Wiring In Series (pro vs con)

[pacific_voyager]

Originally Posted by ramblinrod

Nun uhh! One battery failure and your whole bank is useless.

Only 2v batteries DO NOT FAIL. Utility companies use them all the time.

[Zil]

You do realize every lead acid battery is just 2 volt cells connected in series? I would be very interested in which 2 volt cells do not fail.

[bgillroy]

House bank re-config we completed last year to upgrade from 4 wired in series golf cart batts. Seven 12v Trog T1275 lined up side to side, wire in parallel, short jumpers + and - sides, get about 1K ah. Simple and clean. Added Magnum 2812 inv/cgr w/ full diagnostics. Been working super last 12 months.

[pacific_voyager]

Originally Posted by Zil

You do realize every lead acid battery is just 2 volt cells connected in series? I would be very interested in which 2 volt cells do not fail.

Yes, I'm aware of that. It does not negate what I said. I'll ask you, how many 12v batteries are you aware of with a single cell that fail? It doesn't prove anything, but neither does the fact that 12 volt batteries are made up of individual 2v cells.

My research and observations are that stand-alone high capacity 2 volt cells do not fail. This is backed up by everyone I've asked including people who worked with utility companies that have really big 2V batteries. I'm sure that there are some failures somewhere, but for practical purposes I don't think so.

As to the fellow who just hooked up SEVEN batteries in parallel... that is a recipe for an early degradation of the bank. Parallel strings need to be minimized. One of my sources (Tom Duffy @ solar-biz) believes each parallel string knocks 30% off the life of the bank.

[bgillroy]

The ideal battery bank also is the simplest, consisting of a single series string of cells that are sized for the job. This design minimizes maintenance and the possibility of random manufacturing defects. Suppose you require a 700‑amp-hour (AH) bank. You can approximate that with a single string of 700 AH industrial-size batteries, or two parallel strings of 350 AH batteries, or three strings of 220 AH (golf cart) batteries. Internal cell failures in single string will happen in both series and parallel batt configs. Buy good quality batts, use heaviest and shortest custom marine DC cables.

[noelex 77]

The 2v industrial batteres are made for true deep cycle performance. They are typically rated (not that battery manufacturers’ lab tests mean much in the real world) for 8000 cycles @ 20% discharge and 3000 cycles @ 50% discharge. The standby life is listed as 20+ years.

In practice they make an excellent house bank, with a well proven long cycle life. They should be considered more often, especially for boats with solar as the primary charge source.

The lack of redundancy can be managed by choosing batteries with half the desired capacity. This means wiring two sets of six batteries. The 2v spiral wound batteries are not modified car batteries. The design goal places a high premium on reliability and they seem to have a very low unexpected failure rate so this is arguably overkill.

[john61ct]

3 strings paralleled is a good guideline for maximum to avoid problems from imbalances. Past four def pushing things.

No product categories have zero failures.

Telecom sets yes are very reliable, but lot of that comes from very rarely cycled, and replaced on a calendar schedule, not waiting for any wear to start showing.

[Zil]

Yes. John has it. Also, I want products that are easier to find on most markets. That is not specialized 2 volt cells.

[jason902]

Originally Posted by Bleemus

Really? Dont tell Trojan.

Attachment 145732

Umm that is actually 3 2v cells attached in parallel. Hence the three cell caps. Trojans 2 v battery is the same as their regular L16 with a Parallel instead of a series wiring setup