Second leisure battery debate / challenge.

[r4dent]

Have you checked the setting on the solar controller?

It may be set to prioritize the vehicle battery.

 

[r4dent]

From the op it's a 12v fridge, not a 3way.

Where did OP state that,
I specifically asked for clarification (post #5)

Is the fridge Compressor (Electric only) or absorption (selectable between battery / gas / mains) ?
If you don't know ..what is the make & model?

But I must have missed the reply.

 

[JonnoR]

Yep, hadn't thought about that. With the base vehicle being a Boxer I just assumed a standard factory Motor Home, most which are absorption.
Assume ..makes an ASS out of U & ME but in this case just ME!



Agreed.




Is the fridge Compressor (Electric only) or absorption (selectable between battery / gas / mains) ?
If you don't know ..what is the make & model?

The fridge is a compressor (electric only) - it seems the coachbuilder does not like fitting gas.

 

[JonnoR]

Have you checked the setting on the solar controller?

It may be set to prioritize the vehicle battery.

I have asked if the PV Logic charger (Solar technologies) can prioritise.

 

[JonnoR]

I have again spoken to the manufacturer and they are saying that there is nowhere in the van to fit a second battery, so a bit scuppered there. I suppose I could look at the other technologies but nit sure if the chargers will be compatible - something else to check.

I mentioned about a B2B charger - the guy I spoke to did not know about these. So I guess I will look at this option and get an auto electrician to fit so as not to affect my warranty.

Thank you so much for all the comments and the paper - I need to read.

 

[molly 2]

Warranty doesn’t cover taking battery too low which will have happened here Baz.

Correct as usual Neil, I just bought a new battery I asked about warrenty told 4 years but had to have voltage of above 8 volts ish ,because their test equipment would not operate below a certain voltage so could not test , warrenty would be declined i, bought the battery over the counter from , Battery group Barnsley , huge battery and solar range in stock , have a google bazz

 

[trevskoda]

When i was in our biggest battery shop picking up a new starter battery for my car i ask about l carbon batteries, they had not a clue and just pointed to a crappy les battery on the shelf.

 

[JQB]

Hi All,
Still fairly new to the MH/CV way of life and tbh loving it.

I have a quandary, so just returned from a two week trip around the highlands and islands of Scotland. TBH I am struggling with the leisure battery life (the van and battery are brand new). We want to go off grid for a few days (2-3 tops) at a time and the highlands lend themselves well to this.

However I was finding that the LB (110Ah) would not give us sufficient life. We have a 100W 650wh solar panel but for the first three days in Glen Coe all we saw was rain and no sun, so the LB would never get sufficient to keep it charged up. We even had to resort to driving around for an hr to try and out some juice back into the battery from the engine, but it never really got back up to full strength until we attached it to the EHU for a couple of days. Even longer 2-3 hr drives never saw it back to 13v.

I have asked the coachbuilder who fitted out the van (Peugeot Boxer) to add a second battery but it seems there is no space and they are telling me this cannot be done.

The fridge is the biggest consumer of electric, its a 12v with a tech sheet quoted 3.8A draw, we have LED lights and a Truma - I guess, water pump. Just doing the simple calcs the battery if receiving little or no solar would only last a max of 28hrs (taking it down to dangerous charge levels - which I am not prepared to do) and that is just the fridge alone. We ended up on a few occasions decanting water into water bottles and using torches for light at night. So may as well go back to camping.

Is there anything I am doing wrong OR am I missing something with respect to the charge. I have to say that the van is at home on my drive and the LB charge sitting at 13.4v today with a sunny day.

What are the other solutions available to me to give me extra off grid life. Not really looking to go down the generator route.

Thoughts please.

Many thanks
Jon

Our van came with two 110ah lead acid, a 12v 43w fridge but no solar. Useless off grid. Had 1x100 pv fitted, not good enough either, so had second 100pv fitted. Now fine but not in winter when we have often to run the engine on tickover to provide a boost. A battery to battery charger would be a good idea for very fast engine charging, but have not invested so far as they are expensive. We don't have room for any more fixed pv, but portable is a possibility i guess.For offgrid pv 200w+ is essential plus min 200ah+ of bats, lithium if poss. If you want to use 230v equipment then yoy have to go to maybe 400wpv plus large lithiam capacity plus BtoB .
Just my opinions gatheted over the last mant years which not everyone will second.

 

[trevskoda]

Our van came with two 110ah lead acid, a 12v 43w fridge but no solar. Useless off grid. Had 1x100 pv fitted, not good enough either, so had second 100pv fitted. Now fine but not in winter when we have often to run the engine on tickover to provide a boost. A battery to battery charger would be a good idea for very fast engine charging, but have not invested so far as they are expensive. We don't have room for any more fixed pv, but portable is a possibility i guess.For offgrid pv 200w+ is essential plus min 200ah+ of bats, lithium if poss. If you want to use 230v equipment then yoy have to go to maybe 400wpv plus large lithiam capacity plus BtoB .
Just my opinions gatheted over the last mant years which not everyone will second.

You should never run any engine at tickover for long, futher more there will be very little if nothing from the altrnator.

 

[Pudsey Bear]

I would be very surprised if you could not fit a 2nd LB it would have to be a very small van to not have that amount of spare space, then it's only a matter of thick enough cables.

Lower Consumption is the best way to go if possible.

 

[r4dent]

The fridge is a compressor (electric only) - it seems the coachbuilder does not like fitting gas.

Explains a lot and I'm sorry for assuming it was absorption and misleading you

The fridge is the biggest consumer of electric, its a 12v with a tech sheet quoted 3.8A draw,

That will be the max draw and is used in defining fuse and wire sizes.
Compression fridges do not run 24 hours a day and somewhere in your the tech details there should an average 24 hour usage (in either ah or wh) which will be a better guide to how long the battery will run it. Remember only 50% (assuming a lead battery) of the nominal capacity is available (i.e. 55 ah) before the battery is flat.

 

[merl]

When i was in our biggest battery shop picking up a new starter battery for my car i ask about l carbon batteries, they had not a clue and just pointed to a crappy les battery on the shelf.

That's specialists for ya Trev.

 

[colinm]

Our van came with two 110ah lead acid, a 12v 43w fridge but no solar. Useless off grid. Had 1x100 pv fitted, not good enough either, so had second 100pv fitted. Now fine but not in winter when we have often to run the engine on tickover to provide a boost. A battery to battery charger would be a good idea for very fast engine charging, but have not invested so far as they are expensive. We don't have room for any more fixed pv, but portable is a possibility i guess.For offgrid pv 200w+ is essential plus min 200ah+ of bats, lithium if poss. If you want to use 230v equipment then yoy have to go to maybe 400wpv plus large lithiam capacity plus BtoB .
Just my opinions gatheted over the last mant years which not everyone will second.

Over the last few years I've noticed a few motorhome manufacturers offering compressor fridge set ups with what appears to me to be only enough standalone power for at best one day, I guess they are catering for those who use EHU most of the time. My limited experience of 12v fridges tells me, we need at minimum of 200Ah of battery, 200w of solar, and a B2B, to cover most of our needs and usage.

 

[trevskoda]

Over the last few years I've noticed a few motorhome manufacturers offering compressor fridge set ups with what appears to me to be only enough standalone power for at best one day, I guess they are catering for those who use EHU most of the time. My limited experience of 12v fridges tells me, we need at minimum of 200Ah of battery, 200w of solar, and a B2B, to cover most of our needs and usage.

Correct, and yes folk say it works harder in summer, but the sun keeps batts up, in winter with much less solar if any around nov/dec it still works as with me i dont do heating much and find the battery will last 24hrs no bother from a full charge.

 

[merl]

Remember only 50% (assuming a lead battery) of the nominal capacity is available (i.e. 55 ah) before the battery is flat.

Hmm, not sure where you've got that info from but it's not particularly accurate.informstion.
A lead acid battery (like ALL battery types) age quicker with deeper discharges.
The more you hammer them with deep discharges the shorter their lives will be. 50% is usually touted as the accepted norm for discharging a lead acid battery before harming it but that's misleading because people think that 50% is ok and 60% is harmful. 60% is harmful but so is 50% and so is 40% for that matter but just not quite so bad, it's a sliding scale. You can discharge to 90% if you need to, there's no limit just a sliding scale of harm that starts at 1%.
Now I know that the graph for damage isn't a straight line, it's curved so it's true that the deeper you discharge the damage increases exponentially but if you're prepared to accept 4 times the damage to get twice as much power from the battery that's probably better than sitting in the dark with no telly just because you've already used 1/2 of the available power and your scared that you'll kill the battery if you take it any lower.
To say a 110Ah battery will be flat after delivering 55Ah is not true unless it's already 50% knackered.

 

[wildebus]

Hmm, not sure where you've got that info from but it's not particularly accurate.informstion.
A lead acid battery (like ALL battery types) age quicker with deeper discharges.
The more you hammer them with deep discharges the shorter their lives will be. 50% is usually touted as the accepted norm for discharging a lead acid battery before harming it but that's misleading because people think that 50% is ok and 60% is harmful. 60% is harmful but so is 50% and so is 40% for that matter but just not quite so bad, it's a sliding scale. You can discharge to 90% if you need to, there's no limit just a sliding scale of harm that starts at 1%.
Now I know that the graph for damage isn't a straight line, it's curved so it's true that the deeper you discharge the damage increases exponentially but if you're prepared to accept 4 times the damage to get twice as much power from the battery that's probably better than sitting in the dark with no telly just because you've already used 1/2 of the available power and your scared that you'll kill the battery if you take it any lower.
To say a 110Ah battery will be flat after delivering 55Ah is not true unless it's already 50% knackered.

A good summary

In fact, if one does the maths of discharge rates vs charge cycles that you get with more 'technical' batteries, you can get a mathematical value of the total energy a battery could provide over its service lifetime for the difference discharge levels and very often for good batteries, that equation can be pretty equal.
And then you can apply the purchase cost of the battery into the equation and you get a cost per Ah.

It can often be the case that the cost per Ah when taking the battery down deeper can be the same as treating it very gently. For example, getting 1000 cycles by only going down to 80% SOC may sound great but if you only got 350 charge cycles on that battery when you take it down to 40% SOC, you are actually gettting more out the battery for the same cost. You may be killing it 3 times quicker, but you are getting more than 3 times the total energy out the battery.

Numbers above just made up to show the maths, but to use a real life example, take the Victron Super Cycle Battery, which is a Lead Acid Battery and where Victron quote Cycles for different levels of discharge ....
If you take the 100Ah Super Cycle Battery and discharged it to 100% DoD (so flat - which usually means 10.8V) they quote >300 Cycles; If you only discharge to 60% DoD (taking out 60Ah per cycle), they quote >700 cycle; and at a 40% DoD they quote >1000 Cycles.
on those numbers, you actually get MORE total power (42,000Ah) out the battery by taking it down to 60% DoD than if you are more gentle and only go down to 40% DoD (40,000 Ah total power).
And this 'Super Cycle' is good, but not one of the best batteries you can buy - there are numerous other Lead Carbon Batteries that have better performance and similar patterns for DoD vs total power.


It is a bit like those folk who get a Lithium battery and make sure they never charge it to 100% and never discharge below 20% to get a longer service life from it... Use it fully and you will likely get just as much service time from it (you'll upgrade/change van/BMS will fail while Cells still have life in them) while getting a lot more energy out of it.

 

[r4dent]

Reading the OPs early posts indicates he believes a 110 ah battery will provide a 110 ah of energy. I was just trying to indicate that using 50% of the capacity will involve that battery having no more to give. I know his is over simplification I didn't want to go deep into a complex situation. I accept valid criticism of this simplistic explanation, I'm just trying to provide some guidance to a new comer.

 

[Nabsim]

Well my 3x90ah Bosch PowerFrame battery’s were useless within 12 months from new solely taking too much out of them. Not that many times either but allied to the fact you rarely get them to full capacity unless using hookup most folks won’t have 110ah on a 110ah battery very often if at all.

I would always recommend not taking lead acid too low and work on 50% of stated capacity

 

[trevskoda]

Danger below 10.8 they say, im at worst never below 12.2vbut 12.4v is normal when running the fridge over night.

 

[jacquigem]

Danger below 10.8 they say, im at worst never below 12.2vbut 12.4v is normal when running the fridge over night.View attachment 123150

Interestingly there is a sticker on my sargent control panel which says do not discharge below 10.5 volts or it may damage batteries. I have always thought that would be far too low. I wonder why it's there ?