[wstein25]

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.

 

[cricketo]

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.

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:

https://www.trojanbattery.com/pdf/U.S.%20Battery%20Charge%20Profile%20Full%20%2011-12-13.pdf

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.

 

[remy_martian]

Meanwell is not for automotive use...

 

[EV-Caveman]

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:

https://www.trojanbattery.com/pdf/U.S.%20Battery%20Charge%20Profile%20Full%20%2011-12-13.pdf

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.

 

[EV-Caveman]

Meanwell is not for automotive use...

So, how do you propose he connects everything, and what are the parts he needs to buy in order to get this done? could you post some links on products and how to connect them properly?

 

[cricketo]

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.

I don't know if Trojan makes starter batteries, but the question becomes why would you use a starter battery to power accessories in an EV ?

 

[EV-Caveman]

I don't know if Trojan makes starter batteries, but the question becomes why would you use a starter battery to power accessories in an EV ?

Cause we are taking about a regular 12v not a deep cycle. But hey I might have had this all wrong.

 

[cricketo]

Cause we are taking about a regular 12v not a deep cycle. But hey I might have had this all wrong.

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.

 

[EV-Caveman]

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.
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.

 

[wstein25]

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.
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.

Here’s a possibility: I used to drive a Gen1 Honda Insight Hybrid. That car dispensed with a traditional alternator, and used a tailor made DC-DC converter to keep a very small automotive battery charged. I don’t remember all the specifics, but a brief search at the Insight forum will turn up gobs of information on them. I wish I had remembered this for my project, although I don’t know how difficult they are to find now.

 

[remy_martian]

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.
But here, the keyword warriors are more interested in being right and trying to point out insignificant things....

all I am interested here is a reply from Remy on how to do it right.

Toasting your 12V battery early may be insignificant to you, but not to others.

There's enough info here now for someone to considsr the tradeoffs seek out what they're after.

You don't care about battery longevity so you are dismissive.

Some people don't care about environmental issues (Californians) or replacing a Chinesium power supply at the side of the road now and then.

I am not going to waste my time looking for 48V stuff for someone's build when most systems are at 360V now and they and you are just as equipped to screen out the specifics to a build. There's enough info in this thread for them to decide what to use.

Some people also need tens of watts, some need hundreds, some even need kW, at 12V nominal. Many have oddball system voltages.

Good luck jump starting another car if you're running 12.0V, by the way...instant load dump into your system when the dead battery car starts. Few think twice about jump starting. This goes the other way as well when you have the dead battery. Most dc-dc converters will fail catastrophically if backdriven.

These builds are bespoke for a reason. Including a low volume "manufactured" car. You were happy with using a DC to DC from a 3D printer or computer (or whatever), including making recommendations based on what you may have built for other people, until the issue of battery killing came up.

Buy your $29 Alibaba dc to dc, and deal with the chance of being roadkill when it fails on a busy highway. Or keep buying batteries twice or three times as often. Or see instant fail during a jump start or hookup to a 12V external battery charger.

These are all the builder's call.

 

[EV-Caveman]

Toasting your 12V battery early may be insignificant to you, but not to others.

There's enough info here now for someone to considsr the tradeoffs seek out what they're after.

You don't care about battery longevity so you are dismissive.

Some people don't care about environmental issues (Californians) or replacing a Chinesium power supply at the side of the road now and then.

I am not going to waste my time looking for 48V stuff for someone's build when most systems are at 360V now and they and you are just as equipped to screen out the specifics to a build. There's enough info in this thread for them to decide what to use.

Some people also need tens of watts, some need hundreds, some even need kW, at 12V nominal. Many have oddball system voltages.

Good luck jump starting another car if you're running 12.0V, by the way...instant load dump into your system when the dead battery car starts. Few think twice about jump starting. This goes the other way as well when you have the dead battery. Most dc-dc converters will fail catastrophically if backdriven.

These builds are bespoke for a reason. Including a low volume "manufactured" car. You were happy with using a DC to DC from a 3D printer or computer (or whatever), including making recommendations based on what you may have built for other people, until the issue of battery killing came up.

Buy your $29 Alibaba dc to dc, and deal with the chance of being roadkill when it fails on a busy highway. Or keep buying batteries twice or three times as often. Or see instant fail during a jump start or hookup to a 12V external battery charger.

These are all the builder's call.

Thanks for proving my point!
I am only here to learn and help others.

Toasting your 12V battery early may be insignificant to you, but not to others.

There's enough info here now for someone to consider the tradeoffs seek out what they're after.

You don't care about battery longevity so you are dismissive.

Some people don't care about environmental issues (Californians) or replacing a Chinesium power supply at the side of the road now and then.

I am not going to waste my time looking for 48V stuff for someone's build when most systems are at 360V now and they and you are just as equipped to screen out the specifics to a build. There's enough info in this thread for them to decide what to use.

Some people also need tens of watts, some need hundreds, some even need kW, at 12V nominal. Many have oddball system voltages.

Good luck jump starting another car if you're running 12.0V, by the way...instant load dump into your system when the dead battery car starts. Few think twice about jump starting. This goes the other way as well when you have the dead battery. Most dc-dc converters will fail catastrophically if backdriven.

These builds are bespoke for a reason. Including a low volume "manufactured" car. You were happy with using a DC to DC from a 3D printer or computer (or whatever), including making recommendations based on what you may have built for other people, until the issue of battery killing came up.

Buy your $29 Alibaba dc to dc, and deal with the chance of being roadkill when it fails on a busy highway. Or keep buying batteries twice or three times as often. Or see instant fail during a jump start or hookup to a 12V external battery charger.

These are all the builder's call.

Thanks for proving my point!
You said hooking up all theses is no trouble "box A to box B", and "takes no time", but now you say you will not spend your time showing the guy the opened the post how to do it right (and all you had to do is post a link, can't imagine if you had to actually do the work).

I am only here to learn and to help others with what I learned, unlike you.

 

[remy_martian]

I never said Box A to Box B

I said a choice of Box A or Box B where one meets your requirements, the other doesn't.

Yeah - I haven't helped anybody here on my own time. 🤦‍♂️

My time. My breaks & diversions. Discretionary. You don't get to demand it.

 

[ESyncro]

Why does the dc to dc converter kill 12v lead acid batteries? Because it doesn’t pamper the battery with specific stages? After almost a year after finishing my ev conversion I do now monitor the og starting battery and it is often low and requires a trickle charge every now and then. Is it inevitable that I will go through the 12v batteries more often than when it was an ice vehicle?

 

[remy_martian]

If you're not using a correctly designed DC-DC converter that has lead acid charge profiles, yes.

12V will run your accessories, but the battery will commit suicide on that diet.

 

[ESyncro]

If you're not using a correctly designed DC-DC converter that has lead acid charge profiles, yes.

12V will run your accessories, but the battery will commit suicide on that diet.
[/QUOTE

If you're not using a correctly designed DC-DC converter that has lead acid charge profiles, yes.

12V will run your accessories, but the battery will commit suicide on that diet.

ok thanks. I have an elcon dctodc. I assume it is correctly designed.

 

[MattsAwesomeStuff]

Lead-Acid battery charger has multiple stages in the charge cycle with different voltages to maximize the life of the battery.

I've never heard of this before.

Any battery charger I've ever seen is just a blind power supply. The battery gobbles up power however it can, and that's all there is to it.

Battery specs I've seen have the float level anywhere from 14.4v to 14.9v (alarm batteries, etc).

I've never even heard of a charge profile on lead-acids to optimize... anything.

Source on this? I'm curious to read more.

As far as I know, the only difference between automotive starter batteries and deep cycle batteries is the plate thickness.

Deep cycle batteries will also typically have an extra inch of empty space at the bottom of the container. This is for all the lead that sloughs off through the life of the battery. That way it can sit there and not short out the remaining plate structures. Starter batteries don't have much extra room, so when they start falling apart, they quickly die out.

 

[cricketo]

I've never heard of this before.

Any battery charger I've ever seen is just a blind power supply. The battery gobbles up power however it can, and that's all there is to it.

Battery specs I've seen have the float level anywhere from 14.4v to 14.9v (alarm batteries, etc).

I've never even heard of a charge profile on lead-acids to optimize... anything.

Source on this? I'm curious to read more.

Seriously ? Well, you can start here then: https://support.delta-q.com/hc/en-u...m-Charge-Profile-Should-I-Use-for-My-Battery-

 

[piotrsko]

Where did you think the terms bulk, adsorption and the like came from more than 50 years before lithium ion got invented?

PROPERLY charging a FLA cell is pretty much like charging lipo4 only not as dangerous with respect to voltages and more tolerant of some charging schemes like constant votlage. However: too much current during bulk and it will mimic a lipo with the addition of acidic spray. After a hundred or so years FLA has worked out most of the hazards. Probably the same for lithium in a hundred years.

 

[Electric Land Cruiser]

LEAF DC-DC starts at 14.7 then tapers down to 14.4 then 14.2 for the rest of the journey/charging session.