, not only as a way of over-coming the issues with smart alternator technology, but also because they provide several benefits over split charging systems when used with traditional alternators:

–	Batteries charge much faster when using a Battery-To-Battery charger when compared with direct alternator charging (as found in split charge systems using VSRs, HD relays or diode isolators). This can typically be around 5x faster.
–	A much deeper state of charge can be achieved because the Battery-To-Battery charger uses a multi-stage profile to maximise the depth of charge, something not possible in standard split-charge systems which will typically charge a battery to around 80% of its capacity.
–	Charging will always take place when the engine is running, regardless of the alternator output voltage, because low voltages are boosted to meet the required charging profile.
–	As in a split charge system, the starter and auxiliary batteries are electrically isolated when the engine is not running to ensure that one cannot discharge the other.
–	The charger protects auxiliary batteries from high voltage spikes produced as a result of regenerative braking systems, so preventing damage to sensitive Gel and AGM batteries.
–	The current reaching the auxiliary battery is determined by the charger rating (rather than by the maximum the alternator can produce), meaning that potentially damaging current in-rush is eliminated. This current in-rush can occur in split charge systems if the auxiliary battery is dead-flat or very low and can overload cables and blow fuses if they are not large enough to cope with the alternator output.

[EdBerg]

Thanks for explaining that Scottar. You are correct that they disconnect once the engine is off and only charges with the solar. Also I see your point if the charger fails you lose all ability to charge which is something I didn't think about. I like the idea of the volt gauge which I also didn't think about. It would seem that the VSR and gauge in my set up would be the better idea. I know there are different VSR 's out there, is there a particular one I should look at ?

Also will the VSR fully charge deep cycle house batteries as one of the sales pitches is that a VSR will not fully charge ?

Hi Brett62, have a look at this one, you can download manual for it from that site and it will tell you how it operates.

http://www.intervolt.com/product/vol...ensing-relays/

I had one of these on the old 26ft boat I had and once I had it installed I didn't give it any more thought, I also had one of those manual switches to switch over to the house battery at night whilst anchored to run the lights, stereo, fridge and MFD which was left running for the anchor watch. When the boat was laid up for over 6 months I just connected a charger to the start battery and it would charge up both it and the house battery, I think it charged them separately, this one has adjustable parameters so you can set the voltage switch points.

Cheers

Ed.

[brett62]

The dealer has informed me that the engine has a standard alternator which I am happy with as I can go either way with charging. I told him the reason I was asking and they said that they prefer the DC-DC when doing installations as it's the only way to fully charge a deep cycle battery bank. Said it's also better due to multi stage charging and if you install a quality unit it will charge all the different types of batteries.

I am now undecided which way to go. It seems to be like which is the best fuel to use, 91 or 98. Thank God I don't have too worry about that.

I still need to go down the path of deciding on what batteries to use which is also another mine field. I started researching that today and my head hurts.