Advice on changing batteries to LiFePo please

[peterc10]

Well I have had a look at some charts. They say that 12.67V suggests the batteries are 85% or so charged. By my calculation that suggests that, if they dropped that much with 22.5Ah, their full capacity is about 150Ah, give or take. Is that about right?

 

[Lenny HB]

You need to run a more extensive test at the C20 rate you did your test at the C40 rate and you need to take them down a lot lower to get a true picture, you may find they get down to 50% and just fall over or you may ave very rare AGM's that actually work.

As they are 6 years old and you have made up your mind to fit Lithium you might as well not bother and get the Lithium.

 

[Jimbohorlicks]

Here's my latest home build Peter, 280Ah with a bluetooth BMS, it's all pretty simple stuff, no rocket science involved.

View attachment 584229

Can I ask where you bought your batteries from please?
Thanks.

Sorry ,just back tracked through the thread and can see where they were from,( had visitors so lost a couple or 3 hours on this topic )

 

[two]

Hello, Peter.
I would go for only one Li. I think it would cope with the hairdryer and it would seem that you don't need the extra capacity.
So just get one and save more weight.
I'd change the solar controller and manage the use of EHU manually (not leave it charging).
Plan B would be to simply replace with Gel.

 

[Jimbohorlicks]

Here's my latest home build Peter, 280Ah with a bluetooth BMS, it's all pretty simple stuff, no rocket science involved.

View attachment 584229

Looks a nice set upCan you advise about the BMS ,did you build this yourself or was it an off the shelf purchase, so to speak?

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[Two on Tour]

Looks a nice set upCan you advise about the BMS ,did you build this yourself or was it an off the shelf purchase, so to speak?

It's a Daly 12v 100A 4S Smart BMS. If you are going to be using a big inverter, then you may need to go for a bigger amperage version.

I bought mine from Nigel and Roger who are Funsters.

Daly 12V 100A BMS for 4s LiFePO4 battery — Offgrid Van Life

Daly Smart LiFePO4 4S Battery Management System (BMS) 12V 100A with Bluetooth dongle & temperature sensor. This product is stocked in the UK, so will be shipped to you much faster than if you ordered it from a supplier based in China.

offgridvan.life

 

[the1andonly]

100ah currently£431.09 but 10% off code available

Pardon our interruption...

 

[peterc10]

Thanks for all the help so far. I am trying to decide what size of cable have Hymer installed from the starter and leisure batteries to the EBL. That will give me more information as to how many amps I could get to any B2B that I installed. The EBL is installed next to the leisure batteries and at most 1m from the starter batteries, so cable lengths are short.

I have measured the cables coming out of the back of the EBL and they are 7mm in diameter. Can anybody tell me what the size of the inner core is in mm2 please? Trying to decide whether to have 30A or 50A B2B.

 

[Two on Tour]

I have measured the cables coming out of the back of the EBL and they are 7mm in diameter. Can anybody tell me what the size of the inner core is in mm2 please? Trying to decide whether to have 30A or 50A B2B.

Really depends on the thickness of the insulation used on your cable.

Here are some links that give you some details in the cable O.D. and the conductor cross-section.

Looking at the standard insulation link, it could well be 10mm2

Thin wall insulation - https://www.autoelectricsupplies.co.uk/product/70/category/114

Standard insulation - https://www.autoelectricsupplies.co.uk/product/66/category/11

Battery cable insulation - https://www.autoelectricsupplies.co.uk/product_list/124

 

[Lenny HB]

I have measured the cables coming out of the back of the EBL and they are 7mm in diameter. Can anybody tell me what the size of the inner core is in mm2 please? Trying to decide whether to have 30A or 50A B2B.

How accurately did you measure them?
Approx 7.5mm dia is 10mm sq, 8.2mm dia is 16 mm sq.

I'm fairly certain they will be 16 mm sq, mine are.

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[peterc10]

Really depends on the thickness of the insulation used on your cable.

Here are some links that give you some details in the cable O.D. and the conductor cross-section.

Looking at the standard insulation link, it could well be 10mm2

Thin wall insulation - https://www.autoelectricsupplies.co.uk/product/70/category/114

Standard insulation - https://www.autoelectricsupplies.co.uk/product/66/category/11

Battery cable insulation - https://www.autoelectricsupplies.co.uk/product_list/124

Thanks Paul. I had tried to Google it but didn't come up with that useful information.

How accurately did you measure them?
Approx 7.5mm dia is 10mm sq, 8.2mm dia is 16 mm sq.

I'm fairly certain they will be 16 mm sq, mine are.

Thanks Lenny. Probably not very accurate - just used a tape measure. But you know us civil engineers when measuring, It's OK if it's in the right field .

According to Votronic I can use their 50A B2B with 10mm sq if the lengths do not exceed 5m and they are much shorter than that.

 

[Lenny HB]

According to Votronic I can use their 50A B2B with 10mm sq if the lengths do not exceed 5m and they are much shorter than that.

It will be fine.
How are you planning to wire it?
Via the EBL or by-passing it?

 

[two]

You could always double-up the wiring to get more current.

 

[peterc10]

It will be fine.
How are you planning to wire it?
Via the EBL or by-passing it?

If I do it (still not sure) I will go via the EBL as it uses most of the existing wiring and much easier to do. The only sensible place I can put the B2B near the EBL and batteries means I will need to temporarily remove one of the batteries to have enough space to fit it. So best done when I put new batteries in.

I thought that I could use Gels to save money, but, as you say, the 100A draw from the inverter for hair drying will shorten their life, so probably will fit lithiums at sometime. No point in changing the solar regulator until then as the LRM has a programme for AGMs. When I do I will not change the EBL and be just be a bit careful as to how I use it, especially now I know I can disable the mains charging side just by pulling one fuse out, and it will still leave me with 240v electricity for the fridge etc.

For simplicity I will use the Votronic stuff as the instructions for B2B and solar regulator explain in an easy to understand way how to use them with the EBL. The only thing I am not sure of is what D+ I should use from the EBL, is it the "output D+" on the connector assignment table and "D+ point" on the wiring diagram? From what I have seen the Victron instructions are designed for those with a lot more electrical knowledge than me.

So do I spend my money now or see if I can get another year out of my existing system? That is what I will wrestle with over the weekend.

 

[jongood]

If all this is for a hairdryer, then could your wife manage with one of these?

Broken Link Removed

My wife has shortish hair and she rates hers as 8/10. Its 460 watts.

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[peterc10]

If all this is for a hairdryer, then could your wife manage with one of these?

Broken Link Removed

My wife has shortish hair and she rates hers as 8/10. Its 460 watts.

Can't find a link to exactly what you are referring to. Looks as if it is no longer sold or available.

My wife has long hair.

 

[Lenny HB]

Wiring via the EBL allows the EBL to charge the engine battery from mains but does depend on the model, the downside is that if the split charge relay contacts are carboned up it will reduce the charging current gerry mcg had that problem. I think it's best to by-pass the EBL.

The D+ can be picked up in several places there is a wire into the front of the EBL and there is a Schaudt relay unit probably under the passenger seat that the D+ goes to, driver's seat in your case.

Even if you are not going to keep the van that much longer if you go to Lithium you can swap it to the next van.
Two of my Gels are 6 years old & one is 5 years old if they fell over I would fit Lithium, can't justify it at the moment as apart from age loss my Gels are still performing as new.

 

[Lenny HB]

Can't find a link to exactly what you are referring to. Looks as if it is no longer sold or available.

My wife has long hair.

Buy Angela some scissors.

 

[peterc10]

Even if you are not going to keep the van that much longer if you go to Lithium you can swap it to the next van.

This one is our keeper. Don't see us changing unless I lose my C1, pack up motorhoming altogether, or die.

 

[Two on Tour]

Yvette has very long hair and uses a 2000 watt jobby to dry her hair at home.
For the motorhome she uses one of these hooked up to the 1000 watt inverter. It uses infra red for heat and is rated at 450 watts flat out. It takes longer to dry her hair with the motorhome one, but times not a problem when we are away.

https://www.ebay.co.uk/itm/30422877...d=link&campid=5338547443&toolid=20001&mkevt=1

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[peterc10]

Can I ask where you bought your batteries from please?
Thanks.

Sorry ,just back tracked through the thread and can see where they were from,( had visitors so lost a couple or 3 hours on this topic )

Jimbohorlicks

Jim, I thought you won a half price battery from KS a few weeks ago. Did you get it and what were they like to deal with please. I am thinking of buying from them.

 

[Russell's Dad]

Well I have had a look at some charts. They say that 12.67V suggests the batteries are 85% or so charged. By my calculation that suggests that, if they dropped that much with 22.5Ah, their full capacity is about 150Ah, give or take. Is that about right?

As I have said in other threads....
I thought my AGMs were not doing well but sending a quick email to the manufacturer ( Yuasa) put my mind at rest. 12.7 is a fully charged Yuasa 95ah AGM, so mine are still great!
Maybe check with your manufacturer before you resign yours to the bin. Not all AGMs are 13v when fully charged.

 

[Lenny HB]

This one is our keeper. Don't see us changing unless I lose my C1, pack up motorhoming altogether, or die.

If you go the Gel route and want to maintain your current inverter use to keep within the recommendations and be kind to the batteries you would need to fit 7 x 80ah Gel Batteries. But in practice you would get away with 4 batteries and still get a reasonable life out of them.

If you go the Lithium route you would be OK with 2 x 100 ah or a single 200 ah but do check the spec on them, not all Lithium are equal.

 

[peterc10]

If you go the Gel route and want to maintain your current inverter use to keep within the recommendations and be kind to the batteries you would need to fit 7 x 80ah Gel Batteries. But in practice you would get away with 4 batteries and still get a reasonable life out of them.

If you go the Lithium route you would be OK with 2 x 100 ah or a single 200 ah but do check the spec on them, not all Lithium are equal.

At the moment I am thinking of 2 x 120Ah low profile lithium batteries from KS which are identical in dimensions, holding down arrangement and terminal layouts to the ones I have got at the moment. So a very straightforward swap using the same leads and clamps. I have checked the spec and it says the maximum continuous discharge rate for each battery is 150A, with up to 300A peak surge for the first 15 seconds. I only need 100A for 5 minutes max every 3 or 4 days. They are just over half the weight of my existing batteries so I will save about 26kg total in weight.

I have not got the room or the payload for 4 batteries, let alone 7! The 2 lithiums give me over 200Ah of available power, whereas 2 Gels would give me about 130Ah, assuming I take them down to 20%, They appear to have a reasonably comprehensive BMS and I can see how each is performing via bluetooth. The only downside that I can see with the lithiums when compared with the Gels is the cost. Hence this weekend's argument between me and my wallet As I keep saying "it's only money".

Thanks for all the help you and everybody else have given

 

[Pausim]

So do I spend my money now or see if I can get another year out of my existing system?

If it were me I would spend the money now. One year less worrying about when the old batteries will fall over and the new ones should be good far enough into the future to not be worth worrying about now.

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[Jimbohorlicks]

Jimbohorlicks

Jim, I thought you won a half price battery from KS a few weeks ago. Did you get it and what were they like to deal with please. I am thinking of buying from them.

Hi Peter just seen this ,will pm you.
It was ecotree by the way not KS.

 

[peterc10]

If it were me I would spend the money now. One year less worrying about when the old batteries will fall over and the new ones should be good far enough into the future to not be worth worrying about now.

I agree. But when I passed that message on to the wallet it is still saying no

 

[Lenny HB]

I agree. But when I passed that message on to the wallet it is still saying no

I had that problem recently, I fancied an OLED TV in the end I bought it and told 'er indoors afterwards.

 

[Two on Tour]

I had that problem recently, I fancied an OLED TV in the end I bought it and told 'er indoors afterwards.

 

[Pausim]

I agree. But when I passed that message on to the wallet it is still saying no

Perhaps the wallet needs to see it as one off expenditure as part of it’s ongoing commitment to “Operation Hairdryer”. The terms of several peace treaties rely on “Operation Hairdryer” for maintaining basic services.

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