Another lithium battery question

[Largejj]

Hi everyone I have a swift KonTiki 669 with 500w of solar, 4kw inverter and Victron solar controller , B2B and mains charger.

I have two 110 AGM cheap Halfords batteries about 2 years old. I also have a vanbitz device to keep the engine battery topped up. Vehicle split charge relay disconnected and factory mains charger are turned off. Have not worked out how to wire the step to autoclose and put 12v on fridge after split charge disconnected - actually it stopped working just as was fitting b2b that’s another story!

The motor home has a lot of electrics TV, and we use the car audio for surround sound. On a really dull day when solar is down to less than 50w we can discharge in a day with heater blower on, tv, audio etc. Interestingly the engine battery also discharges to around 11v so suspect it needs replacement (it’s original and 12 years old). Most days we get 150w easily and in full sun we get 350-400w from the solar setup.

ive checked for current leakage ans can get it to 0 if I turn everything off. It’s amazing how many device pulling around 200mA we have

Most days in Uk have more than enough solar for us it is really just the odd overcast day. It was much worse when we just had 300w of panels - roof cannot take any more.

My question is if I wanted to replace the two 110A agm batteries with Lithium etc what could be fitted in same space to maximise storage?

current batteries are under floor in dedicated box and am aware of cold charging issues. I think I could live with this.

Am interested to know what people physically swap two 110A leisure batteries when they go to lithium. Lifepo4’s get good reviews but how many of say the 100amp ones can you fit in the space? Weight saving will be welcome but would like to know how many I can fit (budget permitting)

 

[Slabraider]

Hi,

It sounds like you are reasonably well kitted out for the switch to lithium. If your solar controller and B2B have specific lithium settings then that is a bonus but they generally work well on AGM settings too.

I would suggest you get in touch with Rob at EcoTree lithium as their batteries are designed to be the same size as various lead and agm. They have quite a few different size batteries so it will just be a like for like replacement.

EcoTree have been popping up in a few posts around this forum and everyone has been really happy with the advice and service as far as I can tell. I am getting mine fitted as soon as they can fit me in which I'm super excited about. The main thing for me is the 6 year warranty as it is a big investment for me and want something reliable.

In addition to what you have in your setup I'm getting a shunt so I can monitor how much power is left in the batteries, it's the only way to accurately track the power left in Lithium.

The main thing for you that will benefit your power is the fact the charge easier and faster. When the sun comes out for and hour or two you will get more power into a lithium than an agm so you're making better use of the limited sun you get.

I've done a lot of research into lithium before getting my pound notes out

 

[Guigsy]

Are the Sterling lithium batteries any good? The BMS built in to those includes bluetooth to provide shunt/BMV type information.

 

[Largejj]

Hi,

It sounds like you are reasonably well kitted out for the switch to lithium. If your solar controller and B2B have specific lithium settings then that is a bonus but they generally work well on AGM settings too.

I would suggest you get in touch with Rob at EcoTree lithium as their batteries are designed to be the same size as various lead and agm. They have quite a few different size batteries so it will just be a like for like replacement.

EcoTree have been popping up in a few posts around this forum and everyone has been really happy with the advice and service as far as I can tell. I am getting mine fitted as soon as they can fit me in which I'm super excited about. The main thing for me is the 6 year warranty as it is a big investment for me and want something reliable.

In addition to what you have in your setup I'm getting a shunt so I can monitor how much power is left in the batteries, it's the only way to accurately track the power left in Lithium.

The main thing for you that will benefit your power is the fact the charge easier and faster. When the sun comes out for and hour or two you will get more power into a lithium than an agm so you're making better use of the limited sun you get.

I've done a lot of research into lithium before getting my pound notes out

Yes I am going to measure the battery compartment and see what I can fit in from Ecotree and others. I am told its better to have 1 larger battery with one BMS. I also have the victron energy smart meter fitted with shunt and a Victron GX for remote monitoring via GSM etc. Its a pity Victron do not make a complete battery solution in one that is cost effective and I could then just use the one app for everything.

I am happy to make a large investment with the right warranty etc as I will use this long term off grid.

 

[Slabraider]

I have looked at Sterling batteries and they fall into a category which doesn't suit my use.

The main reason I wouldn't install Sterling and a long list of other brands is a very important point I think you should all be aware of; Prismatic Cells. To cut a long story short, Prismatic cells are not a good cell design for long life unless they are under light use in static installations. If you are going to use them in a motorhome then some of the loads will be quite high, you may be charging them quite fast and the will be bounced around all over the place.

Do some research into Prismatic cells and I suggest you avoid them at all costs for motorhome use. Unless you are building a DIY battery where you can arrange better cooling gaps and replaced damaged cells.

The EcoTree I have chosen have cylindrical cells which don't suffer a lot of the faults which are more likely to occur in prismatic cells. The real Key thing however is COOLING! Prismatic cells rammed together find it very difficult to keep cool and with my inverter or charger running heat will build up in the middle of the cells. The cylindrical are nicely spaced allowing each cell to dissipate heat into the gaps between the cells.

I am not very confident in the electronic gubbins fitted in batteries like the Sterling or LiFOS. I would rather have external Victron equipment tbh. Victron is worth the extra money.

The extra year warranty on the EcoTree isn't a major but the extra year is because the battery is better built so less likely to fail.

At the end of the day you get what you pay for and there is a good reason why the Sterling are so cheap when backed by a major brand. I don't want to buying a new battery for many many years and intend to use them quite heavily like the OP.

Sorry for the long message, I could have gone into a lot more detail

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[Guigsy]

Ecotree may well be higher quality, but I don't think the cell shape is much of an indicator. I'm not convinced that prismatic cells are really an issue for leisure use. Sure, you might be pulling a couple of kW to run the coffee machine, but only for a couple of minutes. During that time, heating within the battery is probably a couple of dozen watts. Leisure use is nowhere near as demanding as use in EVs where kW are being pushed and pulled continuously (and now Tesla use prismatic LFPs, but they are actively cooled). Conventional lead based batteries are effectively prismatic and take similar loads and have similar efficiencies and don't need additional cooling. Finally, cylindrical the cells are still in a sealed box with no active ventilation, so they are just heating a confined air blanket.

 

[Wanderlust]

Ks energy have frost protect built in to the BMS not sure if the others have or not.

 

[Guigsy]

Just messaged Stirling. Their BMS cuts off charging at 0C and re-enables at 5C. Discharge cuts of at -20C.

 

[Wanderlust]

I have no affiliation with them but KS were the only ones giving a 10 year warranty when I bought mine last year, do any others offer this now ? I see sterling is 5 not even sure if it any benefit, would you really be claiming after 8/9 years.

 

[Largejj]

I have just ordered a single 320 AH from Eco Tree. I called up and they gave me a 10% discount code MHF21 so it was £1529.10 in total for 320 AH. The Kon Tiki battery box is 750 length by 300 wide by 280 high. The eco tree 320AH easily fits in here and is much lighter. Will report back when they are fitted at the weekend.

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[Slabraider]

I have just ordered a single 320 AH from Eco Tree. I called up and they gave me a 10% discount code MHF21 so it was £1529.10 in total for 320 AH. The Kon Tiki battery box is 750 length by 300 wide by 280 high. The eco tree 320AH easily fits in here and is much lighter. Will report back when they are fitted at the weekend.

I would be keen to hear how it goes once you have used the 320AH. Can I ask what battery / batteries this will be replacing.

 

[Largejj]

Its replacing two 110 AH AGM's (about 18 months old) nothing wrong with them but with the inverter and low sun you can go from 220ah to 50% in a day or so. Hopefully with 320A I will have much more usable capacity and higher voltage until discharge. Will try not to fully discharge them.

 

[Raul]

If you have a GX, victron has everything and will integrate with your system. You can have linx bms, external bms, al communicating with each other via GX, or the superbatt the black case with bms inside. The beauty with the external bms and shunt, the GX hub will be able to control charge discharge, regardless of temperature. It picks the charger temp, or a temp sens via blue tooth, networked into victron.

 

[royw]

Just to add some manufacturers will manufacture the battery casing to a clients requirement, you can then maximise capacity/physical space ?

 

[Largejj]

If you have a GX, victron has everything and will integrate with your system. You can have linx bms, external bms, al communicating with each other via GX, or the superbatt the black case with bms inside. The beauty with the external bms and shunt, the GX hub will be able to control charge discharge, regardless of temperature. It picks the charger temp, or a temp sens via blue tooth, networked into victron.

I would definitely be interested to learn how I could set the GX up with the battery BMS built into the 320AH eco tree battery. Everything is wired thought the shunt from the victron energy smart meter.

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[funflair]

Its replacing two 110 AH AGM's (about 18 months old) nothing wrong with them but with the inverter and low sun you can go from 220ah to 50% in a day or so. Hopefully with 320A I will have much more usable capacity and higher voltage until discharge. Will try not to fully discharge them.

Is it really max discharge current of 100 amps? and will this be enough for your inverter?

 

[Raul]

I would definitely be interested to learn how I could set the GX up with the battery BMS built into the 320AH eco tree battery. Everything is wired thought the shunt from the victron energy smart meter.

You miss understood, or my poor explanation. Victron works only with their own gear, not third party. I meant victron bms and victron batteries do integrate in all GX devices.
The only compatible third party, is can bus professional 48v packs, like BYD, Pylonthech etc. for energy storage systems ESS. You can read on victron life, and raise question for your requirements, victron staff is very helpful.

 

[royw]

Is it really max discharge current of 100 amps? and will this be enough for your inverter?

I see the 300 KS litium have 150AH max

 

[Guigsy]

I see the 300 KS litium have 150AH max

I think the limitation with a lot of these batteries is maximum current the BMS can sustain rather than the battery chemistry. I'm thinking that if I want to pull 2kW for an invertor, I'm probably better getting a pair of Lithiums, just so the BMS's share the load.

 

[Largejj]

I’ve just asked eco tree this exact question before they dispatch. 100 or 150 max discharge amps could be an issue on rare ocaasions so maybe two smaller batteries is the way to go?

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[funflair]

I think the limitation with a lot of these batteries is maximum current the BMS can sustain rather than the battery chemistry. I'm thinking that if I want to pull 2kW for an invertor, I'm probably better getting a pair of Lithiums, just so the BMS's share the load.

Our Super-b 160ah's have a maximum discharge current figure of 480A so no issue pulling 200A with the inverter, I did read one here that somebody had problems with the 100A max on their BMS, even though they had 3 batteries one BMS was seeing the maximum load and shutting off, they replaced the batteries with something with a greater discharge current and all was well I believe.

 

[Largejj]

I’ve just asked eco tree this exact question before they dispatch. 100 or 150 max discharge amps could be an issue on rare ocaasions so maybe two smaller batteries is the way to go?

Econtree are suggesting it will be fine. I very rarely go over 100amps but it would be useful for a quick boil of kettle etc.

==============

It should handle the load that is required. We do a 48-100 that will operate to 5kw at the same surge.
Best Regards,

Paul
Thanks. One concern I have is the 100 amp discharge limit. I have a 4kw inverter and will occasionally pull larger loads.

Will the 320 handle this out would have been better with a pair of batteries to share the load?

 

[Guigsy]

Econtree are suggesting it will be fine. I very rarely go over 100amps but it would be useful for a quick boil of kettle etc.

==============

It should handle the load that is required. We do a 48-100 that will operate to 5kw at the same surge.
Best Regards,

Paul

Boiling the kettle is a sustained load. 100amps is only 1.2kW, and you need some overhead for invertor losses too.

 

[John H.]

I have looked at Sterling batteries and they fall into a category which doesn't suit my use.

They work fine for me and are happy with my Hymer EBL 29 EHU, Sterling B2B and Votronic Solar controller.

I'm probably better getting a pair of Lithiums, just so the BMS's share the load.

I have two Sterling connected in parallel for that reason.

Just messaged Stirling. Their BMS cuts off charging at 0C and re-enables at 5C. Discharge cuts of at -20C.

Sounds good to me, althjough I normally keep some low heat on in the winter.

 

[Largejj]

Eco tree are now backtracking and suggesting I go 3 or 4 100 or 110amp batteries due to the 100amp discharge limit. Checking options now and will report back.

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[Largejj]

Eco tree have offered me three 100 AH lithium's for same price as the 320 due to the max current issue of 100amps - you can connect as many as you want in parallel. I've purchased another one at discounted price so I am 400AH and can pull 400 amps max discharge - won't do it very often but its good to know you can etc. Also gives me more capacity than I probably need but I only want to do this once and properly. Will report back once they are installed.

 

[HectorsHoose]

Hi everyone I have a swift KonTiki 669 with 500w of solar, 4kw inverter and Victron solar controller , B2B and mains charger.

I have two 110 AGM cheap Halfords batteries about 2 years old. I also have a vanbitz device to keep the engine battery topped up. Vehicle split charge relay disconnected and factory mains charger are turned off. Have not worked out how to wire the step to autoclose and put 12v on fridge after split charge disconnected - actually it stopped working just as was fitting b2b that’s another story!

The motor home has a lot of electrics TV, and we use the car audio for surround sound. On a really dull day when solar is down to less than 50w we can discharge in a day with heater blower on, tv, audio etc. Interestingly the engine battery also discharges to around 11v so suspect it needs replacement (it’s original and 12 years old). Most days we get 150w easily and in full sun we get 350-400w from the solar setup.

ive checked for current leakage ans can get it to 0 if I turn everything off. It’s amazing how many device pulling around 200mA we have

Most days in Uk have more than enough solar for us it is really just the odd overcast day. It was much worse when we just had 300w of panels - roof cannot take any more.

My question is if I wanted to replace the two 110A agm batteries with Lithium etc what could be fitted in same space to maximise storage?

current batteries are under floor in dedicated box and am aware of cold charging issues. I think I could live with this.

Am interested to know what people physically swap two 110A leisure batteries when they go to lithium. Lifepo4’s get good reviews but how many of say the 100amp ones can you fit in the space? Weight saving will be welcome but would like to know how many I can fit (budget permitting)

We are replacing 2 x 100Ah AGMs with 1 x 110Ah lithium as we will have essentially the same Ah’s as the lithium can without damage be dropped by 90% whereas the AGM can only go down to 50%. Great weight saving too. So if you swap your AGMs for 2 x 100 lithium you will get double the useable Ah’s that you have now & gain payload. Physically there’s very little difference in size.

 

[HectorsHoose]

We are replacing 2 x 100Ah AGMs with 1 x 110Ah lithium as we will have essentially the same Ah’s as the lithium can without damage be dropped by 90% whereas the AGM can only go down to 50%. Great weight saving too. So if you swap your AGMs for 2 x 100 lithium you will get double the useable Ah’s that you have now & gain payload. Physically there’s very little difference in size.

Sorry meant to say 1 x 120Ah lithium

 

[JockandRita]

Eco tree have offered me three 100 AH lithium's for same price as the 320 due to the max current issue of 100amps - you can connect as many as you want in parallel.

I would have snapped their arm off.

Do you really need the 4th LifePo4 battery?

Good luck with the installation.

Cheers

Jock.

 

[Clarky]

Do you really need the 4th LifePo4 battery?

Always better to have too much………….as the actress said to the bishop.

Richard.

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