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

 

[Raul]

We have a compressor fridge, tv, blown air heating, etc. and averaged 50ah per day. We added a compressor freezer and we are using a average of 80ah per day. That confirms what Blue Night said above: a compressor will take 30ah per day on average. To sustain our electricity demand we have 600w solar on a MPTT controller, 30a b2b charger and a 70a ehu charger when we do pitch. Batteries are the best bit: 400ah lifepo4. We haven’t plugged in since last winter.

 

[cmcardle75]

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.

Remember that a decent B2B will charge very effectively. If you're moving around, rather than parking for a week and cycling, it makes a big difference. Two hours of driving will easily replace a day's electricity usage even with a compressor fridge.

 

[pappajohn]

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 . ?

Don't believe everything you read.
AGM batteries weren't developed for the military for one thing.... They were a natural progression from lead/acid in the same way lithium batteries have been developed (at a high price)
AGM fail regularly refusing to accept a full charge.
Many installations don't see 18 months before the batteries are cabbage.
GEL are far superior and ordinary lead/acid batteries are better than AGM.
Even the major car manufacturers are dropping AGM batteries because of poor performance.

 

[dodfloss]

Don't believe everything you read.
AGM batteries weren't developed for the military for one thing.... They were a natural progression from lead/acid in the same way lithium batteries have been developed (at a high price)
AGM fail regularly refusing to accept a full charge.
Many installations don't see 18 months before the batteries are cabbage.
GEL are far superior and ordinary lead/acid batteries are better than AGM.
Even the major car manufacturers are dropping AGM batteries because of poor performance.

Morning, I’m sure the dealer told me , the two leisure batteries are green power ones. Don’t know if that makes a difference.

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[dodfloss]

In the end , we will give these batteries a year and see how it goes, if it does not work l will buy lithium .

 

[Lenny HB]

There are AGM batteries & industrial AGM batteries, the industrial ones cost sevel hundred pounds each and are probably OK but it would be cheaper to fit Lithium.
The general purpose ones they fit to Motorhomes are rubbish my last van had AGM's they lasted 18 months Current van I fitted 3 Gels straight away.

Personally I wouldn't have the optional 2nd battery that they will charge a fortune for. Get the standard single battery and see if the dealer will change it for you then you can add a second.
For your use Gel would probably be best as they can be discharged to 20% but they do take longer to fully charge also the charger needs to have the correct charging profile for Gels.

 

[dodfloss]

There are AGM batteries & industrial AGM batteries, the industrial ones cost sevel hundred pounds each and are probably OK but it would be cheaper to fit Lithium.
The general purpose ones they fit to Motorhomes are rubbish my last van had AGM's they lasted 18 months Current van I fitted 3 Gels straight away.

Personally I wouldn't have the optional 2nd battery that they will charge a fortune for. Get the standard single battery and see if the dealer will change it for you then you can add a second.
For your use Gel would probably be best as they can be discharged to 20% but they do take longer to fully charge also the charger needs to have the correct charging profile for Gels.

Thanks Lenny , much appreciated, I’m a total techno phone, that’s why this site is so good. I have people like you who make more easy to understand. Thanks

 

[autorouter]

Maybe it's not relevant to your Adria MH, but you should only use 'sealed' batteries inside a habitation area, under the seats for example. Also called 'Maintenance-free' or VRLA (Valve Regulated Lead-Acid). Gel and AGM are VRLA, and some 'flooded' types. But if it has removable caps to top up the electrolyte with water, it's not 'sealed'.

The electrolyte (sulphuric acid) is a danger if the battery takes a bullet or a shrapnel fragment, so if that's a risk for you, go for gel or AGM for that reason. AGM (absorbed glass mat) fills the space between the plates mechanically, so that the plates are much less likely to distort with strong shocks or vibration. Another reason why the military adopted them. However batteries have a rather more sedate life in a motorhome.

These Green Power AGMs seem to me to be as good as you can get for AGM leisure batteries, but keep in mind what Lenny HB says about AGMs. The main disadvantage of gels is the charge/discharge rate is quite low. Technically it's best to keep the rate below C/5, where C is the capacity. So for 200Ah of battery, keep to 40 amps charge/discharge, or less. That should be no problem unless you are using a high-power inverter.

If you are thinking of lithium in the future, best to ensure the chargers (mains, solar, B2B) have a lithium setting.

 

[dodfloss]

Maybe it's not relevant to your Adria MH, but you should only use 'sealed' batteries inside a habitation area, under the seats for example. Also called 'Maintenance-free' or VRLA (Valve Regulated Lead-Acid). Gel and AGM are VRLA, and some 'flooded' types. But if it has removable caps to top up the electrolyte with water, it's not 'sealed'.

The electrolyte (sulphuric acid) is a danger if the battery takes a bullet or a shrapnel fragment, so if that's a risk for you, go for gel or AGM for that reason. AGM (absorbed glass mat) fills the space between the plates mechanically, so that the plates are much less likely to distort with strong shocks or vibration. Another reason why the military adopted them. However batteries have a rather more sedate life in a motorhome.

These Green Power AGMs seem to me to be as good as you can get for AGM leisure batteries, but keep in mind what Lenny HB says about AGMs. The main disadvantage of gels is the charge/discharge rate is quite low. Technically it's best to keep the rate below C/5, where C is the capacity. So for 200Ah of battery, keep to 40 amps charge/discharge, or less. That should be no problem unless you are using a high-power inverter.

If you are thinking of lithium in the future, best to ensure the chargers (mains, solar, B2B) have a lithium setting.

ThanksAutorouter, Adria are fitting batteries in factory , so I assume they should be safe ones!! . Thanks for your time and helpful advice.

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[dodfloss]

ThanksAutorouter, Adria are fitting batteries in factory , so I assume they should be safe ones!! . Thanks for your time and helpful advice.

Hi Autorouter, the inverter is 2000w. But I will turn it off when not in use.

 

[Lenny HB]

Hi Autorouter, the inverter is 2000w. But I will turn it off when not in use.

If you are using its full power it's far too much for 2 x 100a/h batteries and will probably kill AGM's.

 

[Dave_E]

We took delivery of a new 640 slb supreme last month.The factory fitted solar came with a mppt controller and a 30amp b2b charger.

 

[dodfloss]

If you are using its full power it's far too much for 2 x 100a/h batteries and will probably kill AGM's.

So is it good having a inverter, or can you use it for short periods only?

 

[JJ]

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

I have a 150 watt panel (approx) and 2 Varta 90 amp batteries and it has been enough for 5-7 years off-site motorhoming for me...


JJ

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[Lenny HB]

So is it good having a inverter, or can you use it for short periods only?

Inverters can be very useful if you have a use for them. We use one to charge our e-bikes. Most things that you need charging in the van can be done via 12v chargers which is more efficient.

A 2000 watt inverter running at full power allowing for inefficiency will draw around 180 amps, if you value your batteries you really don't want to draw more than 40 amps out of each battery. If you were only using 1000 Watts that would still be 90 amps absolute max you would want to take out of 2 batteries.

 

[JJ]

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.

I am confused... a friend of mine has AGM leisure batteries fitted and has had trouble free motorhoming for over 5 and a half years from them.

What are your sources of battery information?

How long do yours last?

JJ

 

[Captain Yoghurtpot]

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.

Well explained and very informative post. Thanks

 

[dodfloss]

Inverters can be very useful if you have a use for them. We use one to charge our e-bikes. Most things that you need charging in the van can be done via 12v chargers which is more efficient.

A 2000 watt inverter running at full power allowing for inefficiency will draw around 180 amps, if you value your batteries you really don't want to draw more than 40 amps out of each battery. If you were only using 1000 Watts that would still be 90 amps absolute max you would want to take out of 2 batteries.

Is it better not to have a large inverter and have small 12v plug in inverters , it’s confusing , I was told to get a good inverter! Sorry to keep pestering you Lenny, and I appreciate your time and help on this matter, but I can cancel the fitting of the inverter and save considerable money.

 

[Captain Yoghurtpot]

We have a compressor fridge, tv, blown air heating, etc. and averaged 50ah per day. We added a compressor freezer and we are using a average of 80ah per day. That confirms what Blue Night said above: a compressor will take 30ah per day on average. To sustain our electricity demand we have 600w solar on a MPTT controller, 30a b2b charger and a 70a ehu charger when we do pitch. Batteries are the best bit: 400ah lifepo4. We haven’t plugged in since last winter.

Interesting indeed.
On what van may I ask and are you UK or continent bound?
Am following as I am considering solar, or a van change with solar and other goodies.

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[dodfloss]

We took delivery of a new 640 slb supreme last month.The factory fitted solar came with a mppt controller and a 30amp b2b charger.

Are you happy with the van ?

 

[Dave_E]

The van is absolutely fabulous.So far all good with not a single problem.No rattles easy to drive and great build quality.So much storage I keep forgetting where I have put stuff and a good payload.What's not to like.

 

[Raul]

Interesting indeed.
On what van may I ask and are you UK or continent bound?
Am following as I am considering solar, or a van change with solar and other goodies.

We have converted a wv crafter ourselves. I have a build tread on self conversion section, with great coverage of entire work. most of the time is spent half UK and half abroad.

 

[autorouter]

Is it better not to have a large inverter and have small 12v plug in inverters , it’s confusing , I was told to get a good inverter!

This has been discussed a bit in other threads, such as this one
https://www.motorhomefun.co.uk/forum/threads/motorhome-inverters.223474, including my posts #13 and 28.

An inverter uses a lot of power compared to a single battery or a single solar panel. As Blue Knight says in the current thread (post #24)

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).

That's 140 x 12 = 1680 watt-hours, or 1.68kWh. So a 2kW inverter will soon drain that if used for prolonged periods.

Using an inverter is possible, especially in short bursts like a microwave or hair dryer, but not for fan heaters, water heaters and aircon which are typically on at high power for a long time. The inverter needs to be considered as part of the overall design of the electrical system. It's not impossible, and things are getting better and cheaper all the time, but needs careful consideration.

Low-power devices (100 watts or less) are best powered by 12V DC converters/adapters, like USB adapters and laptop chargers.

 

[dodfloss]

I think I’ll not fit an inverter, seems like to much drain on the batteries, . Thanks for all your time and replies . Very grateful