Scooter (DPV) questions

[Thalassamania]

Be careful of old batteries, they may vent hydrogen gas which could cause an explosion. N

Roger.

Two of the four held a charge, now I'll try the other four and then I'll take any "good" ones down to my comrade's auto shop for a load test.

 

[cool_hardware52]

Roger.

Two of the four held a charge, now I'll try the other four and then I'll take any "good" ones down to my comrade's auto shop for a load test.

Old lead acid batteries are very problematic. If you use these in sets I'd suggest replacing all the cells that will be in series.

Good luck,

Tobin

 

[Thalassamania]

Old lead acid batteries are very problematic. If you use these in sets I'd suggest replacing all the cells that will be in series.

Good luck,

Tobin

I'm sure I will, new batteries have more amp hrs. anyway and do not spill, just sort of interested in the outcome.

 

[Nemrod]

If those are liquid type "motorcycle" batteries I would not use them. They do need to be matched more or less. I know your plenty smart in such matters but I would get new gell cells, cheap ones but new just to be safe. Those things really can explode. N

 

[cool_hardware52]

If those are liquid type "motorcycle" batteries I would not use them. They do need to be matched more or less. I know your plenty smart in such matters but I would get new gell cells, cheap ones but new just to be safe. Those things really can explode. N

Nemrod,

Sealed Lead Acid batteries can also offgas Hydrogen, it's a function of the chemistry. SLA's have pressure vents, that require the internal pressure to exceed ~20 PSI IIRC. Abusive over charging will do it.

That's whay SLA's should always be charged with Automatic chargers. If you do manage to boil the battery you can't add water!

As a side note the reason open wet cells continued to be used in many motorcycles for years after sealed batteries were comon in auto's is the charging systems on many motorcycles are essentially uncontrolled and the battery was expected to "boil".

In any event hydrogen and open armature motors are a bad combo.

Tobin

 

[Nemrod]

Thanks for pointing that out, I did not mean to mislead anyone. Yes, you are correct and I am well aware of those facts. I am more concerned about putting batteries of dubious condition in a closed container, especially old liquid lead acid vented motorcycle types.

Yes, the sealed gell cells will vent hydrogen gas, especially if over charged or charged at high amp rates and I do believe the same if they are drawn at high loads as well.

Hydrogen gas, air, spark= explosion.

At least with the Farrallon the batteries are charged with the nose section off---am I right there?---the Teknas charge through a port with the front section still in place. Prior to charging and operation the Tekna is sat on it's shroud so the charge port opening is upward. I allow at least 30 minutes or more to vent hydrogen out before charging. There is an anti spark capacitor in the charge port. I just put a new one in mine. The Teknas also use hydrogen absorbant bags/pills for added protection against hydrogen accumulations.

I already posted this pic but you can see the sealed gell batteries and yes they have small vents. The gray pills on the upper bulkhead are hydrogen absorbing materials. Note that the motor is mostly sealed---maybe--by a plexiglass bulkhead from the battery compartment. However, the nose light is not--lol. There are also additional bulkheads and absorbant bags not shown in the pic that are installed when the batteries are installed for final assembly.

Do the Farrallons have absorbant materials. I think if I recall the motor is in a seperate chamber?
N

 

[Thalassamania]

There is no absorbant that I know of, I was thinking of adding some. The batteries are in a tray (in the front compartment) that is removed from the vehicle for charging in the open air. There are some small bottles on the battery vents that collect electrolite due to expansion or inverted operation (sealed batteries should obviate the need for these).

 

[Mr.X]

There is no absorbant that I know of, I was thinking of adding some. The batteries are in a tray (in the front compartment) that is removed from the vehicle for charging in the open air. There are some small bottles on the battery vents that collect electrolite due to expansion or inverted operation (sealed batteries should obviate the need for these).

The wafers, or pucks at the top of the Old Tekna image, as well as my newer Mako have hydrogen-absorbing (?) materials added on. I would imagine an Oceanic or Aeris dealer being able to get you a couple? I have no idea how effective they are + I know G.Irvine and Rodney of SS do not use these things as they are deemed largely ineffective? They are charcoal colored and seem to have an orange rubber oring molded in.

The old Farallons...didn't UC (B/Davis) use some in their 70's research diving program?


X

 

[cool_hardware52]

There is no absorbant that I know of, I was thinking of adding some. The batteries are in a tray (in the front compartment) that is removed from the vehicle for charging in the open air. There are some small bottles on the battery vents that collect electrolite due to expansion or inverted operation (sealed batteries should obviate the need for these).

If you can find the hydrogen sorb or catalyst easily I see no reason not to use it, but I'd venture a guess that with SLA batteries it's largely unneccessary. (easy for me to say, when it's you that might blow up )

Older battery chargers often had little or no charge control, at best they were taper chargers. Overcharge was almost certain. No big deal for the battery as one could replace the boiled electrolyte.

An open wet cell that has been driven into overcharge and is offgasing will continue to emit Hydrogen gas for some period after the charge current is removed. If a open wet cell is charged in a scooter hull the risk is obvious, if it's charged out of the hull, and then reinstalled some risk remains.

What is the comparable risk when using SLA batteries and modern "float" chargers? Much less. A modern charger should keep the battery out of overcharge. No overcharge, no Hydrogen. Even if small amounts of Hydrogen are created the internal pressure vents will contain it.

One small point concerning SLA batteries. If overcharged they can vent both Hydrogen, and liquid acid. If the battery is upright you get gas, if the vents are oriented down or to the side you get electrolyte.

Not all SLA batteries use a "gelled" electrolyte. Commonly they use a "suspended electrolyte". This approach uses an absorbent seperator to hold a liquid electrolyte.
This typically provides better performance from the battery, but there is liquid electrolyte present.

Good luck,

Tobin

 

[Thalassamania]

I guess I need to get a new charger and eight SLA batteries with gelled electrolite of the proper size, 12v with as many amp hrs as possible. Does that about sum it? BTW: Thanks a bunch, this has been a great help.