Can I run a 110amp lithium and 110gel in parallel

[Poutie57]

Just a question for all those 12v gurus out there can I run a parallel battery set up with a 110amp gel and a 110amp lithium battery setup, I’m running full victron kit ie: mppt, Orion dc/dc and IP22. Or is this a definite no no

 

[funflair]

Just a question for all those 12v gurus out there can I run a parallel battery set up with a 110amp gel and a 110amp lithium battery setup, I’m running full victron kit ie: mppt, Orion dc/dc and IP22. Or is this a definite no no

Well you can as that is what the Hymer hybrid system does, others including jongood are also doing it but I am not sure of the pros and cons.

 

[Jimbohorlicks]

I would imagine that if you set the mppt charger to the max of the gel battery then it should be OK and wont overcharge it ,but the lithium would be undercharged.If you did it the other way round you could cook the gel battery.
If you kept the separate and ran a battery mastery from the lithium to the gel that would keep the gel topped up. Depends how you want to use your power and if you could easily swap between sources.
We have a 100 ah lithium as the main leisure battery and separate lead batteries than run the TV or other low power appliances as required. We have a separate 100w solar panel for the lead batteries.and 2x 100 for the lithium.
All seems to work for us.

 

[bigtwin]

With appropriate BMS settings it’s fine; contrary to popular belief, lead acid and LiFePo4 have very complementary characteristics.

There are 100s of narrowboaters running that sort of setup and you may get more specific help by posing a question on the ‘12 volt boating group’ Face Book group. Please note that the ‘volt’ term is singular (there is another group with the same name but where the ‘volt’ is plural.

Ian

 

[bigtwin]

I would imagine that if you set the mppt charger to the max of the gel battery then it should be OK and wont overcharge it ,but the lithium would be undercharged.

Indeed, I think the advice on the ‘12 volt boating group’ on FB is to leave all of the charge source profiles set to a lead acid profile. This does undercharge the LiFePo4 but, unlike LA batteries, LiFePo4 batteries are perfectly happy not to be fully charged. Given the rate at which LiFePo4s recharge, this isn’t really a tangible detriment.

Ian

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[Pausim]

Well you can as that is what the Hymer hybrid system does, others including jongood are also doing it but I am not sure of the pros and cons.

I think the Hymer hybrid system has some clever electronics and is more than just a parallel connection.

 

[jongood]

I run a 200ah lifePo4 in parallel with a 220ah gel. all the settings are left as the original gel setup and it works well. as bigtwin said, you do need a bms setup a little softer. I suspect it will work even better with a b2b but thats a complicated option for me.

 

[Poutie57]

Thanks a lot for all your advice

 

[rupert]

yeah I,m running 150ah lithium with 95ah agm in parallel with 50a b2b connected to engine battery.

the lithium will greedily soak up most of the charge the from the alternator via b2b and when charging stops the lithium will continue to charge the agm until full... well that's how I see it, seems to work without issue

 

[Poutie57]

yeah I,m running 150ah lithium with 95ah agm in parallel with 50a b2b connected to engine battery.

Can I ask what settings do you use on your B2b and mppt…. Gel or lithium

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[Poutie57]

Sorry Agm or lithium

 

[Guigsy]

Won't you just end up with a system that's running from lithium pretty much all the time until it's pretty much dead?

 

[bigtwin]

Won't you just end up with a system that's running from lithium pretty much all the time until it's pretty much dead?

Yes, sort of, the LiFePo4 will carry most of the load but if it needs a little help from the leads they’ll provide the backup.
These characteristics are absolutely ideal in terms of capitalising on the benefits of the LiFePo4 and looking after the leads. The LiFePo4 provides the heavy lifting and recharge quicker than the leads (that require long charge times for the last 20% SoC) and, in the event that the leads require a charge, the LiFePo4s will keep them nice topped up. In terms of your comment ‘until it’s pretty much dead, remember that LiFePo4s will provide you with 1,000s of cycles unlike the few 100s provided by leads. It really is a marriage made in heaven. Pure lead systems will die well before either the leads or the LiFePo4s will in this hybrid arrangement.

Ian

 

[Guigsy]

Yes, sort of, the LiFePo4 will carry most of the load but if it needs a little help from the leads they’ll provide the backup.
These characteristics are absolutely ideal in terms of capitalising on the benefits of the LiFePo4 and looking after the leads. The LiFePo4 provides the heavy lifting and recharge quicker than the leads (that require long charge times for the last 20% SoC) and, in the event that the leads require a charge, the LiFePo4s will keep them nice topped up. In terms of your comment ‘until it’s pretty much dead, remember that LiFePo4s will provide you with 1,000s of cycles unlike the few 100s provided by leads. It really is a marriage made in heaven. Pure lead systems will die well before either the leads or the LiFePo4s will in this hybrid arrangement.

Ian

Or... you're carrying 25kg that you're unlikely to ever use. That's leeching power all the time to keep topped off. And when you do use it, it might have life expired. A bad backup is worse than not having one at all.

 

[bigtwin]

Or... you're carrying 25kg that you're unlikely to ever use. That's leeching power all the time to keep topped off. And when you do use it, it might have life expired. A bad backup is worse than not having one at all.

The self discharge level will be a few mA, nothing to worry about. Because you are rarely discharging the lead and always immediately recharging it (unlike in a pure lead setup) you will not find more ideal conditions for keeping a LA in tip top condition.

Your perceived weakness of this arrangement is more applicable to a normal lead acid bank than it is to a hybrid setup. In a LA bank, how can you readily tell if one battery in the bank is in poor health (you can’t )? How many times will the leads in a pure lead bank not have been immediately recharged (partial states of charge on LAs are one of the things that shortens their life)?

Ian

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[Pausim]

I need a bit more convincing. AGM need a higher voltage charge to keep them in good condition and GEL need a long absorption phase to look after them. The LiFePO4 will provide a maintenance level charge voltage only but not lead acid charging voltages. The Li will suck up the main charge keeping the voltage down around the 13.5V level, at the end of the charge the voltage will rise rapidly to say 14.6V but as soon as it reaches the terminal voltage of the Li profile it will shut back to a maintenance level of about 13.5V. When do the lead acid parts of the hybrid get the absorption phase they need?

 

[jongood]

I need a bit more convincing. AGM need a higher voltage charge to keep them in good condition and GEL need a long absorption phase to look after them. The LiFePO4 will provide a maintenance level charge voltage only but not lead acid charging voltages. The Li will suck up the main charge keeping the voltage down around the 13.5V level, at the end of the charge the voltage will rise rapidly to say 14.6V but as soon as it reaches the terminal voltage of the Li profile it will shut back to a maintenance level of about 13.5V. When do the lead acid parts of the hybrid get the absorption phase they need?

thats one of the points if you're not using a B2B, the lifePo4 will take almost all the charge from the alternator until the BMS shuts off effectively isolating itself while the lead/gel/agm acts as a buffer and more likely kicks the alternator into absorption.

 

[bigtwin]

I need a bit more convincing. AGM need a higher voltage charge to keep them in good condition and GEL need a long absorption phase to look after them. The LiFePO4 will provide a maintenance level charge voltage only but not lead acid charging voltages. The Li will suck up the main charge keeping the voltage down around the 13.5V level, at the end of the charge the voltage will rise rapidly to say 14.6V but as soon as it reaches the terminal voltage of the Li profile it will shut back to a maintenance level of about 13.5V. When do the lead acid parts of the hybrid get the absorption phase they need?

In a hybrid arrangement, you need a configurable BMS with separate ‘control’ and ‘hardware protection’ functions. Once the LiFePo4 battery is charged, the control element of the BMS disconnects the LiFePo4 from the charge source leaving the leads connected to the charge source(s) that remain configured with a lead acid charge profile.

However, in most situations, the leads don’t require any charge as it’s the LiFePo4s that have supplied the loads without any assistance from the leads.

Ian

 

[Pausim]

My BMS doesn’t play any part in controlling charging, it is there to protect the battery from extremes and to do cell balancing if needed. The B2B/mains charger profiles control the charging and will shut back to a maintenance voltage as soon as the Li profile terminal voltage is reached.

 

[Poutie57]

What about if you have 2 B2b’s charging the individual batteries, or is that then complicating things more

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[bigtwin]

My BMS doesn’t play any part in controlling charging, it is there to protect the battery from extremes and to do cell balancing if needed. The B2B/mains charger profiles control the charging and will shut back to a maintenance voltage as soon as the Li profile terminal voltage is reached.

In which case this discussion isn’t really applicable to your setup.

For some reason, folks always major on the protection aspect provided by the Battery MANAGEMENT System. As you’ve recognised with your comment re balancing, it also provides a control/management function.

On the batteries on my boat, prior to leaving the boat for any period of time, I regularly used to isolate (via the BMS) both the charge input to the batteries and the discharge outputs leaving the lead acids to supply any (small) loads and to be charged by the solar.

Ian

 

[bigtwin]

What about if you have 2 B2b’s charging the individual batteries, or is that then complicating things more

Do you have 2 B2Bs and have you already paralleled the two batteries?

Ian

 

[Pausim]

In which case this discussion isn’t really applicable to your setup.

For some reason, folks always major on the protection aspect provided by the Battery MANAGEMENT System. As you’ve recognised with your comment re balancing, it also provides a control/management function.

On the batteries on my boat, prior to leaving the boat for any period of time, I regularly used to isolate (via the BMS) both the charge input to the batteries and the discharge outputs leaving the lead acids to supply any (small) loads and to be charged by the solar.

Ian

How many off the shelf LiFePO4 leisure batteries have a BMS that allows you to control the charging function? When I purchased my battery 5 years ago I don’t recall any of them having a BMS that allowed this. I know there are one or two like Fogstar that now have bluetooth connections.

 

[Poutie57]

No I don’t I was just wondering because the charging profiles are different but I do remember when I brought my lithium people said you could set your main ehu charger to gel profile. I now got a victron charger, mppt and B2b and are currently running with a 110 lithium and don’t to go to the expense of buying another lithium battery

 

[bigtwin]

How many off the shelf LiFePO4 leisure batteries have a BMS that allows you to control the charging function? When I purchased my battery 5 years ago I don’t recall any of them having a BMS that allowed this. I know there are one or two like Fogstar that now have bluetooth connections.

I bought mine from Life Batteries who honour the guarantee when used in a hybrid arrangement; they even ’programme’ the BMS with the settings necessary for operating in a hybrid arrangement. They have supplied hundreds of batteries to narrow-boaters who have adopted this arrangement. Many of those report significant cost savings (in terms of diesel saved during charging) following the adoption of this arrangement.

As I said in my previous response, the discussion isn’t really pertinent to your setup.

Ian

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[bigtwin]

No I don’t I was just wondering because the charging profiles are different but I do remember when I brought my lithium people said you could set your main ehu charger to gel profile.

The reason for using a gel charge profile on a pure LiFePo4 setup is an entirely different issue and is associated with avoiding the additional expense of buying a dedicated LiFePo4 charger.

Ian

 

[Pausim]

As I said in my previous response, the discussion isn’t really pertinent to your setup.

The way you have taken the discussion might not be relevant to my set up but is it relevant to the OPs set up? I don’t know whether Poutie57 has the type of BMS that would allow him to control charging as you would suggest. Perhaps my set up is just as relevant as yours.

 

[bigtwin]

The way you have taken the discussion might not be relevant to my set up but is it relevant to the OPs set up? I don’t know whether Poutie57 has the type of BMS that would allow him to control charging as you would suggest. Perhaps my set up is just as relevant as yours.

The question asked is it possible to mix the two battery types and I’ve responded that it is and what factors are important when doing so. The OP will have to decide whether or not his system is compatible with the requirements that I’ve outlined. You have, and yours isn’t.

Ian

 

[rupert]

Can I ask what settings do you use on your B2b and mppt…. Gel or lithium

hi my settings charging max at 14.4volts both mppt and b2b

 

[Poutie57]

The way you have taken the discussion might not be relevant to my set up but is it relevant to the OPs set up? I don’t know whether Poutie57 has the type of BMS that would allow him to control charging as you would suggest. Perhaps my set up is just as relevant as yours.

Yep your right haven’t got the bms which I can play about not even Bluetooth,