Lithium/hybrid lead acid battery system.

I thought I would borrow this info from bbc forum as lithium battery usage has a lot of unanswered questions By users due to its relative newness of lithium battery usage but going to try this on using a lead cell battery for the big motor starting battery paralleled to a lithium with the electronics hooked up also. This would give primary starting/electronics battery system more amps as you could install a small lithium like a 50 amp to your wet cell for back up power to the electronics/starting,,,, and not void the warrantee of some of the big motor manufacturers by increasing availability of amps. Read this posting on using the lead cell hooked parallel to a lithium battery. It’s all an educational process due to lithiums being used now in the marine world.

Lithium-Hybrid

Since the lithium has a higher voltage than the lead when fully charged .... the lead battery will be the "backup battery".

That means when fully charged the lithium would be supplying pretty much all the current to crank the main motor and everything else til the lithium is going dead ... and the BMS currently capability would have to be large enough to handle cranking the main motor.
It also seems to me that system would have to be on charge all the time when not being used or the lead battery will be a parasitic draw on the lithium.
Doesn't seem to me like a good idea without a device that that would regulate things in a smart fashion .... but I could be wrong.

I haven't seen that thread on BBC, does anyone on there have this operational?

Here is the thread that is slow on going in bbc. Lithium/lead acid hybrid system . I asked what about charging when lithium is connected to a wet cell,,,never got a defined answer other than use a agm batterywith the lithium. I know you could hook a charger for each battery to suffice in charging, and there is now some manufacturers starting to make chargers that charge all types.

I'm pretty skeptical about this approach in spite of what that article lays out as a strategy ... but who knows maybe I will learn something.
I think the most prudent approach would be to put that Yandina combiner between the 2.

I've got a lithium now to power my electronics which will take a lot of the load off the starting battery. Right now, I would only connect it to my lead batteries in case of needing for emergency start assist.

Only reason I posted it was that it is a possible solution for the big motor users especially the motors that would void their warantees if using lithium for starting batteries. Also,,,I didn’t know you could mix them. The mix doesn’t work for me as I am totally lithium with my setup.

If you are 100% lithium, you shouldn't have to mess with batteries in your boat for a while. :ThumbsUp

Just curious ... what brand did you go with for the cranking battery?

A few years ago,,downsized my entire rig from glass/big motor, to a G3 1648 with 2015 new 25 electric start Yamaha attached to a Bob’s Machine Shop electric trim/tilt. 50 amp Ionic will not start it,,so hooked all the electronics and the motor and trim/tilt to a 100 amp Ionics and no issues even when the battery is run down to 30%. Helix MDI+, hooked to a Mega 360 and 7 MDI g3n in front, with a 9 MSI g2n in the back, and MK V2 Power Drive 12 volt Hooke in parallel to Ionics 100 amp, 50 amp and can fish 2-3 days with all batteries without recharging. I just added a 30 amp Ionics in parallel to the trolling motor and need to see how it all balances out but the BMS should do just fine in balancing the three in usage as well when charging the 3 at the same time and can keep a close eye on them with the phone app in usage as well as when charging. I still might switch out the 100 on the motor and put the 50 and 30 back on the motor/electronics to see if they work in parallel as that might work. Just don’t know till I play with it.

:ThumbsUp

I will try the 50 and 30 in parallel tomorrow on the motor and electronics hooked up and post the results.