Author Topic: Charging a lithium battery from lead acid system  (Read 1894 times)

elias

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Charging a lithium battery from lead acid system
« on: August 30 2022, 08:38 »
Hi ,
I am thinking to install an 100ah 12v lithium battery for some extra loads I am planning to install. My question is if i can charge it through my current system ( alternator and solar ) . Is there such a b2b charger for lithium batteries from lead acid banks ?

Yngmar

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Re: Charging a lithium battery from lead acid system
« Reply #1 on: August 30 2022, 09:36 »
Yes, and it's called a B2B charger! :)
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elias

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Re: Charging a lithium battery from lead acid system
« Reply #2 on: August 30 2022, 15:28 »
I have one onboard already cause I have by law a dedicated battery and charger for the vhf battery , but will be that charger ok ? Lithium battery should require specific charge process that’s lead acid no?

Yngmar

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Re: Charging a lithium battery from lead acid system
« Reply #3 on: August 30 2022, 16:20 »
You'll have to look at the manual or tell us which one you've got - the crystal ball is cloudy today  ;D

There are definitely B2B chargers suitable for charging LiFePo batteries, Victron Orion series for example and probably many others.
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elias

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Re: Charging a lithium battery from lead acid system
« Reply #4 on: August 30 2022, 16:30 »
You are right , is an DBC1212 https://shelectro.gr/language/en/dc-dc-dual-battery-changers-and-chargers/ no manual unfortunately , it says specifically for lead acid , so I guess is a no

tiger79

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Re: Charging a lithium battery from lead acid system
« Reply #5 on: August 30 2022, 17:53 »
If you buy a 100Ah battery with integral BMS (eg Victron SuperPack), you can charge it basically in the same way that a lead-acid battery is charged.  So you could keep the DBC1212.

Alternatively, you could charge it from the house batteries using a low-loss isolator (eg Victron Argofet).

elias

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Re: Charging a lithium battery from lead acid system
« Reply #6 on: August 31 2022, 06:34 »
So a key factor is to buy a battery with built in BMS so it can self regulate the charging process ?

tiger79

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Re: Charging a lithium battery from lead acid system
« Reply #7 on: August 31 2022, 09:59 »
So a key factor is to buy a battery with built in BMS so it can self regulate the charging process ?

I believe so.  Otherwise, you need to use an external BMS to manage the battery.  Ones with built-in BMS are often described as "drop in" replacements for lead-acid.

Yngmar

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Re: Charging a lithium battery from lead acid system
« Reply #8 on: August 31 2022, 10:05 »
That's probably a smarter idea, as they've got integrated BMS and charging and are easier to use. Cost a bit more, but then you don't need to buy a new B2B charger and come out around the same cost.
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AndyS

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Re: Charging a lithium battery from lead acid system
« Reply #9 on: September 07 2022, 15:44 »
I have been looking at swapping to Lithium batteries for a while, but even with the "drop-in" replacement versions it looks like there are various other modifications needed...on my 2008 boat it would be a minimum of changing the charger and modifying/replacing the alternator to cope with the higher charge voltage and current demand of the Lithium batteries.  Or alternatively using a battery-to-battery charger but losing some charging capability and efficiency.

Just noticed that Ryan of "Ryan & Sophie Sailing" have just made an update video on this.  For me it helped cut through a lot of the conflicting information that is also around. 

The bit on drop-in replacements is at 9:23 in the attached video.

https://youtu.be/vraRhNpEWcE