Secondary battery (1 Viewer)

[elcajon]

Yet another attempt:

Please share me your thoughts on my plan for charging a portable battery for my fridge.

Currently , I have a Jackery 500 which has proven to be inadequate for more than ONE overnight trip for my fridge.
I want to avoid dual battery set up and just need to charge the Jackery in the back as the OEM 110V is too slow.

Plan: run a 4ga from from main battery in engine bay with solenoid isolator

( 12V 200 Amp Continuous Battery Relay Isolator and Relay High Current Relay for Mobile Audio)​

to the back with a fuse. Connect to

Energy Orion 12/24-Volt 20 amp DC-DC Converters​

Connect fuse and then 8 ga to adapter for Jackery at 24 V

Will also run another 8 ga from main battery to the center console for connection to this

Cllena Dual USB Charger Socket 2.1A&2.1A + LED Voltmeter + 3 Socket Cigarette Lighter Adapter 12V Power Outlet + ON-Off Toggle Switch Multi-Functions Panel for Car Marine Boat Rv Camper Truck (Green)​

what do you think?

 

[tbisaacs]

Here is what I did

Travis's house battery install

First, some background. There are a lot of ways to charge phones and run fridges and lights at camp. I've tried them all over 5 years: First-gen lead acid Goal Zero Yeti + solar KISS-style single battery plus solar PWM controller Lithium Goal Zero Yeti + solar Needless to say — I'm a big fan...

forum.ih8mud.com

 

[elcajon]

Hi Travis.

Thanks for the link. I did read your excellent install. However, I am trying to keep mine as simple as possible without need for inverters, solar nor extra batteries.
I like the portability of the of the ALL IN One units like the Jackeries amongst other…..

I do not base camp with the truck ….. we are in the move often….so using the alternator as the charger is all I need at this time.

 

[TeCKis300]

That should work. I'm assuming your Jackery never gets a fair chance to be fully charged? Rather than it not having enough reserve between drives? If so, plan is sound.

 

[elcajon]

That is correct Travis. The Jackery I s plugged into the 110V outlet at the back but could never get enough and the reserve was constantly on the negative .

 

[daneo]

Sounds good to me. 4awg is pushing into overkill territory, which is fine. Invest in a crimper that can handle that size of wire and use crimped connections and ring terminals for any connections.

Www.Batterycablesusa.com is reasonably priced and makes great quality custom cables. They have other goodies you’ll want for the install, too.

Remember to put your first fuse close to the battery connection. I like the redarc fuse holder. They are expensive, but I haven’t found anything I like better. Cheaper than fire damage.

 

[TomEf]

Sounds good to me. 4awg is pushing into overkill territory, which is fine. Invest in a crimper that can handle that size of wire and use crimped connections and ring terminals for any connections.

Www.Batterycablesusa.com is reasonably priced and makes great quality custom cables. They have other goodies you’ll want for the install, too.

Remember to put your first fuse close to the battery connection. I like the redarc fuse holder. They are expensive, but I haven’t found anything I like better. Cheaper than fire damage.

An appropriate crimper definitely makes this kind of wiring a lot easier. This is the one I got, it’s been fine for 4awg wiring: https://a.co/d/2YEhiKT

 

[rlynch356]

Not sure how the jackary takes a charge, but for battery 2 battery connections I alway use a 2nd fuse or circuit breaker in the rear. (I personally prefer Blue sea Circuit breakers since it makes disconnecting easy for maintenance and such.
ymmv..

 

[elcajon]

Thanks for all your input.

 

[elcajon]

@daneo:

What gauge is appropriate to run from the main battery to the back if 4 is overkill ? Is 8 ok vs 6? Thanks.

 

[sdnative]

For your setup I think 4awg is appropriate, 6 is probably ok, but personally I would use 4.

Keep in mind that the largest that will fit the victron terminal is 6awg.

 

[elcajon]

@sdnative:

I thought it is just the lug that you cramp onto the wire…

 

[sdnative]

@sdnative:

I thought it is just the lug that you cramp onto the wire…

Sorry I was thinking you were using the Orion-Tr, which can accept max of 6awg, but looks like you are using the Orion like this:

Orion DC-DC Converters Non-isolated, High power - Victron Energy

Eliminate the need for a high current switch in the input wiring with the remote on/off connector on the Orion DC-DC Converter. Find a dealer near you.

www.victronenergy.com

If so then yes just get the correct sized lug.

 

[TeCKis300]

4AWG is not necessary, but not a bad idea to future proof and provision for future expansion.

 

[OSS]

I was told by an ole timer alternator shop guy... If I want to use the alternator to charge deeply discharged batteries, bring a spare alternator cuz its going to wear out fast, Which was exactly what was happening to mine.
Alternators aren't designed to charge batteries, they're purpose is to run the car electronics - he said

 

[daneo]

@daneo:

What gauge is appropriate to run from the main battery to the back if 4 is overkill ? Is 8 ok vs 6? Thanks.

Gonna run the numbers here in the spirit of "teach a man to fish", but like others have said, if you want to run 4awg, run 4awg. Especially if you think you'd significantly expand this in the future. What follows will be an engineering-style analysis of what a minimum suggested wire gauge would be for this specific application.

The Jackery 500 DC Input has a 100w maximum according to the product page. Amazon product ASIN B07SM5HBK1
We'll call that 110w to bake in 10% margin.

The Orion 12/24-20 has an efficiency of 93%. If we ask it for 110 watts on the output, if it's only 93% efficient, we're asking it for 118.27... watts on the input. We'll call it 123 watts to keep the margin going (and to keep the math wicked simple here in a second )


The Orion 12/24-20 has a minimum input voltage of 9 volts. The lowest I've ever seen a (healthy) Toyota temperature compensating alternator go is 12.3 volts. To supply 123 watts at 12.3V, it will take... 10 Amps on the nose! What a coincidence .

We'll use Ohms law to determine how much voltage we can drop between the power source (alternator) and the load (the Orion).
V=IR
V/I = R
(12.3-9) / 10 = allowable resistance
3.3 / 10 = 0.33 ohms

If we take the fuse and mount cold resistance of 0.9mOhms -> 0.0009Ohms. We'll double it for a warm resistance. 0.0018Ohms.

https://www.victronenergy.com/upload/documents/Datasheet-Midi,-Mega-and-ANL-fuses,-and-fuse-holders-EN-.pdf

And let's double that resistance again to account for the battery connection and the connection at the Orion. 0.0036Ohms. We'll double that again for the ground connection (which, in reality should be much less if you go straight to the nearest frame bolt for grounding. And there's no fuse inline on the GND side -> 0.0072Ohms.

0.33Ohms is our allowable resistance budget. We subtract out the fuse and connectors resistance of 0.0036Ohms.
0.33Ohms - 0.0072Ohms = 0.3228ohms remaining budget for the wire resistance.

I'll assume a 20 foot run with some snaking around the vehicle and some service loop on each end.
Using the calculator here and a little guess and check... Wire Resistance Calculator - Cirris Inc - https://cirris.com/wire-resistance-calculator/#quick-calculator
22AWG would be 0.323ohms wire resistance, so over the resistance budget. 20AWG would be 0.203, so well within budget.

There are a couple phenomenon at work here that make 20AWG a feasible cable size:
1) The actual load is very modest. 100 watts.
2) The load is a charger, not a battery. So the load will be regulated and limited to 100 watts, where a "bare" battery in the back could have large, unmitigated peak currents.
3) There's currently a DC-DC converter in the design that allows a much lower working voltage (9V) than a direct battery-to-load connection (12V for the Jackery DC input).


Reasons NOT to run 20AWG wire:
1) Expansion of other loads in the future
2) Probably similar pain-in-the-butt factor to run a higher gauge, like 8AWG, through the firewall gland as 20AWG.
3) Unaccounted for resistances: wire or connectors corrode a bit, etc.
4) Bad data sheets. The data sheets for the Orion and the Jackery leave lots to be desired to do a real engineering analysis, but I did what I could with the consumer-facing data and piling on margin where we could.

I'd probably run 8AWG myself as a balance between plenty of margin for the current design, some expandability in the future, still straight forward to route through the firewall gland & through the scuff plate channel, works well with the fuse crimps, and likely whatever connector you put on the Orion end.

 

[daneo]

To expand on phenomenon #3 in the previous post, I want to take a look at what it would take to charge the Jackery directly off the vehicle's alternator with no DC-DC...

12.3V minimum alternator voltage - 12.0V minimum input voltage at the Jackery =. 0.3V droop margin.

V/I = R
(12.3-12) / 10 = 0.3V / 10 = parasitic resistance budget = 0.03 ohms

We'll subtract out a similar connector budget again of 0.0072 ohms again. 0.03 - 0.0072 = 0.0228 ohms. That's less than one tenth the wire resistance budget we had with the DC-DC in the setup!

According to the wire resistance calculator, you'd need 10AWG or greater to charge your Jackery 500 directly off the battery with a 20 foot wire length! A wire size much more inline with the conventional wire-sizing wisdom.

Hope this helps!

 

[Smotride]

Yet another attempt:

Please share me your thoughts on my plan for charging a portable battery for my fridge.

Currently , I have a Jackery 500 which has proven to be inadequate for more than ONE overnight trip for my fridge.
I want to avoid dual battery set up and just need to charge the Jackery in the back as the OEM 110V is too slow.

Plan: run a 4ga from from main battery in engine bay with solenoid isolator

( 12V 200 Amp Continuous Battery Relay Isolator and Relay High Current Relay for Mobile Audio)​

to the back with a fuse. Connect to

Energy Orion 12/24-Volt 20 amp DC-DC Converters​

Connect fuse and then 8 ga to adapter for Jackery at 24 V

Will also run another 8 ga from main battery to the center console for connection to this

Cllena Dual USB Charger Socket 2.1A&2.1A + LED Voltmeter + 3 Socket Cigarette Lighter Adapter 12V Power Outlet + ON-Off Toggle Switch Multi-Functions Panel for Car Marine Boat Rv Camper Truck (Green)​

what do you think?

Your plan to address the charging limitations of your Jackery 500 for your fridge during extended trips seems well-thought-out. You're opting for a more efficient method than the OEM 110V by planning to run a 4ga cable from the main battery in the engine bay with a 12V 200 Amp Continuous Battery Relay Isolator. This approach ensures that the main battery isn't drained when the engine isn't running. The use of the Energy Orion 12/24-Volt 20 amp DC-DC Converters to step up the voltage is a good strategy to optimize the charging rate of your Jackery 500. Ensuring a fuse in the setup is crucial for safety and protection against potential electrical issues.

 

[Smotride]

Also running another 8 ga from the main battery to the center console is a practical decision, especially for connecting devices like the Cllena Dual USB Charger Socket with multiple functionalities. This addition not only enhances charging capabilities but also offers versatility in powering other devices.

 

[elcajon]

OMG!!!!!!