Projecta DBC100K 12V 100A Dual Battery Isolator Kit
Before DC-DC chargers became the default recommendation for every setup, electronic dual-battery isolators like the DBC100K were the standard way to keep an auxiliary battery charging off the alternator without draining the starting battery, and they still have a solid place in simpler, older-vehicle setups.
Key features
- 75A continuous / 100A peak charging current
- Voltage-sensing operation — cuts in at 13.4V and cuts out at 12.8V, with a 60-second delay
- Low standby current draw of 30mA, rising to 500mA while actively charging
- Surge protected
- No modification to existing vehicle wiring required
RV use case
This suits simpler setups on older or non-smart-alternator vehicles, where a straightforward voltage-sensing isolator does the job without the added cost of a full DC-DC charger. The manual override function is a genuinely useful inclusion for jump-starting situations, letting you temporarily link the two batteries when needed rather than leaving them permanently isolated.
Pros
- Straightforward, no-frills solution for simpler charging setups
- No modification needed to existing vehicle wiring
- Manual override adds practical flexibility for jump-starting
Cons
- Not suitable for modern smart-alternator vehicles — a DC-DC charger is the correct tool there
- No solar or mains charging input like a combined DC-DC/MPPT unit offers
- Charging performance depends entirely on what the alternator is actually delivering
Best for
Owners with older, non-smart-alternator tow vehicles wanting a simple, cost-effective dual-battery charging solution without stepping up to a full DC-DC charger.
Verdict
For the right vehicle, this is a sensible, affordable solution — but it's worth being honest about whether your tow vehicle actually suits a voltage-sensing isolator, or whether a DC-DC charger is the more appropriate spend.
Projecta DBC100K 12V 100A Dual Battery Isolator Kit
Close-up of the isolator unit and wiring terminals
Cutaway view showing the internal circuit board
Close-up of the power and charging status indicators