Parallel batteries

[Duncan2580]

I am in the process of buying a 305 w solar panel kit. As the lithium batteries are coming down in price I am interested in buying one. My battery is situated under the drivers seat and my question is as I would like the other lead battery moved to the under the passenger seat.
Is this safe to connect the lithium to the lead battery.
Thanks in advance

 

[oldiesontour]

No ,

 

[LithiumConvert]

Is this safe to connect the lithium to the lead battery.

Safe, Maybe. In that it will not go bang. They are both nominally 12 volt.

But you then have a major problem because the different technologies require different charging parameters.

Whatever you do for one will be wrong for the other. So, definately, not a good idea.

Your alternator will not like the presence of the lithium battery.

 

[Jev88]

I always read here on Fun that mixing batteries is a bad idea and they can see why and agree.... However, there are a few popular blogs that show an advantage of combining a lead and lipo battery......but it is beyond my expertise to advise further.

 

[LithiumConvert]

Do not confuse LiPo with the much safer LiFePO4 batteries.

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[Jim]

I am in the process of buying a 305 w solar panel kit. As the lithium batteries are coming down in price I am interested in buying one. My battery is situated under the drivers seat and my question is as I would like the other lead battery moved to the under the passenger seat.
Is this safe to connect the lithium to the lead battery.
Thanks in advance

You'll have much more useable capacity from the lithium than you get now and you might find it is more than enough and won't need two batteries. So you might be better swapping your lead acid for new lithium.

When it comes to fitting, I don't kid myself, I just don't know enough to do it myself, so I find someone who does. If you decide to get one, I'd suggest you do the same.

If you would rather fit it yourself, and plenty do, there are lots of people here who know what they are doing, just ask for help and you'll get it, but they would need to know everything about your van such as the make, model, your alternator, electroblock, or present charger etc before they can help. But they'll help you identify that too.

Lithium batteries really are a game changer, you have the weight saving, extra useable power and they are quick to recharge, and as you say, the prices are coming down.

 

[Jim]

However, there are a few popular blogs that show an advantage of combining a lead and lipo battery

I've read a few of those and the only advantage I can see is for people, who have a good understanding of all things electricity and want to make use of good lead acid batteries they already own. Which is of course fair enough.

However I don't buy the other arguments for this kind of setup. In a boat, with a big array maybe, but not in a van. If money isn't an issue, I'd be giving the lead acid away and replacing it with lithium, rather then messing about with two types of battery.

 

[bigtwin]

To fit lead acid batteries, there are certain key factors that you have to address.

Similarly, to fit LiFePO4 batteries there are certain key factors that you have to address.

Again, to fit a lead acid/LiFePO4 hybrid arrangement there are certain key factors that you have to address.

In each scenario, all of the issues can be addressed with the right knowledge and parts.

To answer your question, provided that you have the knowledge to address the pertinent issues, yes, it is safe to connect a LiFePO4 and lead acid battery in parallel.

However, as with all things electrical, you shouldn’t consider undertaking any modifications to your setup unless you understand what you are doing.

Ian

 

[MichaelT]

Just buy an underseat lithium to replace the lead one

 

[LithiumConvert]

Unfortunately it isn't a case of "Just buy an underseat lithium to replace the lead one".

Plenty of information on here about what else you need to do.

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[MichaelT]

Unfortunately it isn't a case of "Just buy an underseat lithium to replace the lead one".

Plenty of information on here about what else you need to do.

Thats all I did but I dont have a smart alternator.

 

[LithiumConvert]

Thats all I did but I dont have a smart alternator.

Plenty of information on here on why not to do that without a B2B.

Nothing to do with how smart the alternator is.

 

[MichaelT]

Plenty of information on here on why not to do that without a B2B.

Nothing to do with how smart the alternator is.

Yep but I've saved loads and it all works so plenty of reasons not to have B2B but I am fitting one to new van.

 

[LithiumConvert]

plenty of reasons not to have B2B but I am fitting one to new van.

Not a very convincing point of view.

But good to hear you are doing it right on the new van.

 

[Duncan2580]

Safe, Maybe. In that it will not go bang. They are both nominally 12 volt.

But you then have a major problem because the different technologies require different charging parameters.

Whatever you do for one will be wrong for the other. So, definately, not a good idea.

Your alternator will not like the presence of the lithium battery.

Can I ask why it the alternator wont like the lithium battery and thanks for your previous answer

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[Duncan2580]

To fit lead acid batteries, there are certain key factors that you have to address.

Similarly, to fit LiFePO4 batteries there are certain key factors that you have to address.

Again, to fit a lead acid/LiFePO4 hybrid arrangement there are certain key factors that you have to address.

In each scenario, all of the issues can be addressed with the right knowledge and parts.

To answer your question, provided that you have the knowledge to address the pertinent issues, yes, it is safe to connect a LiFePO4 and lead acid battery in parallel.

However, as with all things electrical, you shouldn’t consider undertaking any modifications to your setup unless you understand what you are doing.

Ian

thank you

 

[Duncan2580]

Just buy an underseat lithium to replace the lead one

thanks , thats what i will do but there seems to be more to it than just swope them over

 

[bigtwin]

Can I ask why it the alternator wont like the lithium battery and thanks for your previous answer

To whom is your question aimed?

Ian

 

[Raul]

Can I ask why it the alternator wont like the lithium battery and thanks for your previous answer

A lithium battery can over heat or burn a alternator, because is like a sponge and can accept a very big charge, sometimes more than the alternator can provide on idle. Thats the worst time.
Also, alternator is set/ tuned to charge a traditional Lead battery, meaning high voltage for hrs on end. Lithium does not need or like high voltage for prolonged time.
Hence a gadget to regulate the charge from alternator to lithium is needed. We call that a B2B, battery to battery charger or a Dc-DC converter/charger.
Smart alternator on the other hand is more problematic to charge ANY leisure battery, because its controlled by ECU and will only charge when the starter battery needs it. Fitting a B2B on a smart alternator is a Must even if you charge a Lead or lithium. The B2B will force the smart alternator to charge when you want it/need it to, regardless of the ECU requirements.

 

[Duncan2580]

To whom is your question aimed?

Ian

Lithium convert

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[Duncan2580]

A lithium battery can over heat or burn a alternator, because is like a sponge and can accept a very big charge, sometimes more than the alternator can provide on idle. Thats the worst time.
Also, alternator is set/ tuned to charge a traditional Lead battery, meaning high voltage for hrs on end. Lithium does not need or like high voltage for prolonged time.
Hence a gadget to regulate the charge from alternator to lithium is needed. We call that a B2B, battery to battery charger or a Dc-DC converter/charger.
Smart alternator on the other hand is more problematic to charge ANY leisure battery, because its controlled by ECU and will only charge when the starter battery needs it. Fitting a B2B on a smart alternator is a Must even if you charge a Lead or lithium. The B2B will force the smart alternator to charge when you want it/need it to, regardless of the ECU requirements.

Thanks

 

[RedFrame]

I am in the process of buying a 305 w solar panel kit. As the lithium batteries are coming down in price I am interested in buying one. My battery is situated under the drivers seat and my question is as I would like the other lead battery moved to the under the passenger seat.
Is this safe to connect the lithium to the lead battery.
Thanks in advance

I'm only in Chester, if you want me to pop over to talk through anything.

I wouldn't be advising going down the mixing route though.

Cheers
Red.

 

[Duncan2580]

I'm only in Chester, if you want me to pop over to talk through anything.

I wouldn't be advising going down the mixing route though.

Cheers
Red.

Thanks Red I will be in touch when the solar panel is fitted. I have a 2003 bessacarr 445 which I have have recently bought.

 

[Jim]

No. You are both in the sin bin for your contributions to this thread.

Please read the rules about the ignore system. If you mention the system again, you will have the facility removed and will not in future be able to ignore any person, thread or forum.

One you have ignored someone, pease don't be childish in your use of the system. Unignoring, making comments and then re-ignoring, is against the rules and will result in you losing your ability to ignore anything. Thanks