[RE-wrenches] unique battery bank design question

[Joel Davidson]

On T-105 battery banks, I've used taps with alligator clips so the tap could 
be moved every few days to power 1 amp or less loads. The taps worked 
because I equalized the battery bank every month. I've used voltage-dropping 
resistors (simple and cheap), Vanner equalizers (ambulance grade hardware), 
off-the-shelf DC-to-DC converters (some only lasted 2 years) and custom 
DC-to-DC converters with MPPT. All work well when they are designed for the 
peak load and continuous load, have good heat dissipation and their 
parasitic load is included in the system's energy production.

Joel Davidson

----- Original Message ----- 
From: "Rob Shappell" <rob at nwes.com>
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Sent: Friday, September 02, 2011 6:53 AM
Subject: Re: [RE-wrenches] unique battery bank design question


> As far as I know, The DC/DC and the Equalizers do basically the same thing
> (step up or down). I recollect that the Equalizers are adjustable and can 
> be
> used as a load dump. Enermaxer comes to mind. It's been a long time.......
> but a refresher will be gladly accepted from those in the know.
>
> Rob Shappell
>
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jason
> Szumlanski
> Sent: Friday, September 02, 2011 9:42 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] unique battery bank design question
>
> Yeah, Rob, you and I have talked about this before regarding 12V required
> for generator start/control with a 48V battery bank. In that case we did 
> the
> inefficient thing by charging the generator starting battery with a 12V
> charger off the AC output of the inverter. A separate PV panel was the 
> more
> expensive option. I appreciate your input on this.
>
> What can you tell us about battery equalizers as an alternative to DC-DC
> converters??
>
> Jason Szumlanski
> Fafco Solar
>
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Rob 
> Shappell
> Sent: Friday, September 02, 2011 8:24 AM
> To: 'RE-wrenches'
> Subject: Re: [RE-wrenches] unique battery bank design question
>
> I never, never recommend taps of any sort, but sometimes we have to 
> satisfy
> the needs of the customer. If any taps are done in any manner I would
> recommend AT LEAST an annual reconfig of the taps.
>
> To reduce and/or eliminate the imbalance of the 12 volt and 24 volt taps,
> you could install a 12 volt charging source to the 12 volt tap, a 24 volt
> charging source to the 24 volt tap and the 48 volt loads get a 48 volt
> charging source. The array is still calculated the same, just distributed
> different through different controllers. Is this bullet proof or perfect?
> Nope, but neither are DC/DC converters and the system is much more 
> efficient
> too.
>
> Rob Shappell
>