I haven't found a Schumacher charger that will charge a nearly no voltage battery (with below 5v - 6v in it) without connecting a good or 12.4+v battery to the low volt battery. The Optima and some others will charge on their own regardless of the amount of voltage of the battery you are attempting to recharge. I have a motorcycle battery charger (KTM) that works even on the deadest car battery every time and it will also diagnose the condition of the battery and the entire charging system and if you have the leads backwards. It does AGM, Gel, Flooded and lithium Ion batteries. Had a Die Hard AGM battery out of the wife's Town & Country on a top-of-the-line Schumacher charger the week before last and it wouldn't even budge the 5 volts for several days. So I pulled and topped off another battery to 12.7v and connected it to the T&C dead Die Hard with 1-gauge jumpers and tried again with the Schumacher and got it up to about 8v and that was all with another week's worth of charging in the warm, heated basement shop. Put the KTM Fronius Acctiva Easy 1202 charger on it by itself and in less that a day it was at 12.7 volts and done. Not saying to get a KTM charger but do the search and see if the Optima or similar brand has the same features as the KTM charger. I now only use the Schumacher on a slightly low charged battery kind of like a maintainer and that's very seldom. In hindsight the Schumacher charger was a waste of money.

Check out the features and compare them to Optima and other similar chargers, then decide, click here Fronius Acctiva compact Professional charger

Look for these functions and technologies on other brands then decide.

Functions:

Acctiva Easy
- Suitable for charging and for charge conservation of all lead starter batteries
- Test function for starting capability and generator function
- Charging of deep-discharged batteries possible
- Charging status indicated by segments on display
- 100% safety for vehicle, vehicle electronics and battery
- Compact design and easy connection

Technology:

Active Inverter
- Compact dimensions and low weight for flexible application options
- Optimised charging process for maximum energy efficiency and lower energy costs
- Conservation charging minimises the risk of self discharge, even during longer periods of non-use
- High performance: optimal use of battery capacity