Very fast charging of deep cycle batteries.

Submitted: Thursday, Oct 18, 2012 at 11:52
ThreadID: 98620 Views:10955 Replies:6 FollowUps:12
This Thread has been Archived
The following results of my new battery setup may interest those wanting a fast charging system.
SOC = State of Charge DOD = Depth of Charge (I use a battery down to 50%)

My Fullriver AGM has been retired. It used to take about 6 hours for a 90% SOC charge plus a run overnight to fully charge it - this was too slow for me. When camping and running off the genset, the battery was rarely up to 90% SOC and never up to full charge, until I returned to mains power.

I now charge a Lifeline 150 Ah battery with three 40 Amp battery chargers (non-smart, cheap constant voltage type) that run in parallel with each other – I purchased the CH 40 type chargers from eBay at $95 each. Each is switched individually so as to allow variation of either the load on the genset or the charge rate to the battery. A 150 Ah was used but a 100 Ah Lifeline would have also been suitable with this setup.

Testing on a 240 volt mains supply
With the battery discharged to 50% DOD, and 3 chargers switched on, the charge rate starts at approximately 100 Amps tapering off to 25 Amps in the first hour - achieving about 90% SOC. In the next hour 25 Amps tapers to 5 amps - getting close to full charge in 2 hours. The internal temperature of the battery rose 6 degrees and stabilised at 26 degrees during the first hour.

During these tests the battery was discharged to 50% with a 25 Amp load – charge rates could increase if discharged at a lower rate.

Running on a 2.4 kva Yamaha Genset
The overload breaker tripped out with 3 chargers connected to the 50% DOD battery. When using the genset, I have to start with only 2 chargers connected, at an initial charge rate around 70 Amps - I continue with the 2 for about 10 minutes before switching in the 3rd charger.

Lifeline states that, with repetitive deep cycling, a high charging regime is more beneficial to the cycle life of their battery than low charging rates.

If you go for a system like this, you need to ensure that you check batteries specifications and stay within their specified charging rates. If you can’t obtain these details, doesn’t use the battery as it could overheat dangerously.
You also need to source constant voltage chargers that will run in parallel – many smart chargers won’t do so. (I brought one in initially and tested it before I put together the rest of the system)
Back Expand Un-Read 0 Moderator

Sponsored Links