Battery help

[dodfloss]

I have just put deposit on new van, solar panel and two leisure batteries, we like wild campin. My question is I keep reading on Motorhome fun about mppt and battery master. I’m a total techno phobe. So do I need to order one of these and what do they do ? Thanks for any help and sorry if it is a very stupid question

 

[Zigisla]

MPPT is a type of solar controller. As you will have a controller fitted with your solar set up, ask the fitter if it is an mppt. They are more efficient. Battery master is a device to assist your cab battery charge if your solar controller doesn’t have a cab battery option. Again ask the fitter does it charge both hab and cab. If yes no need for battery master. If no then battery master uses the hab battery to trickle charge the cab battery when certain conditions are met.

 

[dodfloss]

Thanks zigisla, I’m buying adria twin supreme factory solar and batteries will it have a mppt or a battery master at adria factory. Thanks again for your help

 

[funflair]

It won't have battery master and quite possibly will have a standard solar controller that costs a few quid rather than a decent MPPT, it might have something that put charge to you engine battery when the leisure batteries reach 13.6v.

Martin

 

[dodfloss]

Hi Martin, thanks for reply, do you think I should request a mppt to be fitted at factory

Danny

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[autorouter]

A solar controller takes the power generated by the solar panels and charges the battery. There are two types of solar controller, MPPT and PWM.

When the weather is hot and sunlight is strong, the panels heat up, and there is no difference between them. When the panels are cold and the sunlight is weak or the weather is cloudy, MPPT will extract quite a bit more energy from the panels than PWM. But PWM controllers are cheaper than MPPT.

So it depends on your camping lifestyle. If all you ever do is charge off to the south of Spain for the summer, you're not going to get much benefit from an MPPT. If you park up at a ski resort in the winter, there'll be a big benefit.

 

[Zigisla]

Hi Martin, thanks for reply, do you think I should request a mppt to be fitted at factory

Danny

I think it would be best to ask if it is PWM or MPPT and whether it can charge both. Save changing in the future cos MPPT much more efficient and certainly a need for the UK. Cab charging not so important depends on how you use it. Alarm, tracker, radio memory etc all use cab batt; so if static for a while will deplete.

 

[The Wino]

I would get the full spec solar panel size etc and list what you want to use on battery (?TV,inverter for coffee machine hairdryer,lights,water pump, is it a compressor fridge etc) what size batteries do you want to use it outside summer etc. And how many days off grid.
They will all affect what you will need for the panel to do what you want.
Then ask the question!

Of course you could go for loads of solar and batteries and posh controllers and inverter but you will notice an inverse relationship between the weight of the motorhome and your wallet.

 

[dodfloss]

I have ordered 150 panel and two 100 batteries so hoping that will be enough for 5-7 days wild camping

 

[The Wino]

I have ordered 150 panel and two 100 batteries so hoping that will be enough for 5-7 days wild camping

But what load will you have the biggie is is it a compressor fridge.

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[Zigisla]

I have ordered 150 panel and two 100 batteries so hoping that will be enough for 5-7 days wild camping

Are you driving daily or static for 5-7. Driving will be fine for cab batts and will also put a bit back into your hab, but 7 days static in the uk May be a push. You will have to seriously monitor your usage.

 

[StephDeLux]

I have ordered 150 panel and two 100 batteries so hoping that will be enough for 5-7 days wild camping

In Summer you should be fine, but in other seasons this will drain your batteries quite a bit. After such a discharge your batteries will need at least 24 hours charging to go back to full capacity. So, without full sunshine, if you intend to be static say 5 days, drive a day and be static again for a few days and all without EHU, it simply won’t work with anything but lithium and a B2B charger.

 

[dodfloss]

Thanks for reply, what’s b2b is battery to battery? And how do you fit them

 

[Raul]

Solar charge controllers come in two flavours: PWM, and MPTT; pulse width modulator and maximum power point tracking.
The PWM works = amps in-amps out, if you panel is a 7a,it will only charge a max 7a times battery voltage. Does not convert the extra voltage from PV above the battery voltage, into amps.
The MPTT works= power in-power out, it will convert the extra voltage into extra amps. A panel output is variable, its current source is directly dependant on light more than the voltage, if a cloud comes in the amps crashes but the voltage not much. This is when the maximum power point tracker sweeps the PV takes samples and adjusts its power point V A and works its best power harvest for that moment. As the condition change, so the panel output, so the MPP tracker sweeps again and squeezes the max power. The PWM can’t do that, it’s fixed to the panel amps and it switches on and of at a very high frequency to hold the voltage at the set parameters. Before it reaches the absorb ( constant voltage) the pwm charger is directly connected to the panel and is the battery that pulls the voltage down until constant voltage stage. The MPPT is raising or lowering the voltage continuously until it finds the ideal voltage for that given situation in relation to the amps available to extract the maximum power.
The heat can crush voltages, but that is dependable on the panel type and cell construction, nothing to do with the controller. Good panels will come with data expressed as temp coefficient x % per deg C or F. The nameplate values are for 25deg C and any higher will lower the voltage any lower will rise the voltage. There are panels that are very stable on heat and panels that dive, the clue is in the temp coefficient value, the bigger the coefficient, the larger the difference in voltage at different temps.
In a nutshell, a 150w panel is not much to warrant a MPPT type controller, the difference in power harvest is 2/3 of the max panel for the PWM vs full power for the MPPT type. Your call if is worth it.
On another note a lead battery to keep it healthy, it needs a min charging rate 8-12% of its total capacity to be able to charge it within reasonable time. And 10% would be the Goldilocks. For your 200ah batts. You will need a 20 charging amps to put back what you take out in a reasonable time. Your 150w panel can only meet half of the requirement in ideal conditions only, so the rest has to come from other sources. It depends how much you take out and how much the panel can put back in.

 

[Zigisla]

Thanks for reply, what’s b2b is battery to battery? And how do you fit them

It is a device which fools your alternator into thinking your cab battery is low so it will keep the charging amps high. This is then fed into your hab batts charging them many times faster than regular alternator in its own can do. Connects to cab batt and hab batt. Great piece of kit if you use a lot of hab power and move daily, but not too far.

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[The Wino]

I still think it depends on usage. We have had no solar until I fitted it this year often are off site 10 days and never had a flat battery. We use lights a bit in the evening usually no TV gas fridge so mainly just the water pump. I'm confident that with a 100w panel and mppt controller we will be even safer in not getting a flat battery.

 

[autorouter]

Thanks for reply, what’s b2b is battery to battery? And how do you fit them

If your MH is very new, it will have a smart alternator, and regenerative braking. The result of this is that using a simple split charge relay to connect the starter and leisure batteries together does not fully charge the leisure battery. The solution to this is to fit a 'B2B' charger. It is called different names by different brands. There's a good chance you already have a B2B fitted. It's sometimes called a DC-DC Converter or a Battery Booster.

 

[dodfloss]

Sorry for delay in replying, unfortunately I have been ill, much better now. Thanks to all , for your time and explaining in detail. Much appreciated .

 

[Richard n Ann]

I still think it depends on usage. We have had no solar until I fitted it this year often are off site 10 days and never had a flat battery. We use lights a bit in the evening usually no TV gas fridge so mainly just the water pump. I'm confident that with a 100w panel and mppt controller we will be even safer in not getting a flat battery.

We used to manage perfectly with a 40w panel, made over 2 amps in the sun, the battery was recharged by lunchtime

 

[dodfloss]

If your MH is very new, it will have a smart alternator, and regenerative braking. The result of this is that using a simple split charge relay to connect the starter and leisure batteries together does not fully charge the leisure battery. The solution to this is to fit a 'B2B' charger. It is called different names by different brands. There's a good chance you already have a B2B fitted. It's sometimes called a DC-DC Converter or a Battery Booster.

Hi auto router, just spoke to dealer regarding batteries, I asked for 2x100 leisure batteries which he said I’d factory fitted, also 150wsolar panel. It’s a brand new adria twin, delivery date in January . Do you think that is enough for wild camping 2-4 days and will it come with a battery charger? Thanks in advance for any help in this matter

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[Blue Knight]

Hi auto router, just spoke to dealer regarding batteries, I asked for 2x100 leisure batteries which he said I’d factory fitted, also 150wsolar panel. It’s a brand new adria twin, delivery date in January . Do you think that is enough for wild camping 2-4 days and will it come with a battery charger? Thanks in advance for any help in this matter

Just a few questions to help us understand your power needs:

1. Do you have a compressor fridge?
2. Will you use a TV when off-grid and how long for per day?
3. Will your wild camping be all year round?
4. Do you wish to stay in the same location for 2-4 days or will you be driving during that 2-4 day period.
5. Are your batteries of the AGM or wet variety?

All the best,

Andrew

 

[dodfloss]

Hi Andrew, we are expecting delivery of Adria twin in January. It has compressor fridge, no we don’t watch tv all day , I would say no more than a couple of hours all day if that, we like news and sport. Will be wild camping all year round , mostly 2-3 days then move on and use a site for one or two days , depending on site . Mostly long weekends. Holidays of up to two weeks in France , some sites and some wild camping . I have had three Motorhomes before but never wild camped , the boys liked the sites. Agm batteries two additional factory fitted by Adria. I’ll be honest I’m not technically minded so thanks very much for any advice. I just want the van right before we pick up in January.

 

[Lenny HB]

As it is a new van with a Euro 6d engine it will have a smart alternator so it will be fitted with a B2B.
I think Adria come with AGM batteries as standard not the best option for leisure use I would never have AGM's in a Motorhome best to fit either Gels or good quality flooded batteries.
A compressor fridge and wanting to use the van all year round 150 Watts of solar is nowhere near enough depending on your power requirements you are going to need 2-3 times that.

 

[Blue Knight]

Hi Andrew, we are expecting delivery of Adria twin in January. It has compressor fridge, no we don’t watch tv all day , I would say no more than a couple of hours all day if that, we like news and sport. Will be wild camping all year round , mostly 2-3 days then move on and use a site for one or two days , depending on site . Mostly long weekends. Holidays of up to two weeks in France , some sites and some wild camping . I have had three Motorhomes before but never wild camped , the boys liked the sites. Agm batteries two additional factory fitted by Adria. I’ll be honest I’m not technically minded so thanks very much for any advice. I just want the van right before we pick up in January.

Firstly, well done on the Adria PVC as the owners seem to love them - I do too; fantastic bits of kit IMO.

Right then, down to business on your power usage.

Your two 100Ah AGM batteries 'when 100% charged' will allow you to have 140Ah at your disposal since the AGM can be used down to 30% SoC (State of Charge).

Your telly will be rated at 3Ah so 2-3 hours of news bulletins per day will equate to 6-9Ah.

The compressor fridge can be a slight pain in the arse but if you factor in a usage rate of 1.2Ah average over the full 24 hours then the fridge will use 28.8Ah per day.

Your Truma boiler will likely munch the power at a 1Ah rate so if your heating is on for 8 hours then that's 8Ah gone per 24hrs.

The other stuff, lights, water pump etc, will remove 2-5Ah per day so that needs to be factored too.

.......so for every 24-hours, with a compressor fridge running, 2-3hrs of telly, 8hrs of heating and the extra bits mentioned then you'll use anywhere between 44.8Ah and 50.8Ah per full day of wild camping.

You have 140Ah available when at 100% charge so divide one into the other to see how many hours/days you can manage without and external input from the engine alternator, solar unit or the onboard charger while on EHU.

You can almost write off any solar input over the winter, certainly up north, but if you set off with a fully charged battery bank then 3 full 'off grid'days in winter should be easily achievable with a bit of management from you.

The AGMs IMO would not be my first choice for wild camping but you have to work with the gear you have now.

In the summer, you should be able to manage quite happily off-grid with your set-up though.

There are loads of different scenarios and variations that could be applied to the examples above so it's just a case of understanding your power usage rates and how you can replenish the batteries.

I've calculated the figures based on my off-grid set-up so I think they'll work for you too.

All the best,

Andrew

 

[dodfloss]

Andrew, Thank you very much for your time and in-depth and informative reply. Regards Danny

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[dodfloss]

As it is a new van with a Euro 6d engine it will have a smart alternator so it will be fitted with a B2B.
I think Adria come with AGM batteries as standard not the best option for leisure use I would never have AGM's in a Motorhome best to fit either Gels or good quality flooded batteries.
A compressor fridge and wanting to use the van all year round 150 Watts of solar is nowhere near enough depending on your power requirements you are going to need 2-3 times that.

Thanks for your reply and helpful advice Lenny, much appreciated. Regards Danny

 

[dodfloss]

Andrew, Thank you very much for your time and in-depth and informative reply. Regards Danny

Andrew, Thank you very much for your time and in-depth and informative reply. Regards Danny

Hi Andrew, just been reading up on agm and gel batteries, they seem to say agm better for leisure and was originally built for military vehicles, because of their slow discharge And robustness . ?

 

[Blue Knight]

Andrew, Thank you very much for your time and in-depth and informative reply. Regards Danny

Danny, you're very welcome indeed and perhaps a few other Funsters will post-up their experiences too.

In our case we move every one or two days so we've always got some degree of battery replenishment going on via the alternator. Also, we'll try and plan our trips so that we move when the solar is at its weakest and then park and go adventuring when the solar is at its greatest, i.e this way we achieve the maximum solar input on top of the alternator input which we would receive anyway from our travel time.

However, when the going gets tough in the UK (and it does in the winter) then Nicky and I find ourselves forced to access a site with EHU every 5-days just to give the batteries a chance.

I note that you mentioned '4-7 days' in a previous post above and in theory you should be able to achieve most of that with careful journey management, moderate solar input and perhaps a day every week on a site.

Once you collect your van then give the batteries a damn good charge and get away for 3-days while ensuring that you keep an eye on the voltages throughout.

A 'compressor fridge' top tip is to place a couple of freezer ice blocks in your freezer during the day and then move them to the main fridge compartment for the night hours while reducing the fridge settings to a slightly warmer temperature. The ice blocks will help cool the main compartment while helping you to save a bit of power because your fridge will be set to a more economical setting.

In the morning just place the ice blocks back in the freezer section and then revert your temperature setting back to normal.

If everything goes well then you'll become obsessed like me, lol.

Good luck and have fun,

Andrew

 

[Blue Knight]

Hi Andrew, just been reading up on agm and gel batteries, they seem to say agm better for leisure and was originally built for military vehicles, because of their slow discharge And robustness . ?

The best person in the whole world to answer such an AGM-gel question is Lenny Lenny HB who may one day receive a Nobel Prize for his knowledge on said subject.

......over to you Lenny ;-)

 

[dodfloss]

Thanks Andrew, was hoping for longer offgrid but reading advice on site , I was been unrealistic. Thank you very much for your time and advice , it has helped greatly. Advice on this site is brilliant, everyone so helpful. Looking forward to picking up van. I’m fortunate to have a large drive and I have fitted electrical points for charging when at home. Once again thanks.