Re: [Electric Boats] Re: Charging batteries in series?

Regarding Lead-Acid battery BMS -

My Corbin Sparrow uses 13 12V Optimas in series. These are 55Ah AGM lead-acid spiral-wound batteries.

I have a Zivan '156v' charger across the entire string.
I also have thirteen relatively-inexpensive float chargers, one across each battery and permanently installed in the vehicle and all fed by one 120vac plug http://www.batteryspace.com/leadacidsmartcharger08afor12vleadacidbatterywith3stagesfloating.aspx

My simplistic human 'BMS' consists of the following:

I use the Zivan charger for bulk charging. I use a PakTrakr (no longer made) for monitoring the individual battery voltages which allowed me to identify the weak link in the pack; i.e., the one battery in the string that charges up first. I simply put a voltage monitor with an adjustable alarm output on this battery. This alarm circuit (set to 15.0v at 70degF) trips the ac relay which disconnects the Zivan when that one battery hits the limit. At this point the pack is not fully charged, but is not damaged either. The instrument I use for this alarm I had lying around is a marine Cruzpro V55.

Later on, typically overnight, I simply plug in the float charging circuit and each float charger strokes its battery and ensures a full charge before dropping into float.

My five-year-old pack is still going strong with about 10,000 miles on it (compared to a typical Sparrow battery pack life of 3000 miles).

I also used these small float chargers for my onboard 48v Torqeedo setup when I was using Optimas (as well as a 48v bulk charger), but have now gone Lithium...

Hope this helps,

JoeS.




On Jan 18, 2015, at 19:36 , 'Rushd Ironandwood' Rushd@ironandwood.org [electricboats] wrote:

>
>
> Lithium and Flooded lead acid are totally different chemistries and while both should have a BMS, the settings, voltage, temp, charge time, amps, etc are totally different. It is rare that one BMS will satisfy all chemistries.
>
> The best thing is to do a web search for 'BMS for Lead Acid'.
>
> Rush
> TucsonEV.com
>
> From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
> Sent: Sunday, January 18, 2015 8:10 PM
> To: electricboats@yahoogroups.com
> Subject: Re: [Electric Boats] Re: Charging batteries in series?
>
>
> Mike,
> Would you recommend the same thing for my Trojan T145 F.L.A. batteries? If so, what system would you recommend?
>
> Thanks,
> Chris
>
> Sent from myPhone
>
> On Jan 18, 2015, at 09:49, mike@electricyachtssocal.com [electricboats] <electricboats@yahoogroups.com> wrote:
>
>
> Eric was correct in his response. I noticed the same thing but did not respond as I thought it was a casual misstatement. The BMS system is not built in to any cells even with LiFePO4 but they are connected to the cells. The best marine specific built batteries have them included in their battery packs and anyone who spends the money of LiFePO4 batteries should always have a quality BMS.
> As we have begun re-powering larger boat with larger battery packs and marine gensets, we have been recommending consideration of the same battery management system that is critical for LiFePO4 batteries also be incorporated in large AGM packs. Rather than monitoring individual 3v cells, monitoring the 6, 8 or 12 volt batteries themselves. It would also be prudent to use chargers that monitor heat both at the charger and at the battery. Using alarms would be wise as too much in your face data going to the helm could be distracting.
> Just applying good practices.
> Mike
> Electric Yachts of Southern California
>
>
>
>



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