Re: Battery: Where did we go wrong?
 

If they work for you and you like them, ignore my comments, but in my experience they seem to 'get lost' when changing batteries and we would just unplug the charger from the wall and re-plug it in. But it may be we are just too impatient.

Whereas the Deltran seems to have a loving attitude to our batteries much more so: https://www.youtube.com/watch?v=2JlVqfC8-UI

Re: Battery: Where did we go wrong?
 

First off a flooded lead acid battery is not designed to be used or charged in any other position other than upright. They should never be charged on the side as the acid may leak out and the plates may fall out of their brackets and short out.

There are two other types of batteries AGM (absorbed glass mat) may be used horizontal or at an angle but still it is recommended to be charged upright. Gel batteries are better than flooded since the plates are suspended in a jello like liquid helping hold the plates apart and perform better since the gel acts as a dampening agent.

We have transitioned over to AGM batteries for the safety of being sealed and being designed to be used at other orientations. They are also a bit more environmentally friendly since they have nominal lead in them.

Each battery has its pros and cons.

You may want to read this link on basic batteries.
http://www.batterystuff.com/kb/artic...ry-basics.html

Re: Battery: Where did we go wrong?
 

I was under the impression that (according to 2015 rules) everyone had to use Sealed Lead-Acid batteries to power the robot.

Emphasis mine. Maybe I'm misinterpreting?

Re: Battery: Where did we go wrong?
 

Perhaps during non-competition use?

Re: Battery: Where did we go wrong?
 

AGM is a type of sealed lead-acid battery. I don't know why he says they have no lead, because they do.

Re: Battery: Where did we go wrong?
 

Does any AGM battery exist that meets R20?

Re: Battery: Where did we go wrong?
 

Yes. The UPS' manufactured where I work use tons (literally) of Enersys batteries from the same family as the FRC legal models. We recommend that our customers replace them after 3 years. The charge and discharge rates our UPS' subject the batteries to are not as "abusive" (especially discharge) as in an FRC robot so I would expect less than 3 years of life when used in an FRC robot.

Re: Battery: Where did we go wrong?
 

Don didn't say no lead. He said nominal lead. Nominal lead is the lead normal people use. :p . The recycle stream for lead is very good. You return your battery to a recyler, as you should, it will get ground up and made into a new battery. Near zero impact on the environment.

Yes there are AGM batteries that are FRC legal

Re: Battery: Where did we go wrong?
 

At first he said "no" then he changed it to "nominal". If I would have realized it was a typo I never would have said anything.

Re: Battery: Where did we go wrong?
 

I missed that. :] Nominal is a funny word anyway. It can mean approximately normal like all readings are nominal or it could mean insignificant. One the oddities of the English language trying be all things to all people.

In any case FRC legal AGM batteries are lead acid batteries and have sufficient lead in them for the reaction to work.

Re: Battery: Where did we go wrong?
 

AGM batteries actually may have slightly more lead than previous gel cell types. The glass mat allows for closer plate spacing which may allow manufacturers to add one more plate in the same space as previous designs. This gives a little higher energy density and/or available peak current. The reason FRC went to AGM batteries (namely the MK series) came from a donation by MK to supply batteries to every team that year. The AGM design also keeps maximum contact between electrolyte and full plate during the battery's lifetime. This AGM series also lightly reduced the weight of batteries. Previous gel types could be up to 14 lbs when new. As the electrolyte evaporated, the weight went down but so did the available current and energy density.
Batteries used in safety light service are designed to be on trickle charge 24/7 so they have a tendency to outgas and remain at higher temperatures. Many jurisdictions also require safety lighting to provide light for a specific minimum time period. Older batteries in this service will meet that spec. Many building maintenance managers will replace all batteries every three years or sooner, depending on environment.

Re: Battery: Where did we go wrong?
 

Reviving this just to note we had a failure today as well. We were using the Andymark tripple charger for the battery. Open Circuit voltage is 13.52V. I have checked the charger and it is consistently float charging at 13.35-13.40V per battery.

Re: Battery: Where did we go wrong?
 

Based on all your input my guess is that batt was last charged and not erect.
(i.e. on one of its sides)

It is perfectly OK to DISCHARGE the battery in any orientation.

Charging must always be upright to prevent gas accumulation pockets which could cause case bulging due to normal pathways being blocked. In an older battery this may be the more likely scenario. Gas generation is natural in charge mode and normally is re-absorbed. Gas is not normally generated when discharging. (reverse chemistry)

We successfully use FIRST batteries for 6-7 years (since 1999), tho as they get older just for test and evaluation. Our "charge" policy is to always have them on a charger as soon as practical after being used, and always while being stored.

Only exception is if the battery self heated in a particularly push push match - then wait until batt isn't noticeably warm to the touch (~ room temp) before charging.

Every team sould invest in a Battery Capacity tester and keep records (id ea batt ea yr 2016-1, 2016-2.. it can be done manually and produces instructive discharge curves - we use 50A as match average simulated load ~.25 ohm but must be rated a minimum of 500W (use fan) test will fully exhaust batt capacity in ~9 min.. I can send a sample of the data and plot if you send me a personal email if my jpg attachment did not post here 50A Load Discharge graph+data)

Re: Battery: Where did we go wrong?
 

Do you have any recommendation for a battery capacity tester?

Re: Battery: Where did we go wrong?
 

West Mountain Radio

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