This is another question we get asked regularly. Taking the most popular 1kVA generator on the market today (Honda EU10i), this unit can produce a maximum output (for a short period) of 1000Watts. Continuous running, the EU10i can operate at approx 800Watts maximum.
The most popular battery charger’s on the market today range from 15amps-40amp for charging the average caravan/marine application with battery capacities between 100Ah-360Ah. So let’s look at the AC power consumption required by the top brands and see how much power they require to charge you battery bank.
Brand | Model | Amp Rating | AC Power required@240v for maximum output | Watts Per Amp |
| CTEK | XS25000 | 25A | 696W | 27.84W |
| CTEK | M200 | 15A | 696W | 27.84W |
| CTEK | M300 | 25A | 696W | 27.84W |
| Projecta | IC1500 | 15A (selectable 2-4-8-15A) | 240W | 16.00W |
| Projecta | IC2500 | 25A (selectable 2-6-12-25A) | 792W | 31.68W |
| Projecta | IC3500 | 35A (selectable 2-8-16-35A) | 1080W | 30.85W |
| Projecta | IC5000 | 50A (selectable 2-6-12-25-50A) | 1488W | 29.76W |
| OZcharge | OC-PRO1200 | 12A (selectable 1-8-12A) | 175W | 14.58W |
| OZcharge | OC1225U | 25A (selectable 2-15-25A) | 720W | 28.80W |
Enerdrive | ePOWER 40 | 40A (selectable 5-10-20-40A) | 700W | 17.50W |
Enerdrive | ePOWER 60 | 60A (selectable 5-20-40-60A) | 1050W | 17.50W |
All specification taken from the brands respective owners manuals on 20/11/2017
Based on the above table, the best bang for the buck is the Enerdrive ePOWER charger range. Based on 17.50W per amp the Enerdrive ePOWER 40A charger will run comfortably on a Honda EU10i generator at 40A. If you have a battery bank of 3 x 105Ah (315Ah), you could run the ePOWER 60A unit and dial it back when on the generator to 40A, then when back on mains power you can dial it back up for maximum charge.
Based on the original single stage charger back 30+ years ago, the equation to size your charger was 10% of the battery bank size, i.e. 100Ah battery = 10A charger. These days with multi stage charging, designated float algorithms and AGM/GEL battery technology, the equation is now closer to 20%. This being the case, your 2 x 105Ah battery bank (210Ah) is best charged with a multistage charger around 40A.
If you like what you’ve read, you can find even more helpful advice by joining our Enerdrive Unplugged Facebook group! The group is for sharing installations, errors in installations and best practice install guidelines utilising Enerdrive Products across Caravans, Campers and 4WDs. Acting as a space to leave feedback and comments, get inspired and learn from other veteran users along the way!
