crimsonsnake0
10 W
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- Aug 2, 2010
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- 68
hi can anyone tell me if i could combine 2x 12v batts 1x 12v 9ah plus 1x 12v 5ah to make one 12v 14ah ? regards to all crimsonsnake
sla batt question please
- Thread starter crimsonsnake0
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friedwires
100 W
it will work,but the 5 amp hour battery will get hot,and eventualy cook itself trying to keep up.and the larger battery will lose its capacity after a while,and it too will be 5 amp hour.its not such a good idea if you want to get any life out of them.
Rassy
1 MW
I think when two sla batteries of differing AH are hooked together in parallel they will stay at the same voltage during discharge (they must be at the same voltage when connected together). So the bigger battery will provide more of the current, but both batteries will reach their low voltage point at the same time. i.e., should work ok IMHO.
In series, not a good idea to use batteries that are different in any respect.
In series, not a good idea to use batteries that are different in any respect.
PedalingBiped
100 W
Treat the pack as a 5ah. The higher ah batteries will help with the voltage sag but don't drain them below what a 5ah would go.
Rassy
1 MW
I think the OP is asking about hooking these batteries up in parallel. Except for my previous post, it seems as though everyone is answering as though he is hooking them up is series.
Since he is a noob and is asking for help, I think his actual question should be addressed, i.e. does a 12V 5AH plus a 12V 9AH make a 12V 14AH? The answer is yes, in parallel, and it will not hurt either battery.
Now, if he does not know the difference between parallel and series he needs to come back and ask more questions.
If I am wrong, please correct me.
Since he is a noob and is asking for help, I think his actual question should be addressed, i.e. does a 12V 5AH plus a 12V 9AH make a 12V 14AH? The answer is yes, in parallel, and it will not hurt either battery.
Now, if he does not know the difference between parallel and series he needs to come back and ask more questions.
If I am wrong, please correct me.
PedalingBiped
100 W
For parallel, my previous post is corrected,
Treat all batteries as the smallest one, in this case 5ah.
2 5ah batteries in parallel = 10ah
To treat them like a 14ah battery would destroy the small battery. It would be overdrained.
It is ok to do, but you need to be careful. The larger battery will help with with voltage sag but it will destroy the smaller battery is abused.
Treat all batteries as the smallest one, in this case 5ah.
2 5ah batteries in parallel = 10ah
To treat them like a 14ah battery would destroy the small battery. It would be overdrained.
It is ok to do, but you need to be careful. The larger battery will help with with voltage sag but it will destroy the smaller battery is abused.
Rassy
1 MW
I'm sorry PB, but you still confuse me, and probably the OP too. If you hook up two batteries in parallel, they will keep the same voltage at all times, whether being charged, in storage, or being used. So if the batteries are both 12V and have a useful voltage from say 12.5V to 13.5V, they will both reach 12.5V (or whatever the reasonable low voltage is) at the same time.
I agree this probably will not deliver 14AH in e-bike use, but it will equal or exceed the sum of the useable AH from the two batteries when used in a similar manner individualy.
I agree this probably will not deliver 14AH in e-bike use, but it will equal or exceed the sum of the useable AH from the two batteries when used in a similar manner individualy.
crimsonsnake0
10 W
- Joined
- Aug 2, 2010
- Messages
- 68
hi many thanks to you all for the indept answer. i do know the difference between series and paralel but just get them confused i did however ask my question as i wanted to. 1 12v 9ah plus 1 12v 5ah togeather make 12v 14ah but not really advisable seems to be the talk so will get 2x 9 ah and make 18ah. cheers and thanks again.
I have two new cheap 5ah's that I'm going to parallel with two used and weak 2200 mile 9ah's. The 9ah hr series from bb = no good for longevity. Whatever acid is in those batteries causes them to die earlier then the BP's. Standby for meltdown!!!
Actually the reason they often get burned out is because you are running way over a 1C rate on them.
As a result you get tons of sag, short lifespan, etc.
Even big manufacturers spec out their batteries like that. The reason is the ungodly weight of SLA.
As a result you get tons of sag, short lifespan, etc.
Even big manufacturers spec out their batteries like that. The reason is the ungodly weight of SLA.
Here's what they do. The good sla's have heavy plates for lots of cycles. (Evp's and Eb's). The Hr's don't have heavy plates to keep it light but a short lifespan from toxic "super" acid for high amps. The BP series is lighter weight and probably doesn't have "super" acid. If they made the 9ah or 10ah with the heavier plates, I would get that. Doesn't exist though. The 12ah evp' and eb's are way too heavy. Border line for 36volts but that's where I draw the line. I need 48volts.
Success!!! Back up to 18mile range. Probabably could go 20 but I quit when my bms orange lights come on. I don't wait for the red lights. No heat coming from the baby 5ah's. Green lights staying on. One battery is still in really good shape compared to the one I just replaced on warranty.
