Parallel wiring GM 48 volt 12ah lithium manganese to GM 48 volt 10ah LIPO4

[fearlessfostick]

I did a search and found some topics on parallel wiring two batteries together.  It can be done but I have some added considerations.  The GM lithium manganese batteries appear to be troublesome compered to GM's new LiPO4 batteries.  I have the GM manganese battery that I bought with my kit 4 years ago.   The battery cuts out at a sudden heavy load but does ok over medium even loads.  I would like to parallel wire my old battery with a new GM 48 10 ah LIPO4 battery.  The goal would be to increase my ah to 22 hours and make good use of both batteries.  I would charge them separately.
My kit is the 1000 watt 48 volt 902 rear with external controller.  My question - will wiring my (troublesome) lithium manganese battery to a new LIPO4 battery,  damage the new battery or the controller? Your thoughts?

[Marsbar]

I wired LITHIUM and Lead Acid batteries together, using two diodes. Diodes must be able to take the current.

Now I am eager to replace the SLA, planning to have 3 battery packs and only using them 50% in order to make the cells last longer.

My diode bridge:

http://goldenmotor.com/SMF/index.php?topic=5166.0

[Andrew]

If the batteries start off with the same full voltage - maybe?   but don't the two chemistries have differing discharge rates? that could cause a problem as one may discharge quicker than the other, but I am only guessing.   

Don't they have a differing nominal voltage?  i.e Lifepo4 = 3.2v,    and LiMn =3.7v