Date: Wed, 14 Jun 2023 22:46:19 +0000Reply-To: Chris Cary <chriscary48@YAHOO.COM>Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>From: Chris Cary <chriscary48@YAHOO.COM>Subject: Lithium batteryContent-Type: text/plain; charset=UTF-8
I just bought a lithium 100 amp hour battery for under the bench seat. Can I use my regular 12 V charger to charge this battery? Or is there any special charger needed? Thank you.
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Most lithium batteries require matched chargers. However, lithium batteries marketed for automotive or RV use frequently are designed to be charged from the vehicle alternator or a regular car battery charger.
All lithium batteries have a BMS - Battery Management System. The BMS protects the individual cells in the battery from over and under voltage, as well as balance the charge level in the individual cells. The common lithium batteries in from consumer electronics to most EV are lithium-cobalt chemistries (with usually some amount of manganese or vanadium). Each such cell has a 3.7V nominal voltage and 4.2V top of charge voltage. Neither 3x nor 4x of these match car battery chargers.
Lithium batteries compatible with 12V car charging systems have 4 cells of Lithium Iron Phosphate chemistry - LiPO4. These have a 3.3V nominal and 3.6V top of charge voltage matching a car battery charging cycle well. They will also have a BMS keeping each cell balanced. Usually they are packaged in the same format factor battery enclosures as car batteries and with the same type of terminals. The BMS may have a much lower max discharge current that a lead acid, so they may not work as starting batteries, but are excellent for low current use in a camper. Some, typically quite expensive ones have high enough current capability to start a vehicle.