I'm spending more time than I ever imagined getting a DC-DC converter to work. I bought a good one too - Meanwell 200 watt converter. Remy - I don't follow your logic in requiring having a fancy L-A battery charger. Car alternators have been doing an acceptable job for years, and they are constant voltage chargers at or near 13.6 V or so. The newer solid state regulators might trim that voltage based on ambient temperature as a proxy for the battery temperature, IDK. And beyond that, we aren't using them to crank a starter for an ICE. An even better solution would be to toss the 12 volt battery and use a supercapacitor. But my Miata's 12 volt system has very low power requirements.
Looking for advice on DC-DC converters
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The logic is quite simple. If you want to extend the battery life, you have to charge it correctly. Here is a document from one of the major battery manufacturers describing their recommendations:
Trojan Battery | Home
Since 1925 Trojan Battery Company been a leading manufacturer of deep-cycle flooded, AGM, and gel batteries as well as our new lithium-ion battery.
www.trojanbattery.com
The other thing is, when people talk about 12V DC-DC converters, they mean literally that - converters that put out 12.7V or so, which is the equivalent of a fully-charged Lead-Acid battery at rest. That is not the voltage that such battery should be charged at, and will lead to short life expectancy. Alternators as you pointed out have a higher voltage, which corresponds to the bulk stage of the Lead-Acid charging. It is just another compromise to simplify the system design, and will also shorten the life of the battery though not as much as keeping it on 12.7V.
There are multiple avenues to work around this, especially if like you said your 12V power demand isn't great. For one, you can consider an LFP retrofit battery which will be quite happy on 12.7V.
Correct me if I am wrong, but I thought trojan does not make car batteries... only for big rigs and energy storage/deep cycle batteries.The logic is quite simple. If you want to extend the battery life, you have to charge it correctly. Here is a document from one of the major battery manufacturers describing their recommendations:
Trojan Battery | Home
Since 1925 Trojan Battery Company been a leading manufacturer of deep-cycle flooded, AGM, and gel batteries as well as our new lithium-ion battery.
The other thing is, when people talk about 12V DC-DC converters, they mean literally that - converters that put out 12.7V or so, which is the equivalent of a fully-charged Lead-Acid battery at rest. That is not the voltage that such battery should be charged at, and will lead to short life expectancy. Alternators as you pointed out have a higher voltage, which corresponds to the bulk stage of the Lead-Acid charging. It is just another compromise to simplify the system design, and will also shorten the life of the battery though not as much as keeping it on 12.7V.
There are multiple avenues to work around this, especially if like you said your 12V power demand isn't great. For one, you can consider an LFP retrofit battery which will be quite happy on 12.7V.
As far as I know, the only difference between automotive starter batteries and deep cycle batteries is the plate thickness. They use the same chemistry and suffer from the same issues. Now still the thing that is unclear to me is why do you consider a specialized automotive battery that is designed to provide large amount of current for a short amount of time a "regular 12v", and why would you consider using one in an EV. Not only starter batteries don't like being deeply discharged, but also they're significantly oversized in relation to the accessories that they run in terms of discharge current. For an EV it would make more sense to use a much smaller battery similar to those found in UPS systems.
Either way, like I already said earlier it would make a lot more sense to use something like this:
Valence U27-12XP Lithium Ion Battery Module | Greentec Auto
60Ah Li-ion 12V battery accepts high rates of charge and captures several times more energy from regenerative braking for improved fuel economy and reduced emissions
www.greentecauto.com
This was posted in our Classifieds here.
This is getting pretty stupid. I’m not going to answer anymore since all I wanted to do was help the guy that needed help with their DC to DC converter.As far as I know, the only difference between automotive starter batteries and deep cycle batteries is the plate thickness. They use the same chemistry and suffer from the same issues. Now still the thing that is unclear to me is why do you consider a specialized automotive battery that is designed to provide large amount of current for a short amount of time a "regular 12v", and why would you consider using one in an EV. Not only starter batteries don't like being deeply discharged, but also they're significantly oversized in relation to the accessories that they run in terms of discharge current. For an EV it would make more sense to use a much smaller battery similar to those found in UPS systems.
Either way, like I already said earlier it would make a lot more sense to use something like this:
Valence U27-12XP Lithium Ion Battery Module | Greentec Auto
60Ah Li-ion 12V battery accepts high rates of charge and captures several times more energy from regenerative braking for improved fuel economy and reduced emissions
This was posted in our Classifieds here.
But here, the keyword warriors are more interested in being right and trying to point out insignificant things instead of helping the guy that originally open the thread.
all I am interested here is a reply from Remy on how to do it right. Not arguing about batteries.
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