I solve the problem by using the 48 volt ZIVAN NG-1 to bulk charge the batteries to the second stage of charging then switch over to the Dual Pro. Plus I try and limit my drain to the 90 to 80% range but, will occassionally drop down further. I went down as far as 64% one time this year just because I just did not want to fire up the generator. Charging is pretty quick using this method at least it's working for me. The Dual Pro has never dropped out from over heating and the batteries are usually in sync within minutes of each other. If I happen to tie up to a dock with AC I use the Dual Pro exclusively but, I could see how it could probably shutdown prematurely if you have really drained battery bank. But, I don't think I've ever drained down the bank that far on my boat. Capt. Mike
From: David Goldsmith <suntreader@gmail.com>
Subject: Re: [Electric Boats] Re: Battery chargers: Bulk or Individual
To: electricboats@yahoogroups.com
Date: Tuesday, October 19, 2010, 2:34 AM
Arby's experience was very informative. I was planning on a four bank charger for my 48V bank of 6V cart batteries (with four pairs of batteries being charged at 12V by the charger.) The problem of one charger over heating another and the bank becoming badly out of sync makes a lot of sense and would only come up with a lot of experience. This makes me think I'll use a bulk 48v charger and with a PakTrakr monitoring each 6V battery I can tell if one gets low and individually charge it up. David On Mon, Oct 18, 2010 at 10:24 PM, Angela <mstafford@natca.net> wrote: Thanks Arby for hard learned lessons shared. The key in either string or individual charging is how each sub-cell is doing. We can't know without an individual cell monitoring scheme, which is only possible on LiFePO4 or those odd 2V single cell lead acid batteries. With flooded lead acid batteries (FLA), overcharging a cell is no problem (just add water later). Overcharging a SLA battery in a high voltage string is problematic... usually kills the battery. A per-battery overvoltage cutoff circuit would eliminate this weakness with SLA, since the cells internal to an SLA are very closely balanced in their charge and discharge characteristics, and the conservative cutoff voltage would render inconsequential any minor discrepancies.
Appreciatively,
Mark Stafford
PS I was sailing opposite direction to the incoming armada of boats leaving Fleet Week on Saturday for the Alameda Estuary. --- In electricboats@yahoogroups.com, "RagnvaldB" <arbybernt@...> wrote: > > Two Advanced Marine conversions experienced problems with battery chargers last week after particularly deep discharges. I've been a strong advocate of the DualPro PS-4 chargers, and have installed many, including in our own Ericson 27. Last week, San Francisco Bay hosted the Blue Angles and many others to perform for several hours to the delight of many. The Tradewinds Sailing School had their Catalina 30 out, and it spent many hours running under power, far more than usual. It came back with fully depleted batteries, and was plugged in dockside upon its return. The next day, the chargers were showing odd levels of charge, having been plugged in all night. Normally, the boat charges fully overnight. We felt the charger, and it was piping hot, a condition which caused one or more of the chargers to drop out. This probably had happened the day before as well, and as a result, the boat had gone out without a full charge in each battery. After 24 hours on the now fan cooled charger, we had all green LED's, thank goodness. The second boat, a Columbia 27, had a similar situation when the charger timed out. > Brian, the Mainfuse at Trunderstruck-EV, advocates bulk charging for just this reason. He's had several instances where a fresh string has been ruined by an individual charger dropping out and one or more batteries being reverse polarized. Consider that the string current flows through each battery equally, and when a cell is only partially charged, that same current will gradually cause the voltage on the weak cell to reverse as a result. > In conclusion, I'll still use a multiple output charger for equalization every so many cycles, but from now on, all new conversions will get chargers for the entire string. Leaving the dockside with one flat battery is far worst than leaving with a partially charged string. Thanks for the advice, Brian. I wish I had listened the first time... > > Arby Bernt > Advanced Marine Electric Propulsion >
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