Does it work with lithium batteries?

Yes. The start and stop voltages are adjustable, so you can set thresholds for lithium or lead-acid. Retune them if you switch chemistry.

What does the delay function do?

It holds off switching when current is unstable, which cuts rapid on-off cycling of the relay. That protects the relay and smooths charging.

Can the auxiliary battery charge the main one?

Yes. Reverse charging is supported for emergencies, so a charged auxiliary can top up a low main battery.

Is it a DC-to-DC charger?

No. It is a voltage-sensitive relay that connects and disconnects the batteries. It does not boost or regulate charging current the way a DC-to-DC charger does.

The plastic casing is built to keep water and dust out and to take knocks. Mount it in a dry, protected spot where you can.

The isolator unit itself. Wiring, fuses and mounting hardware are not included, so plan for those separately.

Where is the KFFKFF Dual Battery Isolator, 12V 300 Amp cheapest?

At Walmart, for $51.99, as of our latest check.

What do buyers say about the KFFKFF Dual Battery Isolator, 12V 300 Amp?

Rated 5 out of 5 from 2 ratings.

KFFKFF Dual Battery Isolator, 12V 300 Amp

Best price now

$51.99at WalmartChecked Nov 10

Prices are checked against each store and labelled with when.

Visit Walmart

KFFKFF Dual Battery Isolator, 12V 300 Amp

Best price now

$51.99at WalmartChecked Nov 10

Prices are checked against each store and labelled with when.

Visit Walmart

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Price facts

Last seen at $51.99 at Walmart on Nov 10.

Our take on the KFFKFF Dual Battery Isolator, 12V 300 Amp

The KFFKFF Dual Battery Isolator is a voltage-sensitive relay rated for 12V systems and up to 300 amps. It links a main and an auxiliary battery so the auxiliary can recharge the main when its charge drops, and it works with both lithium and lead-acid batteries. Adjustable start and stop voltages, a switching delay and a real-time dual-voltage display set it apart from fixed-threshold isolators. It suits overlanders, van builders and boat owners running a house battery alongside a starter battery.

Best forVan and overland builds with a house batteryBoats with separate starter and accessory banksOwners mixing lithium and lead-acid batteriesCampers charging an auxiliary from the main battery

Pros

Adjustable start and stop voltages for lithium and lead-acid
300 amp rating handles heavy charging loads
Delay function reduces relay chatter from unstable current
Real-time dual-voltage display shows both battery states
Manual and automatic modes
Sealed plastic casing resists impact, water and dust

Cons

Wiring and voltage setup take care; mistakes can drain a battery
Relay-based switching, not a DC-to-DC charger
Voltage thresholds need retuning when battery chemistry changes
No Bluetooth or app monitoring

KFFKFF Dual Battery Isolator, 12V 300 Amp prices at every store

WalmartNew
In stock
$51.99Checked Nov 10
Visit Walmart

About the KFFKFF Dual Battery Isolator, 12V 300 Amp

This is a 12V, 300 amp dual battery isolator, also called a voltage-sensitive relay (VSR). It is made for systems with two batteries. Both batteries charge at the same time, and connected devices keep getting power. It works with lithium and lead-acid batteries.

The start and stop voltage settings are adjustable. A built-in delay reduces frequent switching caused by unstable current. A dual-voltage real-time display shows battery conditions.

It has manual and automatic modes. In manual mode, a fully charged auxiliary battery can reverse charge the starter battery, so the engine can be restarted without jumper cables. The casing is durable plastic with impact resistance, and its design helps keep water and dust out.

Model: VSR005
Rated voltage: DC 12V
Rated current: 300A
Battery types: Lithium and lead-acid
Modes: Manual and automatic
Display: Dual-voltage real-time display
Material: PA6
Color: Black
Dimensions: 3.5 x 3.5 x 3.1 in (90 x 90 x 80 mm), L x W x H
Weight: 0.9 lbs (0.42 kg), including all accessories
In the box: 1 x Dual Battery Isolator Kit, 1 x User Manual

Specifications

color: MulticolorSource

Questions and answers

Does it work with lithium batteries?: Yes. The start and stop voltages are adjustable, so you can set thresholds for lithium or lead-acid. Retune them if you switch chemistry.
What does the delay function do?: It holds off switching when current is unstable, which cuts rapid on-off cycling of the relay. That protects the relay and smooths charging.
Can the auxiliary battery charge the main one?: Yes. Reverse charging is supported for emergencies, so a charged auxiliary can top up a low main battery.
Is it a DC-to-DC charger?: No. It is a voltage-sensitive relay that connects and disconnects the batteries. It does not boost or regulate charging current the way a DC-to-DC charger does.
Is it weatherproof?: The plastic casing is built to keep water and dust out and to take knocks. Mount it in a dry, protected spot where you can.
What is in the box?: The isolator unit itself. Wiring, fuses and mounting hardware are not included, so plan for those separately.
Where is the KFFKFF Dual Battery Isolator, 12V 300 Amp cheapest?: At Walmart, for $51.99, as of our latest check.
What do buyers say about the KFFKFF Dual Battery Isolator, 12V 300 Amp?: Rated 5 out of 5 from 2 ratings.