HELP - Leisure Battery Low in AM

[Red_48]

We’ve been full-time nomads since our Sprinter conversion in March, (10k miles, 140 free camping spots).

With the exception of taking a month out in November, our AGM 250 Ah battery has provided power through the night, dropping to a low of 12v by the mornings.

During that month off we isolated the fridge but left the solar system to keep the dash cam running (in Spain).

Upon embarking on our second leg back to the UK and Scandinavia we noticed that, despite finishing our day of driving with a voltage in the high 13v, it was down in the low 10v come morning. BTW We live a 12v life, so no inverters.

We haven’t added any new loads, and have had a couple of nights on shore power and set the charger to recondition (abet with loads attached).

The battery (now out of 1-year warranty) states a lifespan of 8-10 years (although I understand 3-5 should be expected).

Outside of charging the battery, disconnecting all loads, then returning 2-3 hours later to read the voltage I’m unsure where to start in diagnosing this problem.

I’ve included a design diagram listing all electrical components and connections in the hope the community can suggest:

A) Steps to diagnose the fault

Or

B) An experienced auto electrician (we’re currently near Dorking but will travel)

Loads:

Wallas XC Duo
Maxxfan 7500
Water pump
Dometic CRX65 (always on)
Huawei E5577C (always on)
Blackvue DR590W (always on)

Thanks for reading…

 

[Lenny HB]

I don't think you have a fault just a duff battery. AGM's are pretty useless for leisure battery and quite common for them to fail at not much over a year old.
Had 2 in my last van from new, they both failed at 18 months old. In my current van I got rid of the standard fit AGM and fitted 3 Gels.

 

[Raul]

Consider investing in a battery monitor. That way you can keep track of energy used vs energy put back.
This is a classic example of chronic undercharging. Over time battery looses capacity due to sulphating.
Agm wants a absorb to float at least every other day. Otherwise you will not recover the sulphate and loose capacity.
Voltage is only a indication but not precise estimation of SOC.
You probably run in deficit for some time and now the battery is less than your daily requirement. If you had 2 years out of it then you did well. Agm’s, despite what the seller tells you, you ment to cycle 20-30% DOD, for any meaningful service.
The only time you deep cycle, ( over 50%) is only when you know for sure that you got the luxury of time and amps, enough to complete absorb and 2-3 hrs of float. Drop in float does not mean end of charge;

 

[Red_48]

Thank You

So, assuming the battery is the cause, what battery technology lends itself to life on the road?

I'm assuming there are pros and cons to all solutions, but if AGM's are not the answer I need to replace with something that's better suited. Gel or LiOn?

Also, if I choose another battery technology, what is the equivalent size to an AGM @ 250Ah?

As for the battery monitor. The Victron MPPT gives me this info, but nothing on energy leaving the battery.

P.S. The lighter coloured bars at the top of each column are time spent in float.

 

[peterc10]

I can't find any mention of how these batteries get the charge they need. After all batteries only store energy, they do not generate it. And if you do not generate as much or more energy than you use any battery will end up flat. This time of year solar will rarely be enough. So what else do you use?

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[Red_48]

I have to resort to turning on the engine in the morning and let the Sterling Battery to Battery charger recharge the AGM leisure battery until the solar takes over.

I am concerned that this puts a strain on the vehicle alternator however.

 

[Lenny HB]

I would be more concerned with engine damage if starting from cold and leaving on tickover. That way diesels never get to full operating temperature also a good way of wrecking CAT & DPF. Best to take it for a drive.

 

[DBK]

I have to resort to turning on the engine in the morning and let the Sterling Battery to Battery charger recharge the AGM leisure battery until the solar takes over.

I am concerned that this puts a strain on the vehicle alternator however.

The alternator shouldn't struggle although with some Stirling B2B models they have a temperature sensor fitted to the alternator. What will struggle if you are having to do this often is the engine and exhaust system. Expect problems in time.

To reduce upfront costs just fit a gel battery and see how you get on. Lithium would be better I think but significantly higher initial cost.

 

[pappajohn]

I have to resort to turning on the engine in the morning and let the Sterling Battery to Battery charger recharge the AGM leisure battery until the solar takes over.

I am concerned that this puts a strain on the vehicle alternator however.

What amps is the B2B rated at?
How long are you running the engine?

Your alternator is rated at its max output and it won't be 'strained' as the B2B will be below that amp rating........but it won't do your DPF or cylinder walls much good

 

[peterc10]

I suspect that you are expecting too much from solar this time of year. From your first post I assume that you are no longer in Spain, but are somewhere between the UK and Scandinavia. You also have not told us how much solar you have got, but I suspect it is not enough.

Just because the solar is at a good voltage does not mean it is putting much energy into your batteries. For that you need to know what amps it is putting in. And at this time of year it will probably be too low unless you have a large array of panels. The B2B will be putting in much more amps, but, as others have said, it is best you use it whilst driving around. If you are staying in the same spot for a while you really need an EHU or a generator.

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[Raul]

Right, I can see your solar contribution is a drop in the ocean. Average of 120wh per day is just lights and phone charger.
Also we don’t know how much energy you actually use. How many amps leaves the battery, and how many you put back. Lead batteries, have a average 70% round trip efficiency, so for every 1kwh consumed from battery, you need to put back 1,5kwh.
The best think you can do is get a shunt battery monitor, like victron bmv700, and set it up right.
As for battery depends on your budget. If funds allows, I personally would go right away for LiFePo4 12 monolithic block with bms integrated inside.
If funds are tight I would go for cheap VRLA truck battery to get me out.
No need to spend for AGM, a cheap sealed Lead acid will do. If I would have the means to vent them, then I would go for Flooded 6v blocks like trojan, rolls or even crown. These are solid batteries for mild off grid use or motive power.
The Li option is most economical in the long run, but you need to make sure your ehu charger and B2B can be configured for the new requirements. It’s not the same.
Also try to ad another panel.
I managed 2x 295w panasonic, one fiamma turbo vent and one Maxxfan on a crafter roof, still got space.

 

[Red_48]

Thanks all for battery recommendations and the warning about damage to CAT etc when on tickover.

All questions on spec can be answered by studying the diagram in my original post.

Is there value in running a new battery alongside the current AGM or would mix and matching battery technologies cause problems?

 

[StephDeLux]

Lithium batteries's main advantages are:

• fast charging due to high current absorption and linear charging, they charge as fast from 90% to 100% as from 50% to 60%.
• about 40% weight saving for the same stated capacity
• about double usable capacity compared to AGM (90% of stated capacity for lithium vs. 50% for AGM). This means they are roughly 30% the weight of AGM for the same usable capacity.
• lots of cycles available, even when using 80% of capacity

Of course the main drawback is the initial cost.

And you need to make sure your Sterling Power and Victron changers have a setting that is compatible with the lithium battery you buy if you choose to go that way.

Otherwise, gel batteries are the way to go. Very reliable, can take a beating in the form of deep discharge, but not good to charge fast.

 

[Raul]

Red_48

It’s not good to mix old with new even if they are the same.
The old will take a hammering on charge discharge, while the old one will be a piggy back all the time; eventually killing the new one prematurely.

 

[peterc10]

Thanks all for battery recommendations and the warning about damage to CAT etc when on tickover.

All questions on spec can be answered by studying the diagram in my original post.

Is there value in running a new battery alongside the current AGM or would mix and matching battery technologies cause problems?

Just noticed you have 300w of solar and are in Dorking. At this time of year that will produce nowhere near enough for you to be self sufficient even on sunny days. The combination of short daylight hours and low angles of sun make solar alone impractical. And on cloudy and rainy days it will be even worse.

No point it getting better or more batteries if you can't generate enough energy to fill them.

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[Red_48]

No point it getting better or more batteries if you can't generate enough energy to fill them.

Thank You, guys. Great advice, all.

With our aspiration to see Norway in January, I think peterc10 suggestion of a generator is probably the way to go given our free-camping lifestyle.

I can plug the genie into the shore power charger (Victron Blue Smart IP22 charger) for a boost at sundown and rise. Being in the UK now we can trial this scenario and determine if we also need to replace the leisure battery (which I'd like to avoid given the Xmas expenses!).

So, onto researching generators.

 

[pappajohn]

I can plug the genie into the shore power charger (Victron Blue Smart IP22 charger) for a boost at sundown and rise

A boost is no good, you need a few hours even with a generator.
You need to put the capacity back, not just get a decent voltage showing.

 

[Red_48]

And you need to make sure your Sterling Power and Victron changers have a setting that is compatible with the lithium battery you buy if you choose to go that way.

Looks like the Victron SmartSolar MPPT 100/30 supports Lithium Batteries.

 

[Red_48]

You need to put the capacity back, not just get a decent voltage showing.

Would I need a battery monitor to see capacity? I'm unsure if the Victron Connect app displays capacity.

 

[Raul]

If you get the bmv 712 it’s got the blue tooth built in and you can see it in victron connect. Also the blue solar charger you will need to input custom settings. That preset is to work with a victron bms.
Look for a small 700w inverter generator and you will love it.
The trick is to put the genny on before the sun up for 2 hrs also, so you can bring the voltage up enough to absorb. Once the solar kicks in, sometimes is enough on its on to finish off, rather than burn unnecessary fuel for very little power at the end of absorb.
Inverter generator are very economical and revs up according to the load power. Does not need to buzz at 3600rpm to hold the voltage.
Another name for them is silent suitcase generator.

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[DBK]

Would I need a battery monitor to see capacity? I'm unsure if the Victron Connect app displays capacity.

A battery monitor is the only way to reliably have an idea about remaining battery capacity. They are not perfect but I wouldn't be without mine. It will need a shunt wired into the negative side of the leisure battery but if you did the conversion yourself that shouldn't be hard for you to do. With one fitted you should be able to avoid killing the next battery - see below.

If you are heading to Norway in January I fear you need to replace the battery before you go, given you have seen voltages down to 10. It is (I think) duff and if you need to buy one in Norway you might have to sell a kidney to pay for it.

 

[Allanm]

I think the fact that you let the battery drain down to 12v may be the cause of your battery failure. According to charts I have seen, this means your battery is discharging below its 50% DOD maximum.
Then I am concerned how a 250ah battery can get this low so quickly. Is there something else draining power you are not currently aware of?
We have 2 x 95ah batteries and overnight, they never get below 12.6v, and that is with a heater on all night with electric fan, a couple of hours of satellite tv, charging of phones, water pump and a few lights.
Before you get a new battery, is there any way could reduce your 12v usage.
When we bought our van it was fitted with AGM batteries and I took LennyHB’s advice to ditch them. I’m not sure the alternator was powerful enough to charge them fully when driving.

 

[Red_48]

Dometic CRX65 (always on)
Huawei E5577C (always on)
Blackvue DR590W (always on)

There are no other loads attached overnight. We stopped driving approx 2 hours ago and the battery is currently at 12.74v.

Typically, the morning reading is around 10.8v (taken from the Victron Connect app).

My first assumption was that the fridge was cycling too frequently.
Could a faulty fridge be the cause?

 

[Reallyretired]

If your battery has regularly been down to 10v it is dead.
AGM batteries are not considered much use as leisure batteries.

 

[Raul]

If your fridge cycles to often, try a different setting. I think is 4 settings.
The battery is done. It has a very reduced capacity, beyond your usage requirements.
Also, the cupboard where that fridge sits, make sure it’s got the min. Clearances and adequate vents to the room. Otherwise that compressor will labour very hard till pop.

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[DBK]

A 250Ah battery could run a compressor fridge continually overnight. This is assuming it was fully charged the previous day of course which may be the source of your problems. Battery not being fully charged then exhausted overnight is my guess of what's been happening. Sorry to be the Grinch.

 

[Red_48]

I was afraid that might be the case. This morning reading is 10.64v!

Is this a suitable replacement?

Waterproof 12V 100Ah 120Ah 130Ah 150Ah Lifepo4 battery BMS with bluetooth for 1200w solar system motor home boat RV +10A charger - AliExpress 44

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[Pausim]

There could be import duty to pay on a $ priced battery.

 

[Red_48]

The Wallas XC Duo consumes 8-10A for 5-10 minutes during startup. Then 0.55-0.85A thereafter.

We've already set the Dometic CRX65 to its lowest setting (1.14 Ah/h at +25°C ambient).

If the battery is, as everyone seems to agree, dead. I need to replace it with a unit that will better cope with these demands.

Both my Sterling 'Pro Batt Ultra' Battery-To-Battery Charger 12V/12V 30A and Victron SmartSolar MPPT Charge Controller 100/30 have settings for Lithium-ion batteries.

The question is, would Lithium-on be most suited given its faster recharging rates?

I want to avoid replacing the battery and adding a small generator, only to be left in the same position in a years time.

 

[peterc10]

I was afraid that might be the case. This morning reading is 10.64v!

Is this a suitable replacement?

Waterproof 12V 100Ah 120Ah 130Ah 150Ah Lifepo4 battery BMS with bluetooth for 1200w solar system motor home boat RV +10A charger - AliExpress 44

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

View attachment 353608

Aliexpress is part of Alibaba, which is the Chinese equivalent of Ebay. It will be be shipped directly from China and you will have to pay import duty on it. I doubt you will get any support or enforceable warranty from them.

Lifepo4 batteries can be a minefield and there are several very helpful threads on this forum about them. I suggest you have a search for these and have a good read before jumping in. I also suggest you use a reliable UK based company to supply you one.

Edit. BTW you will not be very popular with your fellow campers or anybody living close by if you start a generator, because there is no such thing as a "silent" generator. I suggest that you will need to find somewhere well away from others to stop if you are planning to use it regularly, especially if you are going to follow the advice to start it before "sun up". Otherwise you may well have problems with finding it one morning! The only really silent generator of electricity is the Efoy and that is not cheap to buy or run.

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