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Paulio avatar image

Battery to Battery Charging.

I Have a Motorhome 12V system (2 x AGM 110AH) with 100W Solar via MPPT 75/15, Mains hookup Amperor 3 stage charger and a VSR split charge from the crank battery with standard alternator. There is also a BMV 700 & Venus GX. I am looking at ways to prolong the life cycle of the batteries after the current batteries lasted only one season. I have identified that the VSR split charge is a crude method of charging and could be improved with a battery to battery charge system. There are plenty on the market but I would prefer to use Victron products. I have found a Victron Energy Orion 7-35/12-3 Buck-Boost regulator that looks to be something like what I need but am unsure if it will give a charge quality comparable to say a Sterling Power 4 Stage Battery to Battery charger. I would be grateful for any advice or recommendations on the system and suitable products. Any tips on system setup improvements would also be appreciated. Thanks in advance.

MPPT - Solar Charge Controllerbattery chargingorion converter
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You don’t mention how your system makes use of the MPPT, but unless it’s only acting as a trickle charger it seems a single 100W panel wouldn’t be enough to seriously charge 2 110ah batts if they are seeing heavy use?

Just wondering if there’s more to the short life cycle of your batts than the split charging.

13 Answers
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi Paulio; thats great to hear that you prefer Victron! :-)


We’re working hard on battery to battery chargers; but expect to have them in stock later this year only I’m afraid.

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That is interested and I am tempted to wait. I wonder if you can help on a couple of questions -

If i add a battery to battery charger to my system is it likely to upset the MPPT solar charge in any way?

Is the new Victron battery to battery likely to have any integration into the Venus os?

Thanks

Do you have more information to share on the timeline for battery to battery chargers? And are we talking real 3 or 4 stage battery chargers that can charge a battery with different chemistry than the source battery?

Yes real charger; no no more info; sorry. See community guideline; that explains why no more info nicely.

I'm interested in a solution as well.

Looking very much forward for Victron battery to battery charger

@mvader Should I get my hopes up for a 48 V /48 V model also :)

@mvader (Victron Energy Staff)
Any update on the battery to battery charger? I'm in the market for a 12v to 24v charger that can be connected to a truck alternator charging system.

I like to try and keep my equipment blue in color ;)

Hi @wikel, production is starting up. Still lots of things that can go wrong; but as it looks now.. its a few months from now that the first models will be in stock.

nebulight avatar image nebulight mvader (Victron Energy) ♦♦ ·

Sounds awesome. I know you guys don't give details before a product launch, but any chance of it having VE.Direct for integration with a Venus device? This would finally enable all my charge sources to be Victron and logged with VRM (and hopefully work with DVCC). Fingers crossed.

Hi @nebulight. No, unfortunately not; the base design which we we took for this didn't allow for that to be put in.

The next iteration: for sure.

nebulight avatar image nebulight mvader (Victron Energy) ♦♦ ·

Thanks for letting me know. I just bought a DC-DC charger from another brand last year so it's good to know I won't have to replace it right away ;)

@mvader (Victron Energy Staff)


Any additional update available? Are we waiting for November as stated below?

wikel avatar image
wikel answered ·

Is the Orion-TR Smart the solution that's coming out at the end of the video here?

https://youtu.be/jgoIocPgOug

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Ha you keep a close eye on things :-).


Yes. And first three isolated models are expected to be in stock soon. (Weeks)


See also johannesburg automechanika blogpost.


Two/three weeks from now I expect to have datasheet and other details online

Christian Lindermann avatar image Christian Lindermann mvader (Victron Energy) ♦♦ ·

Great news!

Keep my fingers crossed, that it will also supports VE.smart Network for monitoring battery temperature while charging....

wikel avatar image wikel mvader (Victron Energy) ♦♦ ·

@mvader (Victron Energy Staff) I'm hoping it has a lot more juice capacity than 15a @ 24v. Looking for a solution that can handle around 75a @ 24v charging from my truck dual alternators to my 720ah lifepo4 bank. Any spec sheets running around?

@wikel See link from Doug above. Largest is 24V/17A (400W) but they can be paralleled for larger output current.

Seems like I would be better off doing a 2 buck boost 12/24 buck boost (50a+25a in parallel) to up convert the alternator output for sending to the camper. Then use a smart solar 150/100 to integrate the current control into my Venus GX system or maybe I'm missing something.

Started getting pricing in for the 12/12-30. Unfortunately it seems Victron has priced this out of the market for me.


It's £275 in the UK (inc tax), or €235 (plus tax) in Spain. The Sterling BB1260 Battery to Battery charger is £270, double the amps, and has a little more functionality, albeit with a clunky interface. To match the Sterling unit, I'd need two Orions at over £500 plus separate temperature sensors.

Techlysmic avatar image
Techlysmic answered ·

New to this thread. Very interested in the B2B charger and EasySolar for my van. What year are these posts - is the last from Victron staff Jan 2019? Anything new?

Absent a solution in the next 2 months, I'm looking at a Sterling BB1260 for my 220a alternator. If I'm reading comments here correctly, this should work fine in line with an EasySolar to my LifePO4 house batteries?

Thanks!

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Hi Techlysmic,

This question and answer is a good case study in why Victron generally don't discuss release dates on the community :)

The next major Victron global event is at METS show in Amsterdam in November. This is typically a big new product launch event for Victron. Here is some info about last years event: https://www.victronenergy.com/blog/2018/11/02/mets-2018-preview-glass-bridge-smart-everywhere/ https://www.victronenergy.com/blog/2018/11/21/mets-2018-marine-success/

I have no information or insight about the release of a battery to battery charger, but that would be the next 'opportunity' to hear about it, and I would expect some news then. There is no saying what that news might be though, immediate release, release date, or info about a delay.

wikel avatar image
wikel answered ·

Any update on the future solution?

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mikedefieslife avatar image
mikedefieslife answered ·

Can't the smartsolar controllers which are really just DC to DC converters be used as battery to battery chargers? Setting the bulk/absorption and float voltages then give you controls over the charging process.

Presumably it could be used in a setup where an alternator charges a starter battery which is then connected to a 50a or 100a Smartsolar controller, which then charges a LiFePO4 bank.

I'm probably totally wrong but it's just something that popped into my head.

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osaether avatar image
osaether answered ·

I have used a Victron DC/DC converter to charge my main batteries from my old bank and vice versa for many years. The last couple of years I have used a Orion-Tr DC/DC. I have set the output voltage of the DC/DC to the temperature compensated absorption voltage of the batteries . I can turn on the DC/DC as well as the direction of charging remotely via the two relays on the Venus GX.

See below for a couple of pictures. To the left is my old bank and to the right my main battery bank. Both 24V nominal. Also a close up of the DC/DC showing the relays that switch direction.

Please note that these DC/DC only works in bulk mode.

And least: sorry for the mess in wiring!




dscf0211-small.jpg (410.7 KiB)
dscf0215-small.jpg (227.2 KiB)
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wikel avatar image
wikel answered ·

I'm interested in a Victron battery to battery charger as well.

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Paul B avatar image
Paul B answered ·

If you are going to replace the battery then seriously look at a Lithium Phosphate battery.

yes they may cost some more but they will last and last,

The L/P will cost about 50% more if you compare usable to usable Capacity and compare to good quality deap cycle L/A batteries, NOTE:- you dont need the same number of batteries, to get the same usable power.

some reasons to change as a example only and exact figures are not quoted ruff only OK but it gives you the idea

basically 2 x n200 lead acid batteryies 400A/H of which you can use MAX 200a/h at 50% Usable

Then a LP say 1 x 200 A/H will replace both the above and give you a MAX 180A/H usable

1/4 the size 1/4 the weight.

plus a L/A battery takes a long time to charge from 80 to 100% so you basically only use 50 to 80% a lot of the time

L/P goes full charge rate all the way to 95% and the last 5% max 1 hr

L/A take out 100 amps then you have to add back 120 amps

L/P take out 100 amps then add back 105


Well worth the extra investment



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Also, the lead acid batteries should be fully charged every day. Not so with L/P, meaning you can drain them much more - any time- and charge much faster at your convenience (sunrise). This gets the full capacity / efficiency out of your charging source.

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Redwood answered ·
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Thanks,

This was on my short list, I already have the equivalent from Ring, but it is rather temperamental. I would prefer to buy from a known brand and Victron products are very highly regarded and would be my first choice.

J Clarke avatar image
J Clarke answered ·

This is most interesting, I will be in the market for a Battery to Battery Charger with solar capabilities this year but will be waiting to see the Victron offering. I am most impressed with the products I have so far.

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t0mb0 answered ·

I would also be interested in this - any more clarification on timescales?

The key feature that would differentiate it from the competition would be a decent capacity solar input. Most existing products have solar inputs but they only cope with max 32v or so which rules out the larger solar panels people tend to use on vans and motorhomes.

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John Schmidt avatar image
John Schmidt answered ·

I have used the REDARC BCDC in-vehicle chargers for years for this purpose in parallel with either limited solar PV or none at all. I also use a remote switch on the dashboard to switch it in/out otherwise your alternator will always be charging (OK in some circumstances)

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Hi John. The REDARC is what i was considering but may hold on for the Victron version to keep the installation tidy.

mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

It wont upset the mppt.


Integration; yes (probably). But limited: no current and power reporting; for example.

Sorry to be vague; but thats what I know by heart.

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Thanks for the info.