Battery woes

[Keith4wils]

I have been running a Sunstar S03 conversion on my wife’s recumbent trike for four years, which she really likes as it allows us to ride together. We have two 16Ah batteries to give decent range and have been touring in the Netherlands. However, the battery charger has now failed. Unfortunately this particular kit is no longer available and I can not find a direct replacement. Given the cost of the batteries, one of which is nearly new, I am reluctant to change the system.
I bought a charger from the usual online market place which seemed to have the same specification as the original. Having soldered the battery connector to the new charger I plugged it in and it failed immediately.
Are the chargers very specific to the battery? I thought that a charger of the correct voltage/ charge current would have worked. Can anyone shed any light on this? Or, can anyone recommend a charger?
Battery spec:
nominal/charge voltage : 25.9/29.4
Capacity 408wh/15.75Ah
Max charge current 8.0A

 

[Deleted member 4366]

Did you get the polarity right?

Did you check the battery terminals and the charge terminals with a voltmeter? If so, what were the voltages?

Before throwing new parts at a bike in an attempt to repair it, you should find out what's wrong.

In principle, any battery charger of the correct voltage should work.

 

[Keith4wils]

Did you get the polarity right?

Did you check the battery terminals and the charge terminals with a voltmeter? If so, what were the voltages?

Before throwing new parts at a bike in an attempt to repair it, you should find out what's wrong.

In principle, any battery charger of the correct voltage should work.

Thanks for the reply, I didn’t check polarity. I assumed that colour of insulation on wires told me all I needed to know. Yes, I now see that I should have checked. I really wanted to know if any charger of correct voltage etc. should work before spending more cash. You have answered that for me, thanks.

 

[Deleted member 4366]

On Chinese chargers, they often use blue for positive and brown for negative. The only way to be sure is to check with a meter.

If you're lucky, you only blew the charge fuse in the battery. Did you check it? What are the voltages on the charger output and the battery charge sockets?

 

[Keith4wils]

Thanks for your help with this.
You are correct about the polarity of the charger, puttting a meter on it shows blue blue positive and red(brown) as negative. I should have checked but it is easy to be wise after the event- hey ho!
Discharged battery voltages are 11.6 on one and 12.3 on the other.
Hopefully I have just trashed the charger, the LED indicator flashes red weakly and inconsistently and the output voltage is 10.2.

 

[Deleted member 4366]

Yes, it looks like you've damaged the charger. They sometimes have two fuses, one on the input and one on the output, but if a fuse was blown, output would be 0v. Most likely, a capacitor blew because they always blow with reverse polarity - normally in spectacular fashion.

It's a shame you didn't ask about it here first because I always warn about the polarity.

 

[Keith4wils]

Thanks again for the guidance. Back onto the market to get another charger, this time I will proceed with greater caution!