Here's the problem I have a 24v/10AH lithium and a 48v/20AH battery I need enough battery to run a 7240 Crystalyte front hub motor . Should I get another 48 v 20 AH battery and put it in parrellel with the 24v and the 48v battery that are connected in series ? Or can I put a 24v 20 Ah battery in parrellel instead , my fear is that the smaller of the two choices of battery will not do the trick of running the electric motor.
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Support V is for Voltage
Someone else will have to help you with your second question, as for putting batteries in series or parallel, remember this;
**** DANGER **** NEVER PUT BATTERIES OF A DIFFERENT VOLTAGE IN PARALLEL **** DANGER ****
In addition, putting a lithium 24 volt in parallel with a lead acid 24 volt is a bad idea, because the lead acid and lithium technologies are different, and they are not the same voltage, even though they may say they are, and the methods of charging the two types are different, so one will overcharge, and one will never get fully charged.
Mixing battery technologies is generally not a good idea.
Tom
Thanks for the warning that there must be care taken with that idea ... but it's not so impossible to mix chemistries as that.
I suggest finding postings by Aerowhatt on this site which goes into a method he uses for a hybrid battery pack method mixing SLA and Lithium-ION batteries.
If fully charged a "24 volt" SLA pack actually reads more than 24 volts, and lithium cell based packs cannot be constructed so that when fully charged they match that voltage. Hence when you connect the two there will be a large spark as the electricity tries to balance between the two packs.
However...
A lithium cell pack can be constructed so it's max voltage is a bit higher than the SLA pack. Keep the lithium pack in parallel with the SLA pack, and use the SLA pack charger to charge the hybrid pack. The lithium side of the pack will be partially charged (not fully charged) and because they're parallel their voltage will stay in sync with each other. Find Aerowhatt's postings about this as he goes into much more detail.
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
what about buying two lifePo4 36V/20AH and connecting them in series and connecting a lifePo4 48 V/20AH in parallel and add the lifePo4 24V/10AH in parallel also to help increase the AH to increase the mileage . Anybody have any views on this solution ?
You can do that, 36-20, series to get 72v 20. You have to use diodes to protect the bms. The problem is that the 20 ah size may still be a bit small to power a hot rod bike. So don't count on maximum lifespan if you are discharging above 40 amps continuous. Most of the 72v bikes I know of have owners with lots of knowledge and have built their own packs out of tool batteries.
At the same voltage, and using diodes, you can run the same voltage in paralell, without worrying about the size of each battery. But it series, you need to match the sizes.
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36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global