12V to charge 24V system
12V to charge 24V system
(OP)
Hey guys, I'm new here so please bare with me.
I have a vendor trying to supply us with a vehicle using a dual battery system and charging at 24v. The entire vehicle including starting, operation and auxiliary is 12v.
First of all, I would like to tell problem that I faced on my project. We were install 24V Lithium Battery(Victron Battery) in our car (12V,90A Alternator) and this battery directly connected to the starter battery (Victron AGM Battery).The starter battery were connected to 12-24V converter to charge this 24V Lithium battery. The connection is simple, from the car alternator -> starter battery -> 12V-24V converter -> 24V Lithium Battery.
However, what we facing today is the car battery burn and puffed-up. Maybe car battery cannot support to charge 24V battery even we use 12V-24V converter due to 12V battery is half power compare to 24V battery or different type of battery using for this system (starter battery used AGM battery to charge Lithium battery) I also not really sure.
Can I have your advice to settle down this problem
Any information will be appreciated.
I have a vendor trying to supply us with a vehicle using a dual battery system and charging at 24v. The entire vehicle including starting, operation and auxiliary is 12v.
First of all, I would like to tell problem that I faced on my project. We were install 24V Lithium Battery(Victron Battery) in our car (12V,90A Alternator) and this battery directly connected to the starter battery (Victron AGM Battery).The starter battery were connected to 12-24V converter to charge this 24V Lithium battery. The connection is simple, from the car alternator -> starter battery -> 12V-24V converter -> 24V Lithium Battery.
However, what we facing today is the car battery burn and puffed-up. Maybe car battery cannot support to charge 24V battery even we use 12V-24V converter due to 12V battery is half power compare to 24V battery or different type of battery using for this system (starter battery used AGM battery to charge Lithium battery) I also not really sure.
Can I have your advice to settle down this problem
Any information will be appreciated.





RE: 12V to charge 24V system
Is your 12V battery grounded to the chassis, or is it installed in series with the DC-DC converter?
You might check voltages across the 12V battery, DC-DC, 24V, etc during operation to see what is really happening during operation and charging.
I would take a lot of care with this, the next time you could lose more than a battery. Risks include battery explosion, chemical burns, fire, hazmat fire (prolly already had that), cooking your wire harness and car electrics(12V system sees 24V).
RE: 12V to charge 24V system
RE: 12V to charge 24V system
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RE: 12V to charge 24V system
Im sorry cant attached the schematic but the connection is from the car alternator -> 12V car battery -> 12/24V DC-DC Converter -> 24V Lithium Battery. All the connection is in parallel.
Voltage across 12V battery is about 13.4V, which mean the 24V battery not backflow to the 12V battery. However, the odd is the input ampere for car battery is much lower that the output. The output ampere of car battery higher about 10A from it input. If this case protracted for more than 2 hours,can it harm the car battery?
Battery cannot last longer, from my experience only stand for less than 3 hours then the car battery will puffed-up.
Sorry im new in this forum, dont know how to include your comment in my reply.
RE: 12V to charge 24V system
RE: 12V to charge 24V system
You are likely abusing this battery well outside of it's design envelope for charging/discharging.
RE: 12V to charge 24V system
The voltage seems like a lead-acid chemistry.
I have never seen a liquid lead acid battery puff up. If it is a gel-cell then those do not withstand over charging and should not be attached to an alternator. I doubt the lithium cell and voltage booster make any difference.
From https://www.batterystuff.com/kb/articles/battery-a..."
" If you are using an alternator to recharge a true Gel Cell a special regulator must be installed."
RE: 12V to charge 24V system
Lead acid and AGM both of this battery were puffed up.
RE: 12V to charge 24V system
Without a schematic, which was requested earlier, it sounds like the alternator, the 12V battery, and the DC/DC converter input are all connected together. When the car is running, the alternator is driving the DC/DC converter, which probably a really bad idea. It's likely that there's some interaction resulting in excessively high voltages being applied to the 12V battery.
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RE: 12V to charge 24V system
RE: 12V to charge 24V system
RE: 12V to charge 24V system
RE: 12V to charge 24V system
My understanding with lithium batteries is that excessive current results in the lithium actually plating the anode, eventually resulting in a short circuit condition between electrodes, breakdown of the cathode, and spikes in pressure and temperature.