B2B… do I need one 🤔

[Just smiffy]

My fiat 3lt ducato 2011 has two new exide 85amp gels, I have 400w of solar going through a victron 100/30 mppt blue solar regulator, I’m a fairly low user of sparks and the main out put is a low wattage kettle in the morning for a cuppa and then occasionally e-bike battery but I tend to charge the e-bike while driving but not always…

Usual phones and low wattage bits charging via usb.. fridge runs on gas.

I’m generally on the move after a couple of days but there will be stationary times of a week or more. I will mostly be in winter sun in Spain and Morocco…

Is it wise to fit one and if so what one, I don’t intend to go lithium until I get my money out of the gels so that could be years…

Over to you…

 

[WESTY66]

Yes, everybody needs one

 

[Tombola]

The victron 30a is a good choice. Some say it runs to hit but ive not had problems. sounds to me you don't really need one.
Do you ever run low as it is ? If so maybe worth it for belt and braces

 

[haganap]

Question 1) do. You want one?
question 2) can you afford one?

Answer yes to either of the above and you definitely "need" one.

 

[haganap]

Just one thing, I'm going through this route right now.. but if you are going lithium, the victron 30 amp was I was told not really adequate..

Only repeating what I was told by the experts

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[Just smiffy]

Yes I can afford one, I was looking at the victron Orion tri-smart 18 as I don’t have lithium.. but what is this isolated and non isolated thing…?

 

[Just smiffy]

Just one thing, I'm going through this route right now.. but if you are going lithium, the victron 30 amp was I was told not really adequate..

Only repeating what I was told by the experts

Definitely no lithium for a good few years… my gels are new and good

 

[Just smiffy]

The victron 30a is a good choice. Some say it runs to hit but ive not had problems. sounds to me you don't really need one.
Do you ever run low as it is ? If so maybe worth it for belt and braces

I’ve only had this set up since spring so haven’t really ever been low, but I tend to be a plan to fail rather then fail to plan…

 

[DBK]

It was a trip down the Mosel which persuaded me to fit one. It was sunny but late in the year so the Sun was low in the sky and the solar wasn't doing a lot. When we moved we only drove a short distance and this didn't recharge the batteries. However, with diesel heating and a compressor coolbox we do use quite a lot of power.

I think only you can decide, if you've coped well so far why should you need to change?

 

[Just smiffy]

My battery bank is also charged while driving with the onboard cbe charger at present…

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[dunnah01]

Very similar spec to me except a bit less solar (2x180W with PWMs) and a bit bigger batteries (2x105Ah lead acid) and managed fine without a B2B for 3 months full time without really driving anywhere in lockdown 1 just of solar. We watched plenty of telly and charged phones, speakers, laptop, iPad etc. We were half way down western France so fairly good solar although we were in a fairly light forest. We're also a 2011 3.0l

 

[Lenny HB]

Yes I can afford one, I was looking at the victron Orion tri-smart 18 as I don’t have lithium.. but what is this isolated and non isolated thing…?

It's to confuse you what else.
You only use an isolated one when you want the starter & leisure battery systems isolated.
On a Motorhome the negatives of both batteries are connected so they are not isolated so the non isolated is the one you need.

As for the B2B unless you are going to do quite a bit in the UK in the winter you don't really need one.

You could probably increase your split charge current quite a bit by increasing the cable sizes to and from the relay you may also need to replace the relay. It would give you results approaching a small B2B for a fraction of the cost.

 

[suavecarve]

I assumed your trike and chair were electric and would need recharging ?

 

[Just smiffy]

I assumed your trike and chair were electric and would need recharging ?

Just the trike, manual chair…

I have two of these, one can get me to 25miles away…

 

[Just smiffy]

It's to confuse you what else.
You only use an isolated one when you want the starter & leisure battery systems isolated.
On a Motorhome the negatives of both batteries are connected so they are not isolated so the non isolated is the one you need.

As for the B2B unless you are going to do quite a bit in the UK in the winter you don't really need one.

You could probably increase your split charge current quite a bit by increasing the cable sizes to and from the relay you may also need to replace the relay. It would give you results approaching a small B2B for a fraction of the cost.

Thanks Lenny because if I did need one i would be passing your way…

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[suavecarve]

Just the trike, manual chair…

I have two of these, one can get me to 25miles away…

View attachment 821849

Do they need recharging ?

Which, to be fair, is a stupid question. How often do you have to recharge them and does your current set up have the ability to do it and just have the solar doing the recharging ?

 

[Just smiffy]

Do they need recharging ?

Which, to be fair, is a stupid question. How often do you have to recharge them and does your current set up have the ability to do it and just have the solar doing the recharging ?

Can be every day…

 

[Feltwell]

I'll show my ignorance now.... the old "elastic trickery" is the one area of a van that I really don't keep up to date on. So, "B2B" is battery to battery - I take it.

My (old - 2006) van runs on technology from that era, no lithium here! The engine charges both the vehicle and hab batteries. I have modest solar, only 100w, but it's enough for our modest power usage. Solar is connected via an MPPT charger to the hab batteries, and I fitted a small gizmo years ago to the hab batteries so that if they are fully charged, via solar or mains, it passes a trickle charge back to the vehicle battery - is that what you mean by a B2B?

 

[suavecarve]

Can be every day…

I reckon you will get away with it. You may struggle if you have a couple days of static and lack of solar power but a B2B isnt going to improve that.
Further South into Spain is obviously better.

 

[Just smiffy]

I fitted a small gizmo years ago to the hab batteries so that if they are fully charged, via solar or mains, it passes a trickle charge back to the vehicle battery - is that what you mean by a B2B?

I suspect you mean/have a battery master, I also have one of those..

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[DBK]

I'll show my ignorance now.... the old "elastic trickery" is the one area of a van that I really don't keep up to date on. So, "B2B" is battery to battery - I take it.

My (old - 2006) van runs on technology from that era, no lithium here! The engine charges both the vehicle and hab batteries. I have modest solar, only 100w, but it's enough for our modest power usage. Solar is connected via an MPPT charger to the hab batteries, and I fitted a small gizmo years ago to the hab batteries so that if they are fully charged, via solar or mains, it passes a trickle charge back to the vehicle battery - is that what you mean by a B2B?

No, a B2B is a gadget, and not an inexpensive one (think £300+) which charges the leisure batteries independently of the voltage the alternator is pushing out. With a split charge system the leisure batteries get the same voltage as the alternator is producing, which is likely to be less than they need to be fully charged. For example, the alternator might be pushing out 12.5 volts but the leisure batteries need say 14.4 volts to be recharged. A B2B can deliver 14.4 volts from the 12.5 volt output from the alternator.

 

[Ava the Adria]

Just one thing, I'm going through this route right now.. but if you are going lithium, the victron 30 amp was I was told not really adequate..

Only repeating what I was told by the experts

The victron 30a is a good choice. Some say it runs to hit but ive not had problems. sounds to me you don't really need one.
Do you ever run low as it is ? If so maybe worth it for belt and braces

We have a 30A b2b (Votronic), feeding 200Ah of lithiums. When the fridge is taking its share of the 30A, there’s not a huge amount left for the hab battery. We can run our fridge on gas whilst driving if we need the full 30A into the batteries, say on a short run, if they’re low. But lithiums will charge faster than lead, so a larger b2b may be better for you. Or as Lenny suggested, beef up the cables (and shorten them) if you can.

 

[Lenny HB]

I'll show my ignorance now.... the old "elastic trickery" is the one area of a van that I really don't keep up to date on. So, "B2B" is battery to battery - I take it.

My (old - 2006) van runs on technology from that era, no lithium here! The engine charges both the vehicle and hab batteries. I have modest solar, only 100w, but it's enough for our modest power usage. Solar is connected via an MPPT charger to the hab batteries, and I fitted a small gizmo years ago to the hab batteries so that if they are fully charged, via solar or mains, it passes a trickle charge back to the vehicle battery - is that what you mean by a B2B?

No you have a Battery maintainer probably a Batterymaster, that is for charging the starter battery from the leisure battery.

A B2B sometimes called a DC to DC charger is to enable the leisure battery to charge from the alternator at a much higher rate.
You can get small ones that charge at 25 amps and ones as big as 120 amps.

 

[Zigisla]

I always wanted one, but that was a want not need. That was until I “went through” two sets of 2 x 95ah batteries in four years.
My name is Michael and I abuse batteries.
I used to use almost all power either overnight or in two or so days - UK. so very little sun for my 150 W solar and only travelled short distances. Hair dryers, kettles and anything else were used off my inverter. Now I have a single 100 ah lithium battery and a 60 amp Sterling B2B. and have never been close to running out of power for the last four years and still abuse the battery like before.
But a low power user might be different. Probably best to see how these gels go first.

 

[Lenny HB]

We can run our fridge on gas whilst driving if we need the full 30A into the batteries, say on a short run, if they’re low.

You shouldn't be running your fridge in gas while driving it's against the construction and use regulations.

You should still get the full 30 amps into the battery from the B2B if your fridge is being fed by a seperate relay.

That is unless you have a CBE electrics system and you have removed the link in the CBE distribution box that then allows the fridge to run from the hab batteries.

If that is the case easy to fit a relay switched by the D+ so the link is connected when the engine is running.

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[Ava the Adria]

You shouldn't be running your fridge in gas while driving it's against the construction and use regulations.

You should still get the full 30 amps into the battery from the B2B if your fridge is being fed by a seperate relay.

That is unless you have a CBE electrics system and you have removed the link in the CBE distribution box that then allows the fridge to run from the hab batteries.

If that is the case easy to fit a relay switched by the D+ so the link is connected when the engine is running.

Van was built for the German market and is fitted with the crash sensors on the gas pipes and regulator. Edit: it has previously passed the TÜV, (which includes hab) so (to my way of thinking) UK con & use is

I’m not convinced the fridge is being fed by a separate relay - it’s all running off a NE237 box of tricks! Which does have a D+ for fridge supply. The batteries do charge quite rapidly…It maybe it doesn’t go through the shunt properly?

Something to look at when back we’re back in the UK

 

[Lenny HB]

Van was built for the German market and is fitted with the crash sensors on the gas pipes and regulator. So (to my way of thinking) UK con & use is n/a in the EU

You can only run appliances that are approved to run while travelling such as Truma or Alde heating, a fridge has a naked flame so it is not permitted.

 

[Feltwell]

No, a B2B is a gadget, and not an inexpensive one (think £300+) which charges the leisure batteries independently of the voltage the alternator is pushing out. With a split charge system the leisure batteries get the same voltage as the alternator is producing, which is likely to be less than they need to be fully charged. For example, the alternator might be pushing out 12.5 volts but the leisure batteries need say 14.4 volts to be recharged. A B2B can deliver 14.4 volts from the 12.5 volt output from the alternator.

Great explanation, thank you!

 

[Feltwell]

No you have a Battery maintainer probably a Batterymaster, that is for charging the starter battery from the leisure battery.

A B2B sometimes called a DC to DC charger is to enable the leisure battery to charge from the alternator at a much higher rate.
You can get small ones that charge at 25 amps and ones as big as 120 amps.

Thank you.

I think a B2B is getting filed under "things I've lived without and hence don't think I really need" then. My van has 2 AGM batteries that I keep expecting to die (they're about 7 years old) but they keep on keeping on, even if by the morning the voltage is getting a bit low! We don't use a lot of power - most interior lights converted to LED, don't watch telly in the van, 3-way fridge, just charge laptop and phones and power the fan for the Truma heating really.

 

[ManTheVan]

Just smiffy, it might be worth checking on the Sterling site, which often has ex-demo stuff for sale cheaply. We have LiFePO4 and I fitted a 30A B2B from the Sterling bargain basement. You would probably need to run dedicated cables from the starter battery to the hab battery, and check Pausim thread on fitting a normally closed relay to avoid the feedback loop.

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