12V motorcycle lithium battery to replace aux battery?

[Darkflow]

Any thoughts on this?

It is possible to get lithium motorcycle batteries from Antigravity with an inbuilt jumpstart feature - so if parasitic drain is too much, they'll go to sleep/disconnect and you can press a button on the battery to reconnect.

For a car in regular use, I'm thinking 12AH (maybe even less) equivalent should be plenty, especially with the jumpstart feature.

One would have to arrange some adapters for to take into account the different terminals.

https://antigravitybatteries.com/products/starter-batteries/restart-oem/at12-bs-rs/

 

[littlescrote]

Sounds great, but pricey. If you value those features, let us know how you get on.

It's a lot cheaper to have a $50 USB chargeable jump pack, and useful for phone charging etc too.

 

[Fjpod]

I wouldn't. I'm not an electrical engineer, but I have heard in other forums that a lithium battery may need more charging to keep it where it should be... Possibly draining the traction battery a little more.

 

[Darkflow]

I'm not an electrical engineer

Well, I am, and your concern is not significant, but thanks.

I'm not seeing why it wouldn't work, but there may well be something I haven't thought of - hence the post.

 

[greendwarf]

I'm not either nor into programming etc. but as the daily "top up" from the main battery is controlled by the car's systems, might the different chemistry cause it to be confused and at least bring up error messages or worse just refuse to charge?

 

[ThudnBlundr]

I'm part of group who are into engine swaps on MG Midgets. Most swaps include removal of the battery tray to allow room for the OHC engine. Quite a few people use lithium batteries as they're much smaller and can be fitted anywhere and anyway up in a more crowded engine bay. The only problem people have seems to be with overheating in that tight engine bay, but that's obviously not an issue here.

It's quite an expensive way to simply "try it"... :roll:

 

[Darkflow]

might the different chemistry cause it to be confused and at least bring up error messages or worse just refuse to charge?

There is a definite 'might' there, to be sure. These batteries have their own internal BMS and are designed to work in the relatively simple environment of a motorcycle electrical system, so that is an unknown. I think 'refuse to charge' is unlikely though. I'm not sure the system even has the capability of isolating the battery from the 12V inverter, although it could be designed that way.

It's quite an expensive way to simply "try it"

It is. I'm thinking that if I did do this, I'd get a 7AH equivalent battery, for about $200. That's small, but should still give quite a few days standby which would be fine for my use case. It would certainly not suit everyone, and having to climb into the back to reset the battery if it goes to sleep is not going to suit everyone either (although one could always power up the back hatch release via the front jump-start terminal).

 

[ThudnBlundr]

Am I missing an ironic tone here? You plan to jumpstart the rear hatch so that you don't have to use a jumpstarter for your 12V

 

[Darkflow]

Am I missing an ironic tone here?

No indeed - you got it. My non-ironic point was that I'm not sure if the battery in question will come out of standby mode with a brief application of power, or whether it is still necessary to physically press the button on the battery.

In practice, I'd expect never to have to do that anyway, barring some unexpected event like an extended hospital stay or something like that.

In general though, I'm sensing a distinct lack of enthusiasm for this idea :?

 

[disconnect04]

Hi, I know I'm a bit late to this but the topic was examined by Daniel Cela & Patrik Alerman for their 2018 masters thesis in electrical engineering. A good read: Study of a 12V Li-ion Battery Solution for Hybrid Vehicles