Posting as a FYI in case others are interested or have other charging systems for DC to DC charging set-ups as an optional method to charge on the water where 120 isn't available or easy to access right after you troll. I researched way too many hours on my set-up so sharing my expectations/experiance with DC to DC on water charging system and yes this is lengthy write up but rather give you too much info then not enough. Skim at will. My 2 cents you can't charge a battery up soon enough and not every location / trip do you have easy 120 volt access to charge right away w/o hastle. I personally hate getting new batteries so anything I can do to keep the old ones lasting longer I do. We have way too many vehicles at our farm that get used for short windows and then sit for months. My last trolling battery is still being used (back up sump pump) and is 8 yrs old now and still strong. I spent way too much time getting it charged up right away and keeping it in top condition (watering it / charging it with smart charger....). Wanted something easier for the new boat so here is my story...
I purchased a new boat this year and it has the Merc 150 Four Stroke (non supercharged) which is stated to have up to 60 amp dedicated battery charging regulated at 14.2 volts and 2/3 at 1000 rpm for output so IMO it should be possible to charge trolling batteries on the water while we motor around. My concern was 2 trolling batteries to charge up each night for our trip up north would be a pain as our cottage is up a hill and bugs are bad at night. So I searched the different forums and found several options but all were fairly spendy and some wouldn't state how their charging system even worked. I'm fairly good with my understanding of electricity and have a neighbor who is a electrician if I'm unsure I bounce things off him.
I looked at StayNCharge, Stealth, Minn Kota at first as that is what the forums normally talk about.
Minn Kota was a flat 10 amp / battery which as anyone who run a MK charge knows it talks a LONG time to charge a deeply discharged deep cycle battery. I have 2 Interstate Pro-29M for example. I checked with my boat dealer and they haven't heard great results from guys using this system unless they are out waterskiing for hours on end and didn't use the trolling motor very long.
Stealth system: I have an idea on what they are doing but the talk around what technology they are using to charge the battery and they do mention that it is dependant on how long you run your trolling motor and your outboard and size of alternator. Was leaning towards this system but frustrated me they wouldn't say it was automatic charging relay (ACR) with a program of sorts to keep the heat down. Will allow AC, DC charging so more of a all in one (well several smaller units that can be stacked) depending on how much you want to purchase. Systems start at the 2/$300 range and go way up for a full blown AC/DC unit. Could purchase 4 6 volt golf cart batteries and still have money left over for other toys was one of my larger drawbacks on this unit so I kept looking.
StaynCharge: Decent web page, prices are listed so no sales talk and then talking you into more money then you expected for a charger as I like transparency on pricing. Unit appears to have a 2 min window it charges 1 battery then switches to the other one (in a 24 volt charging system). Around $275 to charge on the water ($188 if that is all you want) and on the road back home thru your 7 prong wire harness on your vehicle. Cycling thru each battery to keep the heat down sounds good but my concern is if you hit your batteries hard that would be too long when first starting the motor as they are depleted compared to your engine start battery. Not sure what the on/off is based on voltage for the engine start battery but I'm sure it has one or you would have a deeply discharged starting battery that is too low for most gun and fish type so while it didn't state I suspect the same logic to turn on also turns off when voltage drops below say 13 volts.
Battery Isolators are inefficient and generate a fair bit of heat (wasted energy). ACR keep your main starting battery charged and hit the trolling batteries for short bursts till voltage is nearly the same as the motor start battery. I like this as the more deeply discharged the shorter the connected time but higher amps. As you get charged amps go down and voltage goes up all helps keep heat down. I liked this but needed to see how to work this with a series connection for the trolling motor.
This is about where I found the C100 from Yandina and the Troll Bridge 24 also from Yandina. They have much more specs on how it works on line so I could look at the method of charging. In my Battery search Interstate Battery had one of their engineers call me to discuss what batterys I should run (Vendor couldn't answer the question so they got me in touch with their national rep and he had the engineer call me which I felt was over the top but glad Customer Service still exists). In talking he stated due to my experience watering batteries the Pro-29M should be more then enough battery and the yandina charging system based on how I explained the principal it works on to him he felt would complement it well to avoid deep discharges for long periods of time with no concern of heat buildup. So at this point I knew what battery to go with and he didn't steer me away from the charging system. I ended up purchasing both.
I should note when I first heard late on a Friday about Yandina I contacted their Customer Support email around 5 CST (They are EST) and in a few hours I had a personalized response that answered all my questions I had stated. Wow someone else that works way too many hours like myself. ;-) I also asked a question when installing and they were very quick again so I have pre and post sales experience with their CS rep.
I work on our family farm so spring isn't about getting my new boat in the water as quick as possible it is about getting the crops in and making sure they all germinate which this past spring was cold, wet and not the easiest to get everything planted, weeds sprayed, and even had to take out a item we haven't used for 10 yrs, a rotary hoe, to help get the seedlings out of the ground.
The yandina system I used the C100 connect the engine battery to the 1st trolling battery when you exceed 13.3 volts AND x length of time in sec has elapsed. It also disconnect when it drops below around 13.1 and x length of time in sec as well. I forget what the exact time is but I never saw voltage drop too low even on deeply discharged trolling batteries where I had less then 11.5 when I started the outboard last night. The trollbridge senses for the trolling motor and switches batteries from parallel to series as you use your trolling motor. When in parallel both batteries are equalized or just look like 1 HUGE 12 volt battery, when in series you can still charge the 1st trolling battery and when they switch back to parallel they will equalize. I've heard more then my share of sales pitches over the years and as my short time in MO stated "SHOW ME" so I purchased, installed and after my work to get the trolling motor/Humminbird to work as ilink I had a short test and off to upnorth it was. (Had to do drainage tile, Take down 3 grain bins and get the foundation ready for a new one... again fishing is fun but work has to come first and the farm is a hobby not a job on the books so I have a real job too).
1 week test... We used the follow the contour and sometimes autopilot or trolling one waypoint to the next that we marked from fish caught all week long never drift fished at all to test everything out plus if we are catching fish why change what is working. We trolled morning and night but due to the colder temps we weren't getting most in the water to ski. Water temp was 66 degrees most of the week. Smaller lake north of Eagle River, wi so not a bunch of driving around to spots so at night I ran the motor at 1000 RPM at the dock as we got things set-up to clean the fish to help charge things back. Each morning I checked voltage on the trolling batteries and was between 12.74 and 12.82 volts each morning with no charging other then the dc/dc charger. When we waterskied once voltage was steady at 14.2 I knew all was fully charged as well. One morning it was cold, and a nice rain storm pushed so we put the top up and kept fishing as they were hitting yet. Ran for 6 hours of which 3 was pushing hard into the wind around 8-10 on prop speed with a sun top with front clear plastic to help drain the batteries down a bit. When we decided a late lunch / early dinner was in order I decided to hook up the volt meter and watch the motor start battery (on the Humminbird) voltage and the trolling battery 1 voltage. 18 seconds after start-up voltage dropped on the motor battery and jumped up on the trolling battery C100 lit up as it was combined. We watched a bunch of cycles which told me it was doing what I expected and stated. Ran slow in to help charge everything up and idled at the dock with just throttle at 1000 RPM. Once I saw 13.8 or higher steady on the motor I shut it off. I haven't added a charging wire for while trailering the boat. I do plan on doing this as we camp and charging while going back to the campgrounds (Tent non Ele sites) would be helpful as morning and night fishing is typical.
You can run any external charger on 1 , 2 or all 3 batteries if you need. Example last night I ran 5 hrs between 7-9 on the trolling motor trolling Winnebago in 2 ft "walleye chop" into the wind with the top up with my boys. We ended up dashing back at night to the landing and I had run the batteries down a long ways and the kids love crashing the waves at speed. So at home just plugged in the 3 bank charger I have, but one could just connect 1 and it would charge all 3 regardless of which one you connect the charger to which I normally just do.
I have no association with interstate batteries or yandina, The vendor that got me in contact with interstate was Costco (of which I'm only a club member) as I asked them why they didn't stock a larger trolling deep cycle battery so they ended up special ordering me the Pro-29M after the rep/engineer verified the right battery they would recommend. I felt this was not expected by my request but well received CS. I'm by no way saying this is the best charging system ever but the price was $59.99 for the combiner and $82.99 for the trollbridge 24 (Well I got a early season whse sale of 10% off which covered shipping and a few bucks). I did need to purchase cable from the motor start battery to the trolling battery and 1 inline fuse which I put 300 amp as this is just short protection because they are 15 ft away. I ran 4 gauge welding cable with industrial crimped and adhesive backed heat shrink on all connectors. But this is way over kill but I was in a hurry and my company discount made this wire really really cheap. 10-8 gauge is all that would have been needed. Remember as voltage rises less amps are needed to charge so voltage drop isn't as critical as your trolling motor that could pull in my case up to 56 amps anytime. Charging as you near full the amps drop off and your voltage drop becomes almost none.
I share this as I know the $ spent on batteries and if this helps get another season out of your trolling batteries then it will pay for itself in time on the water and less overall battery costs / year on average. At the end of the day not having to worry about what it does as it just does it was great. You can add a switch to force combining (jump start motor start battery for example) or force it to not combine or leave it unconnected to do automatic which is how I currently run it. Neighbor wants to run a switch for me as a favor so I will probably let him do that so if I ever need to help start the motor I can w/o having to use jumpers. I am posting this because I didn't find much information about this charger and felt it should be looked at more closely by others as another option and after hearing so many bad reviews on the MK DC to DC charger.