Lithium Batteries – are they worth it?

Whilst I am posting this information, most of the credit for this must be given to Richard Moore, as Richard has far more electrical experience than I have and certainly understands more of the technical references regarding lithium batteries.

We have however pooled our knowledge, resources and information gathering to provide/write this article on lithium batteries when being used as leisure batteries, mainly in Motorhomes (M/H) but also in caravans. We are also keen to avoid causing any damage to either the M/H, caravan or indeed the expensive new batteries that we may be fitting.

I have to say two things; firstly, neither Richard or I have any affiliation to any of the links or providers and are not receiving a special deal/batteries for free etc and, secondly, all we are trying to do is to find a leisure battery solution that lasts, has power when required and we are able to use that power for the odd night off-grid i.e. when there is no Electric Hook Up (EHU) as opposed to somebody wishing to have 240v when off-grid via inverters for coffee machines, hair straighteners, to recharge E-Bikes etc. with the power all being supplied by leisure batteries.

There are some battery providers out there who say and advertise their lithium batteries as being a ‘plug and play solution’. Richard and I would agree that in certain circumstances this is possible, but it would all depend upon the equipment your M/H came with or you have had fitted. You won’t however be getting the most out of your expensive batteries and may be doing irreparable damage to them or the M/H so beware!

So, let’s look at the advantages and then the requirements of lithium over AGM/Gel batteries – Four of the main advantages of lithium are:

  1. I am sure most of us remember a torch we had as a youngster that when new batteries were put in the light was very bright but over time the light fades until such time as the light went out – well, this is a typical trait of a lead acid battery, with the difference being you can recharge the AGM/Gel battery as opposed to having to replace it.

A lithium battery does not act like the above and in the same situation the light would remain bright until the battery goes flat and then the light would just go out, very much in the same way a mobile phone works today.

As an example, my iPhone (that has a small lithium battery in it) shows the power as a percentage of charge in the top right side of the screen and regardless of it being 100% or 5% of charge the phone works just as it should until it runs flat and then it just goes off – granted it warns me at the 20% power but if I ignore that it continues to work all the way down to 0% when the battery shuts down. I simply plug in my charger and after 3-4 mins I can turn the phone on again and the lithium batteries discussed here work in the same way.

  1. There is a tremendous weight saving as lithium batteries are at least 50% lighter than the normal AGM/Gel batteries of the same size – they can be up to 70% lighter.

3.You can discharge a lithium battery from full to approximately 5-10% of its capacitydepending on the battery – so if it was a 100 amp hour battery you could take thisdown to approximately 5-10 amp hour giving you 90-95 amp hour of usable powerwhereaswitha normalAGM/Gel batteryyoucanonlyuseuptoapproximately50% of its power, meaning that 1x 100 amp hour lithium battery equals almost 2x100amphour AGM/Gelbatteries.

  1. The cycle life (each round of full discharge and then full recharge is called battery cycle life) is up to 10x more than the AGM/Gel batteries so you can charge them and discharge them up to 5,000 times, if not more depending upon the quality of the battery, as opposed to approximately 500 times on a very good AGM/Gel battery.

Normal leisure batteries, such as AGM/Gel require a charge of around 13.7volts whereas a lithium battery requires a charge of around 14.6volts to charge +/- 0.2volts. If we consider the usual battery charging system (EBL) on a M/H or caravan, the more modern units will charge the battery at 14.4volts for approximately 10 minutes, drop the charge down to 13.9volts for approximately 30 minutes and then they will charge the batteries at 13.7volts until the battery is approximately 96% charged, at which time the charger will then switch over onto the vehicle battery and do the same process. Thereafter every 4 hours or so the charging unit will check the batteries to see if they need further charge and go through the above process again, but the above means regardless of the type of battery fitted they never get a full charge – this charging process is not good for lithium batteries – but all is not lost at this first hurdle!

A company, who has been extremely helpful in offering information to assist with this write up, are Apuljack http://www.apuljackengineering.co.uk who has stated it may be able to alter the charge output and make the EBL charge at a constant voltage (this would be dependent upon the EBL you have and a charge/fee may be applicable). As some lithium batteries accept different charge inputs Alupjack can set the output from the EBL to the voltage required to suit the lithium batteries you wish to use i.e. you decide on the lithium battery and the charge input, advise Apuljack of this and they will set the charge rate accordingly.

It may be that even with this modification it will not fully charge the lithium battery as it will stop at 96% charge and then switch over to the vehicle side. Apuljack has advised they can do this for most makes and types of EBL and for the same cost convert the EBL back to the AGM/Gel settings, if required, when you sell your M/H in the future.

Both my and Richard’s M/H have an EBL 102 which, once the Apuljack conversion is completed would suffice and, based on the above, lithium batteries would be a ‘plug and play’ option but you would need to get your EBL converted and you would still need to take the batteries off the vehicle approximately every 2 months and put them on a lithium battery charger to fully charge them and to maintain their full capacity. The same would apply to a caravan and it is a great deal easier as the following would not apply to a caravan but does for M/H’s.

Charging the batteries via the alternator is slightly more problematic in that, if your H/M is Euro 6 compliant (you will probably know this if it has AdBlue) then it will have, what is classed as a, Smart Alternator fitted and, if this is the case, then you will need a DC-DC charger, often referred to as a B2B charging unit (they are both the same thing just with different words to describe them).

It’s likely that you will not cause any damage to the batteries from the Smart Alternator, more the reverse in that there may be damage caused to the alternator as it may over-heat – for further

information I refer you to a document that can be found here;- https://www.practicalmotorhome.com/advice/spotlight-on-smart-alternators

On older M/Hs without a Smart Alternator you may find all that is needed would be a couple of relays fitted and off you go – you would need to check this with the manufacturer.

Again, the M/H’s that Richard and I have both have a B2B charging unit on them, although the output is fairly small at 25amp hours, but it means that it will top the batteries up or indeed fully charge the batteries if driving long distances. More importantly the B2B will regulate and accept the wide range of input voltages produced by the Smart Alternator whilst regulating the charge current and voltage to the batteries.

Most B2B units offer a charge rate of over 40 amp hours, which means that the lithium batteries can be charged extremely quickly via the alternator. However, the downside to this is that the electrical rating of your M/H is probably not able to cope with 40 amp hours going through it, so wiring will be required and that can become expensive when fitting a B2B unit. A solution would be a low charge opt our B2B unit of, say, 25 amp hours.

Most lithium batteries on the market can accept charges of over 50 amp hours and if you had 2x 100 amp hour batteries you could virtually charge these from flat in approximately 4 hours of driving.

If you then decide you wish to use some of the extra power that you have got and convert it into 240v you will need an inverter. Neither Richard or I have given this much consideration as we don’t intend to go down this route so you will need to do you own research but beware this can be a very complex issue.

Prices vary hugely on lithium batteries and I think it is fair to say that the most important part of the lithium battery is the Battery Management System (BMS). The lithium batteries are supplied with a Battery Management System that can monitor and optimize each single cell during charge and discharge, to protect the battery pack from damage against temperature constraints, under voltage, over-charge, over-discharge, short circuit.

The BMS helps to ensure safe and accurate running and will put the battery into sleep mode and will switch it off completely if the battery is being abused. I have referenced some battery suppliers below, of which I believe their batteries to be of good quality and having a decent BMS fitted; –

https://ecotreelithium.co.uk/ https://www.transporterenergy.co.uk/

For the above speak to Rob at Oaktree Motorhomes, who not only owns Oaktree Motorhomes but also owns the rights to import the above batteries, on 01159 303140.

https://www.qualitysource.co.uk/pages/about-us

For the above speak to Rowland on 02039 849289.

Some batteries have a Bluetooth system in-built, that I originally thought was a bit of a gimmick but upon further consideration makes perfect sense. The Bluetooth system will connect to your phone and give you details on status, current draw, charge, how long the batteries will last for assuming the current draw and the battery condition etc. Alternatively, there are several add-on systems, such as the

Victron Energy Smart Monitor unit, where you can attach that to the batteries, and this gives you the Bluetooth functionality.

The reason I have changed my mind about the Bluetooth system is the M/H or caravan display panel will show the battery condition/charge status and if the batteries are on charge (via the EHU) or are under load i.e. you are drawing power. This is fine for the AGM/Gel batteries as when the batteries are being discharged the voltage remaining will drop from 12.7v and on my M/H there is a range of lights showing charge from 12.7v down to 11v so you can effectively track the batteries being discharged.

Lithium batteries will not show a periodic (as above) drop in charge as they constantly put out 12.7v until they are flat so there is no way to know the charge status of the batteries from the display! As such the Bluetooth system would tell me if I was at 100% charge or less purely be picking up my phone

– as said earlier it will also tell me the time left until fully discharged so I will know approx. when I will run out of power.

Richard and I would especially like to thank Ross from Apuljack for his time, patience, knowledge and willingness to help. We would also like to thank Ron from Oaktree Motorhomes who not only offers a full fitting service but also is the UK importer for Eco Tree and Transporter batteries. Finally, thanks go to Rowland from Quality Source (QS Batteries) who has a great understanding and willingness to help.

So, there you have it, my and Richards take on Lithium batteries – am I buying some? Yes, and I am having the Apuljack modification to my EBL.

Is Richard buying some? Yes…once he can find a way to remove his front seats or come out of lockdown and have them fitted?