diy solar

diy solar

Using a Solar Charged LFP to Charge a SUV Lead acid Starter Battery?

A

Ang429

New Member
Joined
Nov 16, 2023
Messages
35
Location
Earth
Hi so im looking to Put a 200W Solar Panel on the Roof of my SUV, And I want this Solar panel to go into an LFP battery, Which that's not a problem. My problem is that I want the LFP to output into a Charger that can maintain the Lead Acid starter battery 24/7, As that battery starts the car, Runs Flood Lights and Hazard lights, e.t.c.

Originally I was going to do solar straight to the starter, But then I realized I would have no Extra power at night. Ive looked at the Renogy DC to DC, Victron has one but it says 12v in 20v out so it seems useless, And while I believe the Renogy would work fine even though its made to take power from the leadacid/alternator and put it into a secondary LFP, some people didn't recommend it since it wasn't really advertised to be made for that.

i found Power Queen Selling this On Board Charger made to Charge Lead Acid, And again their chart shows charging the LFp using both the Starter Battery/Alternator And Solar, But there's a review of someone just using solar (which in my case would be the LFP) to charge a Lead acid battery on its own, So I don't see why I couldn't use the LFP to charge the lead acid, But I'm just wondering everyone's thoughts or if there's a product I'm missing?

Another thing, Is someone recommended getting a Hood Mounted Solar panel, So now I'm interested inalso getting a Hood Mounted solar panel That will be Charging the Lead Acid battery during the day, I guess through another one of the power queen on board chargers, But This means that during the day I don't want the Lead acid to be pulling power from the LFP, I want the LFP to be able to charge up fully, So how can I make it so that during the day the Lead Acid charges from the hood solar rather than the LFP?
 
Tecmate makes a 2A DC-DC battery charger/maintainer: https://www.amazon.com/dp/B08CHCBZN3/

It's a bit pricey, but this isn't a common use case. Most people would wire their lighting to the deep-cycle leisure battery. Starter batteries aren't going to last very long if you're regularly discharging/recharging them. I assume you have reasons.
 
RudyGreene said:
Tecmate makes a 2A DC-DC battery charger/maintainer: https://www.amazon.com/dp/B08CHCBZN3/

It's a bit pricey, but this isn't a common use case. Most people would wire their lighting to the deep-cycle leisure battery. Starter batteries aren't going to last very long if you're regularly discharging/recharging them. I assume you have reasons.
Click to expand...
Being an SUV, I'm not living in it. I just want the ability to have flood or hazard lights running without the worry that the battery would die in an hour and I'd have to jump it. The battery won't really be going up and down much since it would be on this maintainer 24/7, and whenever the engine is running the maintainer should auto stop, and the alternator would maintain the battery instead. Yes this cost $100, but so does the renogy DC to DC, so if this is more made for it then I'm fine with going for this. My only concern is the 2a. The flood or hazard lights alone pull over 2a, so the battery would still eventually drain causing wear from a cycle, or die if left on to long. Do you think the power queen charger i linked won't work?
 
www.ebay.com

VICTRON ENERGY BLUE SMART 12/12V 18A ISOLATED DC/DC BATTERY CHARGER ORION-TR | eBay

Victron Energy Orion-Tr 12/12 18A features It can be optimised for both lead acid and lithium batteries. The Orion is compatible with the smart alternators used in modern vehicles, and can also detect when your engine and alternator are in operation, and adapt charging to suit.
www.ebay.com


This should do what you're after

You need the 'smart' Orion model, suitable for battery charging
 
Ang429 said:
Hi so im looking to Put a 200W Solar Panel on the Roof of my SUV, And I want this Solar panel to go into an LFP battery, Which that's not a problem. My problem is that I want the LFP to output into a Charger that can maintain the Lead Acid starter battery 24/7, As that battery starts the car, Runs Flood Lights and Hazard lights, e.t.c.

Originally I was going to do solar straight to the starter, But then I realized I would have no Extra power at night. Ive looked at the Renogy DC to DC, Victron has one but it says 12v in 20v out so it seems useless, And while I believe the Renogy would work fine even though its made to take power from the leadacid/alternator and put it into a secondary LFP, some people didn't recommend it since it wasn't really advertised to be made for that.

i found Power Queen Selling this On Board Charger made to Charge Lead Acid, And again their chart shows charging the LFp using both the Starter Battery/Alternator And Solar, But there's a review of someone just using solar (which in my case would be the LFP) to charge a Lead acid battery on its own, So I don't see why I couldn't use the LFP to charge the lead acid, But I'm just wondering everyone's thoughts or if there's a product I'm missing?

Another thing, Is someone recommended getting a Hood Mounted Solar panel, So now I'm interested inalso getting a Hood Mounted solar panel That will be Charging the Lead Acid battery during the day, I guess through another one of the power queen on board chargers, But This means that during the day I don't want the Lead acid to be pulling power from the LFP, I want the LFP to be able to charge up fully, So how can I make it so that during the day the Lead Acid charges from the hood solar rather than the LFP?
Click to expand...

You could just get a bigger starter battery, or run two in parallel if you've got space?
 
Ang429 said:
Being an SUV, I'm not living in it. I just want the ability to have flood or hazard lights running without the worry that the battery would die in an hour and I'd have to jump it. The battery won't really be going up and down much since it would be on this maintainer 24/7, and whenever the engine is running the maintainer should auto stop, and the alternator would maintain the battery instead. Yes this cost $100, but so does the renogy DC to DC, so if this is more made for it then I'm fine with going for this. My only concern is the 2a. The flood or hazard lights alone pull over 2a, so the battery would still eventually drain causing wear from a cycle, or die if left on to long. Do you think the power queen charger i linked won't work?
Click to expand...

It seems like every post I have turns into some story I have, sorry part of me being me.

Yea like @SamG340 said, I think you are going to a great deal of work and expense for this small thing.

Now depending on just what "flood" lights are that might change things, but with you saying hazard lights I am thinking the vehicles normal "bright, or high light" Those can take a bit of power. If you are worried about only hazards, get yourself a small 12-ishv battery pack get an inline fuse, and hook it up to that circuit in the vehicle, done, and I would think even a $100 USB type battery would run the hazards all night if need be.

Now if "floods" are "off road" lights, all bets are off. And you are using this vehicle for "camping" or other activity where you want the light up the center of the sun it gets more complex. I would want to know just what is the total draw on those additional lights, and if you had to do an alternator swap to feed those power hungry monsters it is going to get real complex.

If it is a vehicle that sits more then it is driven, two words Battery Tender (the real one) I freely admit I am a big time fanboi, but I have a tractor I bought new 12 years ago and it is still on its original battery. That machine has a tick over 400 hours on it. Battery cranks it like new. Battery tender and the machine sits in an un heated barn with damn raccoons climbing all over the darn thing. (yes I trap) and no I don't kill them, I have become an old softie.

I take them to some federal land and let them go (again yes I know, and I don't care). I will fight that battle on channel 4 if I need to.



1700223038990.png
 
SamG340 said:
www.ebay.com

VICTRON ENERGY BLUE SMART 12/12V 18A ISOLATED DC/DC BATTERY CHARGER ORION-TR | eBay

Victron Energy Orion-Tr 12/12 18A features It can be optimised for both lead acid and lithium batteries. The Orion is compatible with the smart alternators used in modern vehicles, and can also detect when your engine and alternator are in operation, and adapt charging to suit.
www.ebay.com


This should do what you're after

You need the 'smart' Orion model, suitable for battery charging
Click to expand...
I believe this is the Same One as in your Link? Im in the US. Also this will be Under the Hood, So I assume that wont be an issue? it should never get wet. This is showing the Same diagram as every other one of these DC to DC Chargers Where it takes input from the starter and puts it into the auxiliary, But I will be taking from the auxiliary and Putting into the starter, So I need to know that it will auto shut off when the car is started since it will suddenly see the battery at 14V and think that its fully charged. Also the reason that I had Skipped this DC to DC in the past, is because it says right on the device 12V input 20V-30V output. I still think that the Power Queen that I linked my post is the best option because its DC to DC and actually says that it can charge a Lead acid?

 
SamG340 said:
You could just get a bigger starter battery, or run two in parallel if you've got space?
Click to expand...
Theres a limit in Capacity that you can get out of a lead acid, and you will wear it down fast cycling it a lot. And no I cant fit 2 batteries under the hood.
 
fpgt72 said:
It seems like every post I have turns into some story I have, sorry part of me being me.

Yea like @SamG340 said, I think you are going to a great deal of work and expense for this small thing.

Now depending on just what "flood" lights are that might change things, but with you saying hazard lights I am thinking the vehicles normal "bright, or high light" Those can take a bit of power. If you are worried about only hazards, get yourself a small 12-ishv battery pack get an inline fuse, and hook it up to that circuit in the vehicle, done, and I would think even a $100 USB type battery would run the hazards all night if need be.

Now if "floods" are "off road" lights, all bets are off. And you are using this vehicle for "camping" or other activity where you want the light up the center of the sun it gets more complex. I would want to know just what is the total draw on those additional lights, and if you had to do an alternator swap to feed those power hungry monsters it is going to get real complex.

If it is a vehicle that sits more then it is driven, two words Battery Tender (the real one) I freely admit I am a big time fanboi, but I have a tractor I bought new 12 years ago and it is still on its original battery. That machine has a tick over 400 hours on it. Battery cranks it like new. Battery tender and the machine sits in an un heated barn with damn raccoons climbing all over the darn thing. (yes I trap) and no I don't kill them, I have become an old softie.

I take them to some federal land and let them go (again yes I know, and I don't care). I will fight that battle on channel 4 if I need to.
Click to expand...
Flood Lights as in 2x 8" light Bars. They probably pull like 60W When on. Hazard Lights as in 2 Front and 1 Rear Amber Light Bars, Probably also pulling 75W or so. I don't need a new Alternator, Though I may put in a way larger one in the future but that's irrelevant, I just want to Make sure that if the car sat for an hour or more with Amber Lights on, That the battery won't be killed and ruined. Im already trying to figure out why the Voltage of the battery seems to drop very rapidly down to like 11.8V and then sit there When there shouldn't really be any extra draw while the car is off, But that's a separate issue. Not sure what you mean by adding a small 12V battery and hooking it up, Thats not going to do anything, And neither would a 5V USB Battery.
 
Ang429 said:
12V input 20V-30V output
Click to expand...
Sounds like a printing error, sounds like they are talking about the 12v to 24v model.

get the one that says 12v/12v on the case


Ang429 said:
auxiliary, But I will be taking from the auxiliary and Putting into the starter, So I need to know that it will auto shut off when the car is started since it will suddenly see the battery at 14V and think that its fully charged.
Click to expand...

When your 12v starter battery is full the charger will stop charging. In the past this was always done by resistance, but now modern 'smart' chargers do it by technology/computer program


So no it won't turn off when the car turns on, it will stop charging if/when the battery is full
 
Ang429 said:
Im already trying to figure out why the Voltage of the battery seems to drop very rapidly down to like 11.8V and then sit there When there shouldn't really be any extra draw while the car is off,
Click to expand...
Do you mean 11.8v resting, or under load?


If resting, you have either:

A) some phantom draw on the battery (DC rated amp clamp would show this)

Or more likely

B) your starter battery is on its way out


Resting at 11.8v shows battery is at only 20/30% soc

Lead-Acid-Battery-Voltage-Charts-Image-4.jpg
 
SamG340 said:
Sounds like a printing error, sounds like they are talking about the 12v to 24v model.

get the one that says 12v/12v on the case




When your 12v starter battery is full the charger will stop charging. In the past this was always done by resistance, but now modern 'smart' chargers do it by technology/computer program


So no it won't turn off when the car turns on, it will stop charging if/when the battery is full
Click to expand...
The only one that Says 12V/12V is like 2.25X the price because scAmazon And its Not Isolated. If it wont stop charging then Will something be damaged?
 
SamG340 said:
Do you mean 11.8v resting, or under load?


If resting, you have either:

A) some phantom draw on the battery (DC rated amp clamp would show this)

Or more likely

B) your starter battery is on its way out


Resting at 11.8v shows battery is at only 20/30% soc

View attachment 178473
Click to expand...
The Batteries are fine. One is a year old, the other is 3 years old, They test good when full, But both go down in voltage a bit, one more than the other. These are both two of the same car. I just ordered a DC Amp meter so I can see what the car is pulling while its off.
 
Ang429 said:
The only one that Says 12V/12V is like 2.25X the price because scAmazon And its Not Isolated. If it wont stop charging then Will something be damaged?
Click to expand...
No the 'smart' model it won't over charge your battery , it's designed for battery charging ?



I know it's expensive , might be able to find something cheaper in a different brand
 
Ang429 said:
Yeah i found this one at a good price, I was just concerned if it could Damage the Charger or the battery by having The Alternator also charging it.
Click to expand...

That's called running the chargers in parallel, and it should be absolutely fine .






I was wondering, have you considered running the lights directly off your lithium battery , then charging the lithium from the starter battery (when alternator is running) . Basically the other way around to what you're planning

this is way it would normally be done in situation like yours
 
SamG340 said:
I was wondering, have you considered running the lights directly off your lithium battery , then charging the lithium from the starter battery (when alternator is running) . Basically the other way around to what you're planning

this is way it would normally be done in situation like yours
Click to expand...

You lithium battery is much more suitable for 'deep cycle' application like power light bars
 
SamG340 said:
That's called running the chargers in parallel, and it should be absolutely fine .






I was wondering, have you considered running the lights directly off your lithium battery , then charging the lithium from the starter battery (when alternator is running) . Basically the other way around to what you're planning

this is way it would normally be done in situation like yours
Click to expand...
Its way to much wiring to be running through the car into the trunk, using the LFP for Charging means only two wires running under the Floor Through the Firewall to the engine bay Rather than like 20. I also don't want the alternator to charge the LFP at all, its just going to use gas. I just want the LFP to charge off the Solar, And have the LFP maintain the leadacid when the car is off. One more concern I have right now, Is I will have a 35W Solar panel and a 100W solar panel, Both appear to be 17V. i read that Parallel means if one has shade then there will be basically no solar, so should I go for Series Wiring to put them both into the LFP?
 
SamG340 said:
You lithium battery is much more suitable for 'deep cycle' application like power light bars
Click to expand...
I have no plans to Discharge the lead acid with the lights, Its not often that they will even be on with the car off, But the idea is that when they are on, Or if the car sits for a week, The lead acid wont be discharged. I also have Emergency AC Power in the trunk or just power to charge something without having to take a solar generator with me.
 
You must log in or register to reply here.

Similar threads

O
Update from Lead Acid to LFP Batteries
Replies
11
Views
399
robbob2112
robbob2112
P
Using boost converter for charging LiFePO4 from starter battery/alternator
Replies
6
Views
263
Dave911
D
A
How to set up Two Battery Chargers on One Battery?
Replies
2
Views
444
AmpD
A
eXodus
New years resolutions: loosing weight in RV 190AH lead replaced with 100AH LFP. -100lbs 47kg
2 3
Replies
47
Views
2K
Browneye
Browneye
I
Build a variable current limiter for lead-acid battery charging
Replies
5
Views
314
Vigo
V
Back
Top