Page 12 of 12 FirstFirst ... 2101112
Results 111 to 117 of 117

Thread: DC/DC chargers, How do they work and do you really need one.

  1. #111
    DiscoMick Guest
    Yep, folding panel blanket is a goid idea.

  2. #112
    Join Date
    Dec 2014
    Location
    Townsville
    Posts
    268
    Total Downloaded
    0
    I won’t post a pic of the boat here but you can see it on my Facebook page - search ‘Lee Fitzpatrick’.

  3. #113
    Join Date
    Jan 1970
    Location
    Queensland
    Posts
    7,571
    Total Downloaded
    0
    Quote Originally Posted by Barraman View Post
    Oh dear - you asked for it, so here goes!

    There are 4 stages to my battery/VSR/charger experience with the larger of my two boats. The boat is a 6.7 M glass/composite custom build, side console 'barra boat' ,with front and rear casting decks. O/board is a Yamaha 250 Vmax SHO on a Bob's Machine Shop jack plate. Up front is a Minn Kota Ulterra 112lb 36V trolling motor. It has 4 x combo sounders (Humminbird Helix 7 in the console, Helix 10 and Helix 12 G2 mega SIs above the console, and a Helix 12 G1 SI on the front deck - I think they can each draw 1.75A). I run 4 x transducers, including a Humminbird 360.

    We only use the outboard to get to where we want to fish (often a 20 - 30 nm run) and to change spots, and then spend most of our time on the electric trolling motor. We are mono-species fishermen - lure chuckers for barramundi!

    Stage 1: 1 x 120 Ah AGM 'start' battery and 1 x 120 Ah AGM 'house' battery connected via a standard BEP unit that included separate master switches for the start and house batteries, a switch that connects the two batteries in parallel for and "emergency" start, with the VSR between the start and house batteries. The trolling motor is on 3 x 120 Ah AGM batteries that are quite separate from the start and house batteries in any way. The two sets of batteries were put on separate mains smart chargers overnight on multi-day fishing trips.
    After long periods just on the batteries without running on the outboard, I would get 'low voltage' alterts on the sounders.

    Stage 2: I added a second 120 Ah AGM battery to the 'house' (connected in parallel). Better - but still ran out of grunt, as our time on the water also was increasing - 12 hr days of which only maybe 2 were with the outboard running but the electronics were all on.

    Stage 3: Someone suggested ditching the VSR for a 12v DC-12v DC charger, so I fitted a Sterling Pro Charge B 20A unit. Problem with the sounders was solved but now I had a new problem. We were now spending a week at a time fishing the McArthur R in the NT and after about 4 days the trolling motor batteries were starting to struggle. They were not getting sufficient charge overnight and were slowly running down.

    Stage 4: I fitted a Sterling Pro Charger B 12v DC - 36v DC 30A unit between the two 'house' batteries and the three trolling motor batteries.

    PROBLEMS SOLVED!

    We can fish all day for days at a time without running out of power. My mates suggested that I install a small thermonuclear power plant - but that doesn't seem to be required at our present level of activity.

    When mains power is available the start/house batteries are on a Sterling 240v - 12v DC smart charger, and the trolling motor batteries are on a Pro Mariner Pro Sport 20 Plus 20A triple bank (3 x 12v DC) charger. I have a master switch installed to disconnect the 12-36v charger when the trolling motor batteries are on the mains power charger.

    Yes, the boat has 6 x 120 Ah AGM batteries - and they are HEAVY! I would like to change to lithium, but I don't quite trust them. Fires on boats scare the crap out of me - patricularly when fishing in croc and shark central!
    Hi again Barraman, your requirements are not exactly what I would call an RV situation.

    But that aside, your setup works fine for you, so all is well.

    If you do decide to go to lithium batteries, just a couple of suggestions, I sell quite a few of the Sterling Pro Charge B units, primarily for trolling use.

    These units have one of the best Lithium charging algorithms available ( it’s actually a German based program ).

    But because it sounds like you are going to be using these batteries full time, I suggest you use the AMERICAN GEL setting on the Sterling Pro Charge B unit.

    This setting charges at 14.0v, instead of the 14.4v the Lithium setting charges at.

    For normal everyday RV use, the Lithium setting is perfect, but when lithium batteries are use in long term heavy duty use like it sounds you would be using them, the Lithium setting can be a bit hard on batteries, and by using the AMERICAN GEL setting, you will help to extend the life of the batteries.

    The other suggestion is to make sure you get good quality Lithium batteries, as there are some pretty crappy batteries out there now.


    A word of caution, do not use a lithium starting battery with any Yamaha gear as I have heard through the industry that there are problems where they can damage the electronics in these types of motors and companies like Yamaha are voiding warranties if lithium starting batteries are used. Double check this one to be on the safe side and also check to see if using lithium house batteries will also void the warranty. Your trolling batteries are fine.


    While I use to sell ProMariner battery chargers, I now only sell the Sterling versions. They are the same chargers, made through a Joint Venture Development between Sterling and ProMariner, it is just that Sterling offers far better backup, right here in Australia, through Sterling -Power-Australasia.

    https://sterling-power-australasia.com.

  4. #114
    Join Date
    Apr 2019
    Location
    Brisbane
    Posts
    1,528
    Total Downloaded
    0
    Well I kinda had to install a DC-DC today...

    Was a little worried about restricting charge rate to 40amp/hr.

    200amp/hr battery was at 70% when I collected the car....

    Running around today do a few errands with an under performing solar arrangement (Max. Watts was 105) battery was topped up to 100%.

    That was with no load on the battery.

    Fridge on and will stay on and a weekend of camping will give me a better idea

  5. #115
    Join Date
    May 2020
    Location
    Mackay
    Posts
    1
    Total Downloaded
    0

    Play It Safe

    Quote Originally Posted by V8Ian View Post
    ​Mod hat on.

    The OP has asked for a simple explanation of DC DC.
    Please keep comments and answers civil and without bias toward posters or systems, stick to facts.
    This will prevent the thread being shut down.
    DC DC controls the charge voltage and current supplied to the auxiliary battery without interference from the vehicle electrics eg. Spotlights or air conditioner compressor turning off and on.

    This represent a more consistent and precise way to control the charging process and it will also respond appropriately to auxiliary battery only loads eg. fridges.

    Because car alternators are not designed for lithium batteries and these batteries have very low charge resistance (allowing massive charge currents), the alternator can supply this very large current and the battery BMS max currents limits are also very high you can end up with a smoking alternator (with rather bad results), especially if your vehicle is stationary ie. no air flow.

    Other standard lead based batteries (wet, AGM, calciumJ have a high higher charge resistance which self limits the charge current it can accept. If you push high currents into these batteries they will heat up, turning any energy they cannot accept into heat.

    Victron have a very good yout-be video demonstrating this problem with lithiums running off a vehicle alternator.
    This issue applies equally to standard / variable voltage / smart alternators.

    Never run a lithium without a DC DC - DC DC will restrict power transfer to charge the auxiliary to acceptable levels for your alternator.

    DC DC will also galvanically isolate your car electrics from your auxiliary electrics - donÂ’t get them crossed up somewhere else in your wiring - common ground is fine.

    A DC DC will also overcome the voltage drop problem resulting from long wire runs and auxiliary battery loads PROVIDED the DC DC is reasonably close to the auxiliary battery - you need the right voltage at the battery it is charging not down the other end of a long wire where you have already lost 0.5v for example, from wire resistance losses. Prime example - using a DC DC mounted under the bonnet to charge caravan / camper trailer batteries.
    And remember the thicker the wire the less loss per metre of wire.

    Blue Seas have an excellent wire size versus current chart versus run length for selecting the appropriate wire size.
    It also provides choices of acceptable wire run voltage drops and a seperate fuse type / size chart.
    FYI - the standard auto twin pair cable in Australia is not what it may appear. 6mm auto is NOT 6mm2 (more like 4.5mm2). The Blue Seas charts refer to mm2. Also B&S is the same as AWG (one is Aussie and the American Wire Gauge).

    i could go on but will leave it to some reasonable questions.

  6. #116
    Join Date
    Aug 2006
    Location
    Melbourn(ish)
    Posts
    25,996
    Total Downloaded
    0
    Quote Originally Posted by Barraman View Post
    I’m very conscious of hyjacking this thread. I made a simple observation that was relevant - I have replaced the VSR’s in both my boats with DC-DC chargers, and find them to be more effective. How do I judge that? Simply because the ‘low voltage’ warning doesn’t come onto my Humminbird Helix 12 mega sounders as often as used to be the case. Another motivation was that I know of two VSRs that have shorted out and burnt. All the commentary does not change my observation.
    One thing to watch with VSR's is that the current you're asking them to handle isnt above their rating or they burn out...

    If you've got a near flat battery on the "delivery" side of a VSR and a near fully charged battery plus all the ergatrons of an alternator on the supply side its very easy, for a very brief period to dump many buckets of amps across it.

    I've pegged a 200A clamp meter when a VSR clicks in trying to charge a pair of N55's (solar supported house batteries)at a little over 10v from a pair of N70's (winch/start batteries) at 13.7V with a 55A alternator adding its bit. Only takes a couple of handfulls of times and your VSR will clag. Which explains why the owner went through 3 of them before deciding it may not be faulty units (admittedly, they were chineesium alibabwaaaahhh units)
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    TDI D1(parting/ed)
    Tdi autoManual d1 (Kept it for the girlfriend)
    Archaeopteryx 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

  7. #117
    Join Date
    Jan 1970
    Location
    Queensland
    Posts
    7,571
    Total Downloaded
    0
    Quote Originally Posted by jrt70 View Post
    Because car alternators are not designed for lithium batteries and these batteries have very low charge resistance (allowing massive charge currents), the alternator can supply this very large current and the battery BMS max currents limits are also very high you can end up with a smoking alternator (with rather bad results), especially if your vehicle is stationary ie. no air flow.

    Victron have a very good yout-be video demonstrating this problem with lithiums running off a vehicle alternator.
    This issue applies equally to standard / variable voltage / smart alternators.
    Hi jrt70 and sorry mate but that is a complete fabrication, as is the Victron video which has already been covered.

    They get a small alternator and run it at maximum RPM, and maximum load, with no cooling what so ever and it cooks. Surprise, surprise.

    They then get a much bigger alternator and put a current limiting device on it and run it at about half it’s designed maximum current output, and what do you know, it does not cook.

    If they ran the smaller alternator at half its designed current capacity, it to would not cook. Or if they put a decent air flow over it when it was running at maximum output, it wouldn’t have cooked.

    I know of quite a few people who charge lithium batteries direct off their alternators.

    One guy lives in his van full time and regularly charges his 4 x 100Ah lithium house batteries straight off his alternator when driving from one location to another, in his Land Cruiser.

    It is common for him to drive for 3+ hours straight, which means his alternator is running full bore for all that time, and he isn’t “smoking” his alternator when ever he charges his lithium batteries on the run. And he has very thick cabling to his van.


    Another thing, if you were running an alternator at such high revs while stationary, that you risked cooking the alternator because of the lack of air flow. Mate you would cook your motor way before you “smoked” your alternator.

    Finally, yes a DC/DC device can fully charge batteries, but they take hours more than an alternator and even SMART alternators can FULLY CHARGE batteries, you just have to drive long enough for either system to be able to have the time to fully charge the batteries, and when given the time, an alternator will charge the batteries faster.( in a shorter time ).

    B/S is B/S and that is what is used to sell many of these wonder devices.

Page 12 of 12 FirstFirst ... 2101112

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!