Does it Exist--Need a Battery to output 10A/18V over Long Time

[klieberschnitzel]

Looking for a battery expert and even someone who can build batteries. I am looking for a battery that I don't think exists. I have a communications system that is to be isolated for 3years but communicates briefly during that time.
Every month for 3 years it is queried for 1sec. During this time that battery needs to provide 10A/18V for 1second. The challenge that we are coming up against is we need this battery to provide the ame 10A/18V for 1 second 3years later.

Is there such a battery and/or suggestions on how to go about creating one.

Thanks.

 

[davidbeach]

So, why not a solar panel to trickle charge the battery? Even without that, you can put in enough cells to accomplish what you want, it's only money.

 

[klieberschnitzel]

I knew I forgot something in the Subject title.
There is no way to recharge this system. That is the other aspect of the challenge.

This is an isolated underwater system with no access to sunlight.

 

[davidbeach]

You can put together a battery plant of any capacity you wish. All you need is space and money. If you want to go long enough you probably need some primary cells. Perhaps you can run the load from secondary cells and provide a trickle charge from the primary cells. If under water, what is your communications medium?

 

[crisleon]

Maybe there is the method to recharge the battery - let's say the solar panel installed on the buoy anchored over this underwater system (wire connection probably is not to avoid however). It depends how deeply is to be sunken.
Probably there are lighting buoys with independent supplying device. If so - you then have to think out how to transmit this (relatively small) energy under water and how to protect the cable.
The system should be monitored more often, say every day, to get information about the technical state of the solar charger and the battery; in case of failure it would be the time to intervene and to repair (exchange) something, so it would be the chance to have the system in full order in time of this demanded 1sec./month.
Maybe you find the technical support in the naval institution.
Regards
CL

 

[Comcokid]

Your application is similar to systems I've done (the current is much higher), but there is some information missing. What is the normal steady state operating current? Even in high-power pulse systems, it's the quinescent or sleep mode currents that may dominate in the overall system energy needs.

In systems that require a high current pulse the batteries may be buffered by capacitors, or a super-capacitor array. Even using capacitors take some attention to detail to make sure the leakage currents don't drain your batteries.

Of importance from the battery chemistry point is how long this device needs to operate, and at what temperature, and does it eventually need to be recharged. You've indicated it's underwater, so I'll assume the temperature is not much lower than 0C, and you given as an example 3 years. Many chemistries cannot handle low temperatures, and many (especially rechargables) have a self-discharge rate that limits them to no more than a few months.

I would check into:
1) an array of LiMgO2 (inexpensive non-rechargable) buffered by capacitors -or-
2) several LiFePO4 cells in series (rechargable, more expensive, but no capacitor needed) -or-
3) Tadrian lithium thionyl/lithium capacitor type batteries -or-
4) a custom battery pack from Tadrian or other speciality company.

 

[itsmoked]

Sounds like an interesting project.

Your application's demand falls into a nice area for unique solutions.

I agree with Comcokid, the solution is to use non-rechargeable lithium batteries as the primary source. Some have a 10 year life. You'd use an extremely low power micro controller to manage your system timing.

When a message is to be sent the micro would turn on a charge controller to charge a capacitor to a value needed to support your transmission. This allows a low but steady draw from the battery which uses the battery's energy in the most efficient manner, but provides a high current to the load. Once the cap is charged the micro can signal, enable, or execute the transmission.

This would allow the smallest possible system size too.

Depending on a lot of variables, unrevealed so far, I'd also consider this application as possible candidate for energy harvesting which could make the system smaller yet.



Keith Cress
kcress -

http://www.flaminsystems.com