DC-DC Charger vrs VSR set up

[scottar]

That can be another area where the charger can be a good thing Brett - if your starting and house banks are sufficiently different chemistries and require different charging parameters. Not something I have ever bothered with on my own boats or had to deal with on clients though. Andy is probably the best one around here to talk to with regard different requirements for different chemistries as far as charging is concerned. I would still be looking at being able to effectively bypass the charger with a switch and using heavy enough cables for starting / emergency charging if required.

[Alchemy]

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 ?

Brett, I replaced my start batteries after 6 years. One was a bit weak due to the vsr failure years ago. Both batteries are now in my F250 and still going ok. They are Deka Intimidator batteries. Around 780CCA each. They aren’t the cheapest around but are relatively compact and light for their capacity. I have replaced them with the same brand and model. Whitworths have them for around $400 each but I found them online for $330 each, delivered.

My deep cycle batteries were Fullriver. I replaced these last year with Marshall 120ah. These look like they have come out of the same factory as Fullriver. One of the Fullriver batteries is now 10 years old and in my tinnie for sounder and minkota duties. The other died, but I suspect that was my fault as it was an HGL model and not suited to my application. Also I suspect not smart of me to have it paired up with th older DC model Fullriver.

The other advantage of the DC/DC charger is that I have an onboard 240v charger and just plug a lead into boat at home. This keeps my start batteries charged, and while it is on, the DC/DC charger is charging and maintaining my deep cycle batteries.

Regards
Dave

[brett62]

That can be another area where the charger can be a good thing Brett - if your starting and house banks are sufficiently different chemistries and require different charging parameters. Not something I have ever bothered with on my own boats or had to deal with on clients though. Andy is probably the best one around here to talk to with regard different requirements for different chemistries as far as charging is concerned. I would still be looking at being able to effectively bypass the charger with a switch and using heavy enough cables for starting / emergency charging if required.

Scott after some research on batteries it could well be that I decide with different chemistries and house and crank will require different charge rates etc. I will certainly be setting something up to allow emergency starting. I did speak with a auto electrician today and there is a regulator available to do just that. From the conversation I got the impression that he has played a fair bit with marine set ups. Also advised that I install a low voltage shut off as running the deep cycle bank below 12V is not good for the long service life of the batteries.

[brett62]

Brett, I replaced my start batteries after 6 years. One was a bit weak due to the vsr failure years ago. Both batteries are now in my F250 and still going ok. They are Deka Intimidator batteries. Around 780CCA each. They aren’t the cheapest around but are relatively compact and light for their capacity. I have replaced them with the same brand and model. Whitworths have them for around $400 each but I found them online for $330 each, delivered.

My deep cycle batteries were Fullriver. I replaced these last year with Marshall 120ah. These look like they have come out of the same factory as Fullriver. One of the Fullriver batteries is now 10 years old and in my tinnie for sounder and minkota duties. The other died, but I suspect that was my fault as it was an HGL model and not suited to my application. Also I suspect not smart of me to have it paired up with th older DC model Fullriver.

The other advantage of the DC/DC charger is that I have an onboard 240v charger and just plug a lead into boat at home. This keeps my start batteries charged, and while it is on, the DC/DC charger is charging and maintaining my deep cycle batteries.

Regards
Dave

Thanks for the information on the batteries Dave. Just started looking into batteries today and there is so many out there it's mad. Went in to Battery World to see what they had and he suggested 2 x Yuasa Seafarer 780 MF 100ah 780 cca as the cranks and 2 x Century C-12-120DA AGM 120 amp for the house. $1100 for the four batteries. I suppose at the end of the day it doesn't matter how good the batteries are if not maintained correctly you are only going to get minimum service life out of them. It seems you have your system running well and like you I will be leaving the onboard charger on when I am parked up.

I don't quite get when you say that you keep the start batteries on the onboard charger and your DC-DC is also charging at the same time to the house bank. How does that work ?

[scottar]

I find the "regulator" a bit intriguing. Have seen bypasses with a solenoid, relay and push button switch (Redarc) . Let us know more when you do. I couldn't see any mention of emergency starting circuit in the Enerdrive paperwork at a glance.

[Dignity]

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.

I'm confused, (probably a combination of old age and not understanding new technologies) but when I look up the details on the above ctek d250s and many others, the "dual" appears to be related to the Input side and not the Output side. So how does the above charger charge both the starter battery bank and the house battery bank. To confuse the issue further will it or any other dc/dc charger charge say a wet cell and an AGM.

Sam

[Alchemy]

I don't quite get when you say that you keep the start batteries on the onboard charger and your DC-DC is also charging at the same time to the house bank. How does that work ?

My onboard 240v charger is dual output, and connects directly to each battery. I have taken the dc/dc charger feed from the first start battery. I assume the dc/dc charger detects the charge and in turn activates itself to charge, just like it would when getting a feed from alternator.

[Alchemy]

I'm confused, (probably a combination of old age and not understanding new technologies) but when I look up the details on the above ctek d250s and many others, the "dual" appears to be related to the Input side and not the Output side. So how does the above charger charge both the starter battery bank and the house battery bank. To confuse the issue further will it or any other dc/dc charger charge say a wet cell and an AGM.

Sam

Sam, the main advantage of the dc/dc is the dual input and 7 stage charging. In reading about this particular charger it says that once the deep cycles are charged it will divert a charge back to the start batteries. No idea how it does that! I’m not that concerned either as I bought to charge the deep cycle batteries only. I am happy relying on the alternator to keep my start batteries charged.

Regards
dave.

[Alchemy]

Scott after some research on batteries it could well be that I decide with different chemistries and house and crank will require different charge rates etc. I will certainly be setting something up to allow emergency starting. I did speak with a auto electrician today and there is a regulator available to do just that. From the conversation I got the impression that he has played a fair bit with marine set ups. Also advised that I install a low voltage shut off as running the deep cycle bank below 12V is not good for the long service life of the batteries.

Re the emergency starting set up. I use an everyday manual dual battery switch so I can isolate one start battery at night so I know I have a fully charged battery in the morning. One 780CCA battery is enough to start my engine if necessary. Other than that, if I get stuck I can drag out the jumper leads. I have tried to keep my set up as simple as possible.

[Dignity]

Sam, the main advantage of the dc/dc is the dual input and 7 stage charging. In reading about this particular charger it says that once the deep cycles are charged it will divert a charge back to the start batteries. No idea how it does that! I’m not that concerned either as I bought to charge the deep cycle batteries only. I am happy relying on the alternator to keep my start batteries charged.

Regards
dave.

Thanks Dave, maybe I need to read a little deeper as when I look at all the schematics attached with various chargers they all show them connected to the main battery which is why I was confused.

Cheers Sam

[brett62]

Ok so rang Enerdrive to speak with a tech and ask all the questions buzzing around in my head.

First the onboard charger will charge different batteries. The unit I am looking at is a 3 bank 40 amp which allows you to set one bank say house batteries (deep cycle AGM's) and the second bank crank (flooded). It will charge bank 1 first at that you have set and once fully charged bank 2 is then charged. Once all the batteries are charged it goes into float mode for all banks. When on float it monitors both banks and switches over to a top up charge on whatever bank requires it. After so many hours it then goes back into a full cycle which I think he said 7 days.

Next was the DC-DC 40 amp charger. This one was the interesting one for me. First off he said if you have your battery banks set up correct which means only running power from the cranks for engine starting (said running the winch with motor running would be ok) there is no need to have a DC-DC connected as the 120 amp alternator will take care of the start batteries with no issue. (This is what Alchemy is also doing) The DC-DC will keep the house batteries happy and also take care of the solar. The solar will only bring charge to the house batteries not the crank. Now the important question was "can I connect my house bank to the crank bank for a WTF moment" answer was yes and it's as simple as a battery switch with the correct sized cables which is turned off until the WTF moment happens. No regulator, solenoid required and no damage to the DC-DC charger. He said you can also have a VSR installed with a switch over if the DC-DC charger crapped itself you could charge back to the house bank. He did explain how you do this but my head was spinning by this time.

He too recommended installing a low voltage cut off on the house bank. I also asked about charging deep cycle AGM through a VSR set up and he said yes it will charge but not fully and due to the un controlled charging through a standard VSR will shorten the life of the battery. He did say that there are now smarter VSR's available which do a better job with regulating current but are close to the same price as a DC-DC.

[Dignity]

Brett, my head is spinning also. Just a thought, if you have the dc/dc charger on your house batteries why not hook the solar to the crank via a regulator as a backup or when you are doing long drifts. I'm not sure about your anchor winch but mine seems to really sucks the juice when the anchor is being obstinate even with motor running and to rely on the motor topping the battery up may be cutting it fine.

[brett62]

Dignity I don't use the winch much as in deep water anchor reteval I tend to use my float and I also do a lot of fishing at night so solar won't help me then. One reason I will have two crank batteries.

[Dignity]

Dignity I don't use the winch much as in deep water anchor reteval I tend to use my float and I also do a lot of fishing at night so solar won't help me then. One reason I will have two crank batteries.

Not a lot of anchoring either except overnight but a few relocations and an introduction to a pie oven (thanks mojoes) now I'm having to rethink my power options.
Cheers Sam

[TheRealAndy]

IF you are using two different chemistries (ie flooded lead acid for start and AGM for house), then a DC-DC technically is a better option. However a VSR will still charge the different chemistry fine despite what people say. AGM's are actually quite sensitive to higher charging voltages, so a lower charge voltage is better for longevity although it will take longer to fully charge the battery. If the AGM is getting at least 13.5V when charging then it will eventually come up to a full state of charge.

Its also worth nothing that most recreational boat users are highly unlikely to run the engines long enough to fully charge the house battery. The solar will need to take care of that, or you will need to put a 240V charger on it when its at home.

BTW, if you think its a pain in arse figuring all this out, then try find a solution when you have 2 outboards with 2 separate batteries and a house battery!!! There is nothing out there that solves my problems at all. I have some experience with charger design, and I keep telling myself that I am going to design a complete smart battery management system for boats with twin engines, but alas its probably never going to happen. MY current setup using the Enerdrive dual sensing VSR's is not ideal for what I want, but it works ok. The biggest problem I have now is lack of solar panels and battery capacity. I am thinking about using 200ah of lithium to keep the weight down, but the cost is a big turnoff. Also, lithum batteries are very fussy about charge management, and there really is nothing on the market that will take the output from 2 alternators and solar and charge a lithium battery.