B2B CHARGER.

[Mtbcol]

Good evening all. Looking ahead to when We get some lithium, I'm looking at B2B chargers. We are currently running 3 x 110 ah lead acid batteries, charging via a solar panel and a VSR. Whilst this system has served us well for several years, I'd like to upgrade eventually to lithium. I assume I can purchase a B2B charger and run it on my current lead acid batteries until we're ready to go lithium? Would a decent B2B (say victron) be capable of charging lead acid or lithium so it can be used when we change to lithium? Also does it matter what charge rate unit I get, I'm thinking the higher charge rate the quicker our batteries will be charged? All suggestions and ideas welcome.

Thank you.

Colin.

 

[Bigshug]

Victron products normally have pre installed settings for various battery types, so it is just a matter of choosing the preset to suit your batteries.

 

[trevskoda]

Solar requires a match to batteries, ie 100w solar to 100ah batteries, any type.

 

[Robmac]

Solar requires a match to batteries, ie 100w solar to 100ah batteries, any type.

Desirable Trev but not required.

I ran my 240AH with a 100W solar panel for years with no problems.

 

[Mtbcol]

Solar requires a match to batteries, ie 100w solar to 100ah batteries, any type.

We have 320w solar for our 330ah of lead acid

 

[merl]

Most B2Bs have selectable preset charging profiles for various lead acid and lithium, many have user definable settings too.
You're correct in saying that a more powerful unit with a higher current rating will charge your batteries quicker but they also place a greater load on your alternator. It may be best if you can find out what the current rating of your alternator is and take a view as to what sort of load you want to place upon it. Consider that the alternator will also have to recharge your starter battery and power other equipment in your van too like heater motor, wipers, lights and the 3 way fridge while driving at the same time.

 

[Admin]

Good evening all. Looking ahead to when We get some lithium, I'm looking at B2B chargers. We are currently running 3 x 110 ah lead acid batteries, charging via a solar panel and a VSR. Whilst this system has served us well for several years, I'd like to upgrade eventually to lithium. I assume I can purchase a B2B charger and run it on my current lead acid batteries until we're ready to go lithium? Would a decent B2B (say victron) be capable of charging lead acid or lithium so it can be used when we change to lithium? Also does it matter what charge rate unit I get, I'm thinking the higher charge rate the quicker our batteries will be charged? All suggestions and ideas welcome.

Thank you.

Colin.

Hi Colin,

It's great to hear you’re planning the move to lithium. It sounds like you’re already well on your way with a solid setup!

You’re right; you can install a quality B2B charger like the Victron Orion XS 50A now and continue using it with your current lead acid batteries. Then, when you eventually upgrade to lithium, it’s a simple matter of changing the charger’s settings — no need to buy another unit.

I’d recommend the Victron Orion XS 50A Smart DC-DC charger. Here’s why:

• Fully programmable via Bluetooth (using the VictronConnect app)
• Compatible with all battery chemistries, including sealed lead acid, AGM, gel, and lithium (LiFePO₄)
• Automatic engine start detection or D+ signal input, whichever suits your setup
• Fanless and highly efficient, with up to 98% efficiency, it doesn’t even need a heatsink
• Active current limiting and temperature-compensated charging for lead acid
• Bi-directional hardware already included, and Victron have said this feature will be enabled via firmware in future – potentially opening up battery-to-vehicle support.

It supports up to 50A output at 12V. That said, a higher charge rate isn’t always better unless your batteries and cables can handle it — for lead acid, you typically want to charge at around 0.1C to 0.2C, which for your current 3 x 110Ah bank would be around 33A to 66A. So 50A is a sweet spot and gives you some headroom without overdoing it.

Once you switch to lithium, you’ll see the benefit of the faster charge — lithium can typically be charged at 0.5C to 1C, so if you install a 200Ah lithium bank, it can comfortably take the full 50A.

I hope that helps. I'm happy to answer any questions you’ve got about the setup or the transition to lithium!

Cheers,

Phil

 

[trevskoda]

Desirable Trev but not required.

I ran my 240AH with a 100W solar panel for years with no problems.

Takes donkeys to charge, best rate is 10 amps for 100ah battery, divide volts into watts 100 div by 12v- about 9amps on a good day, we dont get a lot of those Rob.

 

[Mtbcol]

Hi Colin,

It's great to hear you’re planning the move to lithium. It sounds like you’re already well on your way with a solid setup!

You’re right; you can install a quality B2B charger like the Victron Orion XS 50A now and continue using it with your current lead acid batteries. Then, when you eventually upgrade to lithium, it’s a simple matter of changing the charger’s settings — no need to buy another unit.

I’d recommend the Victron Orion XS 50A Smart DC-DC charger. Here’s why:

• Fully programmable via Bluetooth (using the VictronConnect app)
• Compatible with all battery chemistries, including sealed lead acid, AGM, gel, and lithium (LiFePO₄)
• Automatic engine start detection or D+ signal input, whichever suits your setup
• Fanless and highly efficient, with up to 98% efficiency, it doesn’t even need a heatsink
• Active current limiting and temperature-compensated charging for lead acid
• Bi-directional hardware already included, and Victron have said this feature will be enabled via firmware in future – potentially opening up battery-to-vehicle support.

It supports up to 50A output at 12V. That said, a higher charge rate isn’t always better unless your batteries and cables can handle it — for lead acid, you typically want to charge at around 0.1C to 0.2C, which for your current 3 x 110Ah bank would be around 33A to 66A. So 50A is a sweet spot and gives you some headroom without overdoing it.

Once you switch to lithium, you’ll see the benefit of the faster charge — lithium can typically be charged at 0.5C to 1C, so if you install a 200Ah lithium bank, it can comfortably take the full 50A.

I hope that helps. I'm happy to answer any questions you’ve got about the setup or the transition to lithium!

Cheers,

Phil

Thanks Phil that's great! One thing I didn't mention is that we've got a normal (not smart) alternator on our van which is a mk 7 ford transit 2011. Will the victron Orion XS50A be suitable?

 

[Admin]

Thanks Phil that's great! One thing I didn't mention is that we've got a normal (not smart) alternator on our van which is a mk 7 ford transit 2011. Will the victron Orion XS50A be suitable?

You’re very welcome, Colin!

Yep — the Victron Orion XS50A will work perfectly with your Mk7 Transit’s standard (non-smart) alternator. In fact, it’s designed to be compatible with both smart and traditional alternators — it just uses different methods to detect when the engine is running.

For your setup, it’ll auto-detect engine-on via voltage sensing, so no need to wire in a D+ trigger unless you want to. The D+ is mainly needed for smart alternators (like those on Euro 6 vehicles) which drop the voltage too low after startup for the charger to detect engine running.

That said, one really important part is making sure your cabling is up to the job — the XS50 can push a lot of amps, and undersized cable will lead to voltage drop, poor performance, and even overheating.

Here’s what I’d suggest:

1. Measure the distance in metres from your starter battery to where the XS50 will be installed.
2. Then measure the distance from the XS50 to your leisure batteries.
3. Plug both distances in metres (one at a time), System nominal DC voltage (V) as 12V and Current draw (Amps) at 54A into this voltage drop calculator from 12V Planet:
https://www.12voltplanet.co.uk/voltage-drop-calculator.html
Adjust the Select cable cross-sectional area (mm2) until you have a voltage drop of less than 3%.
4. Use it to work out the correct cable size for each leg (you want to keep voltage drop under 3% ideally — or 0.36V on a 12V system).
5. Check the cables currently installed in the van. If they’re smaller than what the calculator recommends, they’ll need upgrading.
6. While you’re at it, check your fuse sizes too — the Orion XS50 recommends fuses rated slightly above its current draw, so 60A fuses are usually spot on.

It might sound like a bit of a faff, but getting the wiring right is crucial — it’ll ensure your system is safe, performs properly, and doesn’t waste any charging power as heat in thin wires!

Let me know if you need help running the numbers or choosing cable — happy to help.

Cheers,

Phil

 

[Robmac]

Takes donkeys to charge, best rate is 10 amps for 100ah battery, divide volts into watts 100 div by 12v- about 9amps on a good day, we dont get a lot of those Rob.

As I said though Trev, I had no problems. That's with the usual lights etc, compressor fridge and occasional TV. Although I rarely stay anywhere more than 2-4 days so then the alternator gives them a boost.

So I would say unless you are staying off grid for long periods without the engine being run then 100W is suitable for many people's needs.

I am now upgrading to 600AH Lithiums and 850W of Solar but that is only because I am converting to all electric for cooking, water heating and everything else.

 

[edina]

I have just fitted a Victron Orion XS 50amp on Phil’s recommendation and it is brilliant. A fraction of the size/weight of my previous b2bs and no heat problems. The bluetooth meant I could easily set it up from my phone and see how it was performing.
I have fitted out a few vans and boats using various makes of chargers etc and have now decided to stick with Victron, with one app I can monitor my b2b, mppt and batteries.

 

[trevskoda]

As I said though Trev, I had no problems. That's with the usual lights etc, compressor fridge and occasional TV. Although I rarely stay anywhere more than 2-4 days so then the alternator gives them a boost.

So I would say unless you are staying off grid for long periods without the engine being run then 100W is suitable for many people's needs.

I am now upgrading to 600AH Lithiums and 850W of Solar but that is only because I am converting to all electric for cooking, water heating and everything else.

Im the same and no more than one overnight, but when the van is at home i dont require to plug in excepth nov dec with short dark days.

 

[edina]

Solar requires a match to batteries, ie 100w solar to 100ah batteries, any type.

That’s just a guideline Trev, not a necessity. It just boils down to the more solar the larger the charge

 

[trevskoda]

That’s just a guideline Trev, not a necessity. It just boils down to the more solar the larger the charge

True but in darker days more is best for a fast charge if camping and not driving.

 

[Fisherman]

That’s just a guideline Trev, not a necessity. It just boils down to the more solar the larger the charge

I have never seen the point of this recommendation. My attitude towards solar and batteries is really simple, fit the maximum possible in both battery storage, and solar harvesting. My current van has 2 100ah lithium and 340w solar. I could not practically get any more panels on my roof, and to increase battery capacity I would have to remove the vehicle toolkit from under the passenger seat and fit an additional battery there. But as my current set up gives me more than I need all year round I don’t see the point. I even run a victron 1200 inverter all year round, although I once had to limit its use in winter. My advice is fit as much solar and battery storage as you practically can, and use Victron, which as David stated has dropped significantly in price in recent years, but without any loss in quality or performance.

 

[marchie]

Desirable Trev but not required.

I ran my 240AH with a 100W solar panel for years with no problems.

The Dealer installed a 180w Solar Panel as part of the deal in April 2021 for the 100Ah lead acid battery. Converted to 120Ah Lithium in Jul 2021 then to 230Ah Lithium in Feb 2024. A larger Solar Panel would be useful for quicker recharging if we hammer the battery in poor weather, but it is manageable

Steve

 

[Robmac]

I have never seen the point of this recommendation. My attitude towards solar and batteries is really simple, fit the maximum possible in both battery storage, and solar harvesting. My current van has 2 100ah lithium and 290W solar. I could not practically get any more panels on my roof, and to increase battery capacity I would have to remove the vehicle toolkit from under the passenger seat and fit an additional battery there. But as my current set up gives me more than I need all year round I don’t see the point. I even run a victron 1200 inverter all year round, although I once had to limit its use in winter. My advice is fit as much solar and battery storage as you practically can, and use Victron, which as David stated has dropped significantly in price in recent years, but without any loss in quality or performance.

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Oh I agree Bill.

But Trev's statement that you require 100w per 100AH is a bit misleading and low electricity users would not need this. I ran my first motorhome quite adequately with 90AH and no solar panels for a couple of years.

 

[Robmac]

Oh I agree Bill.

. I ran my first motorhome quite adequately with 90AH and no solar panels for a couple of years.

...before anyone says it - that was not one long trip!

 

[trevskoda]

Oh I agree Bill.

But Trev's statement that you require 100w per 100AH is a bit misleading and low electricity users would not need this. I ran my first motorhome quite adequately with 90AH and no solar panels for a couple of years.

Just a genaral rule, as you well know some folk are electric heavy, im like you and use little, fridge some lights and usb charging for phones