Charging auxiliary battery

[mep1811]

Why can't I use this to charge my auxiliary battery? I have a aux battery pack in the back of the Forester I use to run the fridge at night . During the day I charge up the battery pack with a small inverter and a A/C battery charger. I'd rather to charge of the vehicle charging system.

Since the cargo area in the Forester is limited ,my battery pack is only 40 amps .

Towed Battery Charger Plus for flat towing

RVi Towed Battery Charger Plus, charge line replacement for flat towing a vehicle. Great peace of mind for the towed battery while towing a car behind a motorhome. Often used with RVibrake. TBC+

rvibrake.com

 

[mep1811]

There is no reason it cant charge aux battery.
Its just 80$ worth of RV gizmo whats not needed to charge an ’aux lead acid battery.

Much cheaper than other dual battery kits

 

[Buddha.]

I would use that or some other dc-dc charger before I’d use a converter and a 120v battery charger.

You could just wire the two batteries together but you’d get some voltage drop and the auxiliary battery would be chronically under charged and that would affect its life expectancy.

I would want a unit that bumps up the voltage and has a couple different charge profiles, not a constant fixed voltage.

 

[mep1811]

That is all I need. I've used this unit on a couple of trailers and it worked great.

 

[WVI]

That looks to be pretty easy to use as a charger for an aux bat in a van as well...

 

[john61ct]

Designed for keeping a Full battery topped up, not proper charging - "not compatible with AGM" is a huge red flag!

Check the actual output voltage produced at the target terminals once 98% Full.

If it is in the Float range as per batt makers spec, that is too low for actually charging a deep cycling bank.

 

[mep1811]

I found this for marine use. It is rated for AGM batteries.

Yandina Combiner 100 Battery Combiner - C100

The two battery Yandina Combiner 100 battery combiner is a voltage-sensing relay (13.3 volts) which connects two batteries together when either is receiving a charge. When the charging stops the relay opens allowing each battery operates independently. Yo

www.defender.com

https://www.defender.com/pdf/204578_Yandina.pdf

 

[mep1811]

This one will charge AGM batteries . I used to use this but disliked the connectors Maybe worth another look for my application.

TOAD-CHARGE Dinghy Vehicle Battery Charger/Maintainer

Automatic Battery Charger/Maintainer for Motorhomes

www.lslproducts.net

 

[john61ct]

I found this for marine use. It is rated for AGM batteries.

Yandina Combiner 100 Battery Combiner - C100

The two battery Yandina Combiner 100 battery combiner is a voltage-sensing relay (13.3 volts) which connects two batteries together when either is receiving a charge. When the charging stops the relay opens allowing each battery operates independently. Yo

www.defender.com

https://www.defender.com/pdf/204578_Yandina.pdf

Yes Ann-Marie Foster of Yandina was the OG inventor of "combiners" decades ago, now called VSR / ACRs. Fantastic products, even better suoport.

However just like a IGN solenoid, these are passive voltage devices, really just an automated switch, so no V boost as you get from DC-DC chargers.

Have you determined what the native voltage is at the end of your wire run, resistance from terminator/connectors?

Do you know the charge voltage the mfg specs for your model battery?

Really need those data points before trying to decide what category of device you need.

 

[mep1811]

My system with the inverter is working well. Not the fastest but not designed for hardcore use. A charging system will be better.

This is the battery pack I put together . Two 20 amp deep cycle batteries wired together. Not as pretty as a $500.00 Jackery but it works.

Remote lighting system and 12VDC power supply

My friend lives in Florida and I wanted to make her a remote lighting system and 12VDC power supply for power outages. Tractor supply had 14” Flambeau dry boxes on sale for 50% off and I picked up …

badlandsexpeditions.wordpress.com

 

[WVI]

Thanks for posting mep1811.