Tagged as the "Tai Lo" (that's Cantonese for 'elder brother') to the Bosch C3, the Bosch C7 brings about 12V and 24V charging capabilities (specifically, 12V/7A and a 24V/3.5A), a regeneration mode (16V/1.5A) along with a battery backup mode.

The Bosch C3 on the other hand has 6V and 12V charging capabilities and allows you to select the output amps for 12V charging in either motorcycle mode (0.8A) or car mode (3.8A).

The C3 also has a built-in pulse mode which turns on automatically to assist in charging slightly discharged batteries but has no regeneration mode. 

7 amp charging capability.
On paper, the C7 is obviously better in the sense that it has a 7A charging output and is also able to charge a 24V battery, particularly useful if you are pressed for time and need to bring a battery to full charge in a hurry such as in a workshop environment.

Obviously, the higher the amps, the faster the charging - which is a good thing. What's bad about high amp charging is that it generally leads to a shorter battery life particularly for smaller capacity batteries.

However when charging at 24V, typically used for truck batteries, the C7's amp output drops to 3.5A. While there are 24V batteries with less than 10Ah rating, most 24V batteries in the market are commonly used in trucks which have a rating of over 100Ah, in that scenario, a 3.5A won't be fast enough to be practical in a workshop environment.
Battery Backup Mode.
Despite the shortcomings of a high-amp charging, the C7 however could potentially save you from undue costly repairs from replacing your car's battery; the way most service centres or battery replacement services replaces your battery is usually to jump-start your car via jumper cables from the new battery to the old battery, the technician would then quickly disconnect the old battery, often with the engine running, and quickly install the new battery.

While some view this practice as acceptable, it could potentially fry your car's on-board electronics as any spike in voltage from the alternator will go straight to the electronics.

The safer option is to to use a backup power such as the C7, connected to the car's positive and negative terminals, disconnect the battery and then re-install the battery - all with the engine off. Of course, this can pose a challenge if you're not nearby a power outlet.

C7 Regeneration Mode.
While most smart chargers typically don't specify what type of batteries can be recovered, Bosch however claims that the C7's regeneration mode is only for 'short-term extreme discharge' and that the battery in question must also be a 14Ah (that's amp-hour) rating or higher which rules out most motorcycle batteries and similarly, old, sulphated batteries.

Bosch also states that the battery in question must also be disconnected from the vehicle while in regeneration mode - which makes sense as it's pumping in 16V which could be potentially do serious damage to the car's on-board electronics.

Likewise, this would also mean that it would be quite impractical to revive an extremely discharged battery, such as when you accidentally left the headlights on overnight in a car where you need to constantly keep the electronics powered, unless you have a.) another 'spare' Bosch C7 lying around, or b.) a spare battery to swap.

Since the C7 is essentially a 'semi-automatic' maintenance charger, there is also a high possibility that the user might accidentally damage the vehicle's electronics while attempting to regenerate a discharged battery prior to reading the user manual.

In light of this, we feel a decal that reads "Warning: Remove battery from vehicle prior to running Regeneration Mode!" wouldn't be out of place on the C7.

..and in summary, should you buy the C7 over the C3?

That would depend if you're mostly going to use the Bosch C7 solely for car battery or if you also have motorcycle batteries to charge.

By comparison, the C7 is one of the cheapest 12V, 7A smart charger with a regeneration mode you can get on the market, coupled with the backup power feature, it's value for money.

For the majority of us however, we can rule out the 6V and 24V charging capabilities as marketing bulletpoints and unless you're planning on using the charger as an emergency quick charger, we'd advise you to go with the more flexible C3 which gives you a gentle 12V 0.8A charging option and a 'quick' 12V 3.8A charging.

We would however like to see a more advanced regeneration or desulphate mode including some form of safety feature should the user tries to use regeneration mode with the battery still connected to the car's electronics in a future revision of the C7.

CT Hardware Toptip: If your 24V battery application uses two serial-connected 12V batteries instead of one big 24V battery, you can actually connect two smaller 12V chargers, such as two Bosch C3 pumping out 12V 3.8A, to each of the 12V battery.

#Bosch #batterycharger #maintenancecharger #12Vcharger #24Vcharger #C3 #C7 #carcharger #truckcharger #cthardware #cthardwaretoptip